Land and Food Systems, Faculty of
DSpace
UBCV
Rogers, Charles Bernard Watson
Master of Science - MSc
University of British Columbia
[No abstract submitted]
RHIZOME DEVELOPMENT BI PLMTS WITH SPECIAL REFERENCE TO ALFALFA (MEDIOAGO SP.) Taj Charles Bernard Watson Rogers A Thesis submitted i n Partial Fulfilment of The Requirements for the Degree of MASTER OF SCIENCE IF AGRICULTURE In the Department of The University of B r i t i s h Columbia Apri l , 1941. The author wishes to take this opportunity to thank Dr. G. G. Moe for suggesting this study, for his advice and help throughout; i t s progress, and for kindly placing at the writer's disposal the f a c i l i t i e s of the Department of Agronomy. Shanks are also tendered to Dr. D. G. Laird and Mr. J. L. Bolton for their sugges-tions and assistance, The author especially wishes to express his sincere appreciation for the invaluable aid and helpful criticisms given so willingly at a l l times throughout the past year "by Dr. 7. C. "Brink, whose enthusiasm and encouragement have been so instrumental in bringing this work to a conclusion. Page I. UTTRQDUC TI OF . i II. REVIEW OF LITERATURE (a) Some Introductory Considerations 2 (b) Some Morphological Features of Rhizomes 3 in A l f a l f a . (c) The Functions of the Rhizome3 in Al f a l f a 8 (d) The Story of Alfalfa 15 III. EXPERIMENTAL TOBE (a) Introduction 2? (b) Field Studies 28 • - 19 The Clipping Experiment. 28 Purpose 28 Discussion- of the'Literature 28 Plan of Procedure S3 Observation of Results 59 Conclusion 40 2. The Fer t i l i z e r Experiment. 41 Purpose 41 Plan of Procedure 42 Observation of Results 46 Conclusion 4? (c) Greenhouse Studies 1. The pH Experiment. 47 Purpose 4? Discussion of the Literature 47 Plan of Procedure 48 Observation of Results 51 Conclusion 55 2. The Photoperiodism Experiments. Purpose 55 Discussion of Literature 55 Plan of Procedure 57 Observation of Results 62 Conclusion 71 TABLE OP CONTENTS (Cont'd.) Page IT. CONCLUSION 73 V. SUMMARY ~ 7 4 VI. BIBLIOGRAPHY 7 5 RHIZOME DElffiLOPMEHT , IU PLANTS WITH SPECIAL REFERENCE / -\ .. TO ALFALFA (UEPIOASO SP.) '. • J I. INTRODUCTION With the recognition in recent years of the great economic value of "spread" or "aggressiveness" in forage types of alfalfa (Medicago sp.} the plant investigator should, logically, include in his considerations the underground structures of the plant. Gf the gross earthy parts, roots, crown and rhizomes, perhaps the(latter•deserve the most attention. Rhizomes grow horizontally and may give rise to "both aerial and under-ground parts. Their general nab i t , then, together with the fact that their development varies widely with genetic constitution and environment must give them a real value in determining the competitive relationships and coverage of any individual plant or strain. While the importance of rhizomatous types of a l f a l f a has "been generally conceded no detailed study of their morphology and physiology has yet "been made. The present report is an attempt to meet this deficiency. ' , Excellent material for study was availahle i n the a l f a l f a plots at the University of British Columbia. With interest in the breeding program here centering on the selection of spreading forms, plants erhibiting wide variations in rhizome development were readily obtained. Because of the general similarity of rhizome function in a l l plant species i t seemed desirable to include in this report a rather complete bibliography and literature review of studies of other plants as well as of a l f a l f a . Wherever they are found rhizomatous structures function as organs of reproduction or serve as resting structures during periods of climatic adversity. A broad view is therefore justified. < However, one,finds, actually, that rhizomes have been the subject of very l i t t l e detailed study. This is rather surprising when i t is considered that more than fifteen per cent of plants with perennial habit, including many of the most aggressive forage plants, and most noxious weeds, possess rhizomes. •II. REVIEW- OF LITERATURE (a) Some Introductory Considerations: Many connotations of the term "rhizome" are to be met with in the current literature. The term was f i r s t employed by Ehrhart in 1787 but was not accurately defined by him. Gray (1308) used the term rhizome in a general sense to designate i t as "any prostrate or subterranean stem usually rooting at the nodes and becoming erect at the apex". The term has been used in a more specific sense. Jackson (1916), for instance, distinguishes between rhizomes, stolons, and runners. The rhizome, he believes, is any root stalk or dorsiventral stem of root-like appearance on or under the ground which sends off rootlets and whose apex sends up stems or leaves. He defines a stolon and runner as any "branch disposed to root". Holms (1929), in a plea for consistency, suggested that the term rhizome be applied to any subterranean stem and stolons and runners\respectively:'ito subterranean and aerial axillary shoots^. This i s the usage followed in this report. Acceptance of this definition leads to the conclusion that some species in nearly every distinguishab1e habitat produce rhizomes. In turn, the wide distribution presupposes great variation in form and function. Medic species, for example, possess simple rhizomes useful in food storage; in xeric habitats rhizomes are frequently found functioning as water storage organs or in dispersal of the species; among aquatics there are found a wide'variety of rhizomes ranging from the simple to the bizarre, useful in anchorage, reproduction or storage.. From the rain forests of the tropics to the tundra of polar regions rhizomes may characterize plant species. (b) Some Morphological Features of Rhizomes in Alfalfa. In the Common al f a l f a of commerce (Medicago sativa) prominent development of rhizomes rarely occurs. However in at least tv/o natural groupings in the genus Medicago, generally designated as M. faloata and M. gaetula rhizomes are formed characteristically. In these species the rhizomes are initiated in late summer and arise much as do the shoots in the Common alfalfa from the crown or more rarely from the hypocotylar tissues immediately below the crown. Unlike the shoots, though, which are from the outset positively geotropic and tend to grow upwards, the rhizomes I n i t i a l l y are not actively geotropic but tend to grow horizontally be lew the ground surface for several months. Six to twelve inches of horizontal growth, the amount depending on the environment and genetic make-up, i s commonly produced. In spring, growth becomes positively geotropic and from the rhizome apex and nodes, aerial growth commences. To a greater or less degree the rhizomes produce rootlets from the nodes. Apparently, these may be initiated any time. Oliver (1913) examined alfalfa of many types for rhizome production. Grimm and Turkestan varieties, he noted, often branched laterally before reaching the surface but that the branches seldom produced roots. A high percentage, too, of Grimm, Turkestan, Baltic and Mongolian types, during periods of climatic extremes, were capable of with-drawing their crowns into the s o i l . In such varieties then many of the shoots, rhizome-like, would he initiated below the soil surface. Alfalfa varieties from northern Africa and from the Caucasus and Crimea were found to be free rhizome producers. In some of these types no tap root whatever was produced. Oakley and Garver (1915) record an interesting example of root proliferation in a strain of M, falcata introduced from Russia (S. P. I 28071). Unlike rhizomes which are produced from the crown (which i s morphologically stem tissue) the proliferations observed by these investigators were produced from the tap root or i t s branches f u l l y ten to twelve inches below the ground. Like the rhizomes they developed hori-zontally. At irregular intervals along the lateral roots swellings occurred usually about twice the root in diameter and 4 " ~ 111" in length. New buds formed on these swellings which gave rise to new plant or remained undeveloped. Fibrous roots are sparsely produced on the proliferations and the swellings are as a rule devoid of them. Individuals which develop from these special roots grow connected to the parent for - some.time and may attain a considerable size before developing roots from their bases. In plants other than alfalfa the rhizomes are often quite different in nature. Holms (1929) has attempted to classify them into three types, (l) horizontal homogeneous (2) vertical homogeneous and (5) horizontal heterogeneous. The f i r s t type i s commonest perhaps being best represented in the rhizomes of Tripsacum dactyloides L. Many other monocots and dicots possess this type, among them a l f a l f a . The vertical homogeneous rhizome i s rare, is found only i n Gentiana villosa L., Symplocarpus, spp., Panax and a few others. The third type, composed of slender internodes with alternating tuberous intemodes i s found in Dentaria laciniata and many orchids. -5-Further specific examples might serve to illustrate the diversity of type in rhizomes of different plant species. lot infrequently rhizomes are swollen and tuberous i n nature. Good illustrations of this are to he found in Helianthus tuberosus (Zimmerman and Hitchcock 1938) (Wettstein 1938) and Sweet Potato (Impomea botatas) (McCormick 1916). Jurica (1924) gives an interesting description of vertical rhizomes in Ernygium yuccifolium which form a series of bulb-like parts beneath the ground. The bulbs grow one above the other each year for four years but in the f i f t h and sixth years form flower stalks. After anthesis two secondary buds are initiated and the cycle is repeated. Old plants present thus the appearance of a dense cluster. Jurica notes a similar phenomenon in Smilax herbacea and Podaphyllum peltatum where however annual bifurcation of rhizomes was reponsible for the appearance of a dense cluster in plants of same age. Decay may develop at the posterior end of these clusters, resulting in eventual break-up. An unusual rhizome formation i s encountered in Helianthus scaberrimus native of the prairies of the Western United States. The "fairy rings" produced by this species are found by Cooper and Abraham (1931) to be due to the fact that regenerative buds are found only in the apices of the rhizomes and that the old growth tends to die each year. Thus death of the tissue proceeds outwards from the fecus of the colony and new growth is usually seen as a ring. In the grasses likewise rhizomes develop in various ways. In Kentucky Bluegrass (Poa pratensis L.) Evans and Ely (1935) found that the rhizomes originated from buds at the base of above-ground shoots. Development was at f i r s t downwards with later penetration horizontal. In Canada Bluegrass (Poa compressa), however, the same writers found rhizomes being initiated at the underground nodes of old rhizomes. Quackgrass (Agropyron rep ens L.) Red top (Agrostis alba L.) and Reed Canary Grass (Phalaris arundinacea L.) i t was found spread in this same way. Evans and Ely (ibid) found, as in al f a l f a , rhizome production in these grasses of Northern Ohio to be most active during June, July and August. Tuckey (1940) indirectly confirms this observation. For further information on morphological diversity in rhizomes the works of Kalmykova (1935) Kannenberg (1931) Yystotskii (1928) -Weaver (1930) Heath and Luckwill ( ) Yladmirov (1937) Sower (1935) and Almeida (1928) should be consulted. Possibly because the plant breeder has been the chief investigator interested, the gross morphology and not the histology of the alf a l f a rhizome has been given the most attention. However, a few studies of the microanatomy have been made. Miss Holliday (1952) clearly indicated the stem-like nature of the rhizomes she studied. Hayward (1938) also notes that in common with the aerial stem "the rhizome possesses well-defined casparian strips i n the endodermal layer followed later by a pronounced li g n i f ication of the inner and tangential walls". The cells of the rhizome pericycle, unlike those of the stem, function as a phellogen producing a periderm. He observes further that the rhizome wi l l live for three or four years while the stem dies at the end of each season. While they did not specifically investigate the rhizome 'Wilson (1913), Poczosky (1917) and Winter (1932) have contributed much to the general histology of the a l f a l f a plant. Wilson's observations were not of a detailed character. Poczosky, on the other hand, endeavoured to trace the development of the root system in relation to vegetative reproduction and to winter hardiness. Winter studied mainly the root-stem transition system. Mention might also be made of the contributions which were in part histological of Simonds (1935) and Jones (1928) on the structure of the crown and root of lucerne. In other plants rhizome structure has received more detailed consideration than in a l f a l f a . As in alfalfa, however, most investigators find these organs to have in the main a stem-like histology. Careful work bearing out this contention is found in the paper of Thoday and Woodhead ,(1932)» They note the stem-like nature of the stele but note modifications such as the extensive lignification following cambial activity in older tissues. Wille (1S26) has given us a detailed study of the microanatomy of the principal groups of the Cyperaceae. Fuchs and Zeigenspeck (1926) have described the anatomy of the stems and rhizomes of many orchids. Niki (1927) and Carlson (1938) emphasize the histological differences of stem, root and rhizome in other studies. ^ The origin of rhizomes in the stem tissue and the origin of the adventitious roots arising from the stem-like rhizome have been the subject of much controversy. To judge from the literature studied one maj safely conclude that the pericycle and cortex are the chief initiating tissues. Which happens to be functional i n a particular case depends largely on the species. For details, the papers of Chang (1927) and Hayata (1929) should be consulted. Chouard (1934) also gives an interesting description of the origin of rhizomes from buds produced in the axils of parent bulbs in Sc i l i a adlonis. Contractility of rhizomes, a feature of importance in many plants, has been studied from the histological viewpoint. Ziegenspeck (1927) finds that in Hedysarum comosum the sudden activity of the cambium -8-crushes adjacent tissues inducing rhizome contraction. According to De Tries the shortening of contractile roots, and presumably of rhizomes, is due to growth in parenchymatous cells with anisotropic walls which are more extensible transversely than longitudinally, Thoday (1931) in Oxalis wearnata and Brodiara lactea finds rather that contraction is purely physiological and may be explained by the withdrawal of sap from the cells involved. Other papers of histological interest are those by Browne '(1933), Leandri (1928), Lauder-Thomson (1933), Sumpstine (1931), Gross (1931), Chakraverti (1939), Smih (1951) ,• Carl sen (1327), Howe (1931), Johannson (1929), Wilson (1927) and Taylor (1926). Of especial interest is a paper by Goette (1931) comparing the anatomy of rhizomes of Corwallaria majalis from different habitats. (c) The Functions of the Rhizomes in Alfalfa. Interest in alfalfa improvement has led slowly to the realization of the many and varied functions which the rhizomes may serve. The feature which f i r s t awakened interest was i t s relation to spread and coverage. Important adaptations of alfalfa in i t s native semi-arid Eurasia are i t s well developed tap root and the longevity of the individual plant. With the introduction of alfalfa to cultivation, however, has come the desire for dense stands in new and often very different habitats. In the new areas alfalfa is no longer so long lived. Disease and adverse conditions of climate and soil thin the stand. L i t t l e replacements or compensations occur and grasses and weeds compete vigorously for the areas lost. Accordingly, plant breeders seeking to adapt the plant to new conditions sought plants which would ensure continued dense stands. Rhizoraatous alfalfa seemed to be the goal of the quest. Southern alfalfas, Peruvian, Provence, etc., invariably have small crowns. Individual plants of Grimm, Cossack u t i l i z e areas somewhat more efficiently. Ladak and (Turkestan are almost semi-rhizomatotis and spread appreciably. Mention has been made of types of falcata and gaetula which are truly spreading. Oliver (1913), for example, has found plants of the falcata type from North Africa which produce rhizomes three and one-half inches in length. From the 3ha11ow soil regions of the Caucasus and Turkestan have come other plants with phenomenal spread. Illustrations of how these spreading types are proving of value in present day breeding programs w i l l be given later. (Moe (1928), Myers and Kirk)" The.capacity to send out rhizomes is recognized as a valuable attribute in many other plants of economic value. Swards of Kentucky Bluegrass (Poa pratensis), (Kanneriberg 1931a, 1931b), Bromus inermis, Trifolium subterraneum , various Galamagrostis spp., Agrostis alba, etc., are directly related to rhizome production. Rhizomes may function in the production of new plants from a parent plant. In a l f a l f a this is not commonly seen, but the observations of Oakley and Garver (1913) on i t s occurrence should not be neglected. Trifolium subterraneum, a native of New Zealand, sets l i t t l e seed but is largely dependent on rhizomes for dissemination. This is true also of Calamagrostis rubescens, and is partly true of Smilax herbacea, Eryngium (Jurica 1924), S c i i l a adlami (Chouard, 1934) and Helianthus tuberosus (Zimmerman and Hitchcock, 1938). Age, apparently, has a very important bearing on the regenerative powers of rhizomes. Froese (1938), among others, found rhizomes which were several years old to be most -10-active in Lathyrus pratensis. In Agropyron repens, Ennvere (1937), found regeneration: to be directly related to dry matter content, Scavone (1939) states that ramie rhizomes propagate best at three years of age. An additional reason for special interest in the rhizome of alfalfa i s i t s association with resistance to extremes of heat and cold. The early plant explorers of the U. S. D. A,, Hansen, Meyers and others, noted that rhizomatous alfalfas were found in the extreme heat of the north African rocky soils and in the f r i g i d areas of Siberia, where the subsoil scarcely thawed i n summer. Hansen (1909) records falcata types growing at Verhoyansk, Siberia, latitude 68° N., where minimum temperature experienced i s -90°F. Leschenko (1930) found that i n Erassnokutsk in Russia, after the severe winter of 1927, a l l American, European, and Ukrainian alfalfas k i l l e d out with the exception of one native yellow-flowered rhizomatous species. Schubert (1931) was able to separate hardy and non-hardy strains on the basis of their tendency to form rhizomes. Graber (1927) has stated that the hardiness of Grim, Ontario Variegated and Hardigan i s related to their production of rhizome i n i t i a l s with dense cytoplasm. IQapp (1932) at ZwStzen, Jena, Germany, says that "forms distinguished by winter hardiness are also distinguished by a branching of the roots and in hybrid lucernes the forming of rhizomes is not a rare occurrence." Garver (1922) in a thorough study of hardy and susceptible alfalfas finds that "there are outstanding differences between the root systems of southern grown common and yeliow-f1 owered (falcata) alfalfas in the prominence of the tap root, the development of the branch roots and the number of rhizomes, and in the number and place of the most profuse production of fibrous roots. Extreme forms could be told apart by their underground structures. — 1 1 — . The histological relationships of winter-hardiness in alfalfas have been ascertained by Jones (1928). Young protoplasmic structures such as rhizome and shoot i n i t i a l s seldom show any winter injury, whereas the pith parenchyma, xylem and phloem parenchyma show marked susceptibility. A histological explanation then for the hardiness of young and rhizomatous alfalfas may be concluded. Southworth (1921) also has contributed to these studies. In Common alfalfas the tap root i s the primary storage structure. Of necessity in rhizomatous alfalfas the rhizomes must under-take this function. Pood reserves are stored mainly as carbohydrates. Morozov (1939) finds that inulin-like compounds and hemicelluloses predominate. Of the simple sugars, sucrose i s the most abundant. Smelov and Morozov (1939b) carried their investigations further by determining the carbohydrate reserve separately for roots, rhizomes and stems. The study showed that roots contained mostly Hemicellulose, the rhizomes mainly soluble carbohydrate and the stems both hemicellulose and soluble carbo-hydrate; In another investigation (1939a) they found during t i l l e r i n g and ant lies is to seed setting, rises in reserve carbohydrates. This parallels the experience with other plants, Bromus inermis, Lolium perenne, Al opecur is pratensis, Festuca pratensis and Dactylis glomerata. Malahov (1937) working with Agropyron repens and Weinmann (1940) with Chloris gayana find, similarly, depletion of reserves after and during flowering. They noted also a marked rootward gradient in sugars and hydrolyzable materials as autumn approached. Intimately related to the vigor of a l f a l f a , and i t s storage of reserve food i s cutting practice. The works on this, while numerous, (and only a few of the more significant ones can be mentioned here) seldom -12-take the rhizome specifically into account. Miss Holliday (1932) maices the observation that with heavy clipping or cutting rhizomes are not produced in alfalfa predisposed to vigorous rhizome production. It would seem then that severe depletion of food reserves inevitably reduces rhizome production, and.vigor in a l f a l f a . In Kentucky Bluegrass, however, Ahlgren (1938) found that the carbohydrate content of rhizomes was not appreciably affected by cutting or grazing practice and that in Bromus inermis attempts to increase food reserve by applying f e r t i l i z e r actually reduced the rhizome reserve. Graber and his associates (1927) found also that in alfalfa the frequent cutting of top growth, while ultimately reducing the vigor of the plant, w i l l increase the number of buds, shoots and rhizomes per plant. • ., Accumulation of reserves and hence cutting practice in alfalfa has an important bearing on the survival of the plant in extremes of heat, drought, and cold. Sylven (1934) found that the later the last cut could be taken, the less would be the winter injury and the greater the yield in the f ollov/ing spring. Late cutting permitted over-wintering buds to remain in a hardened condition, while early cutting forced them into activity and a condition of cold susceptibility. Silkett (1937) expressed this physiologically by stating that shoots of plants low in dry matter and high in percent moisture were most susceptible to winter injury. Plants cut in September drew on their root and rhizome reserves to produce f u l l growth, thereby lowering their resistance. Rather and Borrance (1938) found that, in similar manner, f a l l pastured plants suffered more winter injury and developed fewer and less vigorous crown buds. Mark (1936) found a positive correlation between winter injury and root reserves. A single cutting at the end of August lowered the underground reserves of Grimm alfalfa 100$ by October 8th. Reference in this connection should also be made to the