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Growth and development of rice seedlings (Oryza sativa L.) as influenced by water temperatures Herath, Mudiyanselage Walter Herath 1964

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GROWTH AND DEVELOPMENT OF RICE SEEDLINGS (ORYZA SATIVA L.) AS INFLUENCED BY WATER TEMPERATURE by WALTER HERATH B. S. A., The U n i v e r s i t y o f B r i t i s h C o l u m b i a , 1 9 6 3 A THESIS SUBMITTED I N PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF M a s t e r o f S c i e n c e i n A g r i c u l t u r e i n t h e D i v i s i o n o f P l a n t S c i e n c e We a c c e p t t h i s t h e s i s as c o n f o r m i n g t o t h e r e q u i r e d s t a n d a r d THE UNIVERSITY OF B R I T I S H COLUMBIA O c t o b e r , I96I4. In p r e s e n t i n g t h i s t h e s i s i n p a r t i a l f u l f i l m e n t of the requirements f o r an advanced degree at the U n i v e r s i t y of B r i t i s h Columbia, I agree that the L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e f o r reference and study® I f u r t h e r agree that per-m i s s i o n f o r extensive copying of t h i s t h e s i s f o r s c h o l a r l y purposes may be granted by the Head of my Department or by h i s r e p r e s e n t a t i v e s . I t i s understood t h a t , c o p y i n g or p u b l i -c a t i o n of t h i s t h e s i s f o r f i n a n c i a l gain s h a l l not be allowed without my w r i t t e n permission* D i v i s i o n Berpaa^tmeat of P l a n t S c i e n c e The U n i v e r s i t y of B r i t i s h Columbia, Vancouver 8, Canada Date A u g u s t 1 1+, 1 9624-i i A b s t r a c t S i x v a r i e t i e s o f . r i c e , r e p r e s e n t a t i v e o f those c u l t i v a t e d i n C a l i f o r n i a and o t h e r s o u t h e r n r e g i o n s o f the U n i t e d S t a t e s were grown i n a s e r i e s of n i n e e x p e r i m e n t s . I n a greenhouse, seeds were sown i n t o p o t s p l a c e d i n a c o n s t a n t temperature water b a t h p o s s e s s i n g compartments m a i n t a i n e d a t water tempera-tures o f 60°, 7 5 ° , 60° and 90°F. Many c h a r a c t e r i s t i c s o f p l a n t growth and d e v e l o p -ment were i n f l u e n c e d bj water t e m p e r a t u r e . G e n e r a l l y shoot l e n g t h s and w e i g h t s , r o o t l e n g t h s and w e i g h t s , l e a f l a m i n a , l e a f s h e a t h l e n g t h s and stomata number were g r e a t e r a t the h i g h e r , t h a n a t the lower, tempera-t u r e s . The type and i n t e n s i t y o f s i l i c a c r y s t a l f o r -m a t i o n i n the l e a v e s i n c r e a s e d w i t h i n c r e a s e i n tem-p e r a t u r e . Stomata s i z e s were l a r g e r a t lower, than at h i g h e r , t e m p e r a t u r e s . I r r e s p e c t i v e o f p l a n t s b e i n g submerged o r non-submerged, at c o n t i n u o u s or changed t e m p e r a t u r e s , the h i g h e r temperatures produced the g r e a t e s t r e s p o n s e . C a l i f o r n i a n v a r i e t i e s were f o u n d to be more sen-s i t i v e t h a n o t h e r s o u t h e r n v a r i e t i e s i n t h e i r response to b o t h low and h i g h temperature t r e a t m e n t s , i n d i c a t i n g a g r e a t e r range o f a d a p t a b i l i t y . i i i ACKNOWLEDGEMENTS I t a k e t h i s o p p o r t u n i t y t o a c c o r d my a p p r e c i a t i o n a n d t h a n k s t o t h e A s i a F o u n d a t i o n f o r p r o v i d i n g me w i t h f u n d s t o t r a v e l t o C a n a d a a nd t o p u r s u e my s t u d i e s . I am i n d e b t e d t o t h e U n i v e r s i t y o f B r i t i s h C o l u m b i a f o r g r a n t i n g me a g r a d u a t e f e l l o w s h i p f o r t h e y e a r 1963-19614,. My s p e c i a l t h a n k s a r e e x t e n d e d t o D r . D o u g l a s P. Ormrod, D i v i s i o n o f P l a n t S c i e n c e , U n i v e r s i t y o f B.C., u n d e r whose s u p e r v i s i o n t h i s p r o j e c t was u n d e r t a k e n . I am g r a t e f u l t o h i m n o t o n l y f o r h i s d i r e c t i o n a n d a s s i s t -a n c e , b u t a l s o f o r h i s p a t i e n c e a n d warm u n d e r s t a n d i n g w h i c h c o n t r i b u t e d g r e a t l y t o a p r o f i t a b l e a n d a p l e a s a n t p e r i o d o f s t u d y . G r a t i t u d e i s a l s o e x p r e s s e d t o t h e f o l l o w i n g p e r s o n s f o r t h e i r h e l p i n p r e p a r i n g t h i s t h e s i s : Mr. E r n e s t W h e l a n M i s s T r u d e e G o a r d M r s . A. J a c q u e s Thanks a r e a l s o a c c o r d e d t o my t h e s i s c o m m i t t e e : D r . V.C. B r i n k , D i v i s i o n o f P l a n t S c i e n c e D r . D.P. Ormrod, D i v i s i o n o f P l a n t S c i e n c e D r . A . J . R e n n e y , D i v i s i o n o f P l a n t S c i e n c e D r . E.H. G a r d n e r , D i v i s i o n o f S o i l S c i e n c e D r . W.B. S c h o f i e l d , D e p a r t m e n t o f B i o l o g y i v TABLE OF CONTENTS INTRODUCTION L REVIEW OF LITERATURE 5 . MATERIALS AND METHODS . 19. E x p e r i m e n t I . D i f f e r e n t i a l e f f e c t s o f w a t e r t e m p e r a t u r e 21. on s i x v a r i e t i e s o f r i c e E x p e r i m e n t I I . E f f e c t s o f t h r e e t e m p e r a t u r e s on B l u e - 22. b o n n e t a n d C a l o r o E x p e r i m e n t I I I . E f f e c t s o f t h r e e t e m p e r a t u r e s on B l u e - 23. b o n n e t a n d C a l o r o E x p e r i m e n t I V . M o r p h o l o g i c a l d i f f e r e n c e s i n r i c e s e e d - 21+. l i n g s as i n f l u e n c e d b y t h r e e w a t e r t e m p e r a t u r e s E x p e r i m e n t '.'.>V. E f f e c t s o f v a r i e t y a n d t e m p e r a t u r e u n d e r 27. s u b m e r g e d a nd n o n - s u b m e r g e d c o n d i t i o n s E x p e r i m e n t V I . E f f e c t s o f s h i f t i n g among t h r e e t e m p e r a - 28. t u r e s o n g r o w t h c h a r a c t e r i s t i c s o f v a r i e t i e s E x p e r i m e n t V I I . E f f e c t s o f s h i f t i n g among t h r e e t e m p e r a - 29. t u r e s o n groxirth c h a r a c t e r i s t i c s o f v a r i e t i e s E x p e r i m e n t V I I I . I n t e n s i t y a n d t y p e o f c r y s t a l f o r m a t i o n 29. a t t h r e e d i f f e r e n t t e m p e r a t u r e s E x p e r i m e n t I X . C o m p a r i s o n o f r o o t t i p c e l l s p r e s e n t a t 31• t h r e e d i f f e r e n t t e m p e r a t u r e s RESULTS E x p e r i m e n t I 3 -^. E x p e r i m e n t I I . E x p e r i m e n t I I I I4-6. E x p e r i m e n t I V 5 0 . E x p e r i m e n t V 63. E x p e r i m e n t V I 70. E x p e r i m e n t V I I 80. E x p e r i m e n t V I I I . 91. . E x p e r i m e n t I X 98. DISCUSSION 100. SUMMARY AND CONCLUSIONS 1 1U-• LITERATURE CITED 119. V L I S T OF TABLES T a b l e I (A-G) T a b l e I I (A-E) T a b l e I I I (A-E) T a b l e / I V (A-G) T a b l e V (A-E) T a b l e V I (A-E) T a b l e V I I (A-F) T a b l e V I I I (A-E) E f f e c t o f s i x v a r i e t i e s , w a t e r t e m p e r a t u r e and t i m e o f h a r v e s t on s h o o t l e n g t h , s h o o t w e i g h t , r o o t l e n g t h , r o o t w e i g h t a n d s e e d r e s i d u e 35, E f f e c t o f two v a r i e t i e s , w a t e r t e m p e r a t u r e a n d t i m e o f h a r v e s t on s h o o t l e n g t h , r o o t l e n g t h , s h o o t w e i g h t , r o o t w e i g h t , and s e e d r e s i d u e I4.2. E f f e c t o f two v a r i e t i e s , w a t e r t e m p e r a t u r e a n d t i m e o f h a r v e s t on s h o o t l e n g t h , r o o t l e n g t h , s h o o t w e i g h t , r o o t w e i g h t , a n d s e e d r e s i d u e L|_7. E f f e c t o f v a r i e t y , w a t e r t e m p e r a t u r e and t i m e o f measurement on t h e l e a f l a m i n a l e n g t h , l e a f s h e a t h l e n g t h , d i a m e t e r o f s h o o t , number a n d s i z e o f s t o m a t a a n d l e a f l a m i n a w i d t h 51 • E f f e c t o f v a r i e t y , t e m p e r a t u r e , s u b m e r g e n c e and t i m e o f h a r v e s t on t h e s h o o t l e n g t h , r o o t l e n g t h , s h o o t w e i g h t , r o o t w e i g h t , a n d s e e d r e s i d u e 614., E f f e c t o f v a r i e t y , w a t e r t e m p e r a t u r e change a n d t i m e o f h a r v e s t on t h e s h o o t l e n g t h , r o o t , l e n g t h , s h o o t w e i g h t , r o o t w e i g h t and s e e d r e s i d u e 7 3 . E f f e c t o f v a r i e t y , w a t e r t e m p e r a t u r e c h a n g e a n d t i m e o f h a r v e s t on t h e s h o o t l e n g t h , r o o t l e n g t h , s h o o t w e i g h t , r o o t w e i g h t and s e e d r e s i d u e 8 1 , E f f e c t o f v a r i e t y , w a t e r t e m p e r a t u r e a n d t i m e o f o b s e r v a t i o n o n t h e i n t e n s i t y a n d t h e f o r m a t i o n o f t y p e s A, B, a n d E c r y s t a l s , a n d a l s o on t h e l e n g t h o f C and D s i l i c a c r y s t a l s on l e a f l a m i n a . 9 2 , T a b l e I X E f f e c t o f v a r i e t y a n d w a t e r t e m p e r a t u r e o n number o f r o o t t i p c e l l s o f r i c e s e e d l i n g s 9 9 , v i L I S T OP PLATES I. A and B - the number and s i z e o f stomata i n G a l o r o and Bluebonnet a t 60 p 59. II. A and B - the number and s i z e o f stomata i n B l u e b o n n e t , end of the f i r s t week a t 90° and 75 P 60. III. A and B- - the number and s i z e o f stomata i n C a l o r o , end of the second week a t 90° and 75° P 61. IV. a and b C r y s t a l s formed at v. a and b C r y s t a l s formed a t VI. a and b C r y s t a l s formed a t )° -O ) F 85. F 96. F 97. INTRODUCTION R i c e i s one o f t h e w o r l d ' s most i m p o r t a n t c e r e a l , c r o p s . The t o t a l a r e a u n d e r r i c e c u l t i v a t i o n e x c e e d s 200 m i l l i o n a c r e s and i t i s s e c o n d i n a r e a o n l y t o w h e a t . I t i s t h e s t a p l e d i e t o f more t h a n h a l f t h e w o r l d ' s p o p u l a t i o n a n d i t i s e s t i m a t e d t h a t a n a n n u a l i n c r e a s e o f 1.3 m i l l i o n t o n s i s r e q u i r e d t o meet t h e n e e d s o f t h e r i c e c o n s u m i n g p o p u l a t i o n ( G r i s t , 1953)* The two p o s s i b l e methods o f i n c r e a s i n g t h e t o t a l w o r l d r i c e p r o d u c t i o n a r e by i n c r e a s i n g t h e a r e a u n d e r c u l t i v a t i o n o r by i n t e n s i f y i n g t h e methods o f c u l t i v a -t i o n . The a r e a t h a t c a n be p r o f i t a b l y c u l t i v a t e d h a s a l r e a d y b e e n r e a c h e d i n many r i c e g r o w i n g c o u n t r i e s and as a c o n s e q u e n c e , e x p a n s i o n i n t o e c o l o g i c a l l y l e s s f a v o u r a b l e a r e a s i s b e c o m i n g i n e v i t a b l e . Some o f t h e s e a r e a s a r e c o o l e r t h a n t h o s e p r e v i o u s l y c o n s i d e r e d optimum f o r r i c e g r o w i n g . R i c e c u l t i v a t i o n I s a l s o s p r e a d i n g i n t o d r i e r a r e a s where g r o w i n g c o n d i t i o n s a r e s a t i s f a c -t o r y i f i r r i g a t i o n f a c i l i t i e s a r e p r o v i d e d . Hence u n d e r b o t h s i t u a t i o n s , l a r g e r v o l u m e s o f w a t e r a r e r e q u i r e d a nd t h i s w a t e r c a n be p r o c u r e d o f t e n f r o m r e s e r v o i r s w h i c h a r e n o r m a l l y l o c a t e d i n c o o l e r a r e a s . A p a r t i c u l a r c a s e i s t h e S h a s t a Dam w here t h e w a t e r t e m p e r a t u r e j u s t b e l o w t h e dam d r o p p e d 16° G so t h a t 260 r i v e r m i l e s s o u t h f r o m t h e dam h a d a t e m p e r a t u r e 5 d e g r e e s l o w e r t h a n t h a t r i v e r w a t e r t e m p e r a t u r e s i n t h e same a r e a p r i o r t o 2. c o n s t r u c t i o n o f t h e dam. As a r e s u l t o f t h i s l o w t e m p e r a t u r e , r i c e y i e l d s were a d v e r s e l y a f f e c t e d . ( R a n e y , 1 9 6 3 ) . I n a d d i t i o n , c o o l e a r l y g r o w i n g s e a s o n w a t e r c o n d i t i o n s , e s p e c i a l l y i n C a l i f o r n i a , h a v e made i t n e c e s s a r y t o p l a n t c o l d w a t e r t o l e r a n t v a r i e t i e s ( O r m r o d and B u n t e r , 1961) ( F a r l e y , 1950). C o l d w a t e r damage i s known t o o c c u r e v e n i n t h e t r o p i c s when r i c e i s g r o w n a l o n g s t e e p s l o p e s . The t e m p e r a t u r e d u r i n g t h e g r o w i n g s e a s o n f a l l s as l o w as 17° C. C u l t i v a t i o n i n t h e s e a r e a s i s h a p h a z a r d m a i n l y b e c a u s e o f t h e l a c k o f v a r i e t i e s w h i c h a r e s u i t a b l y a d a p t e d t o g r o w i n g i n c o l d w a t e r . The p r a c t i c e o f s o w i n g r i c e i n t o s t a n d i n g w a t e r i s b e i n g a c c e p t e d as a n i m p r o v e d m e t h o d i n most o f t h e r i c e g r o w i n g a r e a s . W i t h t h i s p r a c t i c e t h e t e m p e r a t u r e o f w a t e r c a n become one o f t h e d e t e r m i n i n g f a c t o r s i n s e e d l i n g e s t a b l i s h m e n t . I n c r e d i b l y l o w y i e l d s h a v e b e e n o b t a i n e d when c o l d w a t e r h a s damaged n o n - t o l e r a n t v a r i e t i e s . The s p a r s e s t a n d s w h i c h r e s u l t f r o m p o o r s e e d l i n g e s t a b l i s h m e n t a r e due t o d e t r i m e n t a l p h y s i o l o g i c a l e f f e c t s , h i g h e r i n c i d e n c e o f l o d g i n g o r s u s c e p t i b i l i t y t o p e s t s and d i s e a s e s . Some o f t h e o t h e r symptoms o f c o l d w a t e r damage on m a t u r e p l a n t s a r e d e l a y e d m a t u r i t y , p o o r v e g e -t a t i v e g r o w t h , and t h e p r o d u c t i o n o f s t e r i l e f l o r e t s . I n o r d e r t o c l e a r l y u n d e r s t a n d t h e s e p r o b l e m s t h a t 3 a r e e n c o u n t e r e d i n r i c e c u l t i v a t i o n u n d e r n o n - o p t i m a l c o n d i t i o n s . , a t h o r o u g h u n d e r s t a n d i n g o f t h e g r o w t h a n d d e v e l o p m e n t o f r i c e i n r e s p o n s e t o t h e d i f f e r e n t t e m p e r a t u r e s c o u l d be o f g r e a t I m p o r t a n c e . The e x t e r n a l m o r p h o l o g y o f r i c e does n o t d i f f e r f r o m t h e o t h e r g r a s s e s t o a n y c o n s i d e r a b l e d e g r e e . R i c e p l a n t I s known t o p o s s e s s t h e u n i q u e c h a r a c t e r i s -t i c o f a d a p t a b i l i t y t o b o t h u p l a n d a nd l o w l a n d c w n d i -t i o n s . I t i s u s u a l l y g r o w n as a l o w l a n d c r o p u n d e r f l o o d e d c o n d i t i o n s . I t s a b i l i t y t o a d a p t t o two d i s -s i m i l a r e x t e r n a l c o n d i t i o n s i s a r i d d l e t h a t m o r p h o l o -g i s t s a n d p h y s i o l o g i s t s h a v e n o t b e e n a b l e t o s o l v e s o f a r . T h e r e f o r e , a k n o w l e d g e o f I t s optimum g r o w i n g c o n d i t i o n s w o u l d be n o t o n l y o f e c o n o m i c , b u t a l s o o f e c o l o g i c a l , i m p o r t a n c e . T e m p e r a t u r e i s a n i m p o r t a n t f a c t o r a f f e c t i n g p l a n t g r o w t h a n d u n d e r f l o o d e d c o n d i -t i o n s , w a t e r t e m p e r a t u r e w o u l d be o f e q u a l o r o f more i m p o r t a n c e t o t h e r i c e s e e d l i n g t h a n t h e a i r t e m p e r a t u r e . The p r e s e n t s t u d y was u n d e r t a k e n i n an a t t e m p t t o e l u c i d a t e t h e e f f e c t s o f d i f f e r e n t w a t e r t e m p e r a t u r e s o n s e e d l i n g g r o w t h a n d d e v e l o p m e n t . A g r e a t e r e m p h a s i s was f o c u s e d on t h e i r m o r p h o l o g i c a l a n d a n a t o m i c a l r e -s p o n s e s as a c o n s e q u e n c e o f t h e s e t r e a t m e n t s . N i n e e x p e r i m e n t s w e r e c a r r i e d o u t i n s e q u e n c e f o r t h e p u r p o s e o f a c h i e v i n g t h e s e o b j e c t i v e s . ( 1 ) A p r e l i m i n a r y s t u d y o f t h e d i f f e r e n t i a l e f f e c t s o f w a t e r t e m p e r a t u r e o n t h e g r o w t h o f s i x v a r i e t i e s o f k r i c e i n order to provide a source of information f o r e f f i c i e n t planning of future i n v e s t i g a t i o n s . (2) An evaluat ion of the ef fects of three tem-peratures ( 6 0 ° , 7 5 ° , and 90° P) on the growth and development of Bluebonnet and Caloro seedl ings . ( 3 ) An examination of the morphological d i f -ferences i n r i c e seedl ings , e s p e c i a l l y i n r e l a t i o n to stomatal number and s i z e , width of l e a f lamina and the lengths of l e a f lamina and l ea f sheaths, as. i n -fluenced by three water temperatures. (Ij.) A study of the effects of v a r i e t y , temperatures, and time, on seedl ing growth under submerged and non-submerged condi t ions . (5) A study of the ef fects of s h i f t i n g plants among three water temperatures on growth c h a r a c t e r i s t i c s of v a r i e t i e s . (6) A study of the i n t e n s i t y and type of c r y s t a l formation on the l e a f blade of the r i c e seedl ing at three d i f f erent temperatures. (7) A comparison of the number of root t ip c e l l s present per uni t of root length at three d i f f erent temperatures. 5. REVIEW OF LITERATURE R i c e ( O r y z a s a t i v a L. ) b e l o n g s t o t h e g r a s s f a m i l y ( G r a m i n e a e ) , s u b f a m i l y P o a c o i d a e ( o r F e s t u c o i d e a e ) a n d t r i b e O r y z e a e (Ochse e_t a l , 1 9 6 1 ) . The genus O r y z a c o n t a i n s s i x s p e c i e s o f w h i c h o n l y O r y z a s a t i v a L. i s e c o n o m i c a l l y i m p o r t a n t . The p l a n t s a r e e r e c t , u s u a l l y t i l l e r f r e e l y a n d a t m a t u r i t y h a v e a h e i g h t o f one m e t e r . The stems o r c u l m s a r e s m o o t h a n g l e d , a n d n e a r l y . e n c l o s e d i n p r o m i n e n t l y v e i n e d , g l a b r o u s l e a f s h e a t h s . The l e a f b l a d e s a r e 5 0 - 7 5 cms. o r more l o n g and one t o two cms. b r o a d w i t h a d i s t i n c t l y r o u g h e n e d s u r f a c e . Some o f t h e d i a g n o s t i c g e n e r i c c h a r a c t e r s o f O r y z a a r e as f o l l o w s ( M e t c a l f e , 1 9 6 0 ) : S h o r t c e l l s o v e r t h e v e i n s m o s t l y i n l o n g rows b u t p a i r s a l s o n o t e d . S i l i c a b o d i e s , o v e r t h e v e i n s , m o s t l y o f t h e O r y z a t y p e , b u t t h o s e i n p a i r e d s h o r t c e l l s r o u n d e d t o c r e s c e n t - s h a p e d a n d f i t t i n g i n t o c o n c a v i t i e s i n a d j a c e n t c o r k c e l l s . M i c r o h a i r s p r e s e n t , r a t h e r s h o r t ; e a c h w i t h t h e d i s t a l c e l l o f u n i f o r m d i a m e t e r t h r o u g h -o u t i t s l e n g t h a n d w i t h a r o u n d e d a p e x , o r t a p e r e d t o a more p o i n t e d a p e x . S t o m a t a m o s t l y w i t h t r i -a n g u l a r , b u t some w i t h l o w dome-shaped, s u b s i d i a r y c e l l s . V a s c u l a r b u n d l e s ; more c o n s p i c u o u s l y a n g u l a r i n o u t l i n e . M e s o p h y l l w i t h c h l o r e n c h y m a n o t r a d i a t e ; c o n s i s t i n g o f a r m - c e l l s . B u n d l e s h e a t h s d o u b l e . M e t c a l f e f u r t h e r e x a m i n e d O r y z a s a t i v a L. v a r . v i o i a c e a a n d r e p o r t e d o n t h e d i a g n o s t i c c h a r a c t e r s o f t h e a b a x i a l e p i d e r m i s . S h o r t c e l l s w e r e f o u n d i n rows o f more t h a n f i v e o v e r t h e v e i n s . P a i r e d c e l l s w e r e a l s o s o m e t i m e s p r e s e n t o v e r t h e v e i n s , b u t v e r y i n f r e -q u e n t o r a b s e n t b e t w e e n t h e v e i n s . T h e r e were no 6 macro-hairs present but m i c r o - h a i r s , mostly of II4.-22 microns length were found. These ha ir s were very narrow with uniform diameter throughout t h e i r lengths and with f l a t apices or tapering s l i g h t l y to more pointed apices. Small p r i c k l e ha ir s with rather long points and t rans i t i ons between these and short points were found. S u p e r f i c i a l macro-hairs were rather i n -frequent i n the i n t e r c o s t a l zones. A cont inuat ion of small c u t i c u l a r p a p i l l a e and a few longer, more i n -f l a t e d types were present on the long c e l l s . The l i f e cycle of the r i c e plant i s d iv ided into two phases by Matsuo ( 1 9 5 7 ) : the vegetative growth phase and the generative growth phase. Ear d i f f e r e n -t i a t i o n i s considered to mark the turning point i n the l i f e of the plant from the former to the l a t t e r stage. The vegetative growth stage i s subdivided into two ,stages: The seedl ing stage and the t i l l e r i n g stage. The t i l l e r i n g stage, i s fur ther subdivided into three stages: The ear ly t i l l e r i n g stage at which t i l l e r i n g i s somewhat slow, the peak t i l l e r i n g stage at which a plant i s i n f u l l t i l l e r i n g , and the l a te t i l l e r i n g stage at which i t has slowed down again. The genera-t ive growth i s subdivided into two s tates: The yioung ear-formation stage and the f r u i t i n g stage. While r i c e i s considered to be a t r o p i c a l crop, i t i s grown on an extensive scale i n subtrop ica l and 7 e v e n i n t e m p e r a t e z o n e s . I t c a n be c u l t i v a t e d i n a l m o s t any r e g i o n h a v i n g f o u r t o s i x months a v e r a g e t e m p e r a t u r e s o f 20° t o 25° C and a minumum o f 10° G ( O c h s e , 1961). U s u a l l y i t i s g r o w n i n w a t e r , a l t h o u g h i t i s grown as a d r y l a n d c r o p i n some a r e a s ( G r i s t , 1953). M a t s u o (1957) i n d i c a t e s t h a t a w a t e r t e m p e r a t u r e o f l±0° t o 14.3°- G i s t h e maximum f o r r i c e p l a n t g r o w t h and o 13 C t h e minimum. The o p t i m u m t e m p e r a t u r e f o r g e r m i n a -0 t i o n i s 30-35 G a c c o r d i n g t o M a t s u o , w i t h the.maximum a t i+O0 G, a n d minumum a t 10-12° G, b u t t h e o p t i m u m f o r e a r l y v a r i e t i e s i s g e n e r a l l y l o w e r t h a n i t i s f o r l a t e v a r i e t i e s . The o p t i m u m t e m p e r a t u r e f o r t h e g r o w t h o f l e a v e s o f a r i c e p l a n t i s 20° G a n d t h e minimum t e m p e r a -t u r e 7° o r 8° C. As t o t h e w e i g h t o f d r y m a t t e r o f t h e s e e d l i n g s , t h a t o f s e e d l i n g s g r o w n a t s o i l t e m p e r a t u r e o f a b o u t 32° G i s t h e g r e a t e s t . H o w e v e r , t h e g e n e r a l l y a c c e p t e d o p t i m u m t e m p e r a t u r e f o r t h e g r o w t h o f t h e most h e a l t h y s e e d l i n g s i s 23° C. When t h e t e m p e r a t u r e i s h i g h e r t h a n t h a t , t h e t i s s u e o f t h e s e e d l i n g s becomes s o f t . The o p t i m u m t e m p e r a t u r e s f o r t i l l e r i n g a n d e l o n g a -O o ° t i o n a r e c o n s i d e r e d b y M a t s u o t o be 32-3^ 4- 0 a n d 30-32 G r e s p e c t i v e l y , b u t t h e o p t i m u m t e m p e r a t u r e v a r i e s a c c o r d -i n g t o t h e r i c e v a r i e t y a n d g r o w t h s t a g e o f t h e p l a n t . The e f f e c t o f t e m p e r a t u r e i s e s p e c i a l l y i m p o r t a n t o n t h e r a t e o f g r o w t h . I t i s a l s o b e l i e v e d t h a t t h e o p t i m u m t e m p e r a t u r e may v a r y i n d i f f e r e n t r e g i o n s o f t h e 8. p l a n t a t d i f f e r e n t s t a g e s o f d e v e l o p m e n t o r even-.at d i f f e r e n t t i m e s o f t h e d a y . T h i s w o u l d r e s u l t i n a c h a n g e i n p r o p o r t i o n o f v a r i o u s p l a n t s a n d t h e i r f o r m a n d s t r u c t u r e ( S i n n o b i960) . Went (1957) s t a t e s t h a t t e m p e r a t u r e i s an i m p o r -t a n t t o o l f o r i n v e s t i g a t i o n i n t o p h y s i o l o g i c a l p r o c e s s . E v e n t h o u g h many p r o c e s s e s a r e i n f l u e n c e d b y t e m p e r a t u r e s i m u l t a n e o u s l y , i t was f o u n d t h a t o n l y one c o n t r o l s t h e b e h a v i o r o f an o r g a n i s m a n d t h u s t h e t e m p e r a t u r e e f f e c t on an o r g a n i s m as a w h o l e becomes a n a l y z a b l e . S e v e r a l m o r p h o l o g i c a l f a c t o r s a r e known t o be a s s o c i a t e d w i t h c o l d h a r d i n e s s . L e v i t t (195>6) i n h i s i n v e s t i g a t i o n s w i t h w h e a t o n f r o s t h a r d i n e s s , r e c o g n i z e d some m o r p h o l o g i c a l f a c t o r s w h i c h a r e a s s o c i a t e d w i t h f r o s t h a r d i n e s s , s u c h as d a r k e r g r e e n , s m a l l e r , h a r d e r , more c u t i n i z e d l e a v e s , s m a l l e r l e a f a r e a a n d l e a f w i d t h , r o o t s l e s s h o r i z o n t a l , l e s s t o p g r o w t h , g r o w i n g p o i n t s d e e p e r i n t h e s o i l a n d s m a l l e r f i r s t i n t e r n o d e a n d l e a f . T e m p l e t o n e t a l (1961 ) s t u d i e d t h e e f f e c t o f tem-p e r a t u r e a n d l i g h t o n v e g e t a t i v e d e v e l o p m e n t o f y o u n g , t a l l f e s c u e p l a n t s , a n d f o u n d t h a t t h e i r d e v e l o p m e n t was g r e a t l y i n f l u e n c e d b y t h e t e m p e r a t u r e a n d l i g h t i n w h i c h t h e p l a n t s grew. M o r p h o l o g i c a l d e v e l o p m e n t was n o t a s i m p l e r e s p o n s e t o t h e s e f a c t o r s . T h e r e were i n t e r a c t i o n s among t h e s e e n v i r o n m e n t a l f a c t o r s a n d b e t w e e n e n v i r o n -m e n t a l a n d g e n e t i c f a c t o r s . The w o r k o f M i l t h o r p e (1959) 9. o n t h e e x p a n s i o n o f c u c u m b e r l e a f s u r f a c e , showed a n i n c r e a s e d r a t e o f l e a f e x p a n s i o n a t t e m p e r a t u r e s s up t o 214.