pertinent work of Barr (1936, 1939 and 1940) on root reserves in Convolvulus arvensis. the Bindweed, and to the work of Wettstein (1938) on the tuberous plant He l i an thus tuberosus. Rhizomes may serve an additional purpose in storing water during periods of drought. Falcata alfalfas apparently have special f a c i l i t i e s in this regard* Contrast this with tap roots which store l i t t l e water but seek the water table. The rhizomes, instead of storing water, too, maybe dormant during periods of drought as the work of Almeida (1926) with Nymphaea pubescens Wjlld., and Bailey (1940) with Agropyron smithii, has shown. The role of rhizomes in relation to plant competition is not clear. In many plants rhizomes have a definite value in competition as is well exemplified in many of our perennial weeds. Both Dehay (1939) and Woodcock (1932) found Agropyron repens to have very great powers of spreading i t s e l f . Dehay found i t s rhizomes to have penetrated a living root of Althoea o f f i c i n a l i s whilst Woodcock showed i t to have entered a one year old seedling of Juglans cardiformis. Zade, on the other hand, found the rhizomes of Poa pratensis unable to spread in the presence of Dactylis glomerata. Several other additional functions associated with rhizomes may be mentioned. In certain cases rhizomes w i l l serve to protect plants from a l k a l i , as Hansen (1909) found some rhizomatous strains of M, falcata growing under alkaline conditions in Siberia. Rhizomes on the other hand w i l l not serve to protect al f a l f a against excess acid, as a level of acidity i s soon reached where initiation and growth of rhizomes ceases. Haas (l927), Holliday (1952), Watenpaugh (1936) and Oliver (1913) credit rhizomes with leaving a large amount of humus in -14-the s o i l . "Hhizomatous alf a l f a , although admitted by Koenekamp and Lehmann (1933) to serve as a valuable pasture plant, may also, they claim, suffer considerably from trampling, as a large part of the t i l l e r i n g zone lies near the surface of the ground. (a) • The- Story, of Alfalfa Alfalfa, Medicago sativa L., i s a native of the temperate regions of Western Asia, notably Media, the countries southeast of the Caucasian Range and the northwestern part of modern Persia (Klinkowski, 1933). It is the oldest forage plant known, being mentioned in the Old Testament. The progress of this "queen of the forage crops" was from East to West, following the path of historic civilizations. It reached Greece in King Darius* time in 470 B. C. and took 300 years to reach Italy. About 150-200 B. C. i t obtained a foothold in Forth Africa where i t i s s t i l l found. Whether i t came directly from Asia to North Africa or whether i t was brought by the Romans is not clear. In Asia i t followed the old cara-van routes to China; in Europe i t was limited to the two Mediterranean countries; in North Africa i t was confined to the oases. The 13th century found i t s area of cultivation increased and at this time i t was found in Southern France. At about the same time i t was brought into Spain under the name of " a l f a l f a " or ,rbest of fodder" by the Moors with their invasion of that country. At the start of the 16th century al f a l f a was taken by the Spaniards to Mexico, thence to Peru, Chile, Argentina and Uruguay. Thus in the Western Hemisphere alfalfa was confined at'first to Central and South America. In Europe i t spread from Spain to France about 1550, reaching Belgium i n 1565, and Holland under the name of "Bourgoens hay" at the same time. This "Burgundy hay" reached Hungary around 1587, disappearing shortly. However i t was reintroduced at the end of the 18th century. The black s o i l region of Russia was reached by way of Spain and France, and not from the West Asiatic steppe d i s t r i c t . In Germany i t was f i r s t cultivated in the province of Thuringia in 1710, -16-meeting much opposition at f i r s t , but later i t s real worth was recognised and the rate of expansion of "Old Fraconian hybrid lucerne" was quite extraordinary. While lucerne cultivation had reached great importance in South America as early as the 18th century, i t was unknown in North America un t i l i t arrived in the middle of the 19th century. Alfalfa entered North America by two different routes, one from South America, and one from Germany, Gold seekers brought the "Chilean Glover" from South America to California in 1851-54, also a few years later Missionaries brought i t from Mexico to Colorado, but the intense cold of northern winters prevented this strain penetrating farther north. The most important of the strains introduced was the German strain brought into Minnesota by Wendelin Grimm in 1857. The seed he brought with him was the old Franconian hybrid lucerne which can be traced back in Germany to 1710, i t being introduced into Bavaria at that time by the Cistercian monks of the Ebrach Monastery i n Franconia (Elinkowski, 1933). Much of Grimm's f i r s t plantings died, owing to winterkilling, but by saving some seed each f a l l and planting i t the next spring, through natural selection his strain became hardy enough to withstand Minnesota winters. From i t has sprung the "Grimm" alf a l f a which has contributed so immensely to a l f a l f a production in North America. Another strain of al f a l f a that has proved of especial value to alfalfa growers of Canada and the Middle West is "Ontario variegated". This strain was introduced into the Niagara district in Canada some thirteen to fifteen years after the introduction of the Grimm into Minnesota (Southworth, 1921). The Ontario variegated probably arose from a mixture of two strains with variegated flowers. One strain being introduced in 1871 by a farmer named Bethel, living near St. Catherines, who obtained it from a German shepherd who brought i t from his native country. The other strain also came from Germany in 1875 through the agency of Dr. Cellyer, a medical man then living at a port called Welland, near Niagara. Reference w i l l be made later to both Grimm and Ontario variegated in the discussion on the development of rhizomatous strains of alfalfa in Canada. THE HISTORY OF RHIZOMATOUS ALFALFA Coming more specifically now to the study of rhizome producing types of alfalfa their history v/ill be traced. The Common al f a l f a already studied does not usually spread. However some species do spread, among which are Medicago falcata. L., Medicago gaetula Urb., and some species of Medicago sativa L. Of these M._ falcata i s the most prominent and is important economically. Responsible for the f i r s t introduction of these spreading strains to America was Professor N. E. Hansen of South Dakota. The United States Government seeing the value of alfalfa and the need for hardier strains sent him to Siberia to collect these. Hansen made two tr i p s , the f i r s t in 1897-1898, bringing back Turkestan Alfalfa, and the second in 1906-1908, returning with Medicago falcata. M. platycarpa and M. ruthenica, he also noted, were of l i k e l y agricultural value, but the onset of winter made i t impossible to make any collection. Later a journey was made to Siberia and North Africa to gather more seed of new forage plants, especially alfalfas and clovers i n Siberia, and also to determine how people survive in such vast deserts as the Gobi of Mongolia^ the Salt Steppes of southwestern Siberia, the Hunger Steppe of Turkestan and the Sahara of North Africa. Of the forage plants found in this area were Medicago falcata and Trifolium lupinaster. By way of emphasizing the extreme hardiness of M. falcata v/e may cite examples of where i t was found growing between Verkyozansk, latitude 6&°E. (minimum temperature recorded, - 90.04° F), and Yakutsk, latitude 62° N > (minimum temperature recorded, - 83.92° F.) due north of Lake Baikal, where the subsoil remains frozen a l l year round. Hansen states that the peasants of Siberia have long ago found the value of these alfalfas, M. falaata, especially being an important factor in making the rich cream and1 butter for which Siberia is noted. Medicago falcata (falcata referring to the sickle or falcate shaped pods), is distributed over a wide range of Europe and Asia, but in the milder regions has been largely replaced by Common lucerne. It extends through Western Europe, central and southern Russia, the Crimea, Caucasus, the western two-thirds of Siberia, North China, the Trans-Caspian region, including Turkestan and Persia, through Asia Minor, Afghanistan, and Western India. M. falcata has proved of outstanding value at the dryland Agricultural Experimental Station at Bensentsug, 30 miles east of Samara in the Volga River region of European Russia. This area is in the heart of a vast steppe region suffering from summer droughts and winter cold. Here recurring crop failures have caused distress among the peasants. M. sativa or French lucerne, winterkills and does not endure pasturing, whilst the native M. falcata is perfectly hardy and endures pasturing for at least ten years, being long-lived with a strong root system. The protein content of i t s f i r s t cutting i s two per cent above M. sativa but later cuttings are less. As many as one hundred branches were found by Klingen (Hansen, 1909) from the one plant of M. falcata which when pastured i s of strong upright growth, standing fu l l y waist high in the Steppes, but creeping and having only the ends erect when closely pastured. Recognizing these qualities of M. falcata, Hansen (1909) made many collections of seed of M. falcata. He brought back with him to the United States in 1909, seed from Kharkof Province, southeastern Russia; Omsk, Siberia; Irkutsk, Eastern Siberia; Samara Province in the Volga River region; Don Province of the lower Volga River region, southeastern Russia; and Tomsk, Siberia. These were found to produce fine upright plants, 5-3^ feet high where range v/as not overcrowded. In the native habitat on the banks of Irtisk River near Semipolatinsk, Hansen, in 1908, found i t growing 5' 8" high. He found M. falcata to be relished by stock to withstand considerable pasturing, to green early in the spring, to endure severe summer droughts, to thrive on dry upland soils underlaid with hardpan and to resist a l k a l i . Working with nature, by making use of her work of countless thousands of years in producing a hardy a l f a l f a , Hansen f e l t , i s a sounder policy than that advocated by some workers of selecting hardy types from non-hardy strains. It was in accordance with this belief that M. falcata as one of many economic plants was introduced into the United States and Canada. In addition to Professor 1. E. Hansen Mr. Frank H. Meyer, the United States Department of Agriculture's agricultural explorer, has been responsible for introducing seed of the greater number of various forms of the species especially from localities in Asia. Approximately 50 lots were introduced mostly from Russia where Siberia conditions were very similar to those in the north western American plains. Oliver (1913) utilized a l l these imported strains of M. falcata in his work to produce a new alfalfa variety for pasture which would be -20-winter hardy'and drought resistant. Early in his work Oliver found that these characteristics were associated with the underground development of rhizomes and modified rhizomes. As a result he undertook a very extensive breeding program with the idea in mind of obtaining rhizomatous pasture forms which he hoped would grow in areas in the United States not suited to the standard varieties at the time. He concentrated his efforts, then, upon obtaining plants having good top growth and abundant underground bud potentiality for production of rhizomes, these being formed preferably, well below ground level, with the crown of the plant deeply set in the s o i l . While Oliver was the f i r s t man to do work consciously on rhizomatous alfalfa production, we have mention of other men who observed rhizomatous growth. Even as early as 1733 Jethro Tull noted "perpendicular roots springing from the very branches of the lucerne crown". M. L u l l i n de Chateau-vieux (Duhamel du Monceau, 1759) in 1759 may also have observed them as he speaks of the crown extending i t s e l f every year. These men, however, seemed to have overlooked i t s importance, and credit for calling attention to this character and pointing out its value should be given to Thomas Le Blanc (1791), who, in 1783, mentioned i t s habit of branching below the surface of the ground, i t , consequently, not being choked by natural grasses nor injured by sheep grazing and as well, being hardier than other alfalfas in bearing cold. It may be said that he so understood this strain's value that he tried to introduce i t into general use. Despite the definiteness with which he wrote l i t t l e subsequent attention was paid to his work and i t was soon lost to sight*. Prior to Oliver's work, Blirm (1911) had written an article, "Alfalfas The relation of type to hardiness". Then followed Oliver's (1913) bulletin, referred to previous-ly, on "Some new al f a l f a varieties for pasture", followed by Oakley and Garver's (1913) work "Two types of proliferation in a l f a l f a " the same year. The two types of proliferation referred to by these workers are rhizomatous growth or stem proliferation, and root proliferation not previously mentioned in the literature. This article serves to c a l l attention to peculiarities that have been found in al f a l f a . Following this early work, Oakley and Garver (1917) undertook a very thorough investigation of M. falcata, and established an extensive living collection. It is of interest in connection with the breeding work that Fryer (1930) found two types of SL falcata, one with 16 chromo-somes, and the other with the normal 32 chromosomes. Other than the report by Southworth (1921) of the history of a l f a l f a in the United States and Ontario where he mentions three root systems, one of which i s a branched tap-root with underground stems, and Garver's (1922) histological studies mentioned later, no further references on rhizomatous alfalfa were found un t i l 1930 when certain European workers became interested i n i t . Leschenko (1930) describing lucerne naturally reproduced by means of rhizomes believed he was the f i r s t to mention rhizomatous types in the literature. The type that he described was found at Poltava after the severe 1923-29 winter. At that time a l l nursery stocks of American, West European, Ukrainian, Russian and Turkestan types were killed out. The surviving plant whose rhizomes recovered was a ye11ow-flowered lucerne native of Krassnokutsk. Close examination showed the young shoots which covered i t to be underground shoots. From the crown thick living roots were found, these giving rise to lateral roots from the nodes and extending horizontally 45 cm. before bending and growing downwards. In two years this root system had developed to cover one square meter. Elapp and' Schubert (1931) presented a very far-reaching analysis of the Thuringian hybrid lucerne in which they showed i t s superiority over southern strains. Schubert (1931) was aware of the importance of the roots in promoting winter hardiness i n northern strains. In 1931 he presented a paper, "Observations on the roots of lucerne of different origins" in which he divided lucerne into 3 groups: (l) those i n which the hybrid proportioi was high, and have branch roots (evidently Schubert is here referring to rhizomes as branch roots) at right angles to the main root in which were included lucernes of northern origin, old Franconian and varieties from the E i f e l , the Palatinate and Northern France; (2) those in which the hybrid proportion was low with branch roots mainly turned down and which possess (a) a single unbranched tap root (b) a single forked root, a l l of which were obtained from Grescat, Hungary, Turkestan and Cossack; (3) those in which the hybrid proportion was slight or lacking and were mostly of southern origin such as the Italian, Provence, Spanish, Chilean, South African and, Argentine lucernes. Ho'' mention is made i n the third case of the kind of roots found. Klinkowski (1932) draws attention to various "discoveries" of lucerne forms which produce rhizomes and in particular to a plant recently found by a roadside near Berlin in which this growth was particularly marked. Immediately upon publication of this "discovery" of Herr Klin-kowski, Professor Klapp (1932), under the same heading, states that the formation of rhizomes by hybrid lucerne is no rare thing. Professor Klapp points out for example that production of rhizomes is mentioned in the American literature as characteristic of Medicago falcata and that M. sativa forms have been, known to exhibit short rhizomes. The development of rhizomes under various environmental conditions has been discussed by many European workers. Wick (1932) gives -23-a comparison^of the following varieties grown for five years at nine different places in Germany. Old Franconian, Franconian, Thuringian, Cossack, Grimm, Hungarian, Kaiserie, Provence, Italian and South African. He found Franconian and Thuringian strains with Cossack and Kaiserie taking f i r s t place, Grimm taking intermediate place, whilst the South African, Provence and to a large extent the Italian varieties cannot compete with the others under German conditions. Professor Klapp (1932) in a comparison between southern strains of lucerne and some German 'strains developed at SwMtzen, Jena, after the hard winter of 1928-29, made the following statement: "Forms distinguished by winter hardiness are also distinguished by a branching of the roots, and in hybrid lucernes the. forming of rhizomes is not a rare occurrence." Koenekamp and Lehmann (1933) showed an interest in the "lucerne which sends out rhizomes", remarking on their value as a highly desirable character in a pasture plant but stating that a large part of the t i l l e r i n g zone l i e s near the surface of the ground, where there is danger of injury due to trampling. Also they claim the preparation of M. falcata i n the hybrids is very heavy and that this species is poor as regards second growth. Ufer (1933) studied interspecific hybrids of Medicago gaetula Urb», from Batna, Algeria, and Medicago falcata L., from Muneheberg, Germany, with a view to obtaining strains resistant to cold and drought. The resulting Fx showed an intermediate growth between the two parents and although a f u l l description of the resultant plant is given no reference to i t s hardiness is made. They did prove the contention of Trobut, the French scientist, that M. sativa arose from a cross of M. falcata x M. gaetula, was erroneous. That the energies of these various workers were beginning to bear f r u i t may be gathered with the announcement byIlinkowski (1934) that a new.rhizomatous lucerne for Germany, named E i f e l , had been produced. This E i f e l lucerne is very leafy and much branched, The root system is highly branched with many parts attached at right angles to the main axis. Furthermore there is an abundant formation of fibrous roots. ICoenekamp (1934) published results on a comparison of this E i f e l rhizomatous hybrid lucerne with ten Argentine varieties. He found the difference in root development, though slight, was sufficient to prove the superiority of the Germany hybrid in this respect. Following the progress of the v/ork with rhizomatous alfalfa in Europe, attention is directed again to i t s development in Forth America. Li t t l e information is available of the more recent work. However, a spread of the alfalfa grown has been receiving the attention of a l l breeders, and Dr's. L. F. Graber and H. A. Brink of Wisconsin, and Dr f s . C. H. Myers and D. B. Johnstone-Wallace of Cornell have developed a number of strains of pasture types. Dr. L. E. Kirk, too, now Dean of the Faculty of Agriculture, Saskatoon, states in a letter received from him that while he was at Ottawa, work was being conducted there with rhizomatous strains of Medicago glutinosa. Also Mr. W. J. White, Officer in Charge of the Dominion Forage Crops Laboratory, Saskatoon, says that selections of the more widely creeping types of Medicago glutinosa have been made at that institution. Work is continuing there both with this species and with M. falcata from which a very strongly creeping strain has evolved. For many years the Agronomy Department of the University of British Columbia has been interested in rhizomatous a l f a l f a , the "U.B.C. al f a l f a " developed here representing the fourth generation of a cross between variegated al f a l f a s , Medicago media, and yellow-flowered Medicago falcata. Dr. L. S. IQinck, President of the University of British Columbia, brought from MacDonaId College, Quebec, several cuttings from one plant of M. falcata. Dr. IQinck had obtained the strain from Professor K. E. Hansen of South Dakota, who imported i t from Bussia, probably, although this is uncertain, under the introduction number S. P. 1. 20725. The cuttings were planted and sixty plants propagated from them. Professor Boving, formerly head of the. Department of Agronomy of the University of British Columbia, since retired, grew several short rows of variegated a l f a l f a , both Grimm and Ontario variegated, next to the falcate type designated, to obtain a cross between these in 1917. Using the Don as a maternal parent seed was obtained and planted. Two hundred and f i f t y plant s were grown and only 6 showed hybrid characters^ Dr. G. G. Moe, the present head of the Department of Agronomy (1928) of the University of British Columbia, endeavoured to self these F i plants in 1919 by enclosing them in cheesecloth tents and manipulating the flowers. As so few seeds were produced they were left untented in 1920, a l l other alfalfas being cut back except the six hybrids, and a heavy yield of seed obtained after again manipulating the flowers. In 1921 this seed was set out in rows and the plants permitted to grow several years. In 1924 Dr. Moe planted the seed of these F2 plants, and in 1925 open f e r t i l i z e d seed was taken from a l l 3?s plants that produced seed, this being set out i n a block to establish the Fa stand from which the present writer obtained his material. Most of the plants in this stand are today showing great spread, the one chosen to secure cuttings covering 4 sq, feet. Dr„ Moe mentioned the Don parent in this cross as "being characterized by short, semi-erect -26-stems, a thick matted growth and yellow flowers, rhisomes being formed several inches below the ground and spreading varying distances from the plant." Evidently the plant chosen inherited much of i t s spread from i t s falcata parent, along with more vigorous growth from i t s Grimm and variegated ancestry. III. EXPERlMEM?AI» WOBK-(a) Introduction When the subject of rhizome growth was f i r s t considered as a topic for study, those factors which would likely prove of practical value in the production of rhizomes in alfalfa were given f i r s t consideration. The earlier work was lai d out on this basis. However, as much of this f i r s t v/ork, through unfortunate circumstances, had later to be la i d aside, i t was found necessary to modify the practical point of i view, and lay more emphasis on obtaining definite rhizome growth response, whether this should prove to be of practical value or not. In the experimental work conducted -here rhizomatous strains i of University of British Columbia alf a l f a were studied. The rhizomatous habit of growth was thought to be most valuable for a pasture strain, although i t s worth as a hay crop could not be underestimated