° C , b u t t h e r a t e d e c r e a s e d a t 30° C. The r a t e o f l e a f p r o d u c t i o n a l s o i n c r e a s e d w i t h i n c r e a s i n g t e m p e r a t u r e up t o 2L|° G a n d was c o n s t a n t t h e r e a f t e r . D i f f e r e n c e s due t o t e m p e r a t u r e e f f e c t i n c r e a s e d i n t h e f o l l o w i n g o r d e r ; c o t y l e d o n , l e a f one a n d l e a f t wo. M a t s u o (1953) r e p o r t e d t h a t g e n e t i c a l l y r e l a t e d t y p e s o f r i c e , e v e n t h o u g h o f d i f f e r e n t s t r a i n s , t e n d t o show s i m i l a r morphologj. c a l c h a r a c t e r s when g r o w n u n d e r i d e n t i c a l e n v i r o n m e n t a l c o n d i t i o n s . S e v e r a l a u t h o r s h a v e p a i d much a t t e n t i o n t o t h e s t u d y o f r o o t g r o w t h a t d i f f e r e n t t e m p e r a t u r e s . M a t s u o (1957) r e p o r t e d t h a t b o t h r o o t e l o n g a t i o n a n d r a t i o o f w e i g h t o f r o o t t o w e i g h t o f s h o o t r e a c h a maximum a t a t e m p e r a t u r e o f a b o u t 32° c. S e t h i (191+0) s t a t e d t h a t t e m p e r a t u r e e x e r t s a m a r k e d i n f l u e n c e o n * r o o t g r o w t h . Warm a n d r a i n y s e a s o n s showed b e t t e r g r o w t h w h i l e c o l d s e a s o n s b r o u g h t a b o u t a n i n h i b i t o r y e f f e c t on g r o w t h . E h l e r a n d B e r n s t e i n (1960) r e p o r t e d t h a t s a l i n i t y a n d l o w r o o t t e m p e r a t u r e a r e f a c t o r s t h a t h a v e b e e n shown t o i n j u r e r i c e a n d d e p r e s s y i e l d . De-l a y e d f l o w e r i n g a n d r e d u c e d g r a i n p r o d u c t i o n o f r i c e i n C a l i f o r n i a h a s b e e n t h e r e s u l t o f c o l d i r r i g a t i o n w a t e r ( O r m r o d a n d B u n t e r 1961), ( R a n e y , 1963). I n t h e i r i n v e s t i g a t i o n s E h l e r a n d b B e r n s t e i n f o u n d t h a t a l s o r i c e 10 p l a n t s g r o w n t o a f l o w e r i n g s t a g e a t a r o o t t e m p e r a t u r e o f 18° C h a d s i g n i f i c a n t l y l e s s f r e s h w e i g h t t h a n t h o s e a t 30° c. S u b s e q u e n t g r a i n p r o d u c t i o n was a l s o f o u n d t o be a p p r e c i a b l y g r e a t e r a t t h e h i g h e r r o o t t e m p e r a -t u r e , b u t t h e d r y w e i g h t s o f b o t h r o o t s a n d s h o o t s o f m a t u r e p l a n t s w e r e much g r e a t e r a t 18° t h a n a t 30° G. S t a f f e r a n d G o r d o n (1963) s t u d i e d t h e e f f e c t o f s o i l t e m p e r a t u r e a n d r e p o r t e d t h a t t h e d r y w e i g h t a n d m i n e r a l u p t a k e i n c r e a s e d w i t h i n c r e a s e d t e m p e r a t u r e f r o m 60° t o 80° P. K n o l l e t a l (I96I4) s t u d i e d t h e e f f e c t o f p h o s p h o r u s f e r t i l i z e r o n g r o w t h a n d p h o s p h o -r u s u p t a k e b y c o r n a t s o i l t e m p e r a t u r e s 15 , 20 a n d 25° 0 i n two s o i l s , a n d a l s o f o u n d t h a t d r y w e i g h t i n -c r e a s e d w i t h i n c r e a s e d s o i l t e m p e r a t u r e a n d w i t h i n -c r e a s i n g p h o s p h o r u s l e v e l i n b o t h s o i l s . T h ese i n v e s -t i g a t o r s a l s o f o u n d t h a t l o w r o o t t e m p e r a t u r e s a d v e r s e l y a f f e c t e d t h e d r y w e i g h t o f c o r n a t a l l s t a g e s o f d e v e l o p -ment a nd tf a a t h i g h t e m p e r a t u r e s s t i m u l a t e d g r o w t h . C h r i s t i a n s e n (1963) r e p o r t e d t h a t c h a n g i n g c o t t o n p l a n t s f r o m warm t o c o l d i n h i b i t e d g r o w t h a n d w i t h c o l d t o warm, g r o w t h p r o g r e s s e d a f t e r an i n i t i a l d e l a y . I n t h e i r s t u d i e s o f t e m p e r a t u r e e f f e c t s o n c e l l d i -v i s i o n i n r i c e r o o t t i p s , Yamakawa a n d K i s h i k a w a (1960) f o u n d t h a t h i g h o r l o w w a t e r t e m p e r a t u r e s c a u s e d i r r e g -u l a r i t i e s i n m i t o t i c p r o c e s s e s . I n c r e a s e d v a c u o l a t i o n o f t h e c y t o p l a s m o f c e l l s i n t h e m i t o t i c z one o c c u r r e d a t t e m p e r a t u r e s o f 39° G. A t t e m p e r a t u r e s o f .5° G a n d 11. 1 0° C t h e r a t e o f m i t o t i c p r o c e s s e s was e x t r e m e l y i n h i b i t e d . L o o m i s (195^) w o r k i n g w i t h m a i z e c a l c u l a t e d t h e r a t i o o f c e l l e l o n g a t i o n f o r c o r t i c a l c e l l s w l i t h i n e a c h o f t h e f i r s t f i v e 1 mm. segments o f r a d i c l e g r o w n a t 15° a n d 25° C a n d f o u n d t h a t t h e t e m p e r a u t r e c o - . e f f i c i e n t (Q 10) f o r c e l l e l o n g a t i o n r a t e s were i n t h e o r d e r o f 2-L\. f o r a r i s e o f 10° c . A g r e a t e r r o o t r a m i f i c a t i o n was o b s e r v e d b y F u j i i (1960) i n u p l a n d r i c e t h a n i n swamp r i c e . He s t a t e d t h a t b r a n c h i n g o f r o o t s was c o r r e l a t e d t o r o o t c u r v a -t u r e w h e t h e r n a t u r a l l y o r a r t i f i c i a l l y i n d u c e d . T h e r e -f o r e t h i s g r e a t e r r a m i f i c a t i o n i n u p l a n d r i c e was due t o g r e a t e r r o o t c u r v a t u r e . The r e s u l t s o b t a i n e d b y Y o s h i j i a n d T a k a s h i (1961) w i t h p a p e r c h r o m a t o g r a p h i c a n a l y s i s s u g g e s t e d t h a t t h e '•, b r e a k d o w n o f p r o t e i n b r o u g h t a b o u t b y l o w t e m p e r a t u r e a n d o t h e r t r e a t m e n t s o f r i c e r o o t i s b e c a u s e o f t h e i n -h i b i t i o n o f t h e p r o c e s s o f p o l y m e r i z a t i o n o f t h e amino a c i d s a n d t h i s c o n d i t i o n r e s u l t s i n r e t a r d e d p l a n t g r o w t h . T a k e s i m a e t a l (1963) w o r k e d o n t h e e f f e c t o f s o i l t e m p e r a t u r e u p o n g r o w t h r e g u l a t i n g s u b s t a n c e s b y h o l d i n g t h e r i c e p l a n t s f o r 10 d a y s a t d i f f e r e n t s t a g e s o f g r o w t h a n d v a r i o u s t e m p e r a t u r e s . They f o u n d t h a t t h e g r o w t h p r o m o t i n g s u b s t a n c e s i n t h e r o o t s were h i g h e r f o l l o w i n g t r e a t m e n t a t 1£° a n d 20°, t h a n a t 30° C , and were h i g h e s t when t h e t e m p e r a t u r e was a l t e r n a t e d b e t w e e n 30°/20° a n d 12. 3 0 / 1 5 C; t h e y were a l s o r e d u c e d as t h e p l a n t s g r e w , b e c o m i n g a l m o s t u n d e t e c t a b l e a t t h e t i l l e r i n g s t a g e b u t r e a p p e a r e d when t h e e a r p r i m o r d i a b e g a n t o d i f f e r -e n t i a t e . A c c o r d i n g t o M a t s u o (1957) t h e g e r m i n a t i o n o f r i c e s e e d p r o c e e d s as f o l l o w s : t h e t i p o f t h e c o l e o p t i l e a p p e a r s f i r s t a n d a m e s o c o t y l e n c l o s e d b y t h e c o l e o p -t i l e e m e r g e s . T h e n a p r i m a r y l e a f d e v e l o p s f r o m t h e b a s e o f t h e g r a i n , a n d i s f o l l o w e d by two o r t h r e e l a -t e r a l r o o t s . Many b r a n c h r o o t s d e v e l o p f r o m t h e s e s e m i n a l r o o t s . T a k a s h i (1961) s t u d i e d t h e r e l a t i o n o f w a t e r a b s o r p t i o n t o t e m p e r a t u r e i n t h e g e r m i n a t i o n o f r i c e s e e d . He f o u n d t h e l e n g t h o f a s e c o n d a r y p e r i o d o f s l o w i n c r e a s e i n w a t e r c o n t e n t o f t h e s e e d was m a r k e d l y r e d u c e d as t h e t e m p e r a t u r e was i n c r e a s e d f r o m 15° t o 30° G, b u t t h i s was a l s o a f f e c t e d b y o t h e r f a c t o r s . I n t h e s t u d i e s o f t e m p e r a t u r e , s e e d l i n g d e p t h , a n d a e r a t i o n o n g e r m i n a t i o n o f r i c e , P h i l l i s (1962) f o u n d t h a t f u l l g e r m i n a t i o n was d e c r e a s e d b y i n c r e a s i n g tem-p e r a t u r e a n d b y c e r t a i n o t h e r f a c t o r s . A e r a t i o n o f t h e w a t e r h a d l i t t l e e f f e c t b e l o w 27° C; b e l o w 25° C s e e d l i n g s r e m a i n e d o n t h e s o i l a n d r o o t e d f r e e l y . Up t o 314.° G, a e r a t i o n h a d a n i n c r e a s i n g l y b e n e f i c i a l e f f e c t o n g r o w t h , a n d s e e d l i n g s showed a g e n e r a l t e n d e n c y t o p e n e t r a t e t h e s o i l r a t h e r t h a n f l o a t when a e r a t i o n was p r o v i d e d . A t 3 9 ° G, s e e d l i n g s d i d n o t grow e v e n w i t h a e r a t i o n . 13, R i c e s e e d s a r e b e l i e v e d t o l o s e a g r e a t e r p a r t o f t h e i r w e i g h t when t h e y a r e g e r m i n a t e d i n w a t e r t h a n o n f i l t e r p a p e r , as r e p o r t e d b y Ransom a n d P a r i z a (1958). They went f u r t h e r t o e x p l a i n t h a t t h i s i s due t o t h e f a c t t h a t s o l u b l e s u b s t a n c e s a r e d i f f u s e d i n t o t h e s u r r o u n d i n g w a t e r medium. The chan g e i n q u a n t i t y o f d r y m a t t e r i s c l o s e l y r e l a t e d t o t h e change i n i t s h y -g r o s c o p i c i t y . E r y g i n (1936) a l s o r e p o r t e d t h a t g e r m i -n a t i o n o f r i c e s e e d s u n d e r w a t e r i s a c c o m p a n i e d b y a g r e a t e r l o s s o f d r y m a t t e r a n d c h a n g e s i n p r o p e r t i e s o f c o l l o i d a l s u b s t a n c e s t h a n g e r m i n a t i o n on f i l t e r p a p e r . The v o l u m e o f t h e s e e d l i n g i t s e l f was f o u n d t o i n c r e a s e more r a p i d l y o n t h e f i l t e r p a p e r t h a n u n d e r w a t e r . I n g e n e r a l , i t was f o u n d t h a t t h e enzyme a c t i o n i s s u p p r e s -s e d i n s e e d s g e r m i n a t i n g u n d e r w a t e r . Chapman a n d P e t e r s o n (1962) f o u n d t h a t w a t e r tem-p e r a t u r e s i n t h e r a n g e o f 25° t o 30° C a p p e a r e d t o be t h e m o s t f a v o u r a b l e f o r r i c e s e e d l i n g e s t a b l i s h m e n t . E m e r g e n c e o f t h e s h o o t f r o m t h e w a t e r was most r a p i d a t 30° C, b u t r o o t d e v e l o p m e n t was f a v o u r e d a t l o w e r t e m p e r a -t u r e s . A t 35° C, t h e i n h i b i t i o n o f p r i m a r y r o o t e l o n g a -t i o n was g r e a t e r t h a n t h e i n h i b i t i o n o f s h o o t e l o n g a t i o n . A t 20° C, t h e o p p o s i t e was t r u e . E x p o s u r e t o a w a t e r t e m p e r a t u r e o f I4.50 C f o r 12 h o u r s o r more was l e t h a l t o p r e g e r m i n a t e d r i c e s e e d . The r e a s o n f o r t h e s u p e r i o r g r o w t h o f t h e r i c e c o l e o p t i l e when u n d e r w a t e r i n s t e a d o f i n t h e a i r was U n -i n v e s t i g a t e d b y g r o w i n g d e c a p i t a t e d r i c e c o l e o p t i l e s (1) s u b m e r g e d i n and (2) f l o a t i n g on t h e s u r f a c e o f w a t e r a n d a l s o b y g r o w i n g c o l e o p t i l e s e c t i o n s (1 ) s u b m e r g e d i n and (2) f l o a t i n g o n t h e s u r f a c e o f i n -d o l a c e t i c a c i d s o l u t i o n , Yamada (195^). The a u t h o r s t a t e s t h a t t h e s u p e r i o r g r o w t h o f t h e r i c e c o l e o p -t i l e u n d e r w a t e r i s p r o b a b l y due t o a l o w e r c a p a c i t y o f t h e t i s s u e t o d e s t r o y a u x i n when s u b m e r g e d . He a l s o s u g g e s t e d as a w o r k i n g h y p o t h e s i s t h a t g r o w t h o f t h e r i c e c o l e o p t i l e i s d e t e r m i n e d b y t h e i n t e r a c -t i o n o f two o p p o s i n g f a c t o r s : (1) d e c r e a s e o f a u x i n d e s t r u c t i o n a t l o w e r o x y g e n t e n s i o n ( s u b m e r g e d ) a n d (2) d e c r e a s e d a e r o b i c r e s p i r a t i o n a t l o w o x y g e n t e n s i o n . C o n s i d e r a b l e i n t e r e s t t h e r e f o r e , h a s b e e n shown i n t h e s t u d y o f r i c e p l a n t s u n d e r s u b m e r g e d c o n d i t i o n s . J o n e s (1933) r e p o r t e d t h a t r i c e p l a n t s g r o w n i n s o i l k e p t i n a "mucky" c o n d i t i o n were s h o r t e r a n d p r o d u c e d f e w e r c u l m s a n d r e d u c e d y i e l d o f g r a i n and s t r a w t h a n p l a n t s g r o w n on s u b m e r g e d s o i l . The h i g h e s t a v e r a g e y i e l d was o b t a i n e d f r o m p l a n t s g r o w n i n s o i l s u b m e r g e d s i x i n c h e s d e e p . D o r e a n d T h e v a n (1959) f o u n d t h a t a r u n n i n g w a t e r c o n d i t i o n was b e t t e r f o r t h e g r o w t h o f s e e d l i n g s t h a n was s t a g n a n t w a t e r . A c c o r d i n g t o Kanoe (1950) when t h e a i r t e m p e r a t u r e o f t h e e a r l y g r o w i n g s e a s o n was l o w , c o n t i n u o u s f l o o d i n g 15. p r o m o t e d t h e g r o w t h o f r i c e a n d t h e g r o w t h d e p e n d e d on t h e w a t e r t e m p e r a t u r e . H o w e v e r , l a t e r i n t h e summer s o i l s a t u r a t i o n became an i m p o r t a n t f a c t o r a n d f l o o d i n g was r a t h e r d e t r i m e n t a l t o t h e i r g r o w t h . F l o o d i n g a l s o a f f e c t e d t h e s t r u c t u r e o f t h e l o w e r p o r t i o n o f t h e s t e m s a n d m e c h a n i c a l l y w e a k e n e d them. S u b s e q u e n t w o r k o f Kanoe (1951) i n t h e same d i s t r i c t r e v e a l e d t h a t t h e t e m p e r a t u r e i n May (when t h e r i c e i s s e e d e d ) i s r a t h e r l o w , h e n c e s u b m e r g e n c e r a i s e s t h e t e m p e r a t u r e o f s o i l a n d w a t e r s u r r o u n d i n g t h e r i c e p l a n t s , e s p e c i a l l y a t n i g h t , b e c a u s e o f t h e h i g h s p e c i f i c h e a t o f w a t e r . T h i s c o n d i t i o n p r o m o t e s t h e g r o w t h o f r i c e p l a n t s a n d a d v a n c e s t h e i r d a t e o f h e a d i n g s e v e r a l d a y s . B u t l a t e r i n J u n e , when t h e a i r t e m p e r a t u r e r i s e s , s u b m e r g e n c e becomes l e s s e f f e c t i v e . I n f a c t , i t becomes r a t h e r u n f a v o u r a b l e f o r g r o w t h o f r i c e , m a i n l y due t o t h e l a c k o f a e r a t i o n i n t h e s o i l . I n t h e s u b m e r g e d p l o t s i t was f o u n d t h a t t h e number o f t i l l e r s was i n c r e a s e d i n May s e e d e d p l a n t s a n d d e c r e a s e d i n June s e e d e d o n e s . The l o w e s t t i l l e r i n g l o c u s on t h e m a i n s t e m a l w a y s moved upwards f o l l o w i n g s u b m e r g e n c e . The p o s s i b l e e x p l a n a t i o n o f t h e common o b s e r v a -t i o n t h a t s u b m e r g e n c e i s t h e k e y t o s u c c e s s f u l r i c e c u l t u r e was e x a m i n e d b y C h a u d h r y a n d M c l e a n ( 1 9 6 3 ) . They f o u n d t h a t p l a n t s grew b e t t e r u n d e r f l o o d e d c o n -d i t i o n s t h a n u n d e r u n f l o o d e d c o n d i t i o n s ; a n d t h e s e ^were f o u n d t o be h e a l t h i e r a n d t a l l e r w i t h more numerous 16. t i l l e r s . More f i b r o u s a n d h e a l t h i e r r o o t s were a l s o d e v e l o p e d . Kanoe (1952) s u p p o r t e d t h e t h e o r y t h a t when r i c e p l a n t s a r e g r o w n u n d e r s u b m e r g e d c o n d i t i o n s , t h e o x y -g e n s u p p l y t o t h e i r r o o t s i s m a i n t a i n e d b y means o f t h e a e r i a l p a r t s o f t h e p l a n t . The anatomy o f t h e d e v e l o p i n g r i c e p l a n t i s n o t as w e l l u n d e r s t o o d as t h a t o f some o f t h e o t h e r c u l t i -v a t e d g r a s s e s . A l t h o u g h much w o r k h a s b e e n done o n d e v e l o p e d t i s s u e s a n d o r g a n s , v e r y l i t t l e h a s b e e n done o n t h e s e q u e n c e o f e v e n t s w h i c h c u l m i n a t e i n t h e i r f o r m a t i o n . K a u fman (1959) was one o f t h e f e w who w o r k e d o n t h e a n a t o m i c a l d e v e l o p m e n t o f t h e r i c e p i a n t g i v i n g p r i m a r y c o n s i d e r a t i o n t o t h e s t u d i e s o n o n t o g e n y o f t h e s h o o t a p e x l e a f , s t e m a n d a d v e n t i t i o u s r o o t s . C o n s i d e r a b l e p r o g r e s s h a s b e e n made o n t h e s t u d y o f t h e e f f e c t o f e i t h e r t e m p e r a t u r e o r l i g h t , o r b o t h on t h e g r o w t h o f t h e l e a f s h e a t h a n d l a m i n a o f c e r e a l s . F r i e n d et, a l (1962) r e p o r t e d t h a t u n d e r c o n t i n u o u s i l l u m i n a t i o n , r a i s i n g t h e t e m p e r a t u r e b y 5° i n t e r v a l s b e t w e e n 10° and 25° r e s u l t e d i n p r o g r e s s i v e l y h i g h e r r a t e s o f l e a f i n i t i a t i o n , emergence a n d e x p a n s i o n . The l e n g t h o f t h e l a m i n a i n c r e a s e d w i t h e a c h i n c r e a s e i n t e m p e r a t u r e , b u t t h e b r e a d t h a n d t h i c k n e s s d e c r e a s e d . The g r e a t e s t a r e a o f i n d i v i d u a l l e a v e s was d e v e l o p e d a t 20° c . 1 7 E n j i (1962) made a c o m p a r a t i v e s t u d y o f t h e g r o w t h r a t e s o f u p l a n d a n d swamp r i c e a n d f o u n d t h a t a w a t e r -l o g g e d c o n d i t i o n r e s u l t e d i n ' a r e d u c t i o n a? fit t h e s i z e o f t h e l e a f lamina,- o f u p l a n d r i c e b u t no r e d u c t i o n i n t h e s i z e o f l e a f l a m i n a o f swamp r i c e . As t h e r e i s a l i n e a r r e l a t i o n s h i p b e t w e e n t h e l e n g t h o f l e a f s h e a t h a n d l e a f l a m i n a , t h e r e d u c t i o n o f l e a f s h e a t h l e n g t h o f u p l a n d r i c e g r o w n u n d e r l o w l a n d c o n d i t i o n s l e d t o a c o n s e q u e n t d e c r e a s e i n t h e l e n g t h a n d s i z e o f t h e l e a f l a m i n a . The s t u d y o f s t o m a t a h a s b e e n v e r y u s e f u l f o r s e v e r a l p u r p o s e s . A p a r t f r o m i t s u s e i n d e t e r m i n i n g t h e p h y s i o l o g i c a l s t a t e o f t h e s t o m a t a , i t h a s a l s o b e e n u s e f u l f o r g e n e t i c s t u d i e s , ( S a r v e l l a e t a l 1961). E c k e r s o n (1908) d e v e l o p e d a t e c h n i q u e o f s t u d y i n g s t o -m a t a ; s i n c e t h e n s e v e r a l more i m p r o v e d t e c h n i q u e s h a v e b e e n e v o l v e d , e s p e c i a l l y w i t h t h e u s e s o f p l a s t i c c o v e r s l i p s , ( T u r t o x i960) a n d S c o t c h t a p e ( S a r v e l l a et_ a l 1961). The w o r k o f E c k e r s o n r e v e a l e d t h a t t h e r e i s a m a r k e d v a r i a t i o n i n number and s i z e o f s t o m a t a i n d i f -f e r e n t v a r i e t i e s as w e l l as w i t h i n t h e same v a r i e t y g r o w n u n d e r d i f f e r e n t e x t e r n a l c o n d i t i o n s . T h i s v a r i a -t i o n was f o u n d t o be g r e a t e r i n number t h a n i n s i z e . F u r t h e r , o n most l e a v e s , s t o m a t a a r e e v e n l y d i s t r i b u t e d , a l t h o u g h i n some, e s p e c i a l l y o b l o n g l e a v e s , t h e number was g r e a t e r n e a r t h e b a s e t h a n n e a r t h e t i p a n d g r e a t e r 18 n e a r t h e m i d r i b t h a n n e a r t h e m a r g i n . R i c h a r i a (1961) o b s e r v e d t h a t i n a l a r g e number o f r i c e v a r i e t i e s , t h e g u a r d c e l l s o f t h e s t o m a t a on t h e l e a v e s were d u m b - b e l l s h a p e d ( E s a u , 1961 a n d M e t c a l f e , 1960), b u t t h e g u a r d c e l l s o f t h e c o l e o p t i l e were k i d -n e y - s h a p e d . I n two d i f f e r e n t p a p e r s , J o n e s a n d M i l n e (1963) a n d J o n e s e t a l (1963), a l o n g w i t h e a r l i e r w o r k e r s i d e n t i f i e d s i l i c a c o n t a i n e d o n t h e e p i d e r m i s o f a num-b e r o f s p e c i e s . M e t c a l f e ( 1 9 6 O ) s t a t e d t h a t r i c e h a s m o s t l y O r y z a t y p e c r y s t a l s . S i l i c a i s f o u n d o n t h e e p i d e r m a l c e l l s a n d s o m e t i m e s as i n c l u s i o n s w i t h i n t h e c e l l o r as d e p o s i t s o r i n c r u s t a t i o n s o n t h e c e l l w a l l . S t u d y o f s i l i c a h a s b e e n u s e d t o some d e g r e e f o r t a x -o n o m i c w o r k i n bamboos. A l t h o u g h much w o r k h a s b e e n done i n t h i s r e g a r d w i t h o t h e r c e r e a l s , v e r y l i t t l e e x p l o r a t i o n h a s b e e n made w i t h r i c e . 1 9 . M a t e r i a l s a n d M e t h o d s R i c e s e e d u s e d f o r t h e s e e x p e r i m e n t s was r e c e i v e d i n A u g u s t , 1962 a n d O c t o b e r , 1963 f r o m t h e C a l i f o r n i a R i c e E x p e r i m e n t S t a t i o n , B i g g s , C a l i f o r n i a ( C a l i f o r n i a v a r i e t i e s ) a n d T e x a s R i c e E x p e r i m e n t S t a t i o n , Beaumont, T e x a s ( s o u t h e r n v a r i e t i e s ) . S i x v a r i e t i e s : C a l o r o ( s ) , C o l u s a ( s ) , C a l r o s e (m), ( C a l i f o r n i a } T e x a s P a t n a (1), B l u e b o n n e t (1), and G u l f r o s e (m) ( T e x a s ) were u s e d r e -p r e s e n t i n g s h o r t , medium, a n d l o n g g r a i n t y p e s ( s , m , l ) . One g a l l o n c a p a c i t y p l a s t i c p o t s w ere p a r t i a l l y f i l l e d w i t h s e v e n p o u n ds o f e i t h e r L a d n e r s i l t y c l a y l o a m s o i l o r a s t a n d a r d g r e e n h o u s e m i x s o i l . The p o t s h a d a s p a c e o f f i v e i n c h e s f r o m t h e s o i l s u r f a c e t o t h e b r i m , s o t h a t when s u b m e r g e d t h e t o t a l d e p t h o f w a t e r i n t h e p o t was a b o u t s i x i n c h e s ( f i v e i n c h e s i n t h e p o t a n d one i n c h f r o m t h e b r i m o f t h e p o t t o t h e s u r f a c e o f w a t e r i n t h e t a n k ) . F e r t i l i z e r when u s e d , was m i x e d i n t o t h e s o i l a t t h e r a t e o f 60 p o u n d s o f s u l p h a t e o f ammonia a n d 70 pounds o f s u p e r p h o s p h a t e p e r a c r e . P o t s w e r e s u b m e r g e d f o r a t l e a s t 2I4. h o u r s p r i o r t o s o w i n g i n o r d e r t o a v o i d t u r b i d i t y a n d s e t t l i n g o f s e d i m e n t on t h e s e e d w h i c h was c o n s i d e r e d d e t r i m e n t a l t o g o o d s e e d l i n g e s t a b l i s h m e n t . As a s t a n d a r d t e c h n i q u e , s e e d s were s o a k e d f o r 21\. h o u r s i n a 0.05$ s o d i u m h y p o c h l o r i t e s o l u t i o n b e f o r e p l a c i n g o n m o i s t f i l t e r p a p e r i n p e t r i d i s h e s . T h e s e 20 p e t r i d i s h e s were h e l d a t room t e m p e r a t u r e f o r lj.8 h o u r s , t h e n t h e s e e d s were sown. A c o n s t a n t t e m p e r a t u r e t h e r m o s t a t - r e g u l a t e d w a t e r t a n k i n a g r e e n h o u s e was u s e d f o r t h e s e e x p e r i m e n t s . The s i z e o f t h e t a n k was 8 ' x I4.1 x 1 1 d e p t h a n d i t was i d e a l l y s u i t e d f o r c o v e r i n g t h e p o t s w i t h a n a d e q u a t e l e v e l o f w a t e r . The t a n k was p a r t i t i o n e d i n t o two com-p a r t m e n t s f o r t h e f i r s t e x p e r i m e n t a n d t h e n i n t o t h r e e c o m p a r t m e n t s f o r s u b s e q u e n t e x p e r i m e n t s u s i n g p l y w o o d p a r t i t i o n s . W a t e r t e m p e r a t u r e i n t h e f i r s t c o m p a r t m e n t was m a i n t a i n e d a t 60°P (1>5»"5°C) b y t h e b u i l t - i n a u t o -m a t i c t h e r m o s t a t r e g u l a t e d r e f r i g e r a t i o n u n i t w i t h c i r -c u l a t i o n pump. I n t h e o t h e r two c o m p a r t m e n t s a c o n s t a n t c i r c u l a t i o n was m a i n t a i n e d b y a w a t e r pump m o u n t e d i n t h e t a n k a n d a t h e r m o s t a t a n d h e a t e r h e l d i n t h e w a t e r by means o f l a b o r a t o r y s t a n d s and c l a m p s . T h e s e two c o m p a r t m e n t s m a i n t a i n e d t h e r e q u i r e d t e m p e r a t u r e s 7 5 ° F (2l|°C) a n d 90°F ( 3 2 . 5°C) q u i t e c o n s t a n t l y . L i g h t r e q u i r e m e n t s were s u p p l i e d b y means o f . day-l i g h t a n d a bank o f c o o l w h i t e f l o u r e s c e n t l i g h t s . The l i g h t s were f i x e d t h r e e f e e t a bove t h e s u r f a c e o f t h e p o t s a n d t h e i n t e n s i t y was 900 f o o t c a n d l e s m e a s u r e d b y a W e s t o n M o d e l 756 I l l u m i n a t i o n M e t e r a t t h e s u r f a c e o f t h e p o t s . These l i g h t s were o p e r a t e d b y a n a u t o m a t i c t i m e c l o c k w h i c h was s e t f o r 16 h o u r s o f l i g h t e v e r y 2J+ h o u r s . 