either. Yfork has been carried on at the University of British Columbia in both these regards. The most practical way to determine it s pasturing value was to actually c l i p the plots to simulate pasturing, and also cut them twice or three times a year, weighing each cut to get a record of hay yields. Comparisons with a normal strain would have to be made. Fortunately, a series of alfalfa plots had been set out the same summer in the Agronomy Field to determine the yields from Grimm and University of Br i t i s h Columbia strains sown at different rates of seeding. These were kindly turned over by Dr. Mce to the writer to be used i n his rhizome studies and were ideal for the purpose in mind. If f e r t i l i z e r s were important in accentuating rhizome growth this would be of great value. Accordingly, plots were lai d out to discover just what effect f e r t i l i z e r s had on either initiating or accentuating rhizome growth. More details of this work w i l l he given later under i t s appropriate heading. In conjunction with this f i e l d work, studies were begun in the greenhouse where more controlled methods could he applied to the plants and work done which was impossible to accomplish outdoors. As alfalfa is primarily a plant thriving i n non-acid soils containing calcium, the effects of acid soils on rhizome growth would be of value and so a series of soils of varying acidity were planned to be used to study this effect. Other factors which would have a bearing on production of rhizomes such as length of day and temperature were also studied and these results w i l l be given later. (b) Field Studies 1. The Clipping Experiment, Purposes The clipping experiment was undertaken to study the effects of the removal of the top growth of the alfalfa plants on their rhizome development and on the subsequent yield of hay from the plots. Discussion, of the Literature: / Considerable attention has been paid in the literature to this subject of clipping and i t s effects on plants. This attention is justified as cutting and i t s effects on root reserve is important. The time of cutting has already been shown in previous discussions to be a matter ? of great moment to the alfalfa plant, so much so as to condition its chance of subsequent survival. Thornton and ETicol (1934) studied a more general effect of cutting treatments on alfalfa reserves, both below and above ground. The cutting did not alter the number of nodules, their mean -29-size, nor ; did i t alter total nitrogen content of the plants (tops and roots), "but i t did decrease the nitrogen content of the roots forty per cent, this nitrogen going to the tops and "being removed. When clipping weights were taken, the total yield of the tops increased, but that of the roots decreased, Grandfield (1935) studied alfalfa more in relation to the effects of time of cutting on the storage of food, finding eight to ten inches of f a l l growth must occur after the last cutting to permit maximum storage of root reserves. This maxium storage he found to take place at f u l l bloom. Early and frequent cutting in the bud stage resulted.in lower carbohydrate and nitrogen content of the roots* Harrison (1959) clipped a l f a l f a to one inch, two inches and s i r inches every week for eight weeks and found the one-inch clipped plants had only f i f t y per cent of the dry weight in their roots that they had at the start of the experiment, and only fourteen per cent as much as the uncut ones. The two-inch clipped plants had forty per cent as much, and the six-inch approximately equalled the uncut plants» The stored starch in the roots of the one-inch clipped plants was entirely depleted,; in the two-inch ones i t was partially depleted, and in the six-inch uncut ones an abundant supply occurred. Hildebrand and Harrison (1939) showed how a borderline effect in an alfalfa clipping experiment may occur. Below this line of cutting, poor growth of both tops and roots results, and above i t good growth. This line was found to be between the nine-inch and six-inch levels in an experiment where twelve-inch, nine-inch, six-inch, three-inch and one-inch cuttings were made, was the same for weekly, bi-weekly and monthly intervals of cutting for a period of twelve weeks. Tysdal and Kiesselbach (1939) found a differential response of varieties to time of cutting. The Ladak variety could be made to outyield Grimm by varying the time when i t was cut. Nebraska Common, Hardistan and Grimm, as well as Ladak, a l l showed this effect of different time of cutting. . The investigations undertaken by Holliday (1932), Silkett (1937) and Bather and Dorranee (1938) on the effects of cutting alfalfa have already been discussed i n the general review of literature. They showed that time and frequency of cutting is very important for the laying down of adequate food stores i n the underground parts of the plant. Proceeding from the study of al f a l f a to that of grasses, their manner of growth is found to be affected in very nearly an identical manner to that of a l f a l f a . Harrison (1931) studying the effects of cutting and f e r t i l i z e r s on grass development, found the shorter the grass was cut the smaller was the quantity of roots produced. He shozyed Fescue ti l l e r e d more when cut short than when cut long, whilst Kentucky Bluegrass t i l l e r e d less under similar treatment. Mineral f e r t i l i z e r s did not compensate for lack of top growth in production of roots. The lack of root growth was due to a gradual carbohydrate starvation and not to the. ] buds being cut-off. Nitrogen increased the top growth but the weight of the roots was unaffected by i t s application. Graber (1933) also studied the effect of cutting grass at two levels. He used Poa pratensis, cutting i t "close" and " t a l l " and determined the yields from each for two years. The f i r s t year the oven dried grass from the short cuttings gave the higher yield, making most of this gain i n the f i r s t cutting May 10th. The following year, with three cuttings being taken, the "close" cut f i e l d was found to give the lower yield with weeds five to seven times more abundant than on the " t a l l " cut f i e l d . Graber found that when high potentially productive bluegrass was stimulated by. F2 and moisture supply, the delays in recovery after cutting and removing a large quantity of top growth, may greatly limit subsequent yields. Kuhn and Kemp (1939) found similar effects when cutting a t a l l and a short-growing strain of the same grass* An increase i n the severity of defoliation v/as found to cause a highly significant decrease i n the production of roots, rhizomes and tops* The short-growing strain with-stood the clipping better than the tall-growing strain when both of these grasses were cut at a one-inch or one and one-half-inch level. Graber and Heam (1931) used Kentucky Bluegrass., but f e r t i l i z e d one series of plots with nitrogen, the other series remaining unfertilised. Each of these series was divided into two portions, one receiving one defoliation and the other eight defoliations. After one hundred and twenty-three days of growth, an accumulation of organic foods resulting in increased root and rhizome growth occurred in the f e r t i l i z e d and unfertilized plots of the one defoliated series, as compared to those defoliated eight times. Cutting treatments have been conducted with a variety of other grasses. Wilsie (1940) and co-workers used Napier Grass (Pennisetuta purpureum) under Hawaiian conditions and obtained similar results to those conducted with bluegrass. An increase i n the total yields was obtained as the intervals between the cuttings were raised from six, eight, ten, twelve to fourteen weeks. As palatability forage, protein and ash content decrease with increase in the age of the plants and as a six-week interval caused poor recovery, depleted stand and greater weed competition, an eight-week interval between cuttings was recommended for Hawaiian conditions.., Sturkie (1930), working with Johnson Grass (Sorghum halepense) found any cutting treatment reduces rootstalk development, and the more frequently the cutting is made the greater is this reduction. Hanson and Stoddart (1940) investigated the effects of grazing on bunch wheat grass (Agropyron inerme). They found heavy grazing decreased root weight in the s o i l , decreased basal area, height and number of seed stalks of above ground parts, decreased germination and number of seeds, and decreased carbohydrates in stem bases and roots, as compared to ungrazed- stands. This caused, as would be expected, a general adverse effect on the grass. Sprague (1933), studying Colonial Bent and Kentucky Bluegrass, showed one-half the root system is newly generated each spring. Hence the s o i l and cultural conditions have more effect in the spring than at other times. As compared to uncut grasses, a level cutting of sevens-eighths of an inch with Kentucky Bluegrass showed no change in root development, a seven-eighths of an inch cutting with Bed Top had a reduced effect, and three Bent species even tolerated a one-quarter inch cutting* Graber (1931) in a general summary of the results of cutting on Bluegrass, Red Top, Fescue and Timothy concludes that not only-did the amount of root and rhizome growth and total top growth vary inversely as the frequency of defoliation, but reduced growth sometimes occurred for several months following excessive defoliations. The productive capacity of grasses, he claims, is not alone dependent upon adequate supplies of available nutrients. Moisture, combined with favorable light and temperature, as well as the food reserves of the plant, will also condition this productive capacity. The removal of succulent top growth caused a heavy drain on available nitrogen. This was the f i r s t important factor in growth limitation, but when nitrogen was supplied abundantly, a severe drain was caused on the carbohydrate reserve. With slight opportunity being available for this carbohydrate reserve to be replenished, a limitation in the growth of the grasses naturally resulted. Plan of Procedure: The interest in this cutting experiment centered mainly on the response of the rhizomes of the alfalfa to the various clipping treatments given. Other results such as hay yields were taken to supplement this work-, -, To determine such a response each individual plant would have to he dug up and the rhizomes counted, measured and weighed and comparisons between the different treatments made. This was impossible to do in the plots of a l f a l f a , so individual plants (16 for each cutting treatment) were set out, to be treated identically to the plots, and later, at the conclusion of the experiment, would be dug up, and the measurements made. In the seeded blocks any effect the clipping would have on the rhizomes would show up indirectly through the weight of tops removed. It was logical to believe that i f clipping were tending to initiate new under-ground growth in the form of rhizomes, these, when they come to the surface of the s o i l , would cause the weight of clippings to increase, or i f clipping proved deleterious, as i t was l i k e l y to do, a fal l i n g off in yields of clippings would mean less food was available for top growth and so in a l l probability less for rhizome growth as well. The actual effect on the rhizome growth would be obtainable from the separate experiment already mentioned. . In order to complete the picture of changes taking place in the seeded plots, the plots were charted. The actual number of plants appearing in one square metre from the centre of each plot was determined. Supplementing this count the basal cover was estimated as the per cent of bare ground per square metre. The area was also drawn to show the appearance of the square metre when the recordings were made at the start of the experiment. At the end of two summers* treatment the plots were to be charted again and any changes noted. Each plot was divided into three portions, one on which no cuttings would be made (simulating seed production), one on which two or three cuttings per summer would be made (to simulate conditions where crop was cut for hay), and one clipped every two weeks (to simulate heavy pasturing). Accordingly, every plot had these areas marked off and in each four stakes (12 stakes per plot) were placed to record the exact position of each square metre for f i r s t and final charting. Altogether some thirty plots were treated in this manner, and twenty-five more had just the one square metre charted in each. An oak quadrat frame was made, dove-tailed at the corners ; with cross lines of medium copper wire placed every ten cm. both ways across i t , thus forming one hundred small squares in each of which i t was possible to count the plants and estimate the bare ground. The work of charting was completed by the second week of May, 1940, and arrangements made to begin clipping the plots at once. A lawn mower was to have been used for this work. Growth on the plots seemed very poor so clipping was postponed unt i l more improvement would be shown, which improvement, however, never came, and in July a l l thought of proceeding with the original plans had to be . abandoned. On June 6th the plots were cut as originally intended, and one portion of each was kept cut with a sickle to simulate pasturing conditions. The following photograph in Figure 1, taken on June 6th, 1940, w i l l give some idea of the conditions as they were at that time before the plots were cut, Figure 2 giving a close-up of the same. Figure 1. Photograph taken June 6th, 1940. Rote t h i n , stunted and g e n e r a l l y exhausted appearance of p l a n t s . Figure 2 Close-up of Figure 1, to and lack of vigor. Figure 3 General view of Figures 1 and 2 taken July 8th, 1940 after cutting treatments to show poor comeback. The "seed" portion of plot uncut is at extreme l e f t . The "hay" plot i s next, after growing 21 days and •pas-ture" plot to the right having just been cut. show dwarfed plants Figure 4 Photographed July 8th, 1940, and shows average heights of "seed" and "hay" plots 21 days after "hay" plot was cut. -37-Th.e general appearance of a l l the plots gave every indication of a mineral deficiency existing, despite the fact that basic slag and lime, had been applied in April, 1940. The f i e l d had lain bare for the previous three summers and extensive leaching might be responsible f o r the poor growths obtained. The pronounced yellowing of the foliage seemed to point to a boron or potassium deficiency. One particularly interesting- point, however, was a narrow strip two feet wide and five feet long, extending through one plot, i n which growth was normal, being two feet high and of a rich green coloration. Examination of the roots of these plants showed heavy nodulation, whereas stunted plants merely showed an occasional nodule or usually none. Thus the belief v/as held that the seat of the trouble lay in lack of nodule bacteria, even though inoculation with suitable earth culture had been made before seeding down the blocks. As the season was new approaching July, and being very hot and dry, d i f f i c u l t y was expected in introducing the cultures of Rhizobium meliloti at hand, into the s o i l . This v/as done, however, on July 4th at night by spraying on the cultures followed.by a liberal watering. Eearing that the following very hot and dry weather had k i l l e d the bacteria, as no great improvement was shown, the plots were reinocu-lated with heavier cultures during a rain storm on July 18th. In addition, boron at the rate of fifteen pounds per acre, potassium at one hundred pounds per acre, and during the last application of bacteria, nitrogen at the rate of one hundred pounds per acre were applied. Results were not expected by this time to be shown during the current season but i t was hoped the plants would recover for the next seasons growth. As the principal aim of the w r i t e r was to study rhizome growth, -38-no exact experiments were undertaken to ascertain the reason for this abnormal behavior, but i t would be interesting to see i f mineral or bacterial deficiency were the cause. On July 3rd, therefore, twelve large pots of earth from land similarly treated to seeded blocks, were brought into the greenhouse. "Sick" plants from the f i e l d were placed in them and four were given boron plus f e r t i l i z e r , four bacteria plus f e r t i l i z e r , and four f e r t i l i z e r treatments alone, to see i f the plants would grow normally with the treatment given i n the f i e l d ( i . e. f e r t i l i z e r only), or i f boron and bacteria had any beneficial effect upon them. Later, on July 8th, eight more pots were included, these being treated, four with potassium plus f e r t i l i z e r , and four with no treatment whatsoever. On July 19th nodule bacteria obtained from the roots of the strip of normal alfalfa previously mentioned were placed i n four pots in similar s o i l to the above and inoculated as well onto some more "sick" plants* roots. The pots were brought into the greenhouse. On July 23rd four pots, each containing nodule bacteria, potassium and phosphorus, were brought in. On July 26th eight more, four of which contained nodule bacteria, lime (two tons per acre), and f e r t i l i z e r , and four contained lime (two tons per acre), and f e r t i l i z e r , were also brought into the greenhouse. Whilst i t would have been best to have these a l l brought into the greenhouse at once, this was impossible, so the results obtained are unreliable as far as comparisons between treatments are concerned. The results did serve the purpose in mind, however, which was to see i f normal growth could be obtained from the "sick" plants in the f i e l d . Upon observing the growth of these plants i n the greenhouse, only the lime f e r t i l i z e r pots showed any tendency whatsoever towards abnormal behaviour, these being very stunted and sickly, the others growing -39-normally and showing' a luscious green foliage. Observation of Results: The following results were obtained on February 3rd, 1941, from three of the pots of each set of four in which the roots had been washed out, and set i n a warm place to dry on January 19th, 1941. The top growth at this time was not taken, being- too matured. The remaining pot in each treatment was l e f t to continue growth. Table I weight of Dried Roots of Alfalfa Having Had Different Fertilizers or Bacteria Added. Weights Taken February 3rd, 1941. (Roots From Three Plants in Each Result) 1 Date Placed in Weight Greenhouse Treatment (Grams) 1 g-fulji r 3rd, 1940. Bo - with f e r t i l i z e r ( 3-10 - 8) 34.1 1 " 3rd, 1940. Check - with f e r t i l i z e r (3 - 10 - 8) 21,3 !» 8th, 1940. Check - no f e r t i l i z e r 19.1 1" 8th, 1940. K - with f e r t i l i z e r ( 3 - 1 0 - 8 ) 24.2 •v 26th, 1940. Lime - with f e r t i l i s e r (3 - 10 - 8) (. 8.5 3rd, 1940. Bacteria - (Rhizobium meliloti) with i f e r t i l i z e r ( 3 - 1 0 - 8 ) 27.7 !" 19th, 1940. Bacteria (from Alfalfa nodules) with f e r t i l i z e r ( 3 - 1 0 - 8 ) 13.5 23rd, 1940. Bacteria (from Alfalfa nodules) + K + P 28.4 I Tt 1 26th, 1940. Bacteria (from Alfalfa nodules) + lime + ! f e r t i l i z e r ( 3 - 1 0 - 8 ) 18.6 The photograph in Figure 5, taken April 3rd, 1941, shows the growth as i t occurred at that time, also showing the quadrat frame used and the stakes set in each plot. Indications seem to be that the plots may have a better growth during 1941 than 1940, but s t i l l w i l l not be -40-normal as the borders of the plots have growth three to four inches above the inner portion of the plots. This inner portion is not growing as rapidly as i t should be, and seems to resemble the condition somewhat as they were in the spring of 194Q. Figure 5. Photograph of the same plot as in Figure 1 a n d centre Figure 3, taken April 3rd, 1941. Conclusion: For more significant results a more exact and extensive experiment is required, but the results obtained serve to show that nothing is fundamentally wrong with the land, for when the plants from i t were transferred, using the same s o i l , to pots in the greenhouse they grew normally. Suspicion i s s t i l l directed at the bacteria as being the cause of the trouble, as examination in the spring of 1941 showed nodulation on the plants two to three inches below the ground, but where the nodules should be - at the ends of the roots - they were lacking. The results with -41-application .of two tons of lime per acre in the greenhouse are also of interest. In both cases when the lime was added, the weight of the roots was less than where no lime was used, At present nothing can he put forward in the way of a definite cause for the poor growth in the f i e l d until more work i s done on the problem, or unt i l another season's results are known. Certainly there is no lack of Bo, F, K, and P in the s o i l . Whether the plants w i l l grow better and grow normally during 1941 remains to be seen. From the discussion of the literature given on the effects of cutting the top growth from alfalfa and forage grasses given by other men, we may assume the results that would have been obtained here would have been similar. That i s the "pasture" portions, being cut too frequently and at too low a level, would have had their reserves depleted, no new rhizomes would have been produced, the resulting growth would have been poor and many plants would in a l l probability have died. In the' "hay" plots l i t t l e change other than normal change would have occurred, the plants just increasing in basal area and quantity of roots. If new rhizome growth were to be initiated we would have found i t in the "seed" plots where reserves would have been laid up, strong root growth maintained and the yield of hay from this plot being greater than from the "pasture" or "hay" portions. Unfortunately, this was not able to be proved here. 2. The Fer t i l i z e r Experiment. Purpose: The purpose of this experiment was to determine which f e r t i l i z e r , i f any, gave the most pronounced effect, both in init i a t i o n and maintenance of rhizome growth in a l f a l f a . Hay yields were also to be -42-taken to see i f any correlation existed between yield of tops and yields of rhizomes. Plan of Procedures The alfalfa plants used in this study were to he grown individually, four plants constituting a plot, and each plot to receive th various f e r t i l i z e r s . Top growth yields were to he taken twice or thrice a summer, and at the end of the second summer each plant was to he dug up and a record secured of the weight of the roots, and number, length and weight of rhizomes produced. Accordingly, a site was selected upon which no f e r t i l i z e r had been used for several years previously, which at the time was in grass. This was ploughed. . Inadvertently, "barnyard manure had "been spread over i t and the adjoining f i e l d before the grass was turned under, which may have affected the f i r s t year * s response. The f i e l d was then made ready for transplanting the a l f a l f a . The treatments to be given the plants were to include nitrogen, phosphorus, potassium, sulphur, nitrogen and potassium, complete f e r t i l i z e r , copper and boron, to find out any f e r t i l i z e r effects. In addition, two different lime treatments were to be given, a "moist", "dry" and the "pasture", "hay" and "seed" treatments already referred to when we were discussing cutting effects. Thus, sixteen treatments were to be used, each treatment replicated four times, using one plot for each treatment with four plants to a plot. Thus, sixteen plants