21 The a i r t e m p e r a t u r e was r e c o r d e d b y means o f a T e m p s c r i b e t h e r m o g r a p h a n d t h e w a t e r t e m p e r a t u r e was r e c o r d e d b y a t h r e e p o i n t t h e r m o g r a p h . E x p e r i m e n t 1. A c o m p l e t e l y r a n d o m i z e d d e s i g n was u s e d w i t h a l l o f t h e s i x a f o r e m e n t i o n e d v a r i e t i e s and f o u r r e p l i c a t e s a t e a c h t e m p e r a t u r e ( 6 0 ° and 8 0 ° ) . S e e d s were s o a k e d a n d g e r m i n a t e d i n t h e ' u s u a l way. Tw e n t y f o u r h o u r s b e f o r e s o w i n g , p o t s w e r e f i l l e d w i t h s t e a m - t r e a t e d g r e e n h o u s e m i x s o i l a n d were a r r a n g e d i n two w a t e r t a n k s a c c o r d i n g t o a p r e d e t e r m i n e d r a n d o m e x p e r i m e n t a l d e s i g n . A t t h e e n d o f Zl\. h o u r s t h e s e d i m e n t i n t h e w a t e r h a d s e t t l e d down o n t h e s u r f a c e o f t h e s o i l t h e r e b y p r o v i d i n g a s o f t p u d d l e d s o i l w i t h c l e a r w a t e r , w h i c h was c o n s i d e r e d t o be a f a v o u r a b l e c o n d i t i o n f o r r i c e s e e d l i n g g r o w t h . Sow-i n g was done b y h a n d a n d a t o t a l o f t w e n t y s e e d s were r a n d o m l y d i b b l e d i n t o e a c h p o t . C a r e was t a k e n t o p r e v e n t movement o f t h e p o t s f r o m one p l a c e t o a n o t h e r a f t e r sow-i n g as t h i s w o u l d d i s t u r b t h e s o i l a n d c o u l d d r a s t i c a l l y a f f e c t t h e g r o w t h o f t h e s e e d l i n g . A c o n s t a n t w a t e r tem-p e r a t u r e a n d w a t e r c i r c u l a t i o n were m a i n t a i n e d t h r o u g h o u t t h e e x p e r i m e n t . A t t h e e n d o f t h e f i r s t week f o u r p l a n t s f r o m e a c h p o t w e r e p u l l e d o u t a t random. C a r e was t a k e n t o m i n i -m i z e d i s t u r b a n c e t o t h e s o i l as t h i s m i g h t a f f e c t t h e g r o w t h o f o t h e r s e e d l i n g s . The p l a n t s were p l a c e d I n a p l a n t p r e s s a n d k e p t i n a n a i r d r y e r a t a b o u t 80°C f o r 22 a p e r i o d o f 72 h o u r s . A t t h e e n d o f t h i s p e r i o d , l e n g t h s o f s h o o t s a n d r o o t s were r e c o r d e d . P l a n t s w e r e t h e n s e p a r a t e d i n t o s h o o t s , r o o t s , a n d s e e d r e -s i d u e a nd e a c h p o r t i o n w e i g h e d o n a n e l e c t r i c b a l a n c e . A v e r a g e l e n g t h a nd w e i g h t p e r p o t was c a l c u l a t e d a n d t h i s d a t a was u s e d f o r s t a t i s t i c a l a n a l y s i s , w h i c h was a c c o m p l i s h e d w i t h a n IIB M 1 6 2 0 C o m p u t e r u s i n g f a c t o r i a l a n a l y s i s p r o g r a m s . E x p e r i m e n t 2 . S t e r i l i z e d g r e e n h o u s e s o i l was u s e d f o r t h i s e x -p e r i m e n t , w i t h f o u r t e e n s e e d s sown i n e a c h p o t . A c o m p l e t e l y r a n d o m i z e d d e s i g n w i t h two v a r i e t i e s a n d f o u r r e p l i c a t e s f o r e a c h t e m p e r a t u r e was u s e d . The v a r i e t i e s w e r e C a l o r o a n d B l u e b o n n e t r e p r e s e n t -i n g t h e C a l i f o r n i a n a n d s o u t h e r n t y p e s , as t h e y w ere shown i n E x p e r i m e n t 1 t o be somewhat t y p i c a l o f t h e two t y p e s . Random s a m p l e s o f f o u r p l a n t s were d r a w n e a c h w e e k - f r o m e a c h r e p l i c a t e ( p o t ) . T h e s e p l a n t s were t h e n h a n d l e d a nd m e a s u r e d i n e x a c t l y t h e same way as i n e x -p e r i m e n t 1. 23. E x p e r i m e n t 3. M a t e r i a l s a n d methods u s e d f o r t h i s e x p e r i m e n t w e r e s i m i l a r t o t h o s e i n t h e g e n e r a l o u t l i n e g i v e n f o r t h e p r e v i o u s e x p e r i m e n t s . L a d n e r s i l t y c l a y l o a m s o i l was u s e d f o r t h i s e x p e r i m e n t . The s o i l was s c r e e n e d t h r o u g h a V ' mesh i n o r d e r t o remove s t o n e s , r o o t s , a n d l a r g e c l o d s . F e r t i l i z e r was n o t a p p l i e d as t h e f e r t i l i t y o f t h i s s o i l was p r e s u m e d t o be s u f f i c i e n t l y h i g h f o r r i c e s e e d l i n g g r o w t h . Two v a r i e t i e s , B l u e b o n n e t ' a n d C a l o r o , w e r e u s e d , t h e v a r i e t i e s w e r e r a n d o m i z e d i n e a c h w a t e r , t e m p e r a t u r e w i t h f o u r r e p l i c a t e s . S e eds w e r e t r e a t e d i n t h e same manner as d e s c r i b e d a t t h e o u t s e t . M e t h o d o f d r y i n g , r e c o r d i n g w e i g h t s , and s t a t i s t i c a l a n a l y s i s was t h e same as t h a t f o r e x p e r i m e n t s 1 a n d 2. R e c o r d s were t a k e n f o r o n l y two weeks s i n c e t h e number o f s e e d l i n g s a v a i l a b l e f o r s a m p l i n g f o r t h e t h i r d week was n o t a d e q u a t e . T h i s p o o r g r o w t h d u r i n g t h e t h i r d week c o u l d p r o b a b l y be a t t r i b u t e d t o t h e l o w f e r t i l i t y l e v e l i n t h e s o i l , as t h i s c o n d i t i o n d i d n o t o c c u r i n l a t e r e x p e r i m e n t s i n w h i c h t h e s o i l was t r e a t e d w i t h s u l p h a t e o f ammonia and s u p e r -p h o s p h a t e . T h e r e was a g r e a t e r v a r i a t i o n i n w a t e r t e m p e r a t u r e s i n t h i s e x p e r i m e n t due t o t h e f a u l t y o p e r a t i o n o f t h e h e a t i n g e l e m e n t s w h i c h was c o r r e c t e d b e f o r e s u b s e q u e n t ^o e x p e r i m e n t s were r u n . The t e m p e r a t u r e i n t h e 75 w a t e r b a t h r a n g e d f r o m 68° t o 78° a n d t h e 90° w a t e r b a t h v a r i e d f r o m 85° t o 90°. 21+. E x p e r i m e n t IV The v a r i e t i e s , C a l o r o , G a l r o s e , B l u e b o n n e t , and Texas P a t n a were used i n t h i s experiment t o s t u d y w a t e r tempera-t u r e e f f e c t s on p l a n t c h a r a c t e r i s t i c s o v e r a f o u r week p e r i o d . The seeds were t r e a t e d i n the same way as f o r the p r e v i o u s e x p e r i m e n t s . Ladner s o i l was used w i t h the a p p l i -c a t i o n o f f e r t i l i z e r a t the r a t e o f 60 pounds of s u l p h a t e o f ammonia and 70 pounds o f superphosphate p e r a c r e . Each pot was sown w i t h 10 s p r o u t e d seeds. An e q u a l d i s t r i b u t i o n of seeds on the' s o i l was a c h i e v e d by c a r e f u l l y d i b b l i n g them a t a p p r o x i m a t e l y e q u a l d i s t a n c e s . A c o m p l e t e l y rando-m i z e d d e s i g n w i t h f o u r v a r i e t i e s and thr e e r e p l i c a t e s was used. Weekly s a m p l i n g was done by removing an e n t i r e p o t and r e c o r d i n g the measurements f o r each o f the 10 p l a n t s . Three p o t s were used each week f o r the t h r e e weeks, and a t each week these p o t s were removed on a random b a s i s r e p r e -s e n t i n g the t h r e e t e m p e r a t u r e s . (60° , 75° and 9 0 ° ) . As soon as the p o t s were removed from the t a n k , im-p r e s s i o n s o f stomata were t a k e n f r o m the most r e c e n t f u l l l e a v e s o f t h r e e p l a n t s ( i n t h i s i n s t a n c e one p l a n t f r o m each o f the t h r e e r e p l i c a t e s ) . G e n e r a l l y i m p r e s s i o n s were t a k e n a t a p o i n t one c e n t i m e t e r from the t i p of the l e a f . H ojwever, i t was not p o s s i b l e t o f o l l o w t h i s system con-s i s t e n t l y owing t o the po o r growth o f p l a n t s a t 60° , the l e a f b l a d e s were n ot l o n g o r opened a d e q u a t e l y . However, e v e r y e f f o r t was made t o have u n i f o r m i t y i n s a m p l i n g . I m p r e s s i o n s o f stomata on r i c e l e a f b l a d e s were made on p l a s t i c c o v e r s l i p s i n the f o l l o w i n g manner: P r i m a r i l y 25. l e a f b l a d e s s h o u l d be f r e e o f w a t e r o r a n y f o r e i g n b o d i e s . A l e a f was t h e n c u t i n t o a two c e n t i m e t e r ( t h e w h o l e l e a f i s t a k e n i f t h e l e a f i s l e s s t h a n two cm. l o n g ) l o n g p i e c e s t a r t i n g one c e n t i m e t e r f r o m t h e t i p . T h i s was t h e n i m -m e d i a t e l y t r a n s f e r r e d o n t o t h e s u r f a c e o f a g l a s s s l i d e a n d a c e t o n e was a p p l i e d l i b e r a l l y . U s u a l l y t h i s was a c -c o m p l i s h e d b y s o a k i n g a p i e c e o f c o t t o n w o o l i n a c e t o n e a n d t h e n d a b b i n g i t c a r e f u l l y o n t h e u p p e r s u r f a c e o f t h e l e a f so t h a t a n e v e n s p r e a d o n t h e l e a f s e c t i o n i s o b t a i n e d . Im-m e d i a t e l y f o l l o w i n g t h i s , a 3 / V x 3 / V p l a s t i c c o v e r s l i p was p l a c e d on l e a v e s a n d a n o t h e r g l a s s s l i d e was p l a c e d on t h e c o v e r s l i p . T h i s g l a s s s l i d e i n t u r n was p r e s s e d down w i t h t h e thumb f o r a p e r i o d o f a b o u t one m i n u t e . I t was e s s e n t i a l t h a t a n e q u a l p r e s s u r e s h o u l d be e x e r t e d o n t h e s l i d e a n d i t s h o u l d n o t be moved d u r i n g t h e p e r i o d . - The number a n d s i z e o f s t o m a t a were a s c e r t a i n e d b y p l a c i n g t h e s e p r e p a r e d c o v e r s l i p s o n g l a s s s l i d e s w h i c h i n t u r n w e r e p l a c e d on t h e m e c h a n i c a l s t a g e o f a m i c r o s c o p e . The s i z e o f s t o m a t a was m e a s u r e d b y t h e u s e o f a o c u l a r m i c r o -m e t e r u n d e r X 300 m a g n i f i c a t i o n . The m e a s u r e m e n t s were r e -c o r d e d i n m i c r o n s f o r l e n g t h a n d b r e a d t h f r o m two s t o m a t a f o r e a c h t r e a t m e n t , e a c h week. The a r e a o f s t o m a t a was c a l -c u l a t e d on t h e b a s i s o f t h e f o l l o w i n g f o r m u l a t i o n w h i c h i s a p p l i e d f o r t h e c a l c u l a t i o n o f t h e a r e a o f an e l l i p s e E c k e r s o n ( 1 9 0 8 ) : l e n g t h 2 X T3 2 6 . S t o m a t a l number was d e t e r m i n e d b y c o u n t i n g t h e number o f s t o m a t a t h a t f i l l e d 1 6 s q u a r e s o f t h e o c u l a r g r i d i n t h e f i e l d u n d e r X 300 m a g n i f i c a t i o n . A s t e m d i a m e t e r s i z e s t u d y was a l s o c a r r i e d o u t u s i n g a t e c h n i q u e s i m i l a r t o t h a t u s e d f o r t h e s t u d y o f s t o m a t a m e a s u r e m e n t s . F i v e p l a n t s were t a k e n f r o m e a c h ' p o t o f e a c h t r e a t m e n t and e a c h week. G r o s s s e c -t i o n s o f t h e s t e m were made a b o u t one c e n t i m e t e r above t h e b a s e o f t h e s t e m . ( T h i s was n o t p o s s i b l e i n some o f t h e t r e a t m e n t s as t h e l e n g t h o f t h e s t e m was l e s s t h a n one cm., e s p e c i a l l y a t t h e f i r s t w e e k ) . A t h i n s e c t i o n o f e a c h s t e m was p l a c e d o n a g l a s s s l i d e w i t h a d r o p o f w a t e r and t h e l e n g t h a n d b r e a d t h m e a s u r e d i n t h e same manner as t h e s t o m a t a s i z e . I n t h i s i n v e s t i -g a t i o n , t h e a r e a was n o t c a l c u l a t e d ; i n s t e a d , d i a m e t e r l e n g t h a n d d i a m e t e r b r e a d t h m e a s u r e m e n t s w e r e u s e d f o r s t a t i s t i c a l e v a l u a t i o n . A s t u d y o f l e a f s h e a t h a n d l e a f l a m i n a l e n g t h was c a r r i e d o u t by m e a s u r i n g t h e l e n g t h s o f t h e l e a f s h e a t h a n d l e a f l a m i n a o f t e n p l a n t s r e p r e s e n t i n g e a c h v a r i e t y i n e a c h t r e a t m e n t f o r e a c h week. The most r e c e n t l y o p e n e d f u l l l e a f was u s e d f o r t h i s s t u d y . T h i s was n o t p o s s i b l e i n a l l i n s t a n c e s e s p e c i a l l y a t 6 0 ° . D u r i n g t h e f i r s t week m e a s u r e m e n t s h a d t o be t a k e n f r o m p a r t l y o p e n e d l e a v e s . L e a f w i d t h s were a l s o r e c o r d e d b y m e a s u r i n g t h e l e a f 27. b l a d e s one c e n t i m e t e r f r o m t h e t i p . T h r e e o f t h e most r e c e n t l y o p e n e d f u l l l e a v e s were s e l e c t e d f r o m t h e s e p l a n t s r e p r e s e n t i n g e a c h v a r i e t y f o r e a c h t r e a t m e n t f o r e a c h week. E x p e r i m e n t V Two v a r i e t i e s , B l u e b o n n e t a n d G a l o r o , were u s e d f o r t h i s e x p e r i m e n t a n d t h e g e r m i n a t i o n t e c h n i q u e was c a r r i e d o u t i n t h e u s u a l manner. P o t s were a l s o p r e p a r e d i n t h e same manner as e a r l i e r e x p e r i m e n t s . They were a r r a n g e d i n t h e w a t e r t a n k w i t h h a l f o f them s u b m e r g e d a n d t h e o t h e r h a l f f l o a t i n g . The s o i l i n t h e f l o a t i n g p o t s was w a t e r e d h e a v i l y a t t h e s t a r t u n t i l s o i l s a t u r a t i o n was • r e a c h e d a n d t h e n t h e s o i l was p u d d l e d t o s i m u l a t e f i e l d c o n d i t i o n s . T h i s m o i s t u r e l e v e l was m a i n t a i n e d f o r t h e e n t i r e e x p e r i m e n t . E i g h t e e n g e r m i n a t e d s e e d s o f e a c h v a r i e t y were sown i n e a c h p o t u n d e r b o t h c o n d i t i o n s . A r a n d o m i z e d d e s i g n w i t h 12 t r e a t m e n t s a nd t h r e e r e p l i c a t e s , was u s e d . T h e s e 12 t r e a t m e n t s w e re composed o f a l l c o m b i n a t i o n s o f two v a r i e t i e s , t h r e e t e m p e r a t u r e s , s u b m e r g e d a n d n o n - s u b m e r g e d . P o u r p l a n t s were t a k e n o u t o f e a c h p o t e v e r y week f o r a t o t a l p e r i o d o f t h r e e weeks a n d t h e i r r o o t l e n g t h s w e re m e a s u r e d b e f o r e d r y i n g them i n t h e o v e n . A n a l y s i s o f v a r i a n c e was done f o r e a c h v a r i a b l e fpvm t h e d a t a f o r d r y w e i g h t . The v a r i a b l e s a n a l y s e d were s h o o t l e n g t h , r o o t l e n g t h , s h o o t w e i g h t , r o o t w e i g h t , a n d s e e d r e s i d u e w e i g h t . 28 E x p e r i m e n t VI S i m i l a r t o the p r e v i o u s e x p e r i m e n t s , the methods of g e r m i n a t i o n , sowing and p r e p a r a t i o n o f p o t s were s i m i -l a r t o the p r e c e d i n g one. A c o m p l e t e l y randomized de-s i g n w i t h two v a r i e t i e s , Bluebonnet and C a l o r o , and two r e p l i c a t e s was used. The t r e a t m e n t s were as f o l l o w s : Bluebonnet 6 0 ° Bluebonnet 75° Bluebonnet 90° C a l o r o 6 0 ° C a l o r o 75° C a l o r o 90° Bluebonne't 60°- •75° Bl|iebonnet 75°- .60° Bluebonnet 90°' - 6 0 ° C a l o r o 60°- •75° C a l o r o 75°- •60° C a l o r o 90° -60° Bluebonnet 6 0 ° - 9 0 ° Bluebonnet 75°- • 9 0 ° Bluebonnet 90° -75° C a l o r o 60°- 90° C a l o r o 75°- • 90° C a l o r o 90° -75° The change f r o m one temperature t o a n o t h e r was e f f e c t e d a p p r o x i m a t e l y when the shoots r e a c h e d the wa t e r s u r f a c e l e v e l i n the tank ( a p p r o x i m a t e l y seven i n c h e s f r o m the s o i l s u r f a c e ) . P l a n t s t h a t were grown at 90° were t h e n changed t o 60° and 75° a t the end o f seven days and those t h a t were at 75° were changed at 11+ days (though the growth r a t e i n d i c a t e d t h a t t h e y s h o u l d have been moved t h r e e days e a r l i e r ) . The change from 60° t o the o t h e r two temperatures had to be d e l a y e d due t o the f a i l u r e o f the p l a n t s t o r e a c h the w a t e r s u r f a c e . There-f o r e , t h e s e p l a n t s were changed a t the end o f t h r e e weeks. The c o l l e c t i o n of d a t a and a n a l y s i s o f v a r i a n c e was s i m i l a r t o Exp e r i m e n t V. 29. E x p e r i m e n t V I I T h i s experiment was conducted i n almost the same manner as experiment V I . D e s i g n o f the experiment and the number o f r e p l i c a t e s were the same. New Ladner s o i l w i t h the u s u a l r a t e o f f e r t i l i z e r was used. There was a d i f f e r e n c e i n the t i m e o f change from 75° t o 60° and 90° a n d f r o m 60° t o 75° and 90° as compared t o experiment V I . Changes .'from 75° to 60° and 90° were e f f e c t e d i n t e n days. I t was n e c e s s a r y t o abandon a l l 60° t r e a t m e n t s due t o the f a i l u r e o f s e e d l i n g s t o grow t o the s u r f a c e o f water even a t the end o f f o u r weeks. The cause f o r t h i s l a c k of growth a f t e r t h r e e weeks c o u l d be p o s s i b l y a t t r i b u t e d t o l o w e r t e m p e r a t u r e s r e g i s -t e r e d i n t h i s water tank f o r a p e r i o d o f about two days as a r e s u l t o f f a u l t y a d j u s t m e n t s o f the r e f r i g e r a t i o n u n i t . The a n a l y s i s o f v a r i a n c e was conducted i n the same way as experiment V I , but the t a b l e s f o r i n t e r p r e -t a t i o n were s e t up i n a d i f f e r e n t way. Experiment V I I I A l o n g w i t h e xperiment V I I , a pot f o r each v a r i e t y , B luebonnet and C a l o r o was grown i n each of th e s e water t a n k s f o r a p e r i o d o f f o u r weeks. These p l a n t s s e r v e d as a so u r c e of m a t e r i a l f o r the s t u d y o f s i l i c a c r y s t a l s . Prom the f o u r t e e n t h day on, two p l a n t s were removed a t random e v e r y week from each pot and the most r e c e n t f u l l open l e a v e s were c o l l e c t e d f o r t h i s s t u d y . S e c t i o n s o f l e a v e s two c e n t i m e t e r s i n l e n g t h were c u t from the t i p 30. o f t h e l e a f b l a d e a f t e r r e m o v i n g one c e n t i m e t e r f r o m t h e t i p . T h e s e w e r e t h e n c u t i n t o p i e c e s no l o n g e r t h a n 3g cm. a n d d i p p e d i n v i a l s c o n t a i n i n g m a c e r a t i n g f l u i d . T h i s f l u i d was made up o f t h e f o l l o w i n g com-p o n e n t s : 30$ H 2 0 £ 6 c c . H 2 0 21+ c c . G l a c i a l A c e t i c A c i d 30 c c . 60 c c . T h e s e v i a l s were p l a c e d a t 25°C i n t h e o v e n f o r a p p r o x i -m a t e l y 21+ h o u r s . A t t h e e n d o f t h i s p e r i o d , t h e ma-t e r i a l was w a s h e d i n w a t e r f o r a p e r i o d o f one h o u r c h a n g i n g t h e w a t e r s e v e r a l t i m e s , t h e n p l a c e d i n 1:1 s o l u t i o n o f 100$ E t O H a n d x y l e n e f o r a f e w m i n u t e s . T h e s e w e r e t h e n t r a n s f e r r e d t o a s t a i n i n g s o l u t i o n o f 1:1 100$ EtOH a n d x y l e n e w i t h a b o u t 1$ s a f r a n i n . A f t e r a l l o w i n g t h e m a t e r i a l t o s t a n d i n t h i s s o l u t i o n f o r a p e r i o d o f a b o u t two m i n u t e s t h e m a t e r i a l was w a s h e d i n t h e f o r m e r s o l u t i o n f o r a b o u t two m i n u t e s a n d p l a c e d i n x y l e n e . T h i s m a t e r i a l was t h e n t r a n s f e r r e d o n t o a g l a s s s l i d e a nd p a r t i a l l y t e a s e d a p a r t w i t h d i s s e c t i o n n e e d l e s . S l i d e s w e r e m o u n t e d w i t h C a n a d a b a l s a m a n d were p l a c e d i n t h e o v e n a t a b o u t 80°. One s l i d e was p r e p a r e d f o r e a c h v a r i e t y a t e a c h t e m p e r a t u r e e v e r y week. J o h a n s e n (191+0). P r e p a r e d s l i d e s w e r e e x a m i n e d u n d e r t h e m i c r o s c o p e . 31 C r y s t a l s were d e s i g n a t e d f r o m "A" t o "E" f o r t h e c o n -v e n i e n c e o f m e a s u r e m e n t . As t h e c r y s t a l t y p e s "A" and "B" were n o t f o r m e d a t a l l t e m p e r a t u r e s , o n l y t h e i r p r e s e n c e o r a b s e n c e was r e c o r d e d . "A" was u s e d f o r a b s e n t ; "P" f o r p r e s e n t ; "P" f o r f e w ; "VP" f o r v e r y f e w . I n r e g a r d t o t h e "C" a n d "D" t y p e s , t h e l e n g t h s o f c r y s t a l s w e r e m e a s u r e d a t 75° a n d 90° o n l y s i n c e t h e s e o y s t a l s w e r e n o t a p p a r e n t a t 60° d u r i n g t h e p e r i o d o f i n v e s t i g a t i o n . The "E" t y p e c r y s t a l s were p r e s e n t i n a l l t r e a t m e n t s f o r a l l weeks a n d t h e number p r e s e n t p e r l i n e a l d i s t a n c e o f .066?, mm. was r e c o r d e d a n d two o f s u c h c o u n t s p e r s l i d e w e r e t a k e n . P h o t o g r a p h s o f -these s l i d e s were a l s o t a k e n t o d e p i c t t h e e f f e c t o f t e m p e r a t u r e o n c r y s t a l f o r m a t i o n . A . L e i t z W e t z l e r m i -c r o s c o p e w i t h a n o r t h o m a t a t t a c h m e n t f o r a u t o m a t i c c o n t r o l was u s e d f o r t h i s p u r p o s e . P i c t u r e s were t a k e n a t X 500 m a g n i f i c a t i o n . E x p e r i m e n t I X I n o r d e r t o a s s e s s t h e number o f c e l l s i n r o o t t i p s o f r i c e , t h e t e c h n i q u e d e s c r i b e d b y R i c k l e s s a n d Brc-wn (19I4.8) was c l o s e l y f o l l o w e d . V a r i e t i e s , B l u e -b o n n e t and C a l o r o , were u s e d f o r t h i s e x p e r i m e n t . S e e d s were s o a k e d i n w a t e r a t room t e m p e r a t u r e f o r Z\ h o u r s , a t t h e e n d o f w h i c h p e r i o d t h e y w e r e sown o n t o f i l t e r p a p e r p l a c e d i n s i d e s l i d e d i s h e s w h i c h i n t u r n were 32 f i l l e d w i t h d i s t i l l e d w a t e r . These s l i d e d i s h e s , V x 3 " x 2 3 / V deep, were p l a c e d on c r o c k p o t s , ( 8 " h e i g h t ) t h a t were p l a c e d i n an i n v e r t e d p o s i t i o n i n -s i d e w a t e r b a t h s . Two such s e t - u p s were used a t each of the t h r e e temperatures f o r the two v a r i e t i e s . When these d i s h e s were p l a c e d on the i n v e r t e d c r o c k s , the wa t e r l e v e l of the tank r e a c h e d u s u a l l y about one i n c h below the b r i m o f the d i s h and the d i s t i l l e d water l e v e l i n the d i s h was m a i n t a i n e d almost at the same l e v e l as o u t s i d e . A s l i g h t d e c r e ase i n the water temperature i n s i d e the d i s h was n o t e d a t the b e g i n n i n g , n e v e r t h e l e s s t h e s e d i f f e r e n c e s were not o b v i o u s a f t e r a few hours and w a t e r t e m p e r a t u r e s i n s i d e and o u t s i d e these d i s h e s were the same. F o r t y seeds were sown I n t o each d i s h w i t h an even d i s t r i b u t i o n o f seeds on the f i l t e r p aper. S e e d l i n g s at b o t h h i g h e r temperatures had s u f f i c i e n t r a d i c l e growth from about the s e v e n t h day a l t h o u g h p l a n t s were removed on the 'il+th day. S e e d l i n g s i n the 60° d i s h e s were not read y f o r i n v e s t i g a t i o n u n t i l they were grown f o r 2% days as the l e n g t h o f r a d i c l e was not s u f f i c i e n t l y d e v e l o p e d u n l i k e a t the two h i g h e r t e m p e r a t u r e s . Four s e e d l i n g s f rom each d i s h were removed and were p l a c e d i n d i s t i l l e d w a t e r u n t i l the r o o t s were det a c h e d f r o m the seeds. Immediately upon detachment from the see d s , t h e i r t i p s were i n s e r t e d i n t o h o l e s of a p p r o x i m a t e l y t h e i r own d i a m e t e r i n a p l e x i g l a s s two mm. i n t h i c k n e s s 33 w h i c h r e s t e d on a n o t h e r s h e e t o f g l a s s . When t h e r o o t s were i n p o s i t i o n , t h e t i p s were s e v e r e d b y p a s s i n g a r a z o r a c r o s s t h e s u r f a c e o f t h e p l e x i g l a s s . The p l e x i -g l a s s was t h e n l i f t e d a n d t h e c u t r o o t t i p s were t r a n s -f e r r e d i m m e d i a t e l y t o a s o l u t i o n o f 10$ c h r o m i c a c i d . T h e s e were t h e n p l a c e d f o r 21+ h o u r s b e f o r e t h e y a r e m a c e r a t e d . 3 ^ RESULTS E x p e r i m e n t 1 . S h o o t L e n g t h '• The r e s p o n s e o f a l l v a r i e t i e s t o t h e two w a t e r t e m p e r a t u r e s ( 6 0 ° a n d 8 0 ° P ) i s c o m p a r e d i n T a b l e I A. an d i t i s c l e a r l y e v i d e n t t h a t t h e s h o o t l e n g t h a t 6 0 ° was much l e s s t n a n t h a t . a t 8 0 ° . A h i g h l y s i g n i -f i c a n t t e m p e r a t u r e e f f e c t was' m a i n t a i n e d t h r o u g h o u t t h e p e r i o d o f f o u r w e e k s . A s i g n i f i c a n t t e m p e r a t u r e X v a r i e t y i n t e r a c t i o n was a l s o p r e s e n t e x c e p t a t t h e t h i r d week. U s u a l l y t h e G a l i f o r n i a n v a r i e t i e s h a d more s h o o t g r o w t h t h a n s o u t h e r n v a r i e t i e s a t b o t h t e m p e r a t u r e s ; T e x a s P a t n a a nd B l u e b o n n e t u s u a l l y h a d t h e p o o r e s t g r o w t h a t 6 0 ° a l t h o u g h a n o v e r a l l s i g n i -f i c a n t d i f f e r e n c e among v a r i e t i e s was n o t p r e s e n t . S h o o t W e i g h t < L i k e t h e s h o o t l e n g t h , t h e w e i g h t o f s h o o t s , as i n d i c a t e d i n T a b l e I B, was much l o w e r a t 6 0 ° t h a n 8 0 ° . A h i g h l y s i g n i f i c a n t t e m p e r a t u r e e f f e c t was a l s o m a i n -t a i n e d d u r i n g a l l f o u r w e e k s . S i g n i f i c a n t t e m p e r a t u r e X v a r i e t y i n t e r a c t i o n was p r e s e n t u n t i l t h e e n d o f t h r e e weeks a f t e r w h i c h p e r i o d t h e r e was no s i g n i f i c a n t i n t e r -a c t i o n . V a r i e t i e s d i d n o t show a n o v e r a l l s i g n i f i c a n t d i f f e r e n c e ; h o w e v e r , t h e C a l i f o r n i a v a r i e t i e s u s u a l l y h a d more d r y w e i g h t a t b o t h t e m p e r a t u r e s . 35. Table 1A E f f e c t o f v a r i e t y , w ater temperature,, and time o f h a r v e s t on the snoot l e n g t h of r i c e s e e d l i n g s , (cm.) V a r i e t i e s Texas P a t n a C a l r o s e C o l u s a G u l f r o s e Bluebonnet C a l o r o Average Temp.°P Week 1. 60 .29 .32 80 6.58 11.08 Average 3.1+3 5.70 .38 9.24-0 I+.89 TxV * -.24-2 .38 .35 .36 8.07 8.70 12.62+ 9.2+1 2+.21+ 2+.51+ 6.50 T V ns . Week 2. 60 . 62+ .82 80 25.2+0 .30.10 Average 13.00 15.2+0 .86 33.30 17.10 TxV 1.12 30.20 15.70 T **• .67 27.2+0 12+. 00 V n s . ' .61 31.00 15.80 .79 29.60 60 80 Average Week 3. 1.1+2+ 1.92+ 32.70 2+0.80 17.10 21 .2+0 1.69 39.80 20.80 TxV ns, 1.91 35.50 18.70 T V 1.11 33.00 17.00 ns. 1 .2+0 37.90 19.60 1.58 36.80 Week 2+. 60 2.2+2 2+.03 80 38.2+0 2+5.70 Average 20.2+0 22+..80 3.95 23.20 TxV 3.24-8 1 .80 2.92+ 3.10 38.30 33.80 2+2.20 2+0.10 20.90 17.80 22.60 T V ns. S t a t i s t i c a l A n a l y s i s : . ns.. -x-TxV T V not s i g n i f i c a n t d i f f e r e n c e s a t the 0.05 p r o b a b i l i t y l e v e l . s i g n i f i c a n t d i f f e r e n c e s a t s i g n i f i c a n t d i f f e r e n c e s a t temperature x v a r i e t y i n t e s i g n i f i c a n c e a g a i n s t the e tem p e r a t u r e s . T e s t e d f o r a g a i n s t the temperature x v a r i e t i e s . T e s t e d f o r u n i the temperature x v a r i e t y the 0.05 p r o b a b i l i t y l e v e l , the 0.01 p r o b a b i l i t y l e v e l , r a c t i o n . T e s t e d f o r r r o r term. u n i v e r s a l s i g n i f i c a n c e v a r i e t y i n t e r a c t i o n term, v e r s a l s i g n i f i c a n c e a g a i n s t i n t e r a c t i o n term. 3 6 . T a b l e 1 B E f f e c t o f V a r i e t y , w a t e r t e m p e r a t u r e , a n d t i m e o f h a r v e s t on t h e s h o o t w e i g h t o f r i c e s e e d l i n g s , (gm.). V a r i e t i e s T e x a s P a t n a C a l r o s e C o l u s a G u l f r o s e B l u e b o n n e t C a l o r o A v e r a g e Temp. 0 F Week 1 . 