would be necessary for each treatment, making a total of two hundred and f i f t y - s i x plants in the experiment. If i t had been possible, these two hundred and f i f t y - s i x cuttings would have been taken from, one parent plant to avoid strain differences as much as possible, but one parent would not supply so large a number, so sixteen parents had to be used. These were selected -43-for their great spread from a block of F 4 plants of the University of British Columbia rhizomatous type alfa l f a * Sixteen cuttings v/ere obtained from each of these, having a bit of root and top growth attached and transplanted to the f i e l d March 30, 1940. Figure 6 i s a photograph of the plan of the f i e l d layout. The rows A, B, C, D, run lengthwise, each containing the sixteen treatments randomized, as do the plots 1, 2, 3, 4, and 5, 6, 7, 8, and 9, 10, 11, 12, and 13, 14, 15, 16 of a l l rows. Unfortunately, the plants themselves were not randomized, but v/ere trans-planted systematically. An error was thus introduced which made statistical analysis of the results impossible. When the results from the clipping experiment were seen to be unattainable for the current summer, yet hoping they would be obtain-able the following summer, the "pasture", "hay", and "seed" plots in the f e r t i l i z e r experiment were accorded the same treatment as the clipping experiment plots, in order tc keep the treatments i n both experiments identical. That i s , when the clipping experiment plots received their f i r s t cut the "pasture", "hay" and "seed" plots also were cut, and later the "pasture" only i n both cases. Thus, instead of the "pasture" plants in the f e r t i l i z e r experiment being cut every two weeks, they were cut only twice during the summer. The following table gives the kind and rate of f e r t i l i z e r s used Element . Wanted' .. F e r t i l i z e r Used ''."'. Sate of | Application I ' !" . ' P -•• K S m Sodium nitrate 'JQriple-superphosphate iiiuriate of potash Gypsum Triple-super * muriate, of potash 1 100 lbs. / acre 1 113 " " 100 " " 300 " " 213 " " -44-Element Fertilizer Kate of Wanted Used Application N H Complete 313 lbs. / acre Cu Copper sulphate 60 " " Bo Boric acid 15 " " Lime Slaked Lime - Ca(0H)2 l g tons / acre Lime 3 M " The different plants used in the various treatments are designated by the location of their parent in the alfalfa block. Plant or Strain Location of Plant I i Plant or Strain Location of Mother Plant 1 6A - 32 - 2 9 6A - 48 - 1 2 61 - 32 - 6 10 6A - 51 - 1 3 6A - 32 - 21 11 6A - 51 - 2 4 6A - 32 - 24 : 12 6A - 51 - 4 5 6A - 32 - 27 13 6A - 52 - 7 6 6A - 33 - 18 14 6A - 56 - 11 7 6A - 36 - 1 15 6A - 72 - 14 8 6A - 46 - 1 ; i 16 6A - 73 - 17 FIELD PLAN ILK ID Llfi|4.Llf 4D 511 4C 14Nffl 5D m 5C D.PK 6D 2DBY D.P 70 rc EN 8D 3D 10D 110 12D JCl*15.C«9.S 13D I4D 15D 2BRY I6D MM I6C EC it 3NDU "2C im 9.5 8C 1IHS1 UK IOC J0.P nc m 1?C IJPHLI L6Bc 13C 14C i 15C V 35 6.W1 36 m 4B 5!E "5B «f m 86 ~9B "10B M iifl L5Cu 126 I3B "I4B; 158 14NPI 1A m 12N 3A IB 4A 11.K 5A im 6A 7f\ mm 6A\9A 9.5 m m ]6fla m SSBD5UI' lap m\ 1M\ISA I6» Figure 6 A photograph of the fi e l d plan for the fe r t i l i z e r experi-ment , showing the treatments accorded each plot. — TREATMENTS — LM0I5T 5. LIME-3TONS. 9.5ULPHER. 13. PK. 2. DRV. 6. PASTURE. 1Q PHOSPHORUS 14.NPK. 3. N0LIME. 7 HAY 11. POTASSIUM. 15 COPPER AIIMF-IVmNS «.SFFQ 12.NITROCFN. 1& BORON Figure 7 Photo taken June 17th, 1940 , 2-g months after the cuttings were transplanted. Figure 8 A close-up taken of one of "phosphorus" plots, secont plot from the right in front row of Figure 7. Photo taken June 17, 1940. -46-Figure 9 Photograph taken A p r i l 18th, 1941, from the same spot as i n Figure 8 to show the great growth made by the c u t t i n g s i n t h e i r f i r s t season. They were cut twice during the summer of 1940, the growth shown coming on mainly since the l a s t week i n March. Observation of R e s u l t s : Two c u t t i n g s were made the summer of 1940, that i s , on June 19th and September 9th. The weight of top growth obtained from each pl a n t was recorded. From the r e s u l t s obtained the n i t r o g e n p l o t s appeared to y i e l d lower than the phosphorus, potassium, F and K, sulphur, and FPK p l o t s , the l a t t e r two g i v i n g greatest r e t u r n s . However, as p r e v i o u s l y mentioned,'the s i g n i f i c a n c e of these, although determined and a s i g n i f i -cance found, was u n r e l i a b l e . The three t o n per acre a p p l i c a t i o n of lime appeared detrimental under f i e l d observations. Agreement was found, t o o , s t a t i s t i c a l l y w i t h these observations, which though cannot be proved. On A p r i l 3rd, 1941, the t o t a l b a s a l coverage or spread of a l l p l a n t s was made, the "seed" p l o t s being outstandingly greater i n t h e i r spread than the others, but outside of t h i s one treatment no other d i f f e r e n c e s were p o s s i b l e to a s c e r t a i n . -47-• Conclusion: It i s hoped with the material at hand that the experiment may he laid out again with the plants randomized, and so enable differences to be reliably determined, as sufficient evidence presents i t s e l f from this work to show such differences to be present. The lime plots were decidedly inferior in growth to the other plots, and as already stated, the nitrogen ones appeared to yield lower than the phosphorus, potassium, I and It, sulphur and FPK plots. The sulphur and FPK" plots seemed to out yield a l l others. (e) Greenhouse. Studies, 1. The pH Experiment. Purpose: The purpose of this experiment was to ascertain the effect of acid and alkaline s o i l on the growth of rhizomes in al f a l f a . Discus sion of Literature: Alfalfa being a lime-loving plant, growing best in conditions approaching neutrality, i t i s reasonable to suppose a highly acid or alkaline v/ould not only discourage the growth of a l f a l f a , but would discourage rhizome growth on that alfalfa as well. Such a retardation in rhizome-producing al f a l f a has been shown by Holliday (1932) where conditions of high acidity prevail in a s o i l . She finds that rhizomes favor slight alkalinity over slight acidity for their optimum growth. The plants showing greatest rhizome growth in her work were those in a moist s o i l , high in humus and of a slightly alkaline reaction. In other words, soils of a generally good condition for al f a l f a growth w i l l produce alfalfa having the greatest rhizome formation. Other works have shown that excess acidity is unfavorable for alfalfa growth, and so we must assume, for rhizome production in this alfalfa as well. Joffe (1920) grew alfalfa in pots of soil adjusted by means of HgSO^ . and CaCOg to a range of pH 3 to pH 7.1. Germination he found the same from pH 4.5 - 7,0, but greatly reduced below 4 and 5$ the yield of tops increased as pH increased from 3.8 - 7.0 and once established showing normal green color and high vigor; nodule formation, as would be expected, he found to decrease as pH value decreased; root development was shown to be poorer at lower than higher pH; and nitrogen content increased with increase in pH. Haas (1937) conducted similar work to that of Joffe.only he adjusted the pH with different reagents. Instead of growing the alfalfa in pots of s o i l , he grev; seedlings in modified Haagland's solution, adjusting the pH with NaOH, Ca(0H)2 and KOH. Neither approximate neutrality nor moderate alkalinity appeared to be unfavorable to growth, the average growth,being least at pH 5 and greatest at pH 8. The best growth was made in the order, NaOH, KOH, OaJOHjg, which shows the value of calcium for the best growth of alf a l f a . Later in 1936, Watenpaugh showed alfalfa root growth to be meagre in a soil layer under pH 5. Upon addition of lime, however, bringing the pH up to 5,5 - 6.2, good root growth and then good top growth resulted. Poor growth under pH 5 he attributes to deficient nitrogen supply, aluminum toxicity or high H + ion concentration. The root development correlated definitely with the pH and with the replaceable calcium. Growth was checked entirely at pH's of 4.8 whilst those above pH 5 proved satis-factory for good growth. Plan of Procedure: Fa c i l i t i e s were not available for the more exacting experiments*conducted by these previous workers. However, i t was thought that s o i l could be brought to. pH's of 6, 7 and 8. Boxes of s o i l were to be used having these pK's e s t a b l i s h e d by the use of lim e . Cuttings from a pronounced rhizomatous pl a n t i n the f i e l d were t o be placed i n them and the boxes brought i n t o the greenhouse. With t h i s p l a n i n mind, then, some two hundred c u t t i n g s were obtained on November 24th, 1939, i n the f i e l d from pl a n t 29, row 19, i n the composite block of a l f a l f a , t h i s p l a n t having the greatest spread of any seen i n the b l o c k . The c u t t i n g s taken were about three inches long. Rhizome t i p s were p r e f e r r e d , but shoots with green growth already s t a r t e d were al s o used. These were placed two inches apart and three inches deep i n f l a t s of sand. As the p l a n t s had by January 12th a t t a i n e d the proper growth for t r a n s p l a n t i n g , work was immediately begun to prepare s o i l of pH's 6, 7 and 8. By reference to the l i t e r a t u r e , Morgan (1930) and P e t t i n g e r ' s ' ( ) work seemed most s a t i s f a c t o r y f o r the purpose i n mind and Morgan's was chosen. His method was to add lime t o the s o i l to obtain the pH wanted according t o the f o l l o w i n g formula: (CaC0 s required i n tons ) (0.8 x CaOPs absorption f a c t o r ) (for 2,000,000 l b s . s o i l ) 3 ? x (pH wanted - pH found) ! ( (1 acre foot) ) The absorption f a c t o r was obtained from a t a b l e l i s t i n g d i f f e r e n t c l a s s e s o f s o i l . A c cordingly 15 cubic feet of s o i l were brought into the greenhouse on February 3rd, 1940. The p l a n t s were to be placed i n one cubic foot c a p a c i t y boxes to give ample room for rhizome growth. The pH of t h i s ' s o i l was determined by the c o l o r i m e t r i c method and found t o be -50-approximately 6.0. The earth was d i v i d e d i n t o three p i l e s and hydrated lime added according to Morgan's formula, The hydrated lime had a OaGO* equivalent of 135 per cent, so l e s s was needed. This e a r t h was l e f t f o r one week. The r e s u l t s were e n t i r e l y erroneous and was found to he a i r - ? slaked, having been Improperly stored. Rock lime, having a CaC0 3 equivalent of 178 per cent, was then used i n new s o i l and a f t e r s i x more t r i a l s , when the work was checked and rechecked, w i t h f a r more lime being used than Morgan s p e c i f i e d , only the pH 7 f i g u r e could be obtained by March 16th. (The s o i l was considered to be sandy loam, 2.5 - 5 per cent O.M. and at pH 6, f o r using Morgan's t a b l e s ) . As i t was g e t t i n g l a t e i n the year, the " c u t t i n g s " were set i n boxes i n t h i s s o i l at pH 6 and 7, w i t h the hope t h a t the pH 8 f i g u r e could soon be obtained. By A p r i l 16th the pH 8 r e s u l t was s t i l l not obtained, so the e f f o r t was abandoned u n t i l a s e r i e s of s o i l p l u s lime pots could be set up. F i v e boxes were used w i t h s o i l at pH 6 and f i v e at pH 7, these,being set on a bench at the East s i d e of the greenhouse u n t i l December 10th, 1940, when they were removed and washed c l e a n . As so much time and e f f o r t had been spent i n an endeavour to b r i n g the t h i r d p i l e of s o i l up t o pH 8, a s e r i e s of s o i l p l u s lime mixtures were set up t o f i n d . e x a c t l y how much was needed, i n case i t would be p o s s i b l e to repeat the experiment,. Accordingly, 42 " t i n " t i g h t l y s e a l i n g f l o u r cans were obtained, i n each of which one pound of sandy-loam was p l a c e d , obtained from the same f i e l d as greenhouse s o i l (Peas, Oats, Vetch, mixture sown there i n summer of 1940).. F r e s h l y slaked rock, lime i n the form of Ca(0H) 2 was added at various r a t e s and the cans put away J u l y 29, 1940. As p r e v i o u s l y mentioned, the c u t t i n g s were put i n the boxes March 16th, 1940, f i v e being placed i n s o i l to which no lime had been •51-added, and five placed in s o i l to which Ca(OH)g had been added at an. equivalent rate of 4,000 lbs. per acre CaGOg, bringing the pH to approximately 7. These remained on the bench in the east side of the greenhouse u n t i l December 10th, 1940, when the soil was washed from the roots, typical plants were photographed, and the plants set in paper bags in the laboratory to dry. 