6 0 . 0 2 . 0 1 . 0 3 . 0 3 . 0 2 . 0 2 . 0 2 8 0 . 2 0 . 324. . 3 0 . 2 8 .22+ . 3 5 • . 2 8 A v e r a g e . 1 1 . 1 8 .16 . 1 5 . 1 3 . 1 8 TxV T "5HS- V ns . Week 2 . 6 0 . 0 5 . 0 8 . 0 7 . 0 9 .02+ . 0 6 . 0 6 8 0 1 . 3 2 1 . 7 1 2 . 0 5 1 . 6 3 1 .2+6 1 . 8 1 1 . 6 6 A v e r a g e . 6 8 . 9 0 1 . 0 6 . 8 6 . 7 5 . 9 i | TxV -s:--: :- T-:H:- V n s . Week 3 » 6 0 1 . 0 0 . 1 5 • 1 2 . 0 5 . 1 2 , * 3 P 8 0 3 . 3 0 5.2J+ 14-.73 2 . 7 8 24-524. 2+.60 2+.22+ A v e r a g e 1 . 8 6 2 . 6 9 2.2+24. 1 . 2 + 8 2 . 3 0 2 . 3 6 TxV * T V n s . Week i+. 6 0 . 1 5 . 3 2 . 2 8 . 2 5 . 1 1 . 2 2 . 2 2 8 0 8.314- 11.24.1 1 0 . 2 8 7.2+2+ 6 . 9 2 8 . 7 1 8 . 8 5 A v e r a g e I4-.2I4. 5 . 8 6 5 . 2 8 3 . 8 5 3 . 5 2 24..14.7 TxV n s . T V n s . 37 R o o t L e n g t h R e f e r e n c e t o T a b l e I G . shows t h a t f o r r o o t l e n g t h a t t h e f o u r t h week, a h i g h l y s i g n i f i c a n t t e m p e r a t u r e e f f e c t o c c u r r e d w i t h no s i g n i f i c a n t v a r i e t y d i f f e r e n c e o r t e m p e r a t u r e v a r i e t y i n t e r a c t i o n . I n p a r a l l e l w i t h s h o o t l e n g t h , T e x a s P a t n a a nd B l u e b o n n e t h a d t h e p o o r -e s t r o o t g r o w t h a t 6 0 ° , a l t h o u g h t h i s was n o t s i g n i f i -c a n t . T a b l e ID i n d i c a t e s t h e r o o t l e n g t h s m e a s u r e d e a c h week f o r t h r e e weeks a t one t e m p e r a t u r e (80°). D a t a i n t h i s t a b l e show t h a t t h e r e was no s i g n i f i c a n t v a r i e t a l d i f f e r e n c e a n d t h e g r o w t h f r o m one week t o a n o t h e r was s l i g h t . R o o t W e i g h t As f o r r o o t l e n g t h g r o w t h , t h e r e was a h i g h l y s i g n i f i c a n t t e m p e r a t u r e e f f e c t o n r o o t w e i g h t w i t h no s i g n i f i c a n t v a r i e t y d i f f e r e n c e o r t e m p e r a t u r e X v a r i e -t y i n t e r a c t i o n as shown i n T a b l e I E . G a l i f o r n i a n v a r i e t i e s t e n d e d t o be s l i g h t l y s u p e r i o r t o s o u t h e r n v a r i e t i e s a t b o t h t e m p e r a t u r e s a t t h i s f o u r t h week. A c c o r d i n g t o t h e r e s u l t s p r e s e n t e d i n T a b l e I P , t h e r e was no a p p r e c i a b l e v a r i e t y d i f f e r e n c e i n r o o t w e i g h t a t 80° a t t h e e n d o f t h r e e w e e k s . T h i s was a l m o s t c o m p a r a b l e t o t h e r o o t l e n g t h r e s p o n s e . 3 8 . T a b l e 1C E f f e c t o f v a r i e t y , w a t e r t e m p e r a t u r e , and t i m e o f h a r v e s t on t h e r o o t l e n g t h o f r i c e s e e d l i n g s , ( c m . ) . V a r i e t i e s T e x a s P a t n a C a l r o s e C o l u s a G u l f r o s e B l u e b o n n e t C a l o r o A v e r a g e Temp.° P Week 1+. 60 3.36 3.73 i+.38 I+.97 2.1+0 1+.20 3.81+ 80 5.50 7.7*1. 7.72 6 .76 7.26 6.52 6 . 9 2 A v e r a g e 1+.1+3 5-71+ 6.05 5.86 L+. 83 5-36 TxV n s . T V n s . T a b l e 1D E f f e c t o f v a r i e t y a n d t i m e o f h a r v e s t i i r y a 01 n a r y io n t h e r o o t l e n g t h a t one t e m p e r a t u r e . ( c m . ) . V a r i e t i e s T e x a s P a t n a C a l r o s e C o l u s a G u l f r o s e B l u e b o n n e t C a l o r o Temp.°P Week 1. 80 3 . 7 0 1+.17 3 . 6 6 3 . 7 3 3.21J. 1+.55 V n s . Week 2 . 80 L u 5 2 1+.66 5 . 2 0 5 .86 1+.1+5 5 .39 V n s . Week 3» 80 5.50 6 . 1 3 5 .23 5 .60 7 . 0 6 1+.79 V n s . T a b l e 1E E f f e c t o f v a r i e t y , w a t e r t e m p e r a t u r e , a n d t i m e o f h a r v e s t o n t h e r o o t w e i g h t o f r i c e s e e d l i n g s , (gm.). V a r i e t i e s T e x a s P a t n a C a l r o s e C o l u s a G u l f r o s e B l u e b o n n e t C a l o r o A v e r a g e Temp .op Week 1+. 60 .01 . 0 3 . 0 3 . 0 3 .01 . 0 3 . 0 2 80 .1+1 1 . 12 . 8 2 . 6 0 .51+ .71 . 7 0 A v e r a g e .21 . .57 .1+2 . 3 2 . 2 7 . 3 7 TxV n s . T V n s . 39 Temp.°F Week 1. T a b l e 1F E f f e c t o f v a r i e t y a n d t i m e o f h a r v e s t on t h e r o o t w e i g h t a t one t e m p e r a t u r e , (gm.) V a r i e t i e s T e x a s P a t n a C a l r o s e C o l u s a G u l f r o s e B l u e b o n n e t C a l o r o 80 .05 .05 .07 .0i| .05 -10 V n s . Week 2. 80 .12 .20 .22 .30 .17 .22 V #* 80 V e .& 3 ' .55 .38 . .18 .14-7 .38 V n s . T a b l e 1G E f f e c t o f v a r i e t y , w a t e r t e m p e r a t u r e , a n d t i m e o f h a r v e s t on t h e s e e d r e s i d u e o f r i c e s e e d l i n g s , (gm.) V a r i e t i e s T e x a s Temp.° F P a t n a C a l r o s e C o l u s a G u l f r o s e B l u e b o n n e t C a l o r o . A v e r a g i Week 1 . 60 2.214. 2.50 2 . 5 5 2.30 2 . 3 0 2 .55 . " 2.1+6 80 1 . 6 5 1.1I-3 1.62 1 . 3 9 1.66 1.70 1.57 A v e r a g e 1.914-Week 2 . 1 . 9 7 2.08 T x V * 1.81+ T V ns 1 . 9 8 • 2.12. 60 2.01+ 2.25 2.31+ 2.16 2 . 2 2 2.39 2.23 80 . 7 6 .71 . 6 5 . 6 5 .81 . 7 6 . 7 3 A v e r a g e 1.1+0 Week 3 . 1.1+8 1.1+9 TxV ns 1.1+0 . T V 1 .51 n s . 1 . 5 8 60 1 . 5 8 2.05 2.21 1.87. 1 . 9 0 2 . 2 2 1.96 80 . 6 2 • 514- . 6 0 . 61 . .61+ . 5 8 . 6 0 A v e r a g e 1 . 2 2 1.29 1 .1+0 TxV 1 .21+ • T V 1.27 n s . 1 .1+0 Week 60. 1 . 6 7 1.81+ 1.79 1 .28 1.76 1.80 1.69 80 . 5 9 . 6 3 . 6 3 . 5 9 .61 .57 . 6 0 A v e r a g e 1.13 1.21+ 1.21 .91+ 1.18 1.18 TxV T V n s . 24-0 S e e d R e s i d u e S t a t i s t i c a l e v a l u a t i o n i n d i c a t e s t h a t more s e e d r e s e r v e was l e f t o v e r a t 6 0 ° t h a n a t 8 0 ° , as e v i d e n c e d b y t h e d a t a p r e s e n t e d i n T a b l e IG-. T h e r e w e r e no o v e r a l l s i g n i f i c a n t d i f f e r e n c e s among v a r i e t i e s , n e v e r -t h e l e s s G a l i f o r n i a n v a r i e t i e s t e n d e d t o h a v e a l a r g e r s e e d r e s e r v e a t t h e s t a r t b u t a t t h e e n d o f f o u r w e e k s a l l v a r i e t i e s h a d a p p r o x i m a t e l y t h e same amount l e f t . A s i g n i f i c a n t t e m p e r a t u r e v a r i e t y i n t e r a c t i o n was p r e -s e n t i n t h e e x p e r i m e n t , e x c e p t a t week t w o . A h i g h l y s i g n i f i c a n t d i f f e r e n c e b e t w e e n t e m p e r a t u r e t r e a t m e n t s p r e v a i l e d d u r i n g t h i s p e r i o d . 24.1. E x p e r i m e n t I I Shoot L e n g t h Reference t o Table I I A shows t h a t a s l i g h t v a r i e t a l d i f f e r e n c e e x i s t e d i n shoot l e n g t h , but t h i s d i f f e r e n c e was masked by l a r g e t emperature e f f e c t s . The d i f f e r e n c e i n response to the t h r e e temperatures was g r e a t l y a m p l i -f i e d by the low response t o 60° and h i g h response to 90°. L e n g t h o f shoot p r o g r e s s i v e l y i n c r e a s e d w i t h time a t a l l t e m p e r a t u r e s , and the g r e a t e s t i n c r e a s e was under the h i g h e r temperature regimes. The growth response of C a l o r o t o a l l t h r e e t e m p e r a t u r e s was g r e a t e r up t o two weeks a t w h i c h time b o t h v a r i e t i e s behaved almost e q u a l l y . Root L e n g t h There was no measurable r o o t growth a t 60° d u r i n g t h e f i r s t two weeks. However, i t i s e v i d e n t from the d a t a o f Tab l e I I B t h a t C a l o r o tended t o have l o n g e r roots a t t h r e e weeks a t 60° a l t h o u g h t h i s e f f e c t was not s i g n i f i c a n t . At the o t h e r two t e m p e r a t u r e s , C a l o r o was s u p e r i o r t o B l u e -bonnet f o r the f i r s t two weeks and t h e r e a f t e r b o t h v a r i e t i e s showed about the same e x t e n t o f growth. Shoot Weight Shoot w e i g h t d a t a as p r e s e n t e d i n Table I I C shows t h a t no temperature X v a r i e t y i n t e r a c t i o n o c c u r r e d d u r i n g any p e r i o d , a h i g h l y s i g n i f i c a n t d i f f e r e n c e among tempera-t u r e s was p r e s e n t a l l the time and a h i g h l y s i g n i f i c a n t v a r i e t y d i f f e r e n c e was p r e s e n t f o r the f i r s t two weeks w i t h C a l o r o s u p e r i o r t o Bl u e b o n n e t . 1+2. T a b l e 11A E f f e c t o f v a r i e t y , w a t e r t e m p e r a t u r e , a n d t i m e o f h a r v e s t o n t h e s h o o t l e n g t h o f r i c e s e e d l i n g s , (cm.) V a r i e t i e s B l u e b o n n e t C a l o r o A v e r a g e Temp. F Week 1. 60 1.00 . 9 8 .99 75 3.17 • 1+.55 3.86 90 7.25 8 .55 7.90 A v e r a g e 3.80 1+.69 TxV n s . T V n s . Week 2. 60 1.1+0 1.71+ 1.57 75 11+.57 21 .07 17.82 90 17.83 26.87 22.35 A v e r a g e 11.27 16.56 TxV T V n s . Week 3 . 60 2.65 3.36 3.00 75 29.18 21+. 91+ 27.06 90 28.57 33.70 31.13 A v e r a g e 20.13 20.67 TxV n s . T V n s . T a b l e 11B E f f e c t o f v a r i e t y , w a t e r t e m p e r a t u r e , a n d o f h a r v e s t on t h e r o o t l e n g t h o f r i c e s e e d l i n g s , (cm.) V a r i e t i e s • B l u e b o n n e t C a l o r o A v e r a g e Temp.°P Week 1.-* 75 2.10 2.63 2.36 90 2.63 3.18 2.91 A v e r a g e 2.37 2.90 TxV n s . T n s . BV n s . Week 2.-«-75 1+.1+5 ' 7.07 5.76 90 5.59 6.11 5.85 A v e r a g e 5.02 6.59 TxV n s . T n s . V* Week 3« 60 1 .77 3.08 2.1+2 75 6.15 6.83 6.1+9 90 6.91+ 6.50 6.72 A v e r a g e l+.9f? 5*1+7 TxV n s . T * V n s . • No m e a s u r a b l e r o o t g r o w t h a t 60 P f o r weeks 1. a n d 2. Table 11 G E f f e c t ' o f v a r i e t y , w ater t e m p e r a t u r e , and time o f h a r v e s t on the shoot w e i g h t o f r i c e s e e d l i n g s , (gm.) , •> V a r i e t i e s B luebonnet C a l o r o Average Temp.°F Week 1. 60 .03 .01+ .03 75 .08 .18 .13 90 .22 .28 .25 Average .11 .17 TxV ns. T V •sc--:;-Week 2. 60 .08 .10 .09 75 .58 1.18 .88 90 1.03 1.31+ 1.19 Average .56 .87 TxV ns. T V Week 3. 60 .13 •§3 • 1 § 75 1.97 2.80 2.38 90 3.3A . 3.56 3.1+5 Average 1.81 2.19 TxV ns. T V ns. Table 11 D E f f e c t o f v a r i e t y , w ater t e m p e r a t u r e . and time o f h a r v e s t on of r o o t w e i g h t o f r i c e s e e d l i n g s , (gm.) V a r i e t i e s B l uebonnet C a l o r o Average Temp.°P Week 1 . 75 .02 .01+ .03 90 .01+ .07 .06 Average .03 .06 TxV ns. T V Week 2. * 75 .08 .20 90 .21+ .27 Average .16 .21+ TxV ns. T V * Week 3. 60 .,01+ .05 .01+ 75 .19 .35 .27 90 .1+8 .69 .59 Average .21+ .J>b TxV n s . T V n s . -»- No measurable r o o t growth a t 60 F f o r weeks 1 . and 2. R o o t W e i g h t The b e h a v i o u r o f r o o t w e i g h t as shown i n T a b l e I I D i s c o m p a r a b l e t o t h a t o f s h o o t w e i g h t . Increase*., i n r o o t w e i g h t was d i r e c t l y r e l a t e d t o w a t e r t e m p e r a t u r e w i t h a h i g h l y s i g n i f i c a n t t e m p e r a t u r e e f f e c t i n a l l week V a r i e t y d i f f e r e n c e s were s i g n i f i c a n t up t o t h e s e c o n d week w i t h C a l o r o s h o w i n g h i g h e r r o o t w e i g h t . S e e d R e s i d u e J u s t as w i t h t h e s e e d r e s e r v e l o s s shown i n t h e f i r s t e x p e r i m e n t , r e s u l t s o f t h e s e c o n d e x p e r i m e n t , i n T a b l e H E , show more s e e d r e s i d u e l o s s a t h i g h e r tem-p e r a t u r e s t h a n a t l o w t e m p e r a t u r e s . I n o t h e r w o r d s , s e e d r e s i d u e l o s s was i n v e r s e l y r e l a t e d t o t e m p e r a t u r e . L o s s a t 75° a n d 90° was g r e a t e r f r o m t h e e n d o f t h e f i r s t week t o t h e e n d o f t h e s e c o n d week as r e p o r t e d e a r l i e r , w h e r e a s t h e 60° t r e a t m e n t c a u s e d a g r a d u a l de-c l i n e t h r o u g h o u t t h e p e r i o d . L o s s i n C a l o r o was more e v i d e n t t h a n B l u e b o n n e t , h e n c e a t e m p e r a t u r e X v a r i e t y i n t e r a c t i o n was p r e s e n t , e x c e p t a t t h e f i r s t week. 1+5. T a b l e 11E E f f e c t o f v a r i e t y , w a t e r t e m p e r a t u r e , and t i m e o f h a r v e s t on t h e s e e d r e s i d u e o f r i c e s e e d l i n g s , (gm.) V a r i e t i e s V B l u e b o n n e t C a l o r o A v e r a g e Temp.°P Week 1 . 60 2 . 0 8 2.1+9 2 . 2 9 75 1 . 8 9 2 . 1 8 2 . 0 3 90 1 . 6 7 1 . 8 0 1 .71+ A v e r a g e 1 . 8 8 2 . 1 6 TxV n s . T «• V Week 2 . 60 2 . 0 9 2 . 3 2 2 . 2 0 75 1 . 2 8 . 8 2 1.05 90 . 61 . 6 2 . 6 2 A v e r a g e 1 . 3 3 1.25 TxV -:HC- T V n s . Week 3 . 60 1 . 8 8 2 . 1 2 2 . 0 0 7 5 . 8 2 . 6 7 . 7 5 90 .55 . 5 5 .55 A v e r a g e 1 . 0 8 1 . 1 2 TxV T V n s . 14-6. E x p e r i m e n t I I I . Shoot L e n g t h Data i n Table I I I A are s i m i l a r to the p r e v i o u s o b s e r v a t i o n s r e p o r t e d f o r shoot l e n g t h i n experiments I and I I . The d a t a r e v e a l t h a t i n t h i s experiment h i g h t e m p e r a t u r e s were more c o n d u c i v e to shoot l e n g t h growth w i t h C a l o r o s u r p a s s i n g Bluebonnet b o t h weeks. I t i s however p o s s i b l e t o assume t h a t a s i g n i f i c a n t d i f f e r e n c e i n v a r i e t y might not appear, i f t h i s e xperiment was conducted f o r a f u r t h e r p e r i o d o f two weeks. I n t h i s e xperiment growth a t 60° was s u p e r i o r t o t h a t i n the p r e v i o u s two e x p e r i m e n t s . Root L e n g t h As r e v e a l e d by the d a t a i n Table I I I B , t h e r e was no s i g n i f i c a n t d i f f e r e n c e between v a r i e t i e s . Root l e n g t h o f C a l o r o tended t o exceed t h a t o f Bluebonnet a t 60° and 7 5 ° , but at 90° Bluebonnet r o o t l e n g t h was s l i g h t l y l a r g e r . The o n l y s i g n i f i c a n t e f f e c t was t h a t o f tempera-t u r e a t the f i r s t week, when r o o t growth a t 75° exceeded t h a t a t 60° and 90°W. Shoot Weight The w a t e r temperature e f f e c t on shoot weight f o r b o t h weeks i s c l e a r l y shown i n Table I I I C . A l t h o u g h t h e r e was a temperature X v a r i e t y i n t e r a c t i o n i n the second week, the o v e r a l l e f f e c t o f temperature was s i g n i f i c a n t . Shoot weight g e n e r a l l y f o l l o w e d the p a t t e r n o f the shoot l e n g t h . 1+7. T a b l e 111A E f f e c t o f v a r i e t y , water t e m p e r a t u r e , and time o f h a r v e s t on the shoot l e n g t h o f r i c e s e e d l i n g s , (cm.). Temp. P 60 75 90 Average Week 1 . V a r i e t i e s B luebonnet 2.19 3.76 10.81 5.58 TxV T ns, C a l o r o Average 2 . 2 7 1+.81+ 17 . 5 9 8.23 V ns. 2.23 1+.30 114-.20 Week 2. 60 5.30 9 .37 7.33 75 8 . 3 9 18.10 13.21+ 90 20.23 33.07 26.65 Average -:' 1 1'w31 •' * 20.18 TxV * T -»- V * Tab l e 111B E f f e c t o f v a r i e t y , w a t e r t e m p e r a t u r e , and time o f h a r v e s t on the r o o t l e n g t h o f r i c e s e e d l i n g s , (cm. ) . V a r i e t i e s B luebonnet C a l o r o Average Q Temp. P Week 1. 60 1 . 9 0 3.29 2.59 75 3.89 1+..62 1+.22 9 0 3-37 2.57 2.97 Average 3.03 3.1+9 TxV ns. T -«- V n s . Week 2. 60 3.75 6.23 1+.99 75 3.89 5.16 1+.52 90 3.97 3.51+ 3.75 Average 3.87 1+.98 TxV ns. T ns. V ns. Table 111C E f f e c t of v a r i e t y , water t e m p e r a t u r e , and time o f h a r v e s t on the shoot - weight o f r i c e s e e d l i n g s , (gm. ) . V a r i e t i e s Bluebonnet C a l o r o Average Temp.°P Week 1. .15 60 .10 .21 75 .21 .36 .29 90 .71+ 1.19 .96 Average .35 .59 TxV n s . T ?HC- V Week 2. 60 .37 .67 .52 75 .60 1.55 1.07 90 1.85 3.08 2.1+6 Average .91+ 1.77 TxV T V n s . 1+8. R o o t W e i g h t The r o o t w e i g h t , as s e e n i n T a b l e I I I D, was h i g h l y v a r i a b l e , p a r t i c u l a r l y a t t h e h i g h e r t e m p e r a t u r e s . T h i s i n c o n s i s t e n c y i n t h e r o o t d e v e l o p m e n t c o u l d be p a r t i a l l y a t t r i b u t e d t o t h e h i g h o r g a n i c m a t t e r a nd l o w c l a y c o n -t e n t o f t h e g r e e n h o u s e s o i l t h a t was u s e d f o r t h i s e x -p e r i m e n t . T h e r e was a s i g n i f i c a n t t e m p e r a t u r e X v a r i e t y i n t e r a c t i o n o n l y i n t h e f i r s t week, b u t no o v e r a l l s i g n i -f i c a n t d i f f e r e n c e s b e t w e e n v a r i e t i e s o r b e t w e e n t e m p e r a -t u r e s . The i n t e r a c t i o n i n t h e f i r s t week was a t t r i b u t -a b l e t o t h e g r e a t e r r o o t w e i g h t o f C a l o r o a t h i g h e r t e m p e r a t u r e s . S e e d R e s i d u e The q u a n t i t y o f s e e d r e s e r v e l e f t o v e r , ( T a b l e I I I E ) w i t h r e s p e c t t o v a r i e t y , t e m p e r a t u r e a nd t i m e o f h a r v e s t i s s i m i l a r t o t h e r e s u l t s o f t h e p r e v i o u s two e x p e r i m e n t s . 1+9. T a b l e 111D E f f e c t of v a r i e t y , water t e m p e r a t u r e , and time of h a r v e s t on the r o o t weight of r i c e s e e d l i n g s , (gm.). V a r i e t i e s Temp.°F Bluebonnet C a l o r o Averagi Week 1. ^60 .05 .08 .06 75 .11 .21+ .17 90 .13 .1+0 .26 Average Week 2. TxV .09 T ns. V ; .21+ ns. 60 .37 .21+ .30 75 .07 .28 .17 90 .16 .27 .21 Average TxV .20 ns. T ns . .26 V ns. Table 111E E f f e c t of v a r i e t y , w ater t e m p e r a t u r e , and time of h a r v e s t on the seed r e s i d u e of r i c e s e e d l i n g s , (gm.). V a r i e t i e s /••Bluebonnet C a l o r o Average Temp. P Week 1 . ... 60 2.01 2.13 2.07 75 1.81 1.61+ 1.73 90 1 .08 .81 ."95 Average 1.63 1.53 TxV ns. T V ns. Week 2. 60 1.61+ 1.21+ 1.1+1+ 75 1.12 .67 .90 90 .72 .61 .66 Average 1.16 .81+ TxV T V n s . 50 E x p e r i m e n t I V . L e a f L a m i n a L e n g t h L e n g t h o f l e a f l a m i n a was n o t m a r k e d l y i n f l u e n c e d b y t e m p e r a t u r e a t t h e i n i t i a l s t a g e s as s e e n i n T a b l e I V A, Week I . H o w e v e r , t h e r e was a v a r i e t y d i f f e r e n c e b e y o n d t h e t e m p e r a t u r e X v a r i e t y i n t e r a c t i o n . Though t h i s d i f f e r e n c e was o n l y s i g n i f i c a n t a t Week I , a s l i g h t d i f f e r e n c e i n t h e two g r o u p s o f v a r i e t i e s was m a i n t a i n e d . D u r i n g t h e f i r s t two weeks o f g r o w t h , s o u t h e r n v a r i e t i e s h a d c o n s i d e r a b l y l o n g e r l e a f l a m i n a , b u t a t t h e e n d o f t h e t h i r d week, G a l i f o r n i a n v a r i e t i e s s u r p a s s e d them. D i f f e r e n t r a t e s o f g r o w t h o f l e a f l a m i n a , e x h i b i t e d as a c o n s e q u e n c e o f d i f f e r e n t t e m p e r a t u r e s , w e re o b v i o u s a t t h e e n d o f t h e s e c o n d a n d t h i r d w e e ks. The gap b e -t w e e n 60° a n d 7 5 ° was w i d e r t h a n t h a t b e t w e e n 75° and 90°, f o r w h i c h g r o w t h t e n d e d t o be a b o u t e q u a l . The t e m p e r a t u r e e f f e c t was v e r y o b v i o u s a n d was s i g n i f i c a n t o v e r a n d above t h e t e m p e r a t u r e X v a r i e t y i n t e r a c t i o n a t t h e s e c o n d a n d t h i r d w e e k s . L e a f S h e a t h The e f f e c t o f w a t e r t e m p e r a t u r e on t h e l e n g t h o f l e a f s h e a t h ( T a b l e I V B) was a l m o s t t h e same as t h a t o n t h e l e n g t h o f l e a f l a m i n a . The r e d u c t i o n i n g r o w t h a t 60° was l e s s p r o n o u n c e d a t t h e e n d o f t h e f i r s t week, b u t m o r e s o t h e r e a f t e r . A h i g h l y s i g n i f i c a n t d i f f e r e n c e among t e m p e r a t u r e s was m a i n t a i n e d f o r a l l w e e k s . T h e r e was no o v e r a l l v a r i e t y d i f f e r e n c e d u r i n g t h e f i r s t two 51 T a b l e 1VA E f f e c t o f v a r i e t y , w a t e r t e m p e r a t u r e , and time o f measurement on the l e a f l a m i n a l e n g t h o f r i c e s e e d l i n g s , (cm.). V a r i e t i e s Texas 0 P a t n a C a l r o s e Bluebonnet C a l o r o Ave rag< Temp. P Week 1. ' 60 2.93 1.71 1.93 1 .96 2.13 75 1+.28 2.21 3.01 2.16 2.92 90 2.95 1.75 3.63 2.06 2.60 Average 3.38 1.89 2.86 2.06 ,TxV ## T ns . V Week 2. " 60 1.88 1.56 2.35 1.1+5 1.81 75 19.31 li+.OO 22.25 10.I+3 16.50 90 17.11 11.50 16.1+6 11 .51 11+.15 Average 12.77 9.02 13.68 7.80 TxV T •** V ns. Week 3. # 60 2.36 5.63 1 .61 5.80 3.85 75 23.08 27.1+6 22.01 26 .83 21+. 85 90 23.24-5 21+.00 22.73 22.15 23.08 Average 16.30 19.03 i5.i+5 18.26 TxV T V n s . • Measurements were t a k e n f r o m the second l e a f . " Measurements were t a k e n from the t h i r d l e a f . # Measurements were t a k e n f r o m the f o u r t h l e a f . 52. T a b l e 1 V B E f f e c t o f v a r i e t y , w a t e r t e m p e r a t u r e , a n d t i m e o f measurement o n t h e l e a f s h e a t h l e n g t h o f r i c e s e e d l i n g s , ( c m . ) . Temp. F ' 60 75 90 A v e r a g e " 60 75 9 0 A v e r a g e T e x a s P a t n a Week 1 . 2.30 7.70 6.73 '5.57 Week 2. 1.93 9.75 1 2 . 6 0 8 . 0 9 V a r i e t i e s C a l r o s e B l u e b o n n e t 2.76 7.33 6.63 5.57 TxV n s . 2.15 6.23 7.35 5.2i+ T V ns, 2 . 6 0 1 5 . 3 8 11J-.83 1 0 . 9 3 TxV . T 2 . 7 6 1 0 . 1 8 1 1 . 9 0 8 . 2 8 C a l o r o A v e r a g e 3 . 2 6 6 .33 5.03 14-.87 3.60 15.18 1 3,33 10.70 2 . 6 2 6 . 9 0 6.11-3 2.72 12.62 13.16 V ns, # 60 75 90 A v e r a g e Week 3. 2.25 111.. 06 12.21 9.51 5.31 16.76 15.03 12.37 TxV n s , T 3.20 12.Ii.6 11.86 9.17 5.-4.6 16.00 ll+'.ii.O 11.95 1+.05 111.. 82 13.37 1 M e a s u r e m e n t s were t a k e n f r o m t h e s e c o n d l e a f . " M e a s u r e m e n t s were t a k e n f r o m t h e t h i r d l e a f . # M e a s u r e m e n t s were t a k e n f r o m t h e f o u r t h l e a f . 53. w e e k s , e s p e c i a l l y a t t h e e n d o f t h e f i r s t week when t h e d i f f e r e n c e was h a r d l y p e r c e p t i b l e . The d a t a f o r week 3 i n d i c a t e t h a t G a l i f o r n i a n v a r i e t i e s h a d l o n g e r l e a f s h e a t h and t h e s t a t i s t i c a l a n a l y s i s showed a h i g h l y s i g n i f i c a n t v a r i e t y e f f e c t a t t h i s week. S h o o t D i a m e t e r B o t h d i a m e t e r m e a s u r e m e n t s , l e n g t h w i s e a n d b r e a d t h -w i s e o f c r o s s s e c t i o n s o f s h o o t s g i v e n i n T a b l e s I V G an d I V D r e s p e c t i v e l y , e x h i b i t e d a m a r k e d t e m p e r a t u r e e f f e c t w h i c h i s shown b y t h e s t a t i s t i c a l e v a l u a t i o n . T e m p e r a t u r e X v a r i e t y i n t e r a c t i o n , a l t h o u g h p r e s e n t i n t h e l e n g t h w i s e m e a s u r e m e n t f o r two w e e k s , d i d n o t a p p e a r i n t h e t h i r d week; i n t h e b r e a d t h w i s e measurement t h e r e was i n t e r a c t i o n p r e s e n t o n l y a t t h e e n d o f t h e s e c o n d week. The b r e a d t h w i s e m easurement showed no s i g n i f i -c a n t d i f f e r e n c e s i n v a r i e t i e s e x c e p t a t t h e f i r s t week, w h i l e t h e l e n g t h w i s e showed an o v e r a l l s i g n i f i c a n t d i f f e r e n c e i n t h i s r e s p e c t a t b o t h Weeks 1 a n d 3« When t h e r e s p o n s e o f t h e two g r o u p s were c o m p a r e d , i t was g e n e r a l l y f o u n d t h a t s o u t h e r n v a r i e t i e s h a d a s m a l l e r d i a m e t e r i n r e s p e c t t o l e n g t h w i s e m e a s u r e m e n t s i n a l l weeks a n d b r e a d t h w i s e a t t h e f i r s t week. Number a n d S i z e o f S t o m a t a T a b l e s I V E and I V P g i v e t h e d a t a f o r b o t h s t o m a t a number a n d s t o m a t a s i z e o n t h e u p p e r s u r f a c e o f t h e l e a f 5l+. T a b l e I V G E f f e c t o f v a r i e t y , w a t e r t e m p e r a t u r e , and t i m e o f measurement o n t h e s h o o t d i a m e t e r ( l e n g t h ) o f r i c e s e e d l i n g s , (mm. ) V a r i e t i e s T e x a s P a t n a C a l r o s e B l u e b o n n e t C a l o r o A v e r a g e Temp. P Week 1 60 75. 90 A v e r a g e . 9 8 . 7 5 1.1+1+ 1 .06 1.13 1.17 1 .59 1.29 TxV -«- T .8lt. 1 . 0 8 1 .22 1 .32 V * 1.19 1.41+ 1 .60 1.1+1 1 . 0 3 1.11 1 .i+o Week 2, 60 75 90 A v e r a g e . 9 0 1 .50 2 . 0 2 1 .1+7 1 . 0 0 2 . 0 6 2 .15 1.71+ TxV # T 1 . 0 9 1 .66 2 .13 1 . 6 3 V n s , 1.18 1.77 2.51+ 1 . 8 3 1 .05 1.71+ 2 . 2 0 60 75 90 A v e r a g e Week 3< 1 .01+ 2 . 3 6 3 . 6 0 2 . 3 3 1 .30 3 . 2 5 3 . 9 7 2.81+ 1.15 2 . 0 0 3 . 8 0 2 . 3 2 1.31 2 .77 3 . 6 0 2 . 5 6 1 . 2 0 2 . 5 9 3 . 7 5 TxV n s . T 55. T a b l e I V D E f f e c t o f v a r i e t y , w a t e r t e m p e r a t u r e , a n d t i m e o f measurement on t h e s h o o t d i a m e t e r ( b r e a d t h ) o f r i c e s e e d l i n g s , (mm. ) V a r i e t i e s T e x a s P a t n a C a l r o s e B l u e b o n n e t C a l o r o Average Temp.°P Week 1. 60 . 7 7 .91 .61+ . 8 9 .81 75 . 6 0 ' .89 -83 . 8 9 . 8 0 90 .99 1 .014- .99 1 .93 1 . 0 2 A v e r a g e .79 -91+ . 8 2 .91+ TxV n s . T V #«• Week 2 . 60 . 7 3 .8I4- . 8 9 . 9 8 . 8 6 75 1 . 0 0 1.16 1 . 0 8 . 9 8 1.06 90 1 .22 1.17 1 . 2 2 1 .23 1.21 A v e r a g e . 9 8 1 .06 1 .07 1 .07 TxV •* T -:HC- V n s . Week 3 . 60 .80 .92 . 8 7 . 9 7 . 8 9 75 1.28 1 . 2 2 1.15 1.19 1 .21 90 1.69 1 .61 1.65 1.1+1+ 1 .60 A v e r a g e 1.25 1 .25 1 . 2 2 1 . 2 0 TxV n s . T -:H:- V n s . 56. l a m i n a . The o v e r a l l e f f e c t o f t e m p e r a t u r e s on t h e s i z e o f s t o m a t a was q u i t e v a r i a b l e . T h e r e was a s i g n i -f i c a n t i n t e r a c t i o n a t a l l weeks a p p a r e n t l y b e c a u s e o f d i f f e r e n t v a r i e t y b e h a v i o u r e a c h week. I n g e n e r a l , 75° l e a v e s h a d t h e l a r g e s t s t o m a t a a t t h e f i r s t week ( P l a t e I I B ) , a n d 60° t h e l a r g e s t a t t h e t h i r d week. ( P l a t e s I A a n d I B) The s m a l l e s t number o f s t o m a t a was a t 60° f o l l o w e d b y t h e o t h e r two t e m p e r a t u r e s ; 75° a n d 90° i n t h e o r d e r o f i n c r e a s e ( T a b l e I V E ) a n d P l a t e s I I I A, I I I B a n d I A. The amount o f i n c r e a s e a t h i g h e r t e m p e r a t u r e s d e p e n d e d o n t h e week o f m e a s u r e -ment. The d i f f e r e n c e s i n t h e e f f e c t o f ' t e m p e r a t u r e o n the. number o f s t o m a t a were h i g h l y s i g n i f i c a n t d u r i n g t h e f u l l p e r i o d o f i n v e s t i g a t i o n . A t e m p e r a t u r e X v a -r i e t y i n t e r a c t i o n was p e r c e p t i b l e f o r two weeks f o r s t o m a t a numbers b u t t h i s was a b s e n t a t t h e t h i r d week. The s t o m a t a number a t l o w t e m p e r a t u r e s was u s u a l l y g r e a t e r i n - s o u t h e r n v a r i e t i e s ( P l a t e s I A a n d I B ) , w h i l e a t h i g h e r t e m p e r a t u r e s , t h e r e was a t e n d e n c y f o r a l l v a r i e t i e s t o be a b o u t e q u a l ( P l a t e s I I A and I I I A ) . L e a f L a m i n a W i d t h A n i n t e r a c t i o n o f t e m p e r a t u r e X v a r i e t y i n l e a f l a m i -n a w i d t h o c c u r r e d i n t h e f i r s t week, ( T a b l e I V G ) , due t o d i f f e r e n c e s i n b e h a v i o u r o f B l u e b o n n e t a nd C a l o r o . S i g n i -f i c a n t t e m p e r a t u r e e f f e c t s a t t h e s e c o n d and t h i r d week 57 T a b l e 1VE E f f e c t o f v a r i e t y , w a t e r t e m p e r a t u r e , a n d t i m e o f measurement o n t h e c o u n t o f s t o m a t a o n t h e u p p e r s u r f a c e o f t h e l e a f l a m i n a i n r i c e s e e d l i n g s . Wo. o f s t o m a t a p e r s q u a r e .01+-79 s q . mm,* V a r i e t i e s T e x a s P a t n a C a l r o s e B l u e b o n n e t C a l o r o A v e r a g e Temp. P Week 1 . 60 6.00 5.50 7.00 5.50 6.00 75 8.50 5.00 7.50 5.00 6.50 90 1I4..00 • 15.50 11+.50 13.50 14.37 A v e r a g e 9.50 8.66 9.66 8.00 TxV •* T -»--* V n s . Week 2. 60 6.50 5.50 7.00 3.50 5.62 75 12.00 11 .00 10.50 13.00 11 .62 90 13.50 16.00 13.50 1 2.00 13.75 A v e r a g e 10.66 10.83 10.33 9.50 TxV T ## V n s . Week 3« 60 5.50 3.50 8.50 8.50 6.50 75 8.50 12.00 10.00 12.50 10.75 90 1L|..00 1I+.00 11.50 15.00 13.62 A v e r a g e 9.33 9.83 10.00 12.00 TxV n s . T V n s . c:Note: I m p r e s s i o n s t a k e n f r o m t h e l e a f t i p o f t h e m ost r e c e n t f u l l l e a f . 58. T a b l e I V P E f f e c t o f v a r i e t y , w a t e r t e m p e r a t u r e , a n d t i m e o f meas u r e m e n t o n t h e s t o m a t a s i z e o f t h e u p p e r s u r f a c e o f tjhe l e a f l a m i n a i n r i c e s e e d l i n g s , {JUL, )-«-V a r i e t i e s T e x a s P a t n a C a l r o s e B l u e b o n n e t C a l o r o A v e r a g e Temp.°P Week 1. 60 280 330 260 810 i+20 75 370 51+0 14-70 14-40 450 90 220 340 290 280 280 A v e r a g e 290 410 3I4.O 510 TxV #* T n s . V ns, Week 2. 60 280 210 250 580 330 75 340 530 290 360 380 90 320 270 280 280 290 A v e r a g e 310 340 270 410 TxV -IH:- T n s . V ns, Week 3. 60 380 990 220 430 500 75 300 320 230 290 280 90 350 380 250 300 320 A v e r a g e 340 570 230 34° TxV T n s . V n s . N o t e : f r o m i m p r e s s i o n s t a k e n f r o m t h e l e a f t i p o f t h e most r e c e n t f u l l l e a f . f r o m A = I x I X Where a = l e n g t h b = b r e a d t h . 59 P l a t e l A. Number and s i z e o f s t o m a t a f o r m e d i n B l u e b o n n e t a t 6 0 ° P. P l a t e I B. Number a n d s i z e Q o f s t o m a t a f o r m e d i n C a l o r o a t 60 F. N o t e t h e l a r g e s i z e c o m p a r e d t o B l u e b o n n e t a b o v e . 60. P l a t e I I A. The l a r g e r number a n d s m a l l e r s i z e o f s t o m a t a i s shown ( a t e n d o f t h e f i r s t w e ek) i n B l u e b o n n e t g r o w n a t 9 U W P. P l a t e I I B . L e s s e g number a n d . l a r g e r s i z e i n B l u e b o n n e t a t 75 F ( e n d o f t h e f i r s t week) i s i n d i c a t e d i n t h i s p l a t e . N o t e t h e d i f f e r e n c e i n s i z e a n d number b e t w e e n t h e two t r e a t m e n t s w h i c h l a t e r d i s a p p e a r e d a l m o s t c o m p l e t e l y . 61 P l a t e I I I A. C a l o r o g r o w n a t 90 P. P l a t e I I I B. C a l o r o g r o w n a t 75° P. P l a t e s I I I A a n d B i n d i c a t e t h e g r a d u a l d e c r e a s e i n d i f f e r e n c e b e t w e e n 75 °F a n d 90 *P a t two w e e k s . 62. T a b l e 1VG E f f e c t o f v a r i e t y , w a t e r t e m p e r a t u r e , and t i m e o f meas u r e m e n t o n t h e l e a f l a m i n a w i d t h o f r i c e s e e d l i n g s , (mm.) V a r i e t i e s T e x a s P a t n a G.alrose B l u e b o n n e t G a l o r o A v e r a g e Temp .op Week 1 . 60 1.23 1.00 1.25 .75 1.05 75 1 .50 1.08 2.25 1.16 1 .50 90 1.66 1.33 1.16 1.83 1 .50 A v e r a g e 1.1+6 1.13 1.55 1.25 TxV T ns . V ns . 1.1+1 1.29 2.16 2.52 2.50 2.61+ 2.02 Week 2. 60 1.08 • 1 .00 1.66 75 2.91 2.33 2.66 90 3.33 1.81 2.91 A v e r a g e 2.1+1+ 1.71 2.1+1 TxV n s . Week 3. 60 1.25 1.25 1.83 75 2.91 2.58 3.00 90 3.00 2.25 3.08 A v e r a g e 2.38 2.02 2.63 1 .50 1.1+5 2.66 2.79 1.91 2.56 2.02 TxV n s . T V N o t e : M e a s u r e m e n t s were t a k e n f r o m t h e l e a f t i p o f t h e s e c o n d l e a f a t s e c o n d week a n d t h e t h i r d l e a f a t t h i r d week. 63. were due t o l e s s w i d t h a t 60° c o m p a r e d t o 75° a n d 90° w h i c h were s i m i l a r . The s i g n i f i c a n t v a r i e t y e f f e c t was p r o b a b l y due t o t h e g r e a t e r w i d t h o f t h e l e a v e s -o f t h e s o u t h e r n v a r i e t i e s . E x p e r i m e n t V. S h o o t l e n g t h T a b l e V A shows t h a t s h o o t l e n g t h i n c r e a s e d w i t h i n c r e a s e i n t e m p e r a t u r e ; 90° b e i n g s u p e r i o r t o 75° a n d 60°, r e g a r d l e s s o f w h e t h e r t h e p l a n t s were g r o w n u n d e r s u b m e r g e d o r n o n - s u b m e r g e d o o n d i t i o n . H o w e v e r , t h e d i f f e r e n c e s i n t e m p e r a t u r e b e t w e e n 75° and 90° d e c r e a s e d c o n s i d e r a b l y b y t h e e n d o f t h r e e w e e k s , w h i l e 60° was s t i l l f a r b e l o w t h e h i g h e r t e m p e r a t u r e s . When s u b -m e r g e d a n d n o n - s u b m e r g e d t r e a t m e n t s were c o m p a r e d w i t h r e s p e c t t o e a c h v a r i e t y , i t was e v i d e n t t h a t B l u e b o n n e t ' g r o w s b e t t e r u n d e r s u b m e r g e d c o n d i t i o n s a n d C a l o r o u n d e r n o n - s u b m e r g e d c o n d i t i o n s a f t e r t h e f i r s t week. An o v e r -a l l e v a l u a t i o n o f t h e p e r f o r m a n c e o f t h e s e two v a r i e t i e s r e v e a l e d t h a t C a l o r o was s u p e r i o r t o B l u e b o n n e t i r r e s p e c -t i v e o f t h e s u b m e r g e n c e . S t a t i s t i c a l a n a l y s i s a t t h e t h i r d week showed h i g h l y s i g n i f i c a n t i n t e r a c t i o n s among v a r i e t y X s u b m e r g e n c e , t e m p e r a t u r e X s u b m e r g e n c e a n d t e m p e r a t u r e X v a r i e t y . I n s p i t e o f t h e l a t t e r two i n t e r -a c t i o n s , t h e s i g n i f i c a n t d i f f e r e n c e s among t e m p e r a t u r e s w e re m a i n t a i n e d t h r o u g h o u t t h e p e r i o d . T h e s e d i f f e r e n c e s 6li,. T a b l e VA E f f e c t o f v a r i e t y s u b m e r g e n c e , a n d on t h e s h o o t l e n j s e e d l i n g s . (cm. , t e m p e r a t u r e , t i m e o f h a r v e s t t h o f r i c e V a r i e t i e s Week 1. B l u e b o n n e t C a l o r o A v e r a g e Temp.°P Sub. Non.-sub. Sub. Non . - s u b . 60 1.01 0.91 0 .62 1.18 0.93 75 5.43 2.So "6.29 4.64 4.79 90 14.I8 8.52 20.36 14.45 14.38 A v e r a g e 6.87 4.08 9.09 6.7b TxVxS n s . TxS VxS n s . TxV * T-* V n s . S n s . Week 2 . 60 1.41 1.69 1.47 3.10 1.91 ' 7 5 20.07 8.50 19.47 20.52 17.14 90 28.66 21.63 28.56 36.58 28.86 A v e r a g e 16.71 10.60 16.50 20.06 TxVxS TxS n s . VxS n s . TxV n s . T * V n s . S ns, Week 3* 60 2.51 4.01 3.47 9.84 4.96 75 35.99 23.41 4 L 8 3 43.28 36.13 90 34.57 31.96 38.41 47.42 38.09 A v e r a g e 24.36 19.80 27 .90 33.51 TxVxS n s . TxS VxS TxV T -* V n s . S ns 65. were m a n i f e s t e d m o s t l y due t o t h e l o w r e s p o n s e o f b o t h v a r i e t i e s t o 6 0 ° , p a r t i c u l a r l y B l u e b o n n e t . R o o t L e n g t h A l l t e m p e r a t u r e s showed m a r k e d e f f e c t s o n r o o t l e n g t h ( T a b l e V B ) . G r o w t h was much r e t a r d e d a t 6 0 ° f o r t h e f i r s t two w e e k s . D a t a f o r t h e t h i r d week showed t h a t t h e r o o t l e n g t h s a t 6 0 ° and 75° were a l m o s t e q u a l . G r o w t h r e s p o n s e a t 9 0 ; d u r i n g t h e f i r s t two w e e k s , was g e n e r a l l y l o w e r t h a n 75°» b u t a t t h e e n d o f t h e t h i r d week, t h i s r e s p o n s e was r e v e r s e d . R o o t g r o w t h was r e -t a r d e d a t 6 0 ° e s p e c i a l l y u n d e r s u b m e r g e d c o n d i t i o n s . By t h e t h i r d week, b o t h v a r i e t i e s " b e h a v e d a l m o s t e q u a l l y i n s u b m e r g e d a n d n o n - s u b m e r g e d t r e a t m e n t s . P l a n t s g r o w n u n d e r n o n - s u b m e r g e d c o n d i t i o n s a t 6 0 ° h a d r e l a t i v e l y l o n g e r r o o t l e n g t h t h a n t h o s e g r o w n u n d e r s u b m e r g e d c o n -d i t i o n s . A f t e r a p e r i o d o f t h r e e w e e k s , t h e e f f e c t o f w a t e r t e m p e r a t u r e was r e d u c e d r e s u l t i n g i n t h e a b s e n c e o f m a r k e d d i f f e r e n c e s b e t w e e n t e m p e r a t u r e t r e a t m e n t s . S i m i l a r l y , t h e d i f f e r e n c e b e t w e e n s u b m e r g e d a n d n o n - s u b -m e r g e d t r e a t m e n t s t e n d e d t o d e c r e a s e . T h e r e was a s i g n i -f i c a n t t e m p e r a t u r e X s u b m e r g e n c e i n t e r a c t i o n a t a l l weeks b u t a t e m p e r a t u r e X v a r i e t y i n t e r a c t i o n o n l y a t t h e t h i r d week when B l u e b o n n e t r o o t g r o w t h i n c r e a s e d a t h i g h e r t e m p e r a t u r e s a n d C a l o r o g e n e r a l l y d e c r e a s e d . 66. T a b l e VB E f f e c t o f v a r i e t y , t e m p e r a t u r e , s u b m e r g e n c e , a n d t i m e o f h a r v e s t o n t h e r o o t l e n g t h o f r i c e s e e d l i n g s , (cm.; V a r i e t i e s Week 1. B l u e b o n n e t C a l o r o A v e r a g e Temp.°F Sub. Non.-sub. Sub. Non.-sub. 60 75 90 A v e r a g e 0.00 3.0I|. 3.79 3 . 4 2 1 . 0 5 1 .77 1.21 1.34 0.00 4.70 3.22 3.96 1 .21 3.47 1.92 2.20 1.13 3 . 2 4 2.54 TxVxS ns . TxS VxS ns . TxV n s . T n s . V ns Week 2. 60 75 90 A v e r a g e 1.12 3 .21 3.62 2.65 1.28 2 . 3 0 1 . 8 3 1.80 1.45 5 . 3 2 3.18 3 . 3 2 3 .11 2.73 1 .78 2.54 1.74 3.39 2.60 TxVxS # TxS *- VxS n s . TxV n s . T n s . V n s . Week 3» 60 75 90 A v e r a g e 2.60 3.34 4 . 8 3 3.59 2 . 8 3 2.98 4.55 3.45 1.86 ' 4.98 4 . 5 0 3 . 7 8 5.35 4.20 2.78 4.11 3.16 3.87 4.16 TxVxS ns . TxS VxS n s . TxV * r T n s . V n s . S 67 S h o o t W e i g h t D a t a i n T a b l e V C show t h e d e f i n i t e t e m p e r a t u r e e f f e c t f o r a l l t h r e e weeks on t h e d r y w e i g h t o f s h o o t s . The e f f e c t o f t h e t h r e e d i f f e r e n t t e m p e r a t u r e s was m a i n t a i n e d f o r a l l t h e t h r e e w e e k s , p o s s i b l y w i t h t h e 60° a n d 9 0 ° . b e i n g somewhat more s p r e a d o u t a t t h e t h i r d week t h a n e a r l i e r w e e k s . . C a l o r o had.more d r y w e i g h t when u n d e r n o n - s u b m e r g e d c o n d i t i o n s f o r ' a l l weeks a t a l l tem-p e r a t u r e s , w h e r e a s B l u e b o n n e t was v a r i a b l e . w i t h a t e n -d e n c y f o r h i g h e r w e i g h t u n d e r n o n - s u b m e r g e d c o n d i t i o n a t 60° a n d g e n e r a l l y 90° and u n d e r s u b m e r g e d c o n d i t i o n s a t 7 5 ° . S i g n i f i c a n t d i f f e r e n c e s i n t e m p e r a t u r e e f f e c t s w e r e m a i n t a i n e d t h r o u g h o u t t h e p e r i o d . R o o t W e i g h t As T a b l e V D i n d i c a t e s , r o o t w e i g h t f o l l o w e d a p p r o x i -m a t e l y t h e same p a t t e r n as r o o t l e n g t h w i t h r e g a r d t o t e m p e r a t u r e e f f e c t a n d s u b m e r g e n c e e f f e c t . . A l s o b o t h v a r i e t i e s h a d i n c r e a s e s i n r o o t w e i g h t s c o r r e s p o n d i n g t o t h e i r r o o t l e n g t h s f o r p a r t i c u l a r weeks a n d t e m p e r a -t u r e s . H o w e v e r , u n l i k e t h e r o o t l e n g t h m e a s u r e m e n t s , t h e r e , was no s i g n i f i c a n t t e m p e r a t u r e X s u b m e r g e n c e i n -t e r a c t i o n d u r i n g t h e t h i r d week. T h i s w o u l d t h e r e f o r e i n d i c a t e t h a t a h i g h e r v a r i a b i l i t y p r o b a b l y e x i s t e d i n t h e r o o t i ^ e i g h t d a t a a n d t h a t a v e r y g o o d c o r r e l a t i o n c o u l d n o t be e x p e c t e d b e t w e e n r o o t w e i g h t a n d r o o t l e n g t h f o r v a r i o u s t r e a t m e n t s . 68. Table V C E f f e c t o f v a r i e t y , t e m p e r a t u r e , submergence, and time o f h a r v e s t on the shoot weight o f r i c e s e e d l i n g s , (gm.). V a r i e t i e s Week 1. Bluebonnet C a l o r o Average Temp.°P Sub. Non.-sub. Sub. Non.-sub. 60 .03 .05 .01+ .10 .06 75 .18 .10 .30 .31 .22 90 .1+9 .52 .55 .88 .61 Average .23 .22 .30 .1+3 TxVxS n s . TxS ns. VxS ns. TxV ns. T #* V S n s . Week 2. 60 .09 .11 .11 .23 .13 75 .65 .61 .85 1.1+0 .87 90 1.51+ 1.1+6 1.k7 2.31+ 1.70 Average .76 .72 .81 1.32 TxVxS n s . TxS n s . VxS TxV ns. T V ns. S ns. Week 3» 60 .13 .21 75 2.16 1.54 90 2.80 3.71+ Average 1.69 1.83 .22 .57 .28 2.1+2 4.35 2.62 2.92 5.19 3.66 1.85 3.37 TxVxS ns. TxS VxS ns. TxV ns. T -x V ns. S ns. 69 Table V D E f f e c t o f v a r i e t y , t e m p e r a t u r e , submergence, and time o f h a r v e s t on the r o o t w e ight of r i c e s e e d l i n g s . (gm.) V a r i e t i e s Week 1. B lu e b o n n e t C a l o r o Average Temp.°F Sub. Non.-sub. Sub. Non.-sub. 60 0.00 .03 0.00 .10 .06 75 .05 .Ok .10 .08 .07 90 .33 .05 .09 . .05 .13 Average .19 .04 .09 .08 TxVxS ns. TxS ns. VxS ns. TxV ns. T ns. V ns. S n s . Week 2. 60 .05 .02 .02 .06 .0k 75 .12 .10 .12 .08 .10 90 .07 .07 .17 .08 .09 Average .08 .06 .10 .07 TxVxS TxS ns. VxS ns TxV n s . T ns. V ns. S ns. Week 3. • 60 .02 .04 .03 .15 .06 75 .11 .07 .13 .26 .14 90 .28- .23 .38 .21 .27 Average .14 .11 .18 .20 TxVxS -;c- TxS n s . VxS • ns. TxV ns. T ns. V n s . S n s . 7 0 . S e e d R e s i d u e As o b s e r v e d i n p r e v i o u s e x p e r i m e n t s , t h e r e was more s e e d r e s e r v e a t 6 0 ° t h a n a t 7 5 ° , and a t 75° t h a n a t 9 0 ° ( T a b l e V E ) . T h i s phenomenan was p r e s e n t r e -g a r d l e s s o f s u b m e r g e n c e . V a r i e t a l r e s p o n s e s t o s u b -m e r g e n c e were e v i d e n t f r o m t h e f i r s t week. B l u e b o n n e t t e n d e d t o h a v e a g r e a t e r s e e d r e s e r v e under' s u b m e r g e d c o n d i t i o n s t h a n n o n - s u b m e r g e d a t 6 0 ° f o r t h e f i r s t , two weeks and a t t h i r d week i t was a l m o s t e q u a l t o n o n -s u b m e r g e d t r e a t m e n t s . On t h e o t h e r h a n d , u n d e r n o n -s u b m e r g e d c o n d i t i o n s a t 75° o r 9 0 ° , B l u e b o n n e t h a d more s e e d r e s i d u e w e i g h t f o r a l l t h r e e w e e k s . The b e h a v i o u r o f C a l o r o was n o t c o m p a r a b l e t o B B l u e b o n n e t . U t i l i z a -t i o n o f C a l o r o s e e d r e s e r v e was p r o g r e s s i v e l y g r e a t e r u n d e r n o n - s u b m e r g e d r a t h e r t h a n u n d e r s u b m e r g e d c o n d i -t i o n s , and g r e a t e r t h a n t h a t o f B l u e b o n n e t f o r t h e c o r r e s p o n d i n g t e m p e r a t u r e a n d week. A s i g n i f i c a n t t e m p e r a t u r e e f f e c t p r e v a i l e d . d u r i n g t h e f u l l p e r i o d . E x p e r i m e n t V I S h o o t L e n g t h The d a t a i n T a b l e V I A p r i m a r i l y s u p p o r t t h e e a r l i e r o b s e r v a t i o n s t h a t r e s p o n s e o f s h o o t l e n g t h g r o w t h t o 6 0 ° was much p o o r e r t h a n t h e r e s p o n s e t o 75° o r 9 0 ° . The l a t t e r two t r e a t m e n t s h a d much t h e same e f f e c t a t t h e en d o f f o u r w e e k s . R e s u l t s a t t h e f o u r t h week r e v e a l 71. T a b l e V E E f f e c t o f v a r i e t y , t e m p e r a t u r e , s u b m e r g e n c e , a n d t i m e o f h a r v e s t o n t h e s e e d r e s i d u e o f r i c e s e e d l i n g s , (gm.). Temp.°P 60 75 90 A v e r a g e Week 1 . Sub. 2.14,0 1.71+ 1 . 2 6 1.80 V a r i e t i e s B l u e b o n n e t N o n . - s u b . C a l o r o A v e r a g e Sub. Non.-sub. 2.21+ 2 .13 1 . 2 6 1.88 2 .37 1 . 9 2 1 . 2 6 1.85 TxVxS n s . TxS n s . VxS n s . TxV n s . T Week 2. 2 . M + 1.83 .85 1 .71 V ns 60 75 90 A v e r a g e 2 . 3 6 1 . 9 1 1 . 1 6 S n s . 2.05 1.88 2.39 2.13 2.11 1.22 1.32 1.18 .88 • 1.15 . 6 2 .80 .60 .58 .65 1.30 1.33 1.39 1.19 n s . TxS n s . VxS n s . TxV T V n s . S n s . 60 75 90 A v e r a g e Week 3» 1.78 .71 .59 1.03 1.81 .85 .67 1.11 1.91+ . 6 7 . 6 1 1 . 0 7 1.50 .1+8 .60 .86 1 . 7 6 . 6 8 . 6 2 TxVxS n s . TxS ns VxS * TxV n s . T V n s . S ns, 72 t h a t g rowing p l a n t s a t 90° and cha n g i n g t o 75° was more co n d u c i v e t o growth t h a n growing c o n t i n u o u s l y at 90°. The e f f e c t o f t h i s change began t o show from about the t h i r d week but was s t r o n g l y e v i d e n t a t the end of the • f o u r t h week. B o t h v a r i e t i e s had l o n g e r shoot l e n g t h u n t i l the end o f the t h i r d week when grown a t 75° t h a n a t 75° shifted-- t o 90°. But at the end of f o u r t h week, the s h i f t e d p l a n t s had l o n g e r shoots t h a n the n o n - s h i f t e d . The e f f e c t o f changing from 60° t o tine two h i g h e r tem-p e r a t u r e s was a d e f i n i t e i n c r e a s e i n shoot l e n g t h w i t h a s l i g h t l y g r e a t e r i n c r e a s e at 90° t h a n 75°, however" t h i s d i f f e r e n c e may be n e g l i g i b l e . ' On the o t h e r hand, a change from 90° to- 60° caused a marked decrease i n the r a t e o f growth w i t h time as a r e s u l t o f the c o o l water e f f e c t w hich i s d e t r i m e n t a l t o the growth o f s h o o t s . A change from 75° to 60° e x h i b i t e d even a l e s s e r growth t h a n the change from 90° t o 60°. V a r i e t y C a l o r o had l o n g e r shoots a t almost a l l tem-p e r a t u r e s and weeks. The e f f e c t o f c o o l water on t h i s v a r i e t y was not as sudden as on B l u e b o n n e t ; t h i s i s sup-p o r t e d by the d a t a f o r 75° to-60° and 90° t o 60° i n Table VI A Week 2. However, the response t o h i g h e r temperatures was almost e q u a l f o r b o t h v a r i e t i e s . A s i g n i f i c a n t i n t e r -a c t i o n between temperature 1 X temperature 2 was o b s e r v e d u n t i l the end o f the t h i r d week. T h i s would be due t o the e f f e c t o f changing from one temperature t o a n o t h e r , 73 T a b l e V I A E f f e c t o f v a r i e t y , w ater temperature changes, and time o f h a r v e s t on shoot l e n g t h o f r i c e s e e d l i n g s , (cm.). Second Temperature °P Week 1. 60 75 90 F i r s t Q Temp. P Bluebonnet C a l o r o Bluebonnet C a l o r o Bluebonnet C a l o r o Average 60 .69 .60 .97 .51 .57 .52 .61+ 75 5.06 6.21+ 3.85 4.05 3.38 5.70 4.71 90 11.05 13.67 10.61 16.56 10.45 16.15 13.08 Average 5.60 6.83 5.14 7.04 4.08 7.46 T^TpX V ns. ^ x T g * T ^ V T £ x V n s . T ^ H : - T2ns. V n s . Week 2. * 75 17.24 26.72 23.08 25.24 14.99 16.16 20.57 90 12.39 23.27 21.23 38.02 24.42 34.24 25.59 Average 14.81 25.00 22.15 31.63 19.70 25.20 T^TpXV n s . T^jXT^:-* T ^ V * T ^ V ns. T.,ns. Tpns. V n s . Week 3. 60 1.50 1.56 2.79 2.65 1.86 2.71 75 22.96 25.58 38.85 37.06 24.62 27.95 90 20.12 23.57 38.76 45.36 30.80 46.41 •ge 14.86 16.90 26.80 28.36 19.09 25.69 T ^ T 2 x V ns. T^xT^J- T^xV n s . T ^ V ns. 'T^* T 2 ns. V n s . 2.18 29.50 34.17 Week 4» 60 3.50 4.07 13.52 12.55 15.62 16.92 11.03 75 29.27 35.72 31.70 38.62 37.17 45.10 36.26 90 22.75 29.65 40.95 51.82 33.72 41.55 36.74 Average 18.50 23.15 28.72 34.33 28.84 34.52 T-,x T £ x V ns. T^xT 2 n s . T^xV * T 2 x V n s . T.,* Tg n s . V n s . * At week 1. 90 - 60 90 -75 *«• At week 2. 75 - 60 75 - 90 **# At week 3.' 60 - 75 60 - 90 74. e s p e c i a l l y when 60 was i n v o l v e d . The d a t a o b t a i n e d were a f f e c t e d by both t e m p e r a t u r e s to which the p l a n t s were s u b j e c t e d . Root L e n g t h The d a t a i n Table V I B show t h a t the r o o t l e n g t h was not m a r k e d l y a f f e c t e d by the t h r e e temperatures f o r the f o u r weeks. The e f f e c t o f 60° w a s compared o n l y a t the f o u r t h week as changes were made a f t e r t h r e e weeks i n t h i s c a s e . Growth a t 60° a f t e r the s h i f t s t o h i g h e r tempera-t u r e s e q u a l l e d the growth a t 75° and 90°. The 75° and 90° t r e a t m e n t s f a i l e d t o show as g r e a t an e f f e c t i a s on the shoot growth. I t i s however g e n e r a l l y e v i d e n t t h a t the b e h a v i o u r o f r o o t l e n g t h was h i g h l y v a r i a b l e . There was o n l y a s i g n i f i c a n t v a r i e t y d i f f e r e n c e d u r i n g the f i r s t week due t o the g e n e r a l s u p e r i o r i t y o f C a l o r o and'a tempera-t u r e 1 X V a r i e t y i n t e r a c t i o n d u r i n g the second week. The s i g n i f i c a n t i n t e r a c t i o n was p r o b a b l y due to. the s u p e r i o r r o o t growth o f Bluebonnet a t 75°and C a l o r o a t 90°. S i g n i -f i c a n t temperature e f f e c t s were not shown at any week. Shoot Weight As shown i n T a b l e VI C, g r e a t e r d i f f e r e n c e s i n tempera-t u r e e f f e c t s were f o u n d at 60° among v a r i o u s c o m b i n a t i o n s , whether growing a t 90° and changing t o 60° o r growing at 60° and c h a n g i n g t o 90°. As a g e n e r a l p a t t e r n , i f 60° was e n c o u n t e r e d e i t h e r a t e a r l y stage o r l a t e r s t a g e s the i n -h i b i t o r y e f f e c t o f t h i s temperature on growth was o b v i o u s . 75. T a b l e V I B i E f f e c t o f v a r i e t y , w a t e r t e m p e r a t u r e c h a n g e s , a n d t i m e o f h a r v e s t o n r o o t l e n g t h o f r i c e s e e d l i n g s , ( c m . ) . o S e c o n d T e m p e r a t u r e P Week 1. 60 75 90 P i r s t Q Temp. F B l u e b o n n e t C a l o r o B l u e b o n n e t C a l o r o B l u e b o n n e t C a l o r o A v e r a g e 75 2.87 . 3.55 2.53 4.65 2.24 3.73 3.26 90 2.76 4.27 3.38 3.88 3.00 4.26 3.59 A v e r a g e 2.82 3.91 2.95 4.26 2.62 3.99 T-jXTgXV n s . T 1 x T 2 n s . T ^ V n s . T 2 x V n s . T 1 n s . T 2 n s . V Week 2. * 75 5.15 4.04 4.57 4.19 4.37 3.47 4.30 90 3.76 5.22 3.86 4.8k 4.08 5.19 4.49 A v e r a g e 4.46 4.63 4.22 4.5T £.23 4-33 T 1 x T 2 x V n s . l^ x T g n s . T^xV * T 2 x V n s . T 1 n s . T 2 n s . V n s . Week 3« V{i,'c IS 5.70 4.00 3.92 4.22 4.77 5.57 4.69 90 4.61 4.07 4.39 3.38 4.88 4.60 4.32 A v e r a g e 5.15 k.03 4-16 3.80 4.82 5.08 T q x T 2 x V n s . T ^ T g n s . T ^ V n s . T 2 x V n s . T 1 n s . T £ n s . V n s . Week 4« 60 5.60 75 4.02 90 I4..37 A v e r a g e 4.66 4.57 4.45 6.35 5.85 5.95 5.46 4.52 5.60 3.77 5.12 4.27 4.55 6.27 8.95 5.82 4.97 4.70 5.85 5.12 6.33 5.31 5.31 4.97 T,jXT 2 n s . T^xV n s . T 2 x V n s . T1 n s « T 2 n s . V n s . * A t week 1. 90 • - 60 90 -• 75 « * A t week 2. 75 -• 60 75 -- 90 A t week 3- 60 -• 75 60 • - 90 76 T a b l e V I C E f f e c t o f v a r i e t y , w a t e r t e m p e r a t u r e c h a n g e s , a n d t i m e o f h a r v e s t o n s h o o t w e i g h t o f r i c e s e e d l i n g s , (gm.-).. S e c o n d T e m p e r a t u r e °P Week 1. 60 75 90 F i r s t Temp.°F B l u e b o n n e t C a l o r o B l u e b o n n e t C a l o r o B l u e b o n n e t C a l o r o A v e r a ^ 60 75 9 0 A v e r a g e .01+ .19 .1+2 .22 .01+ .25 .51 . 2 6 .05 . 1 6 .1+1 .20 .03 .17 .58 .26 .01+ .17 .1+1+ .21 .01+ .22 . 6 1 .'29 .01+ .19 .1+9 T ^ T p X V ns . T ^ T 2 n s . T ^ V * T 2 x V n s . T>, T 2 ns . V ns Week 2. * 75 9 0 A v e r a g e .76 .6I4. .70 1.07 1.21+ 1.15 . 8 1 .97 .89 1.15 2.07 1 .61 .56 1.1+0 . 9 8 . 9 2 1.93 1.1+2 .88 1.37 T i p c T 2 x V ns • T >j J C T ^ T ^ V n s . T 2 x V n s . T 1 n s . T 2 n s . V Week 3. * * 6 0 75 9 0 A v e r a g e .10 1.03 . 9 3 .68 . 1 2 2.25 1.1+3 1 . 2 6 .11+ 2.85 3.31 2 . 1 0 .16 2.29 3.61+ 2.03 .12 1 .28 2.00 ., 1.13 .20 2.60 1+.77 2.52 .11+ 2.05 2.68 T ^ T 2 x V # T^xTg n s . T ^ V n s . T 2 x V n s . T 1 n s . T 2 n s . V n s . Week l+. 6 0 75 90 A v e r a g e . . 2 6 1.72 1.55 1.18 . 2 9 3.71 2.09 2.03 .53 3.35 6.1+2' 3.1+3 .61+ 3.90 7.1+5 3 . 9 9 .70 3.66 5.23 3.19 .78 3.91+ 5 .71+ 3.1+9 .53 3.38 1+.75 T ^ T 2 x V n s . T>,xT 2 ** T ^ V n s . TgXV n s . T,, T 2 n s . V n s . * A t week 1. 9 0 - 6 0 9 0 - 7 5 A t week 2. 75 - 60 75 - 90 A t week 3. 60 - 75 60 - 90 77. Growing a t 90 and chan g i n g t o 75 was b e t t e r t h a n grow-i n g a t 90° and chan g i n g t o 60°. The change from 90° t o 75° had the be s t r e s p o n s e . A change from 60° t o 75° was s l i g h t l y p o o r e r t h a n 60° t o 90° f o r the l a s t week. I n t h i s i n s t a n c e , the response o f C a l o r o was g e n e r a l l y h i g h e r than Bluebonnet a t a l l weeks. When C a l o r o was changed, f r o m 90° t o 60° t h e r e was a s l i g h t i n c r e a s e i n w e i g h t . T h i s d i d not o c c u r i n Blu e b o n n e t . Thus the d e t r i -m e n t a l e f f e c t of low temperature was g r e a t e r on Bluebonnet t h a n on C a l o r o . Root Weight As was the case w i t h p r e v i o u s e x p e r i m e n t s , 90° t r e a t -ment produced a s l i g h t l y b e t t e r r o o t growth than 75° o r 60°. I n g e n e r a l , a t a l l temperature c o m b i n a t i o n , C a l o r o r o o t w e i g h t was more t h a n Bluebonnet r o o t w e i g h t . * How-ever a f t e r the f i r s t week t h e r e were no s i g n i f i c a n t o v e r -a l l v a r i e t y d i f f e r e n c e s . A s i g n i f i c a n t temperature e f f e c t was p r e s e n t o n l y a t the end o f the f i r s t and f o u r t h weeks. There was a l s o a temperature 2 X v a r i e t y e f f e c t a t the t h i r d week, p r o b a b l y because Bluebonnet was s u p e r i o r at , temperature 2 o f 75° and C a l o r o s u p e r i o r .at Temperature 2 o f 90° Seed Residue Data i n Table V I E show t h a t the h i g h e s t l o s s o f seed r e s e r v e was a t the h i g h e s t temperatures under b o t h s i t u a -t i o n s e i t h e r c o n t i n u o u s l y a t the same t e m p e r a t u r e , t h a t i s 78. T a b l e VI D E f f e c t o f v a r i e t y , w a t e r temperature change, and time o f h a r v e s t on r o o t w e i g h t o f r i c e s e e d l i n g s , (gm.) Second Temperature °F Week 1. 60 75 90 F i r s t Temp.°F Bluebonnet C a l o r o Bluebonnet C a l o r o Bluebonnet C a l o r o Average 75 .Ok .07 .04 .04 .0k .07 .05 90 .08 .07 .07 .08 .06 .11 .08 Average .06 .07 .05 .06 .06 .09 ns. T 1 x T 2 n s . T ^ V ns . T 2xV ns . T 1 Mi T 2 ns. V -»-Week 2. a 75 .08 .09 .14 .21 .07 .14 .12 90 .15 .18 .17 .19 .13 .21 .17 Average .11 .14 .15 .20 .10 .17 n s . T^xTg n s . •J^xV ns . T 2xV ns . ns. T 2 ns. V ns . Week 3. He-75 .22 .22 .26 .13 .13 .25 .20 90 .10 .09 .17 .13 .16 .32 .16 Average .16 .16 .22 .13 .14 .28 T^xT^xV ns . T^xTg ns. T,,xV ns . T 2 x V * T 1 ns. T 2 ns. V ns • Week k. 60 .31 .10 .12 .17 .14 .21 .17 75 .19 .26 .22 .22 .43 .48 .30 90 .20 .59 .61 .39 .47 .46 Average .23 .28 .31 .33 .32 .39 T xT 2 xV ns. as. T ^ V ns. TgXV ns. T-j * T 2 n s . V n s . * At week 1 . 90 - 60 90 75 ii-. »- At week 2. 75 - 60 75 - 90 itii-, * At week 3« 60 - 75 60 - 90 79 T a b l e V I E E f f e c t o f v a r i e t y , w a t e r t e m p e r a t u r e c h a n g e , a n d t i me o f h a r v e s t o n t h e s e e d r e s i d u e o f r i c e s e e d l i n g s , (gm.). S e c o n d T e m p e r a t u r e °F Week 1. 60 75 90 F i r s t Temp. F B l u e b o n n e t C a l o r o B l u e b o n n e t C a l o r o B l u e b o n n e t C a l o r o A v e r a g i 60 2.33 2.35 2.52 2.37 2.29 2.36 2.37 75 2.31 2.19 2.11 2.12 2.12+ 1.98 2.124, 90 1 . L L O 1.51 1.55 1 .14,1 1.32 1.2+8 1.U-24-A v e r a g e 2.01 2.02 2.06 1 .97 1 .91 1 . 924-T x1 xTgXV n s . T^xTg ns . T ^ V n s . T 2 x V ns . T 1 T 2 n s . V n s . Week 2. * 75 1 A 5 .92 1 .22 1.01 1.18 .82 1 .10 90 1.28 1.05 .92 .724. .67 ..57 .87 A v e r a g e 1.36 .99 1.07 .87 .93 .69 T ^ T g X V n s . T ^ T 2 * T ^ V n s . TgXV n s . T 1 n s . T 2 n s . V n s . Week 3. *# 60 2.13 2.18 2.13 2.08 1.96 2 .08 2.09 75 1.13 .91 .66 .76 .70 ,.kl+ .77 90 1.07 .82 .63 .59 .65 .57 .72 A v e r a g e 1.1+1+. 1.30 1.11+ 1.11+ 1.10 1.03 T ^ T 2 x V n s . T^jXTg n s . T,,xV n s . T 2 x V n s . T 1 * T £ V n s . Week i+. 60 2*18 1.89 1.32+ 1.86 1.23. .93 1.57 75 .91 .63 .56 .60 .62 .63 .66 90 *96 .73 .68 .59 .61 .57 .69 A v e r a g e 1.35 1.08 .86 1.02 .82 .71 T ^ T g X V n s . T ^ x T 2 T ^ V n s . T £ x V T 1 .* T g n s . V n s . # A t week 1. 90 - 60 90 - 75 ** A t week 2. 7 5 - 6 0 7 5 - 9 0 A t week 3. 60 - 75 60 - 90 80. 75° o r 90°, o r when changed from 75° t o 90° o r 90° to 7 5 ° . The seed r e s i d u e w e i g h t s f o r a l l these h i g h e r tem-p e r a t u r e c o m b i n a t i o n s were almost e q u a l d u r i n g the t h i r d and f o u r t h weeks. Seed r e s i d u e a t 75° was h i g h e r a t the f i r s t week. Ex p e r i m e n t V I I Shoot L e n g t h • ' " A h i g h l y s i g n i f i c a n t temperature d i f f e r e n c e was p r e -sent d u r i n g a l l f o u r weeks as i n d i c a t e d i n Table V I I A. When p l a n t s were grown c o n t i n u o u s l y a t 60°, the s h o o t s were g e n e r a l l y o b t a i n e d from p l a n t s th at were grown a t 90° and l a t e r (end o f one week) changed t o 7 5 ° . G e n e r a l l y v a r i e t y C a l o r o had l o n g e r shoot l e n g t h than Bluebonnet and the d i f -f e r e n c e was r a t h e r c o n s i s t e n t i n a l l weeks e x c e p t i n g the secon'd week. I n the 90° c o n t i n u o u s t r e a t m e n t , C a l o r o was , found' t o be h i g h e r a t the second week and b o t h v a r i e t i e s •o o e q u a l the t h i r d and f o u r t h weeks. The 75 t o 90 t r e a t m e n t was g e n e r a l l y next h i g h e s t t o c o n t i n u o u s 90° and o f the two v a r i e t i e s , C a l o r o was f o u n d to be s u p e r i o r t o Bluebonnet t h r o u g h o u t the p e r i o d . The n e x t , i n o r d e r , o f performance a t d i f f e r e n t w ater temperatures were those grown at 75° c o n t i n u o u s l y . I n t h i s t r e a t m e n t , C a l o r o had more shoot l e n g t h u n t i l the t h i r d week and th e n was reduced almost t o the l e v e l o f Bl u e b o n n e t . Treatments w i t h s h i f t s f r om 90° t o 60° and 75° t o 60° performed a l m o s t e q u a l l y o r p o s s i b l y w i t h a s l i g h t i n c r e a s e i n the l a t t e r a t the f o u r t h week. I n b o t h c a s e s , C a l o r o was s u p e r i o r t o Bluebonnet a t a l l weeks. 81. Table V I I A E f f e c t o f v a r i e t y , w ater temperature changes, and time o f h a r v e s t on shoot l e n g t h o f r i c e s e e d l i n g s , (cm.). Week 1. Temperatures V a r i e t i e s 60-60 75-60* 75-75 75-90* 90 -60^ 90-75 # 90-90 Average Bluebonnet ,k6 3.56 11.28 12.28 10.7k 7.66 C a l o r o .61 3.1+3 11.55 17.95 1k.86 9.68 Average .54 3.49 11.41 15.11 12.80 TxV T V ns. Week 2. Bluebonnet ' .95 1 2 . l 6 # # 2 k . 0 6 20.76 #^11.62 29.09 28.57 18.17 C a l o r o 1.31 15.74 26 .50 25.41 15-38 16.27 32.10 18.96 Average 1.13 13.95 25.28 23.08 13.50 22.68 30.33 TxV T -::--»- V n s . Week 3. Bluebonnet 1.95 14-65 20.75 2k.50 12.95 33.00 30.65 19.77 C a l o r o 2.70 14.90 27.20 29.40 14-45 25.80 30.15 20.65 Average . 2.32 14.77 23.97 26 .95 13.70 29-40 30.40 TxV ns. T V ns. Week k. Bluebonnet 3.35 14.25 29.90 28.85 10.25 33-75 32-35 21.81 C a l o r o 4.80 15-15 29.55 35.90 13-35 43.85 32.50 25.01 Average 4.07 14.70 29 .72 32.37 11.80 38.80 32.42 TxV ns. T V ns. Note: No 75-60 and 75-90 p l a n t s a t week 1. # S h i f t e d a t time o f h a r v e s t . ## S h i f t e d f o u r days b e f o r e t h i s h a r v e s t , 82 R o o t L e n g t h When t h e e f f e c t o f h i g h e r t e m p e r a t u r e t r e a t m e n t s as shown i n T a b l e V I I B a r e c o m p a r e d , i t i s e v i d e n t t h a t 75° t o 90° and c o n t i n u o u s 90° h a d a l m o s t t h e same i n -f l u e n c e on r o o t l e n g t h . When c o n t i n u o u s l y g r o w n a t 9 0 ° b o t h v a r i e t i e s r e s p o n d e d - a l m o s t i n t h e -same manner. T r e a t m e n t s 75° t o 6 0 ° a n d 9 0 ° t o 6 0 ° b o t h p e r f o r m e d e q u a l l y o r w i t h a s l i g h t l y b e t t e r g r o w t h a t 75° t o 60°. V a r i e t y B l u e b o n n e t h a d s l i g h t l y l o n g e r r o o t s t h a n C a l o r o a t 75° t o 6 0 ° d u r i n g t h e t o t a l p e r i o d o f g r o w t h . A t . 9 0 ° t o 60° i t was f o u n d t h a t C a l o r o was a b e t t e r p e r f o r m e r t h a n B l u e b o n n e t . When t h e o v e r a l l t e m p e r a t u r e e f f e c t o n v a r i e t i e s was i n v e s t i g a t e d a t d i f f e r e n t t e m p e r a t u r e s , , i t was shown t h a t B l u e b o n n e t r o o t s .were s h o r t e r t h a n C a l o r o r o o t s f o r t h e f i r s t two weeks a n d t h e r e a f t e r , t h e r e v e r s e t o o k p l a c e . S i g n i f i c a n t d i f f e r e n c e s i n t e m p e r a t u r e e f f e c t s w e r e s h o w n - i n a l l w eeks.• T h e r e was a l s o a h i g h l y s i g n i f i -c a n t t e m p e r a t u r e X v a r i e t y i n t e r a c t i o n a t t h e f o u r t h week, p r o b a b l y b e i n g due t o t h e s h a r p d i f f e r e n c e s shown b e t w e e n t h e two v a r i e t i e s a t c o n t i n u o u s 75° a n d p o s s i b l y 9 0 ° t o 6 0 ° . S h o o t W e i g h t A c c o r d i n g t o t h e d a t a p r e s e n t e d i n T a b l e V I I G, tem-p e r a t u r e t r e a t m e n t a t 9 0 ° t o 75° h a d t h e h i g h e s t s h o o t w e i g h t . T h i s i s c o m p a r a b l e t o t h e o b s e r v a t i o n s made i n s h o o t l e n g t h . A t t h i s t e m p e r a t u r e , B l u e b o n n e t was h e a v i e r t h a n C a l o r o d u r i n g t h e s e c o n d a n d t h i r d week w h i l e C a l o r o 83. Table V I I B E f f e c t o f v a r i e t y , w a t e r temperature changes, and time o f h a r v e s t on r o o t l e n g t h o f r i c e s e e d l i n g s , (cm.). Temperatures Week 1. V a r i e t i e s 60-60 75-60 75-75 75-90 90-60^ Bluebonnet C a l o r o Average .90 TxV n s. T 2.81 2.23 2.52 V ns. 5.75 4.43 90-75 F 90-90 Average 4.28 5.62 4.45 4.20 4.14 4.17 5.2' Bluebonnet C a l o r o Average Week 2. 2.15 1 .52 1.83 5.22 4.97 5.10 TxV ns. T Bluebonnet C a l o r o Average Week 3* 3.05 5.25 2.30 5.05 2.67 5.15 Bluebonnet C a l o r o Average 3.05 4.05 3.55 TxV -: 5.20 4.70 4.95 :- T 4.85 4.98 4.91 V ns, 4.50 6.60 5.55 TxV ns. T V ns, Week 4» 10.05 4.00 7.02 V ns. ,4.5o # # 2.94 5.45 4.97 3.55 3.24 7.95 3.90 6.60 4.25 7.27 4.07 7.75 3.70 8.45 4.55 8.10 4.12 4.01 4.15 4.08 8.50 5.25 6.87 8.55 9.20 8.87 3.96 5.57 4.77 7.60 6.40 7.00 10.90 11.00 10.95 3.94 4-31 5.82 5.20 7.02 6.56 Note: -::-No 75-60 and 75-90 p l a n t s a t week 1 . # S h i f t e d a t time o f h a r v e s t . ## S h i f t e d f o u r days b e f o r e t h i s h a r v e s t , 8k. was h e a v i e r t h a n B l u e b o n n e t a t t h e f o u r t h week. The n e x t b e s t r e s p o n s e was o b s e r v e d a t 9 0 ° u n t i l , t h e t h i r d week, w i t h C a l o r o s h o w i n g a n i n c r e a s e d g r o w t h o v e r B l u e -b o n n e t . The p e r f o r m a n c e o f 75° t o 9 0 ° was s l i g h t l y l e s s t h a n t h e p r e v i o u s t r e a t m e n t a n d i n t h i s t r e a t m e n t t o o , C a l o r o was s u p e r i o r t o B l u e b o n n e t . T r e a t m e n t o f c o n t i n -uous 75° h a d h i g h e r w e i g h t t h a n e i t h e r 1$°' t o 6 0 ° ' o r 9 0 ° t o 6 0 ° a n d a l l t h e s e C a l o r o h a d more w e i g h t t h a n B l u e -b o n n e t . The c o n t i n u o u s 6 0 ° t r e a t m e n t showed fee l e a s t s h o o t w e i g h t b u t w i t h - m o r e w e i g h t f o r C a l o r o t h a n B l u e - ' b o n n e t . . The e f f e c t s o f t h e s e c o n d t e m p e r a t u r e s w e re f o u n d t o be q u i t e m a r k e d , s u c h ' a s 9 0 ° t o 6 0 ° and 75° t o 6 0 ° , a n d t h i s s t r o n g i n f l u e n c e was n o t e d i n b o t h v a r i e t i e s a l m o s t t o t h e same e x t e n t , a l t h o u g h - C a l o r o m a i n t a i n e d a h i g h e r * w e i g h t u n t i l t h e e n d o f t h e p e r i o d . S i g n i f i c a n t d i f f e r e n c e s i n o v e r a l l t e m p e r a t u r e e f f e c t s w e r e p r e s e n t f o r a l l weeks a n d t e m p e r a t u r e X v a r i e t y i n -t e r a c t i o n s due t o t h e d i f f e r e n t b e h a v i o r o f v a r i e t i e s a t " d i f f e r e n t t e m p e r a t u r e s , were p r e s e n t f o r t h e s e c o n d a n d f o u r t h week. R o o t W e i g h t R o o t W e i g h t ( T a b l e V I I D) showed t h e same p a t t e r n o f r e s p o n s e as i n p r e v i o u s t a b l e s w i t h r e s p e c t t o c o n t i n u o u s 6 0 ° , c o n t i n u o u s 75° and c o n t i n u o u s 9 0 ° . I n a l l t h e s e t r e a t m e n t s C a l o r o was g e n e r a l l y s u p e r i o r t o B l u e b o n n e t . A f t e r t r a n s f e r f r o m 75° t o 6 0 ° , t h e r o o t w e i g h t i n c r e a s e 8 5 . Table VII C E f f e c t of v a r i e t y , water temperature changes, and time of harvest on shoot weight of r i c e seedl ings , (gm.). Temperatures Week 1. V a r i e t i e s 6 0 - 6 0 75-60* 75-75 75-90* 90-60 90-75 9 0 - 9 0 Average Bluebonnet .02 . 1 3 .14-5 . 3 9 .36 . 2 7 Caloro .OLL .11 .1+2 .60 . 5 3 .31+ Average .03 . 1 2 .1+1+. .1+9 .1+1+ TxV ns. T V * Week 2. Bluebonnet . 1 9 . 7 0 .92 .90 .71+ 1.89 2 .15 1 . 0 7 Caloro .21 .99 1.14-9 1.61+ .91 1 .25 2 . 18 1.21+ Average .20 .814, 1 .20 1.27 .82 1.57 2.16 TxV T * V ns. Week 3. Bluebonnet . 1 3 1 .05 2.07 3.1+0 1.12 1+.31+ 3.31+ 2.21 Caloro .27 1.33 3 .25 1+.36 1 .20 1.95* 7.09 2 .78 Average .20 1.19 2.66 3.88 1.16 3 . 1 5 5.22 TxV ns. V ns. Week Li.. Bluebonnet .22 1 .05 3.60 6.09 .88 11 .13 7 .25 1+.31 Caloro .ii.0 1.80 1. 21+* 9.26 1.37 1 5 . 3 0 2 .23* : 5.33 Average .31 1.14-3 2.1+2" 7.67 1.13 13.21 1+.71+ TxV «• T * V ns. Note: * No 75-60 and 75-90 plants at week 1. * The growth of Caloro was adversely af fected by algae and poss ib ly unfavourable"soi l -condi t ions . 86 T a b l e V I I D E f f e c t o f v a r i e t y , w a t e r t e m p e r a t u r e c h a n g e s , a n d t i m e o f h a r v e s t on r o o t w e i g h t o f r i c e s e e d l i n g s , (gm.). T e m p e r a t u r e s Week 1. V a r i e t i e s 60-60 75-60" 75-75 75-90""" 90-60 90-75 90-90 A v e r a ^ B l u e b o n n e t .01 ,0k .07 .09 .Ok .05 C a l o r o .02 .02 .08 .10 .08 .06 A v e r a g e .01 .03 .07 .09 .06 TxV n s . T -* V n s . Week 2. B l u e b o n n e t .11 .17 .17 .11+ .16 .17 .11 .14 C a l o r o .08 .22 .29 .25 .16 .19 .24 .20 A v e r a g e .10 .19 .23 .19 .16 .18 .17 TxV T n s . V * Week 3. B l u e b o n n e t .05 .12 .22 .39 .23 .76 .55 .33 C a l o r o .08 .2k .61 .70 .17 .26* .65 .38 A v e r a g e .06 .18 .k1 .54 .20 .51 .60 TxV # T n s . V n s . Week 4* B l u e b o n n e t .07 .15 M .67 .13 1 .22 1 .22 C a l o r o .07 .22 . i k * : 1.51 .13 2 .27 .25^ * .65 A v e r a g e .07 .16 .38" 1.09 .13 1.74 .73" • TxV T n s . V n s . N o t e : No 75-60 a n d 75-90 p l a n t s a t week 1. * P o o r r o o t g r o w t h p o s s i b l y due t o p o o r s o i l c o n d i t i o n . 8 $ . was n e g l i g i b l e y e t C a l o r o showed a h i g h e r w e i g h t than Bluebonnet. The e f f e c t o f 90° t o 60° and 75° t o 60° was e s s e n t i a l l y the same, w i t h C a l o r o a g a i n b e i n g h i g h e r i n r o o t w e i g h t . A l s o a t 75° t o 90° and 90° to 75° the performance of C a l o r o was s u p e r i o r . The r a t e o f growth r e l a t i v e . t o the p r e v i o u s growth under b o t h these t r e a t -ments was c o n s i d e r a b l y h i g h e r a t the f o u r t h week. Seed Reserve Averages o f a l l t r e a t m e n t s f o r the two v a r i e t i e s s e p a r a t e l y as g i v e n i n Table- V I I E, showed' a h i g h e r seed r e s i d u e weight f o r Bl u e b o n n e t . H i g h e s t w e i g h t was r e -c o r d e d f o r Bluebonnet a t 60° and t h e next two i n o r d e r of decrease were 75° t o 60° and 90° to 60°. Treatments 75° t o 90° and 90° t o 75° b o t h had drops i n r e s i d u e w e i g h t s almost o f the same magnitude. I n the former t r e a t m e n t , Bluebonnet had more weight f o r a l l weeks w h i l e i n the l a t t e r t r e a t m e n t , Bluebonnet had more weight f o r -the f i r s t two weeks o n l y . Both the above t r e a t m e n t s showed the g r e a t e s t l o s s at the end o f the f i r s t week. Seed r e s i d u e l o s s a t c o n t i n u o u s 90° and c o n t i n u o u s 75° a l s o f i t t e d i n t o t h i s p a t t e r n , i n d i c a t i n g a g r e a t e r l o s s at the i n c e p t i o n o f h i g h temperature e f f e c t . A d i f f e r e n c e f r o m t h i s s i t u a t i o n was the l o s s o f seed r e s i d u e a t 60° which was g r a d u a l f o r a l l weeks, so t h a t the l o s s f r om each week to the ne x t was almost e q u a l i n magnitude. T h i s d e c r e a s e d e f f e c t was a l s o e x h i b i t e d i n t r e a t m e n t s 88. T a b l e V I I E E f f e c t o f v a r i e t y , w a t e r temperature changes, and time o f h a r v e s t on seed r e s i d u e o f r i c e s e e d l i n g s , (gm.). Week 1 Temperatures V a r i e t i e s B luebonnet C a l o r o Average Bluebonnet C a l o r o Average Bluebonnet C a l o r o Average Bluebonnet C a l o r o Average 60-60 75-60* 75-75 75-90* 90-60 90 -75 90-90 Average 2.1+2 2.1+3 2.21 2.06 2.11+ 1.60 1 .73 1.66 1 1 1 .69 •H-2 .55 1.1+7 1.59 1.53 1.88 1.85 TxV ns. T V n s . Week 2. 2.91 2.79 2.85 1.65 1.51 1.58 1.29 .92 1.10 1.11+ .66 .90 1.55 1.37 1.1+6 •84 .8T .83 .60 .63 .61 1.1+2 1.21+ TxV ns. T V -:c-Week 3. 2.60 2.01+ 2.32 1.38 1.13 1.25 .79 .72 .75 .72 .68 .70 1.39 1.17 1.28 .1+0 .83 .62 .61 .67 .61+ 1.12 1.03 TxV n s. T V ns. Week 1+. 2.00 1.58 1.79 1.12 .89 1 .00 .73 .61 .67 .63 .58 .60 1.08 .89 .98 .58 .67 .62 .73 .62 .67 .98 .83 TxV ns. T V Note: "No 75-60 and 75-90 p l a n t s a t week 1 89. w h e r e 60 was f o l l o w e d b y e i t h e r o f t h e h i g h e r t e m p e r a -t u r e s . S t a t i s t i c a l a n a l y s i s i n d i c a t e d t h a t t h e r e was a h i g h l y s i g n i f i c a n t d i f f e r e n c e i n t e m p e r a t u r e e f f e c t f o r a l l w e e k s . A s i g n i f i c a n t d i f f e r e n c e i n v a r i e t i e s was a l s o shox«i a t t h e s e c o n d week a n d a g a i n a t t h e f o u r t h week due t o t h e h i g h e r s e e d r e s i d u e w e i g h t s o f B l u e b o n n e t . F r e s h W e i g h t T a b l e V I I F shows t h e g e n e r a l p a t t e r n o f w e i g h t i n c r e a s e w i t h an i n c r e a s e i n t e m p e r a t u r e a n d w i t h weeks o f g r o w t h . W i t h t h e e x c e p t i o n o f t r e a t m e n t s i n v o l v i n g 6 0 ° t h e r e was no a p p a r e n t r e l a t i v e i n c r e a s e f r o m t h e f i r s t week t o t h e t h i r d week. T h e r e f o r e , t r e a t m e n t s 9 0 ° t o 75° , c o n t i n u o u s 9 0 ° , 75° t o 9 0 ° and c o n t i n u o u s 75° h a d w e i g h t i n c r e a s e s o f t h e same g e n e r a l o r d e r . T r e a t m e n t s 75° t o 6 0 ° and 9 0 ° t o 6 0 ° were e s s e n t i a l l y t h e same w e i g h t , a n d c o n t i n u o u s 6 0 ° h a d t h e l o w e s t r e s p o n s e o f a l l t h e t r e a t m e n t s . A l l t r e a t m e n t s e x c e p t -i n g t h e l a t t e r one where b o t h v a r i e t i e s were e q u a l h a d C a l o r o s u r p a s s i n g B l u e b o n n e t . S t a t i s t i c a l e v a l u a t i o n i n d i c a t e d t h a t t h e r e was a s i g n i f i c a n t d i f f e r e n c e i n t e m p e r a t u r e e f f e c t s u n t i l t h e e n d o f t h e t h i r d week. 90. T a b l e V I I F E f f e c t o f v a r i e t y , w a t e r t e m p e r a t u r e c h a n g e s , a n d t i m e o f h a r v e s t o n t o t a l f r e s h w e i g h t o f s e e d l i n g s , ( g m . ) . " T e m p e r a t u r e s Week 1. 60-60 75-60+ 75-75 75-90+ 90-60 9 0 - 7 5 9 0 - 9 0 A v e r a g e V a r i e t i e s B l u e b o n n e t . 0 3 . 0 k . 0 6 .07 . 9 6 . 0 5 C a l o r o . 0 k • 0k . 0 6 .09 . 0 7 . 0 6 A v e r a g e .0k . o k . 0 o . 0 8 . 0 6 TxV n s . T :- V % Week 2 . B l u e b o n n e t . 0 k . 0 5 . 0 6 . 0 8 . 0 6 . 13 . . 13 . 0 8 C a l o r o . 0 k . 0 6 .10 . 1k . 0 7 . 1 0 .17 . 1 0 A v e r a g e . 0 k . 0 6 . 0 8 .11 . 0 7 .11 .15 TxV -:HC- T * V n s . Week 3 . B l u e b o n n e t . o k . 0 7 .16 .26 . 1 0 . . k 0 • k9 . 2 2 C a l o r o .Ok .11 . 2 5 • k7 .09 . 3 2 . 5 9 . 2 7 A v e r a g e • . 0 k .09 . 2 0 . 3 6 .09 . 3 6 • 5k TxV n s . T * V ns Week k» B l u e b o n n e t .11 . 17 . 5 0 . 5 0 . 15 . 8 5 . 7 5 • k 3 C a l o r o .11 . 15 . 5 2 1 . 0 2 .17 2 . 0 5 .18+ + . 6 0 A v e r a g e .11 .16 .51 . . 7 6 . 16 1 . k 5 • k7 TxV -:c- T n s . V n s . N o t e : + P l a n t s were n o t a v a i l a b l e f o r h a r v e s t a t week 1. ++ P o o r g r o w t h p o s s i b l y due t o u n f a v o u r a b l e s o i l c o n d i t i o n . 91 E x p e r i m e n t V I I I The t e m p e r a t u r e e f f e c t o n c r y s t a l f o r m a t i o n was c l e a r l y shown by t h e o c c u r e n c e o f more t y p e s a nd numbers o f c r y s t a l s a t h i g h e r t e m p e r a t u r e s , ( T a b l e V I I I A t o E ) . T h e r e was no a p p r e c i a b l e d i f f e r e n c e b e t w e e n t h e two v a r i e t i e s i n t h e n u m b e r s , t y p e , and l e n g t h o f c r y s t a l s f o r m e d a t a l l t e m p e r a t u r e s . A t 9 0 ° , a t l e a s t f o u r c r y s t a l t y p e s w e re d e p o s i t e d , ( P l a t e s V l f t a n d V I b ) and a t 75° t h r e e o r more t y p e s were d e p o s i t e d , ( P l a t e s V a and V b ) . U s u a l l y two o r t h r e e t y p e s o f c r y s t a l s were f o r m e d a t 6 u ° and t h e i n t e n s i t y o f s i l i c a d e p o s i t i o n was c o n s i d e r a b l y l o w e r ( P l a t e s I V a a n d I V b ) . C r y s t a l s "A" a n d "D" t y p e s were n o t o b s e r v e d a t 6 0 ° . The number o f "B" a n d "C" were a l s o e x t r e m e l y l o w . O n l y c r y s t a l "E" was a l w a y s p r e s e n t . -When t h e number o f c r y s t a l s o f t h e "E" t y p e p e r .066;: mm. l i n e a r d i s t a n c e was c o m p a r e d a t d i f f e r e n t t e m p e r a t u r e s , i t was f o u n d t h a t t h e r e was a s l i g h t , t e n d e n c y f o r a g r e a t e r , n u m b e r t o o c c u r a t h i g h e r tem-p e r a t u r e s . A c o m p a r i s o n o f t h e two v a r i e t i e s r e v e a l e d t h a t B l u e b o n n e t was s l i g h t l y h i g h e r t h a n C a l o r o , ( T a b l e V I I I E ) . C r y s t a l "A" t y p e t e n d e d t o d i s a p p e a r a t t h e e n d o f t h r e e weeks i n s p i t e o f t h e i r o c c u r e n c e a t t h e two e a r l i e r weeks f o r a l l t e m p e r a t u r e t r e a t m e n t s ( e s p e c i a l l y a t 9 0 ° ) . 92. T a b l e V I I I A "A" Type Week I I Temp. 60 75 90 E f f e c t o f v a r i e t y , water t e m p e r a t u r e , and time o f o b s e r v a t i o n on the i n t e n s i t y and the f o r m a t i o n o f "A" and "B " type s i l i c a c r y s t a l s on the l e a f l a m i n a o f r i c e s e e d l i n g s . A P P VP absent p r e s e n t few v e r y few Bluebonnet C a l o r o Week I I I Bluebonnet C a l o r o A F P A VP P Temp. 60 75 90 A A P A VP VF Week IV Temp. 60 75 90 Bluebonnet C a l o r o A A A A A A Table V I I I B "B" Type Week I I Bluebonnet C a l o r o Temp. 60 75 -90 P P P A F P Week I I I Bluebonnet C a l o r o Temp. 60 75 90 F P P A P F Week IV Bluebonnet C a l o r o Temp. 60 P A 75 F P 90 P VP 9 3 . T a b l e V I I I C E f f e c t o f v a r i e t y , w a t e r t e m p e r a t u r e , a n d t i m e o f o b s e r v a t i o n o n t h e i n t e n s i t y a n d t h e l e n g t h o f "C" t y p e s i l i c a c r y s t a l s o n t h e l e a f l a m i n a o f r i c e s e e d l i n g s . "C" Type Week I I B l u e b o n n e t G a l o r o A v e r a g e Temp. 60 VP A 11.5 75 11.0 12.0 90 13.5 18.5 16.0 A v e r a g e 12.3 15.3 Week I I I B l u e b o n n e t C a l o r o A v e r a g e Temp. 60 A A 15.8 75 15.0 16 . 5 90 11.5 15.5 13.5 A v e r a g e 13.3 16.0 Week I V B l u e b o n n e t C a l o r o A v e r a g e Temp. 60 A A 75 15.0 16 .5 15.8 90 1LL.5 16 .5 15.5 A v e r a g e '11+. 7 16 .5 T a b l e V I I I D (Same T r e a t m e n t s as i n T a b l e V I I I C) "D" Type Week I I B l u e b o n n e t C a l o r o A v e r a g e Temp. 60 A A 75 18.5 22 . 5 20 .5 90 19 .5 22.0 20.8 A v e r a g e 19.0 22 . 3 Week I I I B l u e b o n n e t C a l o r o A v e r a g e Temp. 60 A A 75 19.5 19.5 19.5 90 19.0 23.0 21.0 A v e r a g e 19 .3 21 .3 Week I V B l u e b o n n e t C a l o r o A v e r a g e Temp. 60 A A 75 28.0 27.0 27.5 90 19.5 21.5 20.5 A v e r a g e 23.8 2LL.3 F a c t o r i a l a n a l y s i s - Week X t e m p e r a t u r e X v a r i e t y . No s i g n i f i c a n t d i f f e r e n c e s w e r e p r e s e n t f o r b o t h t y p e s o f c r y s t a l s . 9k. T a b l e V I I I E E f f e c t o f v a r i e t y , w a t e r t e m p e r a t u r e , a n d f o r m a t i o n o f "E" t y p e o f c r y s t a l s o n t h e l e a f l a m i n a o f r i c e s e e d l i n g s . "E" Type V a r i e t i e s Week I I Temp.°P 60 75 90 A v e r a g e B l u e b o n n e t k.o k - 5 6.0 1+.8 C a l o r o 1.5 k.o k.S 3.3 A v e r a g e 2.8 k-3 5.3 Week I I I Temp.°F 60 75 90 A v e r a g e B l u e b o n n e t 3.0 k.O 5.0 k . o C a l o r o 3.0 3.5 5.0 3.8 A v e r a g e 3.0 3.8 5.0 Week I V Temp.°P 60 75 90 A v e r a g e B l u e b o n n e t 3.0 k . o 5 .o k . o C a l o r o 3.0 k . o k . o 3.7 A v e r a g e 3.0 k . o k .5 F a c t o r i a l a n a l y s i s - week X t e m p e r a t u r e X v a r i e t y No s i g n i f i c a n t d i f f e r e n c e s were p r e s e n t . 9 5 . P l a t e I V a P l a t e I V b P l a t e s I V a and b show t h e c r y s t a l s f o r m e d a t 6 0 P t e m p e r a t u r e t r e a t m e n t s . C r y s t a l "E" t y p e i s n o t i n f o c u s t h o u g h p r e s e n t i n b o t h p i a t e s . P l a t e V b. P l a t e s V a and b show c r y s t a l s C,D, and E t y p e s f o r m e d a t 75* F; B t y p e c r y s t a l s a r e a l s o f r e q u e n t t h o u g h n o t i n f o c u s . 9 7 . P l a t e VI b . In P l a t e s VI a a n d b , r e p r e s e n t i n g 90* F t r e a t m e n t s , f o u r t y p e s o f c r y s t a l s a r e shown, A, G, D, a n d E. Though B i s n o t s e e n i n t h e s e two f i e l d s , i t i s a l s o p r e s e n t a t 9 0 ° F. 98 An e x a m i n a t i o n o f T a b l e s V I I I C a n d D, shows t h a t a l t h o u g h t h e l e n g t h o f t h e "C" t y p e c r y s t a l s f o r t h e f i r s t two weeks a t h i g h e r t e m p e r a t u r e s was n o t t o o c o n -s i s t e n t , an a l m o s t e q u a l l e n g t h was o b s e r v e d a t t h e e n d o f t h r e e weeks. I n g e n e r a l , t h e v a r i e t y C a l o r o h a d l a r g e r c r y s t a l s t h a n B l u e b o n n e t . T h e r e was no d i f f e r -e n c e i n t h e l e n g t h o f "D" c r y s t a l s as a c o n s e q u e n c e o f v a r y i n g t e m p e r a t u r e s f o r t h e f i r s t two w e e k s . The o c c u r r e n c e o f g r e a t e r l e n g t h s a t 75° a t t h e f o u r t h week h o w e v e r , was o b s e r v e d . T h e r e were no o b v i o u s d i f f e r e n c e s b e t w e e n C a l o r o a n d B l u e b o n n e t a l t h o u g h t h e f o r m e r h a d somewhat l a r g e r c r y s t a l s . d u r i n g t h e t h r e e weeks, a n d t h e d i f f e r e n c e t e n d e d t o d e c r e a s e w i t h t h e t i m e . E x p e r i m e n t I X R o o t T i p C e l l s As shown i n T a b l e I X A, t h e r o o t t i p s o f C a l o r o a n d B l u e b o n n e t b o t h h a d a l a r g e r number o f c e l l s when g r o w n a t 60°. The number was i n t e r m e d i a t e a t 75° and was l o w e s t a t 90°. The d e c r e a s e i n c e l l number f r o m 6 0 °to 75° was g r e a t e r i n C a l o r o t h a n B l u e b o n n e t . I n g e n e r a l , b o t h v a r i e t i e s h a d a g r e a t e r d r o p f r o m t h e 60° t o 75° and a l e s s e r d r o p f r o m t h e 75° t o 90°. The a v e r a g e number o f r o o t t i p c e l l s f o r a l l t h r e e t e m p e r a t u r e s was more f o r C a l o r o t h a n f o r B l u e b o n n e t . 99. T a b l e I X E f f e c t o f v a r i e t y a n d w a t e r t e m p e r a t u r e o n t h e number of' r o o t t i p c e l l s o f r i c e s e e d l i n g s , (number o f c e l l s p e r mm. r o o t t i p ) . T e m p e r a t u r e °P B l u e b o n n e t C a l o r o A v e r a g e 60° 6000 8700 7000 11000 6I4.OO 9600 A v e r a g e 61+00 9800 8100 75° 5100 6200 5000 6000 55oo 5800 A v e r a g e 5200 6000 5600 90° J4.100 3900 3800 3600 14.100 3600 A v e r a g e 1+000 3700 3850 TxV T n s . V n s . 100. DISCUSSION The d a t a o b t a i n e d f o r s h o o t l e n g t h a n d s h o o t w e i g h t i n d i c a t e d t h a t t h e l e a v e s I n a l l v a r i e t i e s a r e l o n g e r a n d s e e d l i n g s w e i g h more a t t e m p e r a t u r e s o f 90° t h a n a t 75° a n d a t 80° o r 75° t h a n a t 60°F. C a l i f o r n i a v a -r i e t i e s g e n e r a l l y h a v e l o n g e r l e a v e s a n d s e e d l i n g s w e i g h more t h a n s o u t h e r n v a r i e t i e s g r o w i n g u n d e r t h e same c o n -d i t i o n s . I n p a r t i c u l a r C a l o r o l e a v e s a r e g e n e r a l l y l o n g e r a n d t h e s e e d l i n g s h e a v i e r t h a n B l u e b o n n e t . B l u e -b o n n e t h a d l o n g e r l e a v e s u n d e r s u b m e r g e d c o n d i t i o n s t h a n u n d e r n o n - s u b m e r g e d , b u t i t was n o t c o n s i s t e n t l y h e a v i e r u n d e r s u c h c o n d i t i o n s . On t h e o t h e r h a n d , C a l o r o was b o t h l o n g e r a n d h e a v i e r u n d e r n o n - s u b m e r g e d c o n d i t i o n s . C h a u d h r y a n d McLean (1963) r e p o r t e d t h a t r i c e s e e d l i n g s o f s o u t h e r n v a r i e t y z e n i t h m a n i f e s t e d d i f f e r e n c e s i n g r o w t h due t o d i f f e r e n t s u b m e r g e n c e t r e a t m e n t s o n l y a f t e r 37 d a y s . I n t h e i r e x p e r i m e n t t h e y f o u n d t h a t p l a n t s u n d e r f l o o d e d c o n d i t i o n s grew t a l l e r , p r o d u c e d h e a l t h i e r t i l l e r s a n d m a i n t a i n e d t h e i r s u p e r i o r i t y u n t i l m a t u r i t y o v e r t h o s e under- u n f l o o d e d c o n d i t i o n s . I t i s q u e s t i o n -a b l e w h e t h e r t h e same r e s u l t s c o u l d be m a i n t a i n e d w i t h a C a l i f o r n i a n v a r i e t y l i k e C a l o r o . P r e v i o u s g r o w i n g c o n d i t i o n s d i d n o t n o r m a l l y , m a r k e d l y a f f e c t t h e r e s p o n s e t o a new g r o w i n g c o n d i t i o n o i n t h e p r e -s e n t e x p e r i m e n t s . When t h e t e m p e r a t u r e was r e d u c e d t o 60°, g r o w t h o f s h o o t s a l m o s t c e a s e d . The C a l i f o r n i a v a r i e t y , 101 . C a l o r o , tended t o grow f a s t e r d u r i n g the f i i ? s t week i n 60° a f t e r t r a n s f e r f r o m a h i g h e r t e m p e r a t u r e . When grown a t 75°, a f t e r 90°, growth c o n t i n u e d unabated, w i t h C a l o r o showing an advantage a f t e r t h r e e weeks. At h i g h e r c o n t i n u o u s t e m p e r a t u r e s , 75° o r 90°, b o t h v a r i e -t i e s i n c r e a s e d growth e q u a l l y . I t i s g e n e r a l l y conceded t h a t the s t u d y o f r o o t s i s more d i f f i c u l t t h a n the s t u d y o f s h o o t s . A l t h o u g h the p l a n t s were grown under submerged c o n d i t i o n s i n most e x p e r i m e n t s , i t was found d i f f i c u l t t o remove i n -d i v i d u a l p l a n t s f r o m a p o t w i t h o u t p o s s i b l y l e a v i n g a p a r t o f the r o o t system i n the p o t . I n the submerged and non-submerged e x p e r i m e n t , t h i s d i f f i c u l t y was p a r -t i c u l a r l y e n c o u n t e r e d i n the f o r m e r t r e a t m e n t . Never-t h e l e s s , a p l a n t s t u d y w i t h o u t r o o t s t u d y i s c e r t a i n l y i n c o m p l e t e and t h i s knowledge of r o o t , h a r d though i t may be t o g a i n , s h o u l d be v i g o r o u s l y sought. I n the development of the r o o t system, b o t h r o o t l e n g t h and weight response t o temperature are somewhat comparable to the response o f shoot l e n g t h and w e i g h t . Root l e n g t h and w e i g h t i n c r e a s e d w i t h an i n c r e a s e i n t e m p e r a t u r e . Takano (1957) r e p o r t e d t h a t b o t h r o o t e l o n g a t i o n and the r a t i o : . i o f r o o t w e i g h t t o weight o f top r e a c h e d a maximum at temperatures around 32° C. Yamakawa (1961) o b s e r v e d t h a t i n two low temperature t r e a t m e n t s , (5°C and 10°C), the m i t o t i c p r o c e s s i n the r o o t t i p s o f r i c e was g r e a t l y r e d u c e d as compared to a 102 25 C t r e a t m e n t , s h o w i n g l e s s i n t e n s i t y o f c e l l d i v i s i o n i n 5°G t r e a t m e n t t h a n i n 10°C t r e a t m e n t . A l s o t h e e l o n g a t i o n o f c o r t i c a l c e l l s i n t h e r o o t t i p s w h i c h r e c e i v e d t h e l o w t e m p e r a t u r e showed a m a r k e d i n h i b i t i o n when c o m p a r e d t o t h a t i n t h e h i g h t r e a t m e n t ( 2 5°G), b u t no s i g n i f i c a n t d i f f e r e n c e b e t w e e n th e l o w t e m p e r a t u r e t r e a t m e n t s was s e e n . H o w e v e r , t h i s r a t e o f r o o t c e l l d i v i s i o n a nd c e l l e l o n g a t i o n c o u l d d i f f e r d e p e n d e n t on t h e v a r i e t y b e i n g u s e d . I n t h e p r e s e n t s t u d y i t was n o t e d t h a t s o u t h e r n • v a r i e t i e s h a d a t e n d e n c y t o d e v e l o p S h o r t e r r o o t l e n g t h t h a n t h e C a l i f o r n i a n v a r i e t i e s a t l o w t e m p e r a t u r e s . On t h e o t h e r h a n d , t h e r e was no d i f -f e r e n c e among t h e v a r i e t i e s i n r o o t l e n g t h a t • t h e e n d o f t h r e e weeks a t h i g h t e m p e r a t u r e s . R o o t g r o w t h u n d e r s u b m e r g e d c o n d i t i o n s d e p e n d e d t o a g r e a t e x t e n t o n t h e w a t e r t e m p e r a t u r e . A t 60° t h e g r o w t h was h i g h l y r e t a r d e d , w h e r e a s a t 75° o r 90° t h e r o o t s y s t e m g r e w l o n g e r a n d a c c u m u l a t e d more d r y w e i g h t B u t u n d e r n o n - s u b m e r g e d c o n d i t i o n s , p l a n t s i n t h e 60° t e m p e r a t u r e h a d r e l a t i v e l y b e t t e r r o o t g r o w t h t h a n 60° u n d e r s u b m e r g e d c o n d i t i o n s . T h i s c o u l d be e x p l a i n e d o b y t h e f a c t t h a t , u n l i k e t h e s u b m e r g e d 60 t r e a t m e n t , a i r t e m p e r a t u r e f o r n o n - s u b m e r g e d p l a n t s ( a b o u t 75°) h a d a n i n f l u e n c e on t h e g r o w t h o f s h o o t s w h i c h may h a v e c a u s e d more a c c u m u l a t i o n o f d r y m a t t e r i n t h e r o o t s y s -tem. I t i s a l s o l i k e l y t h a t t h e s u r f a c e l a y e r o f t h e 103. p o t h a d a s l i g h t l y h i g h e r t e m p e r a t u r e t h a n t h a t o f t h e w a t e r b a t h (60°). F u r t h e r m o r e t h e r e a d y a v a i l a b i l i t y o f o x y g e n t o t h e r o o t s y s t e m as a r e s u l t o f n o n - s u b -m e r g e n c e c o u l d a l s o be a c o n t r i b u t o r y f a c t o r . . S a t o (19^1) o b s e r v e d t h a t t h e s u b m e r g e n c e o f r i c e d u r i n g l o w t e m p e r a t u r e r e g i m e s h a s a b e n e f i c i a l e f f e c t o n g r o w t h , as a r e s u l t o f r a i s i n g t h e s o i l a n d w a t e r t e m p e r a t u r e s s u r r o u n d i n g t h e r i c e p l a n t s , e s p e c i a l l y a t n i g h t b e c a u s e o f t h e h i g h s p e c i f i c h e a t o f w a t e r . Bub when t h e a i r t e m p e r a t u r e r i s e s f a i r l y h i g h , s u b -m e r g ence t e n d s t o be l e s s e f f e c t i v e a n d c o u l d e v e n be d e t r i m e n t a l t o t h e g r o w t h o f t h e r o o t s y s t e m as a r e -s u l t o f l a c k o f d r a i n a g e a n d a e r a t i o n . On t h i s b a s i s i t c o u l d be e x p l a i n e d e a s i l y t h a t t h e c a u s e f o r b e t t e r r o o t a n d s h o o t g r o w t h was t h e e f f e c t o f h i g h e r tem-p e r a t u r e s u n d e r s u b m e r g e d c o n d i t i o n s . C o m p a r i n g t h e two v a r i e t i e s g e n e r a l l y , B l u e b o n n e t h a d l o n g e r r o o t s a t 90° u n d e r s u b m e r g e d c o n d i t i o n s a n d a t 90° o r 75° u n d e r n o n - s u b m e r g e d c o n d i t i o n s , w h e r e a s C a l o r o h a d l o n g e r r o o t s a t 75° u n d e r s u b m e r g e d a n d a t 60° o r 75° u n d e r n o n - s u b m e r g e d c o n d i t i o n s . S h i f t i n g o f p l a n t s f r o m one t e m p e r a t u r e t o a n o t h e r h a d no a p p r e c i a b l e e f f e c t o n t h e r o o t l e n g t h . H o w e v e r , t h e w e i g h t o f r o o t s i n d i c a t e d t h a t when t e m p e r a t u r e s w e r e d e c r e a s e d f r o m 75° t o 60°, o r 90° t o 60°, t h e grow -almost c e a s e d . On t h e o t h e r h a n d , i f t e m p e r a t u r e s were 10k. i n c r e a s e d f r o m 60° t o 7 5 ° , 60° t o 90°, o r 75° t o 90°, t h e w e i g h t o f r o o t i n c r e a s e d , t h e m a g n i t u d e o f i n -c r e a s e b e i n g d e p e n d a n t on t h e s u b s e q u e n t t e m p e r a t u r e . I f t h e p l a n t s were a l l o w e d t o grow a t t h e s e c o n d tem-p e r a t u r e s f o r a l o n g e r p e r i o d , g r e a t e r d i f f e r e n c e s w o u l d be m a n i f e s t e d . I n a l m o s t a l l t e m p e r a t u r e t r e a t -m e nts C a l o r o r e s p o n d e d w i t h more g r o w t h t h a n B l u e b o n n e t and m a i n t a i n e d t h e s u p e r i o r i t y u n t i l f o u r weeks when b o t h v a r i e t i e s t e n d e d t o be e q u a l i n w e i g h t a t h i g h e r t e m p e r a t u r e s . Chapman a n d P e t e r s o n ( 1 9 6 2 ) r e p o r t e d t h a t s e e d l i n g s w e r e more f i r m l y a t t a c h e d t o t h e s o i l when g r o w n a t l o w t e m p e r a t u r e s a n d were l o o s e l y a t t a c h e d t o t h e s o i l o r f l o a t i n g i n w a t e r I f t h e t e m p e r a t u r e s were a r o u n d 35°G, i n s p i t e o f t h e i r h a v i n g w e l l d e v e l o p e d r o o t s y s t e m s . S i m i l a r o b s e r v a t i o n s were made i n t h e s e r i e s o f e x p e r i -ments c o n d u c t e d f o r t h i s s t u d y . T h e r e was a h i g h i n c i -d e n c e o f f l o a t i n g s e e d l i n g s i n t h e 90° t e m p e r a t u r e w a t e r bath... T h i s phenomena was o c c a s i o n a l l y p r e s e n t a t 75° a n d c o m p l e t e l y a b s e n t a t 60°. I t was a l s o o b s e r v e d t h a t t h e number o f f l o a t i n g s e e d l i n g s ' was g r e a t e r w i t h t h e u s e o f g r e e n h o u s e s o i l t h a n w i t h h e a v i e r s o i l . P r o m t h e r e s u l t s o f e a r l i e r w o r k , i t was e v i d e n t t h a t a d i r e c t c o r r e l a t i o n e x i s t s b e t w e e n r o o t w e i g h t s a n d s h o o t w e i g h t s . H e nce a h e a l t h y s e e d l i n g s h o u l d n o t o n l y h a v e a w e l l - d e v e l o p e d a b o v e - g r o u n d g r o w t h , b u t a l s o 105. a s a t i s f a c t o r y u n d e r g r o u n d g r o w t h . T o g a r i a n d T a k a s h i (1961) s u p p o r t e d t h e i d e a t h a t r o o t s a r e n o t o n l y t h e o r g a n s w h i c h a b s o r b t h e n u t r i e n t s and w a t e r , b u t t h e y a l s o s y n t h e s i z e t h e v a r i o u s c h e m i c a l s u b s t a n c e s n e c e s -s a r y f o r g r o w t h . T h e r e f o r e a r e d u c t i o n i n t h e t e m p e r a -t u r e b r i n g s a b o u t an i n h i b i t i o n o f t h e p r o c e s s c o n c e r n e d w i t h t h e p o l y m e r i z a t i o n o f amino a c i d s ; t h i s i n t u r n b r i n g s a b o u t a n i n c r e a s e i n n o n - p r o t e i n n i t r o g e n a n d a c o r r e s p o n d i n g d e c r e a s e i n p r o t e i n . As a c o n s e q u e n c e o f t h e i n h i b i t i o n o f t h e s e p h y s i o l o g i c a l f u n c t i o n s , t h e g e n e r a l g r o w t h o f t h e p l a n t i s r e t a r d e d ! S e e d w e i g h t a n a l y s i s c a r r i e d o u t by t h e a u t h o r (1962) showed a h i g h v a r i a t i o n among d i f f e r e n t v a r i e t i e s . C a l i f o r n i a n v a r i e t i e s w e r e h e a v i e r t h a n t h e s o u t h e r n v a r i e t i e s . H o w e v e r , t h e r e was no d e f i n i t e c o r r e l a t i o n b e t w e e n t h e o r i g i n a l s e e d w e i g h t a n d s h o o t w e i g h t . T h e r e -f o r e , i t i s e v i d e n t t h a t t h e s u b s e q u e n t y i e l d o f a p l a n t d o e s n o t n e c e s s a r i l y d e p e n d on i t s s e e d s i z e . N e v e r t h e -l e s s , g e r m i n a t i o n o f r i c e u n d e r w a t e r i s a c c o m p l i s h e d b y a g r e a t e r l o s s o f d r y m a t t e r a n d c h a n g e s i n p r o p e r t i e s o f c o l l o i d a l s u b s t a n c e s . E r y g i n (1936) s t a t e d t h a t t h e s u p e r i o r p e r f o r m a n c e o f C a l i f o r n i a n v a r i e t i e s i n s e e d -l i n g e s t a b l i s h m e n t may be p a r t l y a t t r i b u t e d t o t h i s i n -h e r e n t a d v a n t a g e . U n d e r g r a d u a t e T h e s i s . 106. G e n e r a l l y t h e s e e d r e s e r v e was f o u n d t o d e c r e a s e p r o g r e s s i v e l y w i t h t i m e a t a l l t h r e e t e m p e r a t u r e s . A l t h o u g h t h e ' C a l i f o r n i a n v a r i e t i e s h a d a h i g h s e e d r e s e r v e a t t h e i n i t i a l s t a t e s o f g r o w t h , t h e r a t e o f d e c r e a s e was r e l a t i v e l y h i g h e r t h a n t h e s o u t h e r n v a -r i e t i e s , a n d as a c o n s e q u e n c e , b o t h t y p e s o f v a r i e t i e s w e r e l e f t w i t h a b o u t t h e same amount o f s e e d r e s e r v e a t t h e e n d o f f o u r w e e k s . More s e e d r e s e r v e was u s e d a t h i g h e r t e m p e r a t u r e s , a n d t h e s e e d r e s e r v e w e i g h t s r e c o r d e d a t e a c h week a p p e a r e d l e s s w i t h i n c r e a s e i n t e m p e r a t u r e i n t h e f o l l o w i n g d e c r e a s i n g o r d e r : 60°, 7 5 ° , and 90°. The l o s s o f s e e d r e s i d u e w e i g h t a t 60° f o r e a c h week was much s l o w e r a n d r e g u l a r t h a n a t 75° and 90° f o r w h i c h t h e g r e a t e s t l o s s was i n t h e f i r s t week a n d a l e s s p r o n o u n c e d l o s s d u r i n g s u b s e q u e n t w e e k s . V a r i e t y d i f f e r e n c e s showed a d e c r e a s e w i t h an i n -c r e a s e i n t e m p e r a t u r e a n d w i t h t i m e a f t e r s o w i n g . U n d er s u b m e r g e d c o n d i t i o n s , a t a l l t e m p e r a t u r e s , B l u e b o n n e t g e n e r a l l y u s e d r e l a t i v e l y more s e e d r e s e r v e t h a n C o l o r o , w h i l e u n d e r n o n - s u b m e r g e d c o n d i t i o n s , t h e r e v e r s e was t r u e . When s e e d l i n g s were moved f r o m one t e m p e r a t u r e t o a n o t h e r , t h e r e was a m a r k e d e f f e c t o f t h e s u b s e q u e n t t e m p e r a t u r e s on t h e s e e d r e s e r v e l o s s . When c h a n g e d f r o m 75° t o 60° a n d 90° t o 60°, t h e y b e h a v e d i n t h e same 107. way, a f t e r the f i r s t week, as though they had been grown a t 60°. S i m i l a r l y , 75° t o 90°, and 9 0 ° t o 75° showed the same p a t t e r n o f b e h a v i o r , w i t h g r e a t e r d e c r e a s e s a t the end o f the f i r s t week f o l l o w e d by subsequent s l i g h t d e c r e a s e s . E n j i (1962) worked w i t h two v a r i e t i e s r e p r e s e n t i n g u p l a n d and swamp r i c e and e s t a b l i s h e d the t h e o r y t h a t t h e r e i s a l i n e a r r e l a t i o n s h i p between the l e n g t h o f l e a f s h e a t h and t h a t o f l e a f l a m i n a i n b o t h v a r i e t i e s o f r i c e . A r e d u c t i o n i n the l e n g t h o f the u p l a n d r i c e v a r i e t y t h a t was brought about by w a t e r l o g g e d c o n d i t i o n s was caused by a decrease i n the l e a f l a m i n a and t h e r e -f o r e l e d to a decrease i n the s i z e o f the p l a n t . I n the swamp- r i c e v a r i e t y t h e r e was no such r e d u c t i o n i n the l e n g t h o f l e a f s h e a t h o f p l a n t s grown under w a t e r l o g g e d c o n d i t i o n s . C o n s e q u e n t l y , t h e r e was no d i f f e r e n c e i n the l e n g t h of l e a f l a m i n a and i n the s i z e o f l e a f l a m i n a under b o t h d r y and w a t e r l o g g e d c o n d i t i o n s . I n the p r e -s e n t i n v e s t i g a t i o n a s i m i l a r c o r r e l a t i o n between l e a f s h e a t h and l e a f l a m i n a was sugg e s t e d . The r e l a t i o n s h i p o f l e a f l a m i n a l e n g t h to the l e n g t h of l e a f s h e a t h was c l e a r l y e v i d e n t when the C a l i f o r n i a v a r i e t i e s were com-p a r e d w i t h s o u t h e r n v a r i e t i e s . The l e a f s h e a t h of the f o r m e r grew l o n g e r than s o u t h e r n v a r i e t i e s by the end of two weeks, and the l e a f l a m i n a f o l l o w e d the same p a t t e r n and grew l o n g e r than the l a t t e r v a r i e t i e s by 1 0 8 . t h e e n d o f t h r e e w e e k s . The w a t e r t e m p e r a t u r e c a u s e d d i f f e r e n c e s i n t h e l e a f s h e a t h l e n g t h w h i c h g e n e r a l l y was a s s o c i a t e d w i t h c o r r e s p o n d i n g i n c r e a s e s o r d e c r e a s e s i n l e a f l a m i n a l e n g t h . P l a n t s g r o w n a t 6 0 ° h a d s h o r t e r l e a f s h e a t h s a nd l e a f l a m i n a a nd t h o s e grown a t 7 5 ° o r 9 0 ° were b o t h c o n s p i c u o u s l y l a r g e r . A c c o r d i n g t o W a t s o n (191+7) t h e d r y m a t t e r p r o d u c -t i o n o f p l a n t s c a n be r e l a t e d t o t h e L e a f A r e a I n d e x . Hence b r o a d e r l e a v e s w i t h l o n g l e a f l a m i n a i n r i c e s h o u l d y i e l d more d r y w e i g h t . T h i s i s p o s s i b l e w i t h -i n l i m i t s as F r i e n d e_t a l ( 1 9 6 2 ) r e p o r t e d t h e l e n g t h o f l e a f l a m i n a i n M a r q u i s w h e a t i n c r e a s e d w i t h e a c h i n -c r e a s e i n t e m p e r a t u r e b u t t h e b r e a d t h a nd t h i c k n e s s d e c r e a s e d . The g r e a t e s t a r e a o f i n d i v i d u a l l e a v e s was f o r m e d a t 2 0°C. I n t h e p r e s e n t e x p e r i m e n t s , t h e l e a f w i d t h m e a s u r e m e n t s o f G a l i f o r n i a n a n d s o u t h e r n v a r i e t i e s a t d i f f e r e n t t e m p e r a t u r e s p r o d u c e d r e s u l t s t h a t c o u l d be s u p p o r t e d b y t h e f i n d i n g s o f t h e s e p r e v i o u s i n v e s t i -gatoa?'s& L e a v e s m e a s u r e d f r o m p l a n t s g r o w n a t h i g h tem-p e r a t u r e s were b r o a d e r , v i z . , 7 5 ° and 9 0 ° , a n d t h e n a r r o w e s t w e re f r o m 6 0 ° t e m p e r a t u r e s . A l t h o u g h s o u t h e r n v a r i e t i e s h a d b r o a d e r l e a v e s , i t i s assumed t h a t t h e i n c r e a s e i n t h e l e n g t h o f l e a f l a m i n a i n C a l i f o r n i a n v a r i e t i e s more t h a n c o m p e n s a t e d f o r t h i s l o s s i n w i d t h a f t e r t h r e e weeks o f g r o w t h . The chang e i n t h e r e l a t i v e l e a f w i d t h o f r i c e l e a v e s i s t h u s , a m o r p h o l o g i c a l r e s p o n s e 109. t o w ater t e m p e r a t u r e . The shoot d i a m e t e r was a l s o f o u n d to v a r y w i t h the w a t e r t e m p e r a t u r e . Shoots a t 60° were the s m a l l e s t and at 90° were the l a r g e s t . I n the b r e a d t h w i s e measurement, s o u t h e r n v a r i e t i e s had a s m a l l e r s i z e a t the b e g i n n i n g and a f t e r a p e r i o d o f about t h r e e weeks, they e q u a l l e d the C a l i f o r n i a n v a r i e t i e s . On the o t h e r hand, i n the l e n g t h w i s e measurement the v a r i e t y d i f f e r e n c e was con-t i n u o u s l y m a i n t a i n e d w i t h the C a l i f o r n i a n v a r i e t i e s b e i n g l a r g e r t h a n s o u t h e r n v a r i e t i e s . E c k e r s o n (1908) s t a t e d t h a t marked v a r i a t i o n s , p a r t i -c u l a r l y i n number and a l s o i n s i z e o f stomata, o c c u r not o n l y i n d i f f e r e n t v a r i e t i e s of the same s p e c i e s , but a l s o i n the same v a r i e t i e s grown under d i f f e r e n t e x t e r n a l c o n d i -t i o n s . The p r e s e n t s t u d y showed, as i n d i c a t e d by E c k e r s o n , t h a t stomata e x h i b i t d e f i n i t e responses to d i f f e r e n t water t e m p e r a t u r e s . The o v e r a l l e f f e c t o f temperature on a l l v a r i e t i e s was t o i n c r e a s e the s i z e o f stomata at 7 5 ° , d u r i n g the f i r s t two weeks o f growth a n d , l a t e r to reduce t o the s i z e of stomata a t 90°. P l a n t s f rom 60° temperature t r e a t m e n t g e n e r a l l y had stomata l a r g e r t h a n e i t h e r 75° o r 90°. To compensate f o r the decrease i n s i z e , t h e r e was an i n c r e a s e i n the number of stomata a t 75° and 90°, the s m a l l e s t number b e i n g a t 60° and the l a r g e s t b e i n g a t 90°. The s i z e and number o f stomata on d i f f e r e n t v a r i e t i e s a t v a r y i n g t e m p e r a t u r e s was a l s o i n v e s t i g a t e d and the r e s u l t s 1 TO. c l e a r l y p o i n t e d o u t t h e g e n e r a l d i f f e r e n c e i n t h e s i z e b e t w e e n t h e s o u t h e r n a n d C a l i f o r n i a n v a r i e t i e s , p a r t i -c u l a r l y a t 6 0 ° . E c k e r s o n a l s o r e p o r t e d t h a t t h e r e was a g r e a t v a r i a t i o n i n t h e number o f s t o m a t a a t d i f f e r e n t t e m p e r a t u r e s . I n t h e p r e s e n t e x p e r i m e n t s i t was g e n e r a l -l y o b s e r v e d t h a t t h e number o f s t o m a t a a t t h e l o w tem-p e r a t u r e was g r e a t e r i n s o u t h e r n v a r i e t i e s , w h i l e a t h i g h e r t e m p e r a t u r e s , t h e t e n d e n c y was f o r t h e C a l i f o r n -i a n v a r i e t i e s t o be e q u a l o r t o h a v e a s l i g h t l y h i g h e r number. As a r e s u l t o f t h e d i f f e r e n t r a t e o f p r o d u c t i o n o f l e a v e s a t t h e t h r e e t e m p e r a t u r e s , t h e same l e a f b l a d e was n o t a v a i l a b l e e a c h week f o r s t o m a t a l s t u d y . T h e r e -f o r e , d i f f e r e n t l e a v e s a t t h e s e t e m p e r a t u r e s were u s e d and as a r e s u l t , t h e r e was a v a r i a t i o n w i t h i n t e m p e r a -t u r e s a t d i f f e r e n t w e e k s . Ochse e t a l (1961 ) r e p o r t e d t h a t 2.2k m. t o n s o f d r y r i c e p e r h a . remove a b o u t 13k k g . o f s i l i c o n d i o x i d e ( S i 0 2 ) . S u b s t a n t i a l p o r t i o n s o f t h e l e a f b l a d e were f o u n d t o be s i l i c i f i e d a f t e r a p e r i o d o f f o u r weeks g r o w t h . The i n t e n s i t y and q u a l i t y o f t h e t y p e o f s i l i c a c r y s t a l s f o r m e d v a r i e d a t d i f f e r e n t w a t e r t e m p e r a t u r e s . M e t c a l f e ( 1 9 6 0 ) r e p o r t e d t h a t r i c e p o s s e s s e s s i l i c a - b o d i e s o f t h e O r y z a t y p e , t h o u g h o t h e r t y p e s c o u l d be p o s s i b l e b e t w e e n v e i n s . J o n e s e t a l (1 9 6 3) s t a t e d t h a t t h e p r o c e s s o f s i l i c i f i c a -t i o n b e g i n s v e r y e a r l y i n v e g e t a t i v e g r o w t h . T h i s t h e r e -f o r e s u g g e s t s t h a t t h e s i l i c a i s n o t a r i g i d d e p o s i t when 111. i t r s j u s t l a i d down s i n c e i t a p p a r e n t l y does n o t p r e -v e n t t h e e x t e n s i o n o f i m m a t u r e c e l l s . E v e n i n t h e ma-t u r e p l a n t , s i l i c a may s o m e t i m e s l a c k r i g i d i t y . I t i s d i f f i c u l t t o p o s t u l a t e w h e t h e r t h e s i z e o f t h e c r y s t a l i s a r e f l e c t i o n o n t h e s i z e o f t h e c e l l a t t h e t ime o f o b s e r v a t i o n . D i f f e r e n t w o r k e r s h a v e d i f f e r e n t t h e o r i e s w i t h r e g a r d t o t h e ^ d e p o s i t i o n o n c r y s t a l . H o wever, J o n e s (1963) r e f e r s t o N e t o l i t s k y ' s w o r k where he f o u n d t h a t a number o f s p e c i e s c o n t a i n e d s i l i c a i n t h e e p i -d e r m a l c e l l s ; s o m e t i m e s t h e s i l i c a was p r e s e n t as i n -c l u s i o n s w i t h i n t h e c e l l a n d s o m e t i m e s as d e p o s i t s o r i n c r u s t a t i o n s on t h e c e l l w a l l . I t i s t h e r e f o r e d o u b t -f u l w h e t h e r t h e s i z e o f s i l i c a b o d i e s w o u l d be c o n s i s -t e n t e n o u g h t o u s e as a mea s u r e o f t h e e p i d e r m a l c e l l s . N e v e r t h e l e s s , t h e p r e s e n c e o f many t y p e s a n d a h i g h e r p e r c e n t a g e o f t h e s e t y p e s i n i n c r e a s e d t e m p e r a t u r e s , d e f i n i t e l y i n d i c a t e s a r e l a t i o n s h i p b e t w e e n t h e o c c u r -r e n c e o f s i l i c a b o d i e s a n d h i g h t e m p e r a t u r e t r e a t m e n t s e i t h e r d i r e c t l y o r i n d i r e c t l y . V a r i o u s a u t h o r s h a v e r e p o r t e d d i f f e r e n t l y on t h e c e l l d i v i s i o n o f r o o t t i p s a n d c e l l e l o n g a t i o n . B u r s t r o m (1956) s t a t e d t h a t w i t h t h e i n c r e a s e i n t e m p e r a t u r e t h e f i n a l c e l l l e n g t h d e c r e a s e s o w i n g t o a s h o r t e n e d d u r a t i o n o f t h e e l o n g a t i o n a n d s u g g e s t e d a 10°G ( f o r cucumber r o o t t i p s ) f o r o p t i m a l e l o n g a t i o n . Y e t Yamakawa (1960) r e -p o r t e d t h a t t h e e l o n g a t i o n o f c o r t i c a l c e l l s i n t h e r o o t 112. t i p s w h i c h r e c e i v e d t h e l o w t e m p e r a t u r e t r e a t m e n t s (5°.10°C ) showed a m a r k e d i n h i b i t i o n as c o m p a r e d t o 25°G t r e a t m e n t s . He f u r t h e r s t a t e d t h a t t h e m i t o t i c p r o c e s s i n t h e r o o t t i p s was e x t r e m e l y i n h i b i t e d c o m p a r e d t o 25°G t r e a t m e n t . Hence a c c o r d i n g t o h i m , op t i m u m c e l l d i v i s i o n a n d e l o n g a t i o n t o o k p l a c e a t 25°G. The d i s a g r e e m e n t i n t h e o b s e r v a t i o n s o f t h e s e two a u t h o r s c o u l d be due t o t h e f a c t t h a t t h e y w o r k e d w i t h two d i f f e r e n t s p e c i e s . I n t h e p r e s e n t s t u d y , t h e number o f c e l l s f r o m r o o t t i p s o f r i c e s e e d l i n g s d i f f e r e d a c c o r d i n g t o t h e g r o w i n g t e m p e r a t u r e s o f t h e p l a n t s . C e l l numbers were f o u n d t o be l o w e r i n t h e h i g h e r t e m p e r a t u r e s a n d h i g h e r i n t h e l o w e r t e m p e r a t u r e s . T h i s d e c r e a s e i n number w i t h i n c r e a s e i n t e m p e r a t u r e was more p r o n o u n c e d i n t h e v a r i e t y C a l o r o . T hese r e s u l t s may be s u p p o r t e d f u r t h e r b y t h e f i n d i n g s o f Brown a n d R i c k l e s s (19k8) who showed t h a t t h e r a t e o f d i v i s i o n i n c r e a s e d a t 25° G and d e c r e a s e d a t 5°» T h i s phenomenon was o b s e r v e d i n a l l t h e n u t r i e n t c u l t u r e s w o r k e d w i t h . I t i s t h e r e f o r e p o s s i b l e t o e x -p l a i n t h a t Yamakawa's f i n d i n g s d i d n o t n e c e s s a r i l y i n -d i c a t e a g r e a t e r number o f c e l l s a t 25>°C. Howe v e r , c e l l d i v i s i o n was more a t 25°G, b u t c e l l e l o n g a t i o n was a l s o more a t t h e same t e m p e r a t u r e . C e l l e l o n g a t i o n does n o t o c c u r a t t h e same r a t e a t l o w t e m p e r a t u r e s l i k e c e l l d i v i s i o n , as Yamakawa f o u n d t h a t t h e e l o n g a t i o n o f r o o t s 1 1 3 . was n o t p e r c e p t i b l e i n s p i t e o f t h e c e l l d i v i s i o n t h a t o c c u r r e d t o some d e g r e e i n l o w t e m p e r a t u r e s . T h e r e f o r e , i t i s v e r y p o s s i b l e t h a t c e l l d i v i s i o n t o o k p l a c e a t a g r e a t e r r a t e a t 6 0 ° i n t h e p r e s e n t e x p e r i m e n t s and c e l l e l o n g a t i o n t o a l e s s e r d e g r e e . B u r s t r o m ' s o b s e r v a t i o n t h a t t h e f i n a l c e l l l e n g t h d e c r e a s e s w i t h a n i n c r e a s e i n t e m p e r a t u r e w o u l d be p o s s i b l e o n l y a t h i g h e r t e m p e r a -t u r e s , h o w e v e r t h e h i g h t e m p e r a t u r e r e s p o n s e o f d i f f e r e n t s p e c i e s w o u l d v a r y m a r k e d l y . 114. SUMMARY AND CONCLUSIONS The p r e s e n t s t u d y was u n d e r t a k e n w i t h t h e o b j e c t o f e l u c i d a t i n g t h e e f f e c t s o f w a t e r t e m p e r a t u r e s o n t h e f o l l o w i n g m o r p h o l o g i c a l a n d a n a t o m i c a l c h a r a c t e r s : l e n g t h o f s h o o t s and r o o t s , w e i g h t o f s h o o t s , r o o t s , a n d s e e d r e s i d u e , l e n g t h o f l e a f l a m i n a a n d l e a f s h e a t h , d i a m e t e r o f s h o o t s , s t o m a t a number a n d s i z e , t h e number and t y p e o f s i l i c a c r y s t a l s on t h e l e a f b l a d e , and t h e number o f c e l l s p e r g i v e n u n i t l e n g t h a t t h e r o o t t i p . B o t h C a l i f o r n i a n a n d s o u t h e r n v a r i e t i e s w e r e u s e d f o r t h e s e e x p e r i m e n t s m a i n l y f o r t h e p u r p o s e o f c o m p a r i s o n a n d p o s s i b l y w i d e n i n g t h e s c o p e o f t h e s e i n v e s t i g a t i o n s . The r e l a t i v e e f f e c t s o f w a t e r t e m p e r a t u r e on t h e g r o w t h o f s h o o t s w e re c l e a r l y shown i n a l l t h e e x p e r i -ments t h a t were c o n d u c t e d . G r o w t h a t 6 0 ° was s t r o n g l y r e t a r d e d a n d as a c o n s e q u e n c e t h e s h o o t s o f s e e d l i n g s w ere p o o r l y d e v e l o p e d . I n c o n t r a s t t o t h i s , 9 0 ° was f o u n d t o be t h e most f a v o u r a b l e t e m p e r a t u r e f o r s h o o t g r o w t h . The t e m p e r a t u r e o f 7 5 ° a l s o o f t e n showed a l m o s t t h e same e f f e c t s as 9 0 ° . G e n e r a l l y i t was f o u n d t h a t t h e C a l i f o r n i a n v a r i e t i e s h a d b e t t e r s h o o t g r o w t h t h a n s o u t h e r n v a r i e t i e s u n d e r a l l t h e c o n d i t i o n s u s e d i n t h e s e i n v e s t i g a t i o n s . The e f f e c t o f t e m p e r a t u r e o n r o o t g r o w t h a p p e a r e d t o be l e s s t h a n on s h o o t g r o w t h , y e t t h e p a t t e r n o f b e -h a v i o u r a t t h e t h r e e t e m p e r a t u r e s was t h e same. The 115. two h i g h e r t e m p e r a t u r e s (75° a n d 90°) t e n d e d t o be much c l o s e r i n t h e i r e f f e c t s on r o o t g r o w t h . The v a -r i e t y C a l o r o was f o u n d t o be s u p e r i o r i n r o o t g r o w t h a l t h o u g h t h i s was n o t c o n s i s t e n t . The l o s s o f s e e d r e s e r v e was i n v e r s e l y r e l a t e d t o t h e i n c r e a s e i n tem-p e r a t u r e . A s l i g h t d e v i a t i o n f r o m t h i s g e n e r a l t r e n d was p e r c e p t i b l e where r a t e o f d e c r e a s e t e n d e d t o be more p r o n o u n c e d w i t h i n c r e a s e d t e m p e r a t u r e a t t h e i n i t i a l s t a g e s f o l l o w e d by a somewhat g r a d u a l d e c r e a s e . S eeds o f C a l i f o r n i a n v a r i e t i e s a r e i n h e r e n t l y h e a v i e r t h a n s o u t h e r n v a r i e t i e s b u t t h e r a t e o f l o s s i n t h e f o r m e r was f o u n d t o be g r e a t e r t h a n t h e l a t t e r , p a r t i -c u l a r l y when C a l o r o a n d B l u e b o n n e t w e r e c o m p a r e d . E v e n u n d e r s u b m e r g e d c o n d i t i o n s , C a l o r o u t i l i z e d s e e d r e -s e r v e more r a p i d l y e s p e c i a l l y dur-ing t h e . . . f i r s t two weeks a n d t h e r e a f t e r t h e w e i g h t l o s s was q u i t e g r a d u a l . The l e n g t h o f l e a f l a m i n a was s t r o n g l y a f f e c t e d b y t h e l o w t e m p e r a t u r e a n d a w i d e gap b e t w e e n 60° a n d t h e two h i g h e r t e m p e r a t u r e s was s t r i k i n g l y e v i d e n t . The d i f f e r e n c e b e t w e e n 75° and 90° was l e s s . The C a l i f o r n i a n v a r i e t i e s , a l t h o u g h s h o r t a t t h e f i r s t week, s u r p a s s e d t h e s o u t h e r n v a r i e t i e s a t t h e t h i r d week. L e a f s h e a t h g r o w t h a l s o r e s p o n d e d t o t e m p e r a t u r e i n a l m o s t t h e same manner. S o u t h e r n v a r i e t i e s were I f o u n d t o p o s s e s s i n h e r e n t l y b r o a d e r l e a v e s . H owever, t h i s m o r p h o l o g i c a l c h a r a c t e r i s t i c 116 was o b s e r v e d t o c h a n g e w i t h t e m p e r a t u r e . I n c r e a s e i n w a t e r t e m p e r a t u r e r e s u l t e d i n an i n c r e a s e i n . l e a f l a m i n a w i d t h . The r e s p o n s e o f s o u t h e r n v a r i e t i e s i n t h i s r e s p e c t was g r e a t e r t t h a n C a l i f o r n i a n v a r i e t i e s . The u n f a v o u r a b l e c o n d i t i o n s p r o d u c e d b y t h e l o w t e m p e r a t u r e h a d a s t r i k i n g e f f e c t o n r e d u c i n g s h o o t d i a m e t e r . H o w e v e r , t h e l e n g t h w i s e a n d b r e a d t h w i s e mea-s u r e m e n t s b e h a v e d s l i g h t l y d i f f e r e n t l y . The b r e a d t h -w i s e m easurement was s m a l l e r i n t h e s o u t h e r n v a r i e t i e s a t t h e f i r s t two weeks b u t a f t e r t h a t t h e s e m e a s u r e m e n t s were e q u a l t o t h o s e o f C a l i f o r n i a n v a r i e t i e s , w h e r e a s t h e l e n g t h w i s e m e a s u r e m e n t s showed a g r e a t e r s i z e f o r a l l weeks a n d a t h i g h e r t e m p e r a t u r e s t h e r e l a t i v e g r o w t h was i n c r e a s e d . T h e r e f o r e , i t a p p e a r s t h a t t h e l e n g t h -w i s e g r o w t h o f t h e s h o o t o f t h e r i c e p l a n t r e s p o n d s more t o e x t e r n a l c o n d i t i o n s t h a n t h e b r e a d t h w i s e g r o w t h . G e n e r a l l y i t was f o u n d t h a t t h e number o f s t o m a t a a t l o w e r t e m p e r a t u r e s was l e s s t h a n a t h i g h e r t e m p e r a -t u r e s . b u S o u t h e r n v a r i e t i e s h a d more a t l o w t e m p e r a t u r e s b u t a t h i g h e r t e m p e r a t u r e s b o t h g r o u p s o f v a r i e t i e s h a d e s s e n t i a l l y t h e same number. P l a n t s g r o w i n g a t 60° h a d c o n s i s t e n t l y l a r g e r s t o m a t a , a n d t h o s e a t 7 5 ° were l a r g e r t h a n t h o s e a t 90° f o r t h e f i r s t two w e e k s . L a t e r t h e y b o t h h a d t h e same s i z e s t o m a t a . C a l o r o h a d l a r g e r s t o -m a t a a t l o w t e m p e r a t u r e s , w h i l e i n c o n t r a s t B l u e b o n n e t h a d a l m o s t t h e same s i z e f o r a l l t h r e e t e m p e r a t u r e s , e s p e c i a l l y d u r i n g t h e l a t t e r p a r t o f t h e p e r i o d . 117. The p e r f o r m a n c e o f C a l o r o i n r e s p e c t t o s h o o t g r o w t h u n d e r b o t h s u b m e r g e d a n d n o n - s u b m e r g e d c o n d i -t i o n s was e v i d e n t l y s u p e r i o r t o B l u e b o n n e t a t t h e two h i g h t e m p e r a t u r e s . A g a i n when t h e g r o w t h o f C a l o r o was c o m p a r e d u n d e r t h e two c o n d i t i o n s a t t h e h i g h e r t e m p e r a t u r e s , i t was a p p a r e n t t h a t t h e b e t t e r r e s p o n s e was u n d e r s u b m e r g e d c o n d i t i o n s . I n c o n t r a s t a t 60° C a l o r o h a d b e t t e r s h o o t g r o w t h u n d e r n o n - s u b m e r g e d c o n d i t i o n s a n d B l u e b o n n e t u n d e r s u b m e r g e d c o n d i t i o n s . The l a t t e r v a r i e t y was r a t h e r c o n s i s t e n t on t h e s h o o t l e n g t h b a s i s b u t i n c o n s i s t e n t on t h e s h o o t w e i g h t b a s i s . N o n - s u b m e r g e d c o n d i t i o n s a t h i g h e r t e m p e r a t u r e s were f o u n d t o be u n f a v o u r a b l e f o r r o o t g r o w t h w h e r e a s a t t h e l o w t e m p e r a t u r e (60°) r o o t g r o w t h was f a v o u r e d u n d e r n o n - s u b m e r g e d c o n d i t i o n s . When p l a n t s f r o m b o t h v a r i e t i e s w e r e s h i f t e d f r o m warm t o c o l d w a t e r (75° o r 90° t o 60°) t h e e f f e c t o f t h e l o w t e m p e r a t u r e was s u d d e n a n d m a r k e d p a r t i c u l a r l y d u r i n g • the. f i r s t week, b u t t h e g r o w t h o f C a l o r o was f o u n d t o c o n t i n u e f a s t e r t h a n B l u e b o n n e t . I f t h e s h i f t was made i n t h e o p p o s i t e d i r e c t i o n ( c o l d t o warm) i t was c l e a r l y e v i d e n t t h a t t h e g r o w t h a t t h e new t e m p e r a t u r e was much b e t t e r , a n d a g a i n w i t h C a l o r o s u p e r i o r t o B l u e -b o n n e t . A s h i f t f r o m 90° t o 75° was b e t t e r t h a n h o l d i n g p l a n t s a t a c o n s t a n t t e m p e r a t u r e o f 90° . The number o f c e l l s p e r u n i t r o o t l e n g t h a t t h e l o w 118 t e m p e r a t u r e was g r e a t e r t h a n a t h i g h e r t e m p e r a t u r e s . The a v e r a g e number o f r o o t t i p c e l l s f o r a l l t h r e e t e m p e r a t u r e s was more f o r C a l o r o t h a n f o r B l u e b o n n e t . The i n t e n s i t y a n d t y p e o f s i l i c a f o r m e d a t d i f -f e r e n t t e m p e r a t u r e s v a r i e d a c c o r d i n g t o t h e t e m p e r a -t u r e . A t l e a s t f i v e t y p e s o f c r y s t a l s w e r e o b s e r v e d a t d i f f e r e n t s t a g e s o f g r o w t h a t a l l t h e t e m p e r a t u r e r e g i m e s . The t y p e s a n d number o f c r y s t a l s p r e s e n t a t 60° were t h e s i m p l e s t a n d t h e l e a s t , u s u a l l y b e i n g two t o t h r e e t y p e s . T e m p e r a t u r e s o f 7 5 ° p r o v i d e d a more f a v o u r a b l e c o n d i t i o n f o r s i l i c a f o r m a t i o n a n d a t l e a s t t h r e e t y p e s w e r e p r e s e n t a t one t i m e . The number p r e -s e n t was a l s o much h i g h e r t h a n a t 6 0 ° . A t 90° b o t h t y p e s a n d number t e n d e d t o i n c r e a s e . 119. LITERATURE CITED 1. Brown, R., a n d R i c k l e s s , P. A new method f o r t h e s t u d y o f c e l l d i v i s i o n a n d c e l l e x t e n s i o n w i t h some p r e l i m i n a r y o b s e r v a t i ons on e f f e c t o f t e m p e r a t u r e and o f n u t r i e n t s . Roy. S o c , L o n d o n , (B) 136: 110-125, 191+8. 2 . B u r s t r o m , H. T e m p e r a t u r e a n d r o o t c e l l e l o n g a t i o n . P h y s i o l . P l a n t . 9: 682-692, 1956. 3. C h a u d h r y , M.S., a n d McLean, E.O. C o m p a r a t i v e e f f e c t s o f f l o o d e d a n d u n f l o o d e d s o i l c o n d i t i o n s a n d n i t r o g e n a p p l i c a t i o n on g r o w t h a n d n u t r i e n t u p t a k e b y r i c e p l a n t s . A g r o n . J o u r . 55: 565-567, 1963. !+. Chapman, A.L., and P e t e r s o n , M.L. The s e e d l i n g e s t a b l i s h m e n t o f r i c e u n d e r w a t e r i n r e l a t i o n t o t e m p e r a t u r e and d i s s o l v e d o x y g e n . C r o p S c i e n c e 2: 391-395, 1962. i 5. C h r i s t i a n s e n , M.N. I n f l u e n c e o f c h i l l i n g u p o n s e e d l i n g d e v e l o p m e n t o f c o t t o n . P l a n t P h y s i o l . 38: 520-522, 1963. 6. D o r e , J . , a n d T h e v a n , P.Y. . S t u d i e s o n s e e d g e r m i n a t i o n a n d s e e d l i n g g r o w t h i n _ r i c e ( O r y z a s a t i v a L.) T r o p . A g ' r i . T r i n . 36: 15-33, 1959. 7 . E c k e r s o n , S.H. The number a n d s i z e o f t h e s t o m a t a . B o t . Gaz. I4.6: 221-22LL, 1908. 8. E h r l e r , W., and B e r n s t e i n , L. E f f e c t s o f r o o t t e m p e r a t u r e , m i n e r a l n u t r i t i o n a n d s a l i n i t y o n t h e g r o w t h a n d c o m p o s i t i o n o f r i c e . B o t . G a z. 120: 6 7 - 7 J + , 1958. 9. E n y i , B.A.C. C o m p a r a t i v e g r o w t h - r a t e s o f u p l a n d a n d swamp r i c e v a r i e t i e s , Ann", o f B o t . 2 6 : L L 6 7 - ! + 8 7 , 1962. 10. E r y g i n , P.S. xChange i n a c t i v i t y o f enzymes, s o l u b l e c a r b o h y d r a t e s , and i n t e n s i t y o f r e s p i r a t i o n o f r i c e s e e d s g e r m i n a t i n g u n d e r w a t e r . P l a n t P h y s i o l . 11: 821-832, 1936. 120. 11. E s a u , K. Anatomy o f s e e d p l a n t s . J o h n W i l e y a n d Sons I n c . E d . 2, 376 p p . L o n d o n , 1961. 12. F r i e n d , D . J . L . , H e l s o n , V.A., a n d F i s h e r , J . E . L e a f g r o w t h i n M a r q u i s w h e a t , as r e g u l a t e d b y t e m p e r a t u r e , l i g h t i n t e n s i t y , a n d day l e n g t h . Can. J o u r . B o t . I+0: 1299-1311 , 1962. 13. P u j i i , Y. On t h e d e v e l o p m e n t o f b r a n c h r o o t s on s u c c e s s i v e n o d e s i n r i c e p l a n t s . ( J a p a n e s e ) P r o c . C r o p . S c i . S o c . J a p a n 29: 66-68, 1960. (Ab. i n f i e l d c r o p a b s . 15: 196, 1962) 1I+. F u r b y , E.B. N o t e s . A g r i . G a z . 61: 208, 1950. 15. G r i s t , D.H. R i c e . Longmans, G r e e n , a n d Co., L o n d o n . 331 p p . , 1953* 16. J o n e s , L.H.P., a n d M i l n e , A.A. S t u d i e s o f s i l i c a i n t h e o a t p l a n t . P l a n t a n d S o i l 18: 207-219, 1963. 17. , a n d Wadham, S.M. S t u d i e s o f s i l i c a i n t h e o a t p l a n t . P l a n t a n d S o i l 18: 358-371, 1963. 18. J o n e s , W.J. E f f e c t s o f d e p t h o f s u b m e r g e n c e on t h e c o n t r o l o f b a r n y a r d g r a s s a n d t h e y i e l d o f r i c e g r o w n i n p o t s . J o u r . Am. S o c . A g r o n . 25: 578-583, 1933. 19. K a n o e , S a t o . S t u d i e s o n t h e e f f e c t o f f l o o d i n g i r r i g a t i o n f o r r i c e p l a n t s ( P r e l i m i n a r y r e p o r t ) . P r o c . C r o p . S c i . S o c . J a p a n 19: 45-1+8, 1950. (Ab.. i n r e c o r d s o f r e s e a r c h e s U n i v . o f T o k y o 1: 9,0959) 20. S t u d i e s o n t h e f l o o d i r r i g a t i o n o f r i c e p l a n t (2) The e f f e c t s o f c o n t i n u o u s s u b m e r g e n c e o n t h e g r o w t h a n d t i l l e r i n g o f r i c e p l a n t . P r o c . C r o p S c i . S o c . J a p a n 20: 1+1 -14,5, 1951 . (Ab. i n r e c o r d s o f r e s e a r c h e s U n i v . o f Tokyo 2: 5,(1952) 21 . Some o b s e r v a t i o n s on t h e c o n s u m p t i o n o f o x y g e n b y r i c e r o o t s g r o w n i n w a t e r c u l t u r e s . P r o c . C r o p S c i . S o c . J a p a n 21: 16-17, 1952. (Ab. i n r e c o r d s o f r e s e a r c h e s U n i v . o f Tokyo 3« 4 (1953) 121 . 22. K a u f m a n , P.B. D e v e l o p m e n t o f O r y z a s a t i v a L. E a r l y s t a g e s i n h i s t o -g e n e s i s o f t h e s t e m and o n t o g e n y o f t h e a d v e n t i t i o u s r o o t s . P h y t o m o r p h o l o g y 9: 382-1+01+, 1959. 23. 214,. D e v e l o p m e n t o f t h e s h o o t o f O r y z a s a t i v a L. I . S h o o t a p e x . P h y t o m o r p h o l o g y 9: 228-21+2, 1959. D e v e l o p m e n t o f t h e s h o o t o f O r y z a s a t i v a L. I I . L e a f h i s t o g e n e s i s . P h y t o m o r p h o l o g y 9: 277-311, 1959. 25. K n o l l , H.A., B r a d y , N.G., a n d L a t h w e l l , D.J. E f f e c t o f s o i l t e m p e r a t u r e a n d p h o s p h o r u s f e r t i l i z a t i o n o n t h e g r o w t h a n d p h o s p h o r u s c o n t e n t o f c o r n . A g r o n . J o u r . 56: 11+5-11+7, 196k. 26. E f f e c t o f r o o t zone t e m p e r a t u r e a t v a r i o u s s t a g e s o f g r o w i n g p e r i o d o n t h e g r o w t h o f c o r n . A g r o n . J o u r . 56: 11+3-1 [4,5, 196k. 27. J o h a n s e n , D.A. P l a n t m i c r o t e c h n i q u e . M c G r a w - H i l l , 523 pp. L o n d o n , 191+0. 28. L e v i t t , J . M o r p h o l o g i c a l f a c t o r s a s s o c i a t e d w i t h h a r d i n e s s i n t h e h a r d i n e s s o f p l a n t s . A g r o n . J o u r . 6: 61-63, 1956. L o o m i s , W.E. G r o w t h a n d d i f f e r e n t i a t i o n i n p l a n t s . I o wa S t a t e C o l l e g e P r e s s , Ames, I o w a . 1+58 p p . 1958. 30. M a t s u o , T a k a n e . R i c e c u l t u r e i n J a p a n . M i n i s t r y o f A g r i c u l t u r e a n d F o r e s t r y , J a p a n e s e Gov. T o k y o . 128 p p . 1957. 31. G e n e c o l o g i c a l s t u d i e s on c u l t i v a t e d r i c e . B u i . N a t . I n s t . A g r j i c . S c i . , S e r i e s D 3. 1952-53. (Ab. i h ' r e c o r d s o f r e s e a r c h e s i n t h e F a c u l t y o f A g r i c . U n i v . o f Toky o 3* 7, 1954) 32. M c D o n a l d , D.G. A e r i a l s o w i n g o f r i c e . A g r i . G a z e t t e o f New S o u t h W a l e s 72: '505-508, 1961. 33. M e t c a l f e , C R . Anatomy o f t h e M o n o c o t y l e d o n s , I . G r a m i n e a e . C l a r e n d o n P r e s s , O x f o r d . 731 P P . 1960. 31+. M i l t h o r p e , F . L . S t u d i e s o n t h e e x p a n s i o n o f t h e l e a f s u r f a c e . The i n f l u e n c e o f t e m p e r a t u r e . J o u r . E x p t . B o t a n y 10: 233-21+9, 1959. 122. O c h s e , J . T . , S o u l e , M.J. J r . , D i j k m a n , M.J., and W e h l b i n g , C. T r o p i c a l a n d s u b t r o p i c a l a g r i c u l t u r e . M a c M i l l a n Co., New Y o r k , V o l . 2, 1 446 p p . 1961 . O r m r o d , D.P., a n d B u n t e r , W.A. J r . The e v a l u a t i o n o f r i c e v a r i e t i e s f o r c o l d w a t e r t o l e r a n c e . A g r o n . J o u r . 53: 133-134, 1961. P h i l l i s , E . The g e r m i n a t i o n a n d e s t a b l i s h m e n t o f r i c e s e e d sown i n t o w a t e r . A u s t . J o u r . E x p . A g r i c . A n i m . Hustr. 6: 181-184, 1962. (Ab. i n f i e l d c r o p a b s . 1 6 : 69, 1 9 6 3 ) Raney, F. R i c e w a t e r t e m p e r a t u r e . C a l i f . A g r i . 17: No. 9, 4, 1963. R a n s o n , S.L., a n d ' P a n z a , B. E x p e r i m e n t s o n t h e g r o w t h i n l e n g t h o f p l a n t o r g a n s . I I . Some e f f e c t s o f d e p r e s s e d o x y g e n c o n c e n t r a t i o n . J o u r . E x p t . B o t . 6: 80-93, 1955. R i c h c h a r i a , R.H., a n d Roy, J.K. O b s e r v a t i o n s o n s t o m a t a i n c o l e o p t i l e o f O r y z a s a t i v a L. C u r r . S c i . 30: 30-31. (Ab. i n f i e l d c r o p a b s . 15 : 199, 1962) S a r v e l l a , P., M e y e r , R . J . , a n d O v i n g s , A. A s c o t c h t a p e m e t h o d f o r c o u n t i n g o r m e a s u r i n g s t o m a t a . C r o p . S c i . 1: 81-82, 1961. S e t h i , R.L. R o o t d e v e l o p m e n t i n r i c e u n d e r d i f f e r e n t c o n d i t i o n s o f g r o w t h . I n d i a n D e p t . o f A g r i . M e m o i r , B o t a n y s e r i e s 18: 57-80, 1930. S i n n o t , E.W. P l a n t M o r p h o g e n e s i s . M c G r a w - H i l l Go. I n c . , T o r o n t o . 550 p p . 1960. S t o f f e r , V.R., a n d G o r d o n , E.V.R. E f f e c t o f s o i l t e m p e r a t u r e a n d s o i l m o i s t u r e o n t h e p h y s i o l o g y o f sor g h u m . A g r o n . J o u r . 55= 447-450, 1 9 6 3 . T a k e h a s h i , N. The r e l a t i o n o f w a t e r a b s o r p t i o n t o g e r m i n a t i o n o f r i c e S c i . * R e p s . R e s . I n s t . , T o h o k u ( D ) , 12: 61-71, 1961. (Ab. i n f i e l d c r o p a b s . 16. 688, 1 9 6 3 ) 123. T a k e s i m a , H., Hameda, E., a n d S a t o , T. S t u d i e s o n t h e e f f e c t s o f s o i l t e m p e r a t u r e s on r i c e p l a n t g r o w t h . E f f e c t s o f s o i l t e m p e r a t u r e upon g r o w t h r e g u l a t i n g s u b s t a n c e s a n d m e t a b o l i s m o f c a r b o h y d r a t e s a n d n i t r o g e n . ( J a p a n e s e ) Yamgata U n i v e r s i t y , ( A g r i . S c i . ) 3: 393-400.. (Ab. i n t h e f i e l d c r o p a b s . 16. 1963) T e m p l e t o n , W.G. J r . , M o t t , G.O., a n d B u l a , R . J . Some e f f e c t s o f t e m p e r a t u r e a n d l i g h t o n g r o w t h a n d f l o w e r i n g o f t a l l f e s c u e , F e s t u c a a r u n d i n a c e a 1. N e g a t i v e D e v e l o p m e n t . C r o p . S c i . 1: 216-219, 1961. T u r t o x S e r v i c e D e p a r t m e n t L e a f l e t 31 : i960 W a t s o n , D.J. C o m p a r a t i v e p h y s i o l o g i c a l s t u d i e s on t h e g r o w t h o f f i e l d c r o p s . 1. V a r i a t i o n i n n e t a s s i m i l a t i o n r a t e s a n d l e a f a r e a b e t w e e n s p e c i e s a n d v a r i e t i e s a n d w i t h i n a n d b e t w e e n y e a r s . A n n a l s B o t . L o n d o n , 11: 1+1-76, 1947. Went, F.W. Some t h e o r e t i c a l a s p e c t s o f e f f e c t s o f t e m p e r a t u r e o n p l a n t s . I n f l u e n c e o f t e m p e r a t u r e o n b i o l o g i c a l s y s t e m s . Am. P h y s i o l o g i c a l S o c . I n c . , 163-174, 1957. Yamada, N. A u x i n r e l a t i o n s h i p o f t h e r i c e c o l e o p t i l e . . P l a n t P h y s i o l o g y 29 (1): 92-96, 1954. Yamakawa, Y u t a k a S t u d i e s on t h e e c o l o g i c a l v a r i a t i o n s o f t h e g r o w t h o f r i c e p l a n t c a u s e d b y s h i f t i n g o f c u l t i v a t i o n s e a s o n i n warm r e g i o n s i n J a p a n . A g r i c . B u i . o f t h e S a g a U n i v e r s i t y , 11+5-147 ( r e p r i n t e d E n g l i s h t r a n s l a t i o n ) 1962. a n d K i s h i k a w a , H. On t h e e f f e c t o f t e m p e r a t u r e u p o n d i v i s i o n a n d e l o n g a t i o n o f c e l l s i n t h e r o o t o f r i c e p l a n t s . . P r o c . C r o p S c i . S o c , J a p a n 2 6 : 94, 1957. ( R e p r i n t e d E n g l i s h T r a n s l a t i o n ) E f f e c t o f t e m p e r a t u r e o n t h e c e l l d i v i s i o n i n r o o t t i p s o f r i c e p l a n t w i t h s p e c i a l r e f e r e n c e t o d i u r n a l v a r i a t i o n o f w a t e r t e m p e r a t u r e , a n d l o w t e m p e r a t u r e . A g r i c . B u i . , S a g a U n i v e r s i t y , J a p a n . 1960. Y o s h i j i , T o g a r i , and T a k a s h i , O n t a n i S t u d i e s o n t h e p h y s i o l o g i c a l f u n c t i o n o f t h e c r o p . r o o t s . P r o c . C r o p S c i . ' S o c , J a p a n 29: 71-74, 1960. (Ab. i n r e c o r d s o f r e s e a r c h e s U n i v . o f Tokyo 11: 3 (1961) 

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