'Observation of Be suits : . The appearance of the rhizomes originally set out as cuttings in the boxes of sane corresponded with Oliver's (1913) \ description* Each had short internodes, and was marked at intervals by "rudiments of leaves and very large stem-clasping stipular growths at each internode covering a dormant bud." Thes stipules gradually turned reddish in color as occurs naturally when they push to the surface of the ground. The cuttings set in the flats of sand were again observed on November 27th, the reddish coloration of the stipules was s t i l l seen and new green leaves appeared on a l l the cuttings. On examining the underground portions, slight swellings were noticed around the cut edges®. By December 1st the new green growth was more pronounced and the under-ground swellings had increased. Upon examination again on December 6th these swellings'had assumed the shape of definite nodules which on some appeared to be developing into minute roots. By January 3rd the tops had grown three inches, and by January 12th this top growth had become very pronounced; the roots had attained a length of two inches, but no rhizome growth was being initiated. The plants remained in these boxes of sand u n t i l March 16th, when they were transferred to boxes of soil which were at pH's of 6 and 7. Boxes of soil at pH 8 were not obtained, so the f i n a l results given -52-on rhizome growth are only those from the so i l at pH 6 and 7. Later on figures were obtained which, i f time would have permitted, would have enabled s o i l at the original ranges of pH 6, 7 and 8 to have been used. This information was obtainable from the samples of so i l plus lime already mentioned as having been set aside July 29, 1940. These were taken out on October 25, 1940, and the pHrs determined. A sample of s o i l one-half an inch by two and one-quarter inches long was taken from each can in order to do this, and the pH found by means of a hydrogen quinhydrone potentiometer. The results that were obtained are given below in Table II. It i s seen that to obtain a pH of around 8, 12,220 -25,550 pounds per acre of lime as CaGOg, must be added per acre. For a similar s o i l , Morgan claimed only 4,000 pounds per acre of lime as GeDQ^ need b e added. Table II 1 J Cat OH) 2 [Can Ho.I Added 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 p.00 gins. J 0.00 " lo.oo " I 0.25 " |0.50 " |0.75 " ]1.00 gms. 11.25 " 11.50 75 00 2.25 2.50 2.75 3.00 3.25 3.50 3.75 4.00 4.25 4.50 I'1 (2 t? tt tf »» tt tt tt tt tt tt tt tt I 'Equivalent . I | CaC03 Added \ — *•* J i in Ibs./acre: PH an I go. 0 0 0 ,530 ,060 ,590 ,120 ,650 9,280 10,810 12,220 13,750 15,280 16,810 18,540 19,870 21,400 22,930 24,460 25,500 27,080 5„7 6.0 5. 9 6.2 6.5 5.5 7.1 7.3 7.9 7.6 8.0 8.0 7.3 8.0 7.7 7.9 7.9 8.2 7.9 8.1 8.5 II 2 2 23 24 25 26 27 28 29 130" 31 32 33 34 35: 36 37 38 40 41 42 Ga\0HT2" Added aiquivalent \ |)aC05 Added j jin lbs./:acrei pH tt tt tr tt 4.75 gms, 5.00 " 13 & 2 0 5.50 " 5.75 6.00 6. 25 6.50 6.75 " 7.00 " 7.25 " 7*50 " 7.75 " 8.00 " 8.25 " 8.50 " 8.75 " 9.00 "•• 9i25 '* 9.50 9.75 ti •tr.. 28,610 30,570 32,100 33,630 35,160 36,660 38,190 39,720 40,350 42,770 44,500 45,830 47,360 48,880 50,430 51,950 53,490 54,990 56,420 57,950 59,480 8.3 8.4 7.9. 8.4 8.4 7.9 8.0 8.5 8.1 8.5 8.6 8.5 8.5 8.5 8.4 8.7 8.6 8.7 9.3 9.3 9.1 - 5 3 -,With our f i r s t set.of soil using hydrated lime that had air slaked, we applied 26,000 pounds of CaCOg per acre to get a pH of 7.1, showing the slow reaction of CaCOg. Later, after several t r i a l s using OaO on fresh s o i l , 4,000 pounds per acre CaOOg gave a pH of 7.1, which serves to illustrate the faster reaction of CaO. When this was doubled in an effort to bring pH up to 8.0, an actual decrease to pH 6.8 was noticed, which was checked, and showed either an error in the f i r s t reading of pH 7.1, or in the colorimetric determinations, or variations in the s o i l . As this is 4,000 pounds per acre short of the f i r s t figure given in the above pH 8.0 range, i t is seen why we could not get our greenhouse soil up to pH 8.0. The following graph, making use of the figures in Table II, shows the buffering power of the lower (West) portion of Agronomy Field when lime is added. This graph would seem to indicate that l i t t l e . d i f f i c u l t y would be obtained i n securing'soil at pHf s of approximately 7.9, 8.3 and 8.6. These are where °the curve flattens out. (See P. 55a) The boxes of s o i l at pH's of 6 and 7, containing the alfalfa plants, were removed from the bench i n the east side of the greenhouse December 10, 1940. The s o i l was washed from the roots, and after photo-graphing the plants, they were dried in the laboratory. The dry weights of these plants were taken February 28, 1941, and are given in Table III. Table III \ 5 Plants i n Soil | at pH 6 5 Plants in Soil at pH 7 Top Growth Roots Rhizomes I : 1 Tcio Growth I Roots jRhisomes _ 17.5 gmsi 53.8 gms. 2„2 gms. 53.0 gms. J173.5 gms. 16.3 gms. -53 (a)-—54— These results show that the five plants at pH 7 had top growth and root growth three times the weight of those five plants at pH 6, j whilst the rhizome growth was nearly eight times that at the power pH. To give a better idea of how remarkably different was the rhizome development in the two cases, the following pictures were taken* In these plants at pH 6 no rhizome growth was evident, but where i t did occur i n other plants the growth was very stunted aid thin. In the plant at pH 7, on the other hand, a great outward projection of the rhizomes took place, these being very sturdy and thick, of white appearance and tending to braich frequently. Note, too, the much better and heavier growth of tops and roots in the latter case. Figure 10 Plant from pH 7 s o i l to the l e f t , and from pH 6 s o i l to the right. Note lack of rhizome growth and generally poorer growth in latter case. Figure 11 A close-up of rhizomes from Figure 10 to show more clearly their growth, origin and manner of dividing. -55-Conclusiom From the r e s u l t s of t h i s experiment we may conclude that there i s a c r i t i c a l pll helow which rhizome development w i l l not occur. H o l l i d a y (1932) showed that conditions f a v o r i n g growth of a l f a l f a w i l l favor an abundant rhizome growth, i f g e n e t i c a l f a c t o r s f o r such growth are present. Excess a c i d i t y c e r t a i n l y does not favor a l f a l f a growth. In t h i s e x p e r i -ment i n the s o i l at pH 7 conditions were very s u i t a b l e f o r a l f a l f a , as the s o i l was nearly n e u t r a l and abundant lime was present. Just how much t h i s lime contributed to the e f f e c t s seen could only be proved by reducing a c i d i t y by other means than lime and comparing the r e s u l t s with those obtained here. I t i s reasonable to suppose, however, that rhizomes w i l l not form below a c r i t i c a l ; pH. Above t h i s they w i l l develop, lime accentu-a t i n g t h e i r growth by supplying more i d e a l conditions f o r the p l a n t , enabling more vigorous growth to be made, more photosynthesis to be c a r r i e d on, and hence more food to be a v a i l a b l e f o r underground storage. 2 The Photoperiodism Experiments'! Purpose % The-purpose of t h i s experiment was to observe any e f f e c t s which short and long day-length would have on the rhizome development i n a l f a l f a . D i s c u s s i o n of L i t e r a t u r e : From the voluminous l i t e r a t u r e a v a i l a b l e on the e f f e c t s of photoperiods on p l a n t s , i t has been found that c r i t i c a l l i g h t periods occur i n the normal development of every p l a n t . A t t e n t i o n has been con-f i n e d more to the response of the leaves, stems, and flowers to changes i n day l e n g t h , than to the response of the underground portions of p l a n t s . P l a n t s r e q u i r i n g a long day f o r normal growth and reproduction, w i l l , -56-under a short day f a i l to produce flowers. Hie reverse holds true f o r normal short day p l a n t s , these under a long day f a i l i n g to flower, t h e i r growth remaining vegetative throughout the treatment with.long days. This e f f e c t ' o f a l t e r n a t i o n of normal day length was found by"Chailakhian and Aleksandrovskaia (1935) to be c a r r i e d over by p l a n t s from t h e i r seedling stage to t h e i r time of flow e r i n g and maturity, even when the day length was only a l t e r e d f o r a short time i n the seedling stage. The length of time the e f f e c t s of t h i s abnormal day length may be held may be exemplified by the work of Stoughton and Hole (1937) on the short day pla n t T i t h o n i a . speciosa. Here the short day treatments were given at the time of p l a n t i n g the seeds, remained f o r a c e r t a i n period and then normal day length was restored.- The e f f e c t , of t h i s treatment was seen 70 days l a t e r at the time of i n i t i a t i o n of f l o w e r i n g . This was observed to be 9 days e a r l i e r than plant's not given so many short day treatments when young. Ha sumo v (l'93l) concludes "that experimental evidence i s presented which suggests that a true photoperiodic a f t e r - e f f e c t i s seen only i n the a c c e l e r a t i o n of reproductive processes and development of the organism, a short day a f t e r - e f f e c t thus being p o s s i b l e only f o r short day planet)and a long day a f t e r - e f f e c t f o r long day p l a n t s " . There appear to be c r i t i c a l photoperiods, too, i n the formation of underground p a r t s . Evans and Watkins (1939) found Kentucky Blue Grass needed long days to produce rhizomes w h i l s t Canada Blue Grass needed short days. Under long days Kentucky Blue Grass produced upright shoots, elongated internodes, and same i n f l o r e s c e n c e s . The rhizome growth was shown to be greater under the long days of l a t e spring and e a r l y summer than the short ones of f a l l and e a r l y spring. Canada Blue Grass gave qui t e the opposite response, under the long day i t s shoots were decumbent, -57-i t s stems were not elongated, no inflorescences were formed and rhizome growth was. greatest i n l a t e f a l l and e a r l y spring. The e f f e c t s of photoperiod on rhizome growth should he com-pared with i t s e f f e c t s . o n tuber formation as these two structures are somewhat s i m i l a r i n f u n c t i o n . Rasumov (1931) found a short photoperiod favored maximum tuber formation, a long photoperiod g i v i n g a l i m i t e d pro-d u c t i o n of tubers but extensive top development i n the tuberous p l a n t s he studied. Combining these two l i g h t p e r i o d s , Rasumov found that w i t h the -same p l a n t s long photoperiods a f f o r d i n g extensive vegetative growth, which, followed by short photoperiods gave a maximum y i e l d of tubers. Here the abundant top growth e s t a b l i s h e d by the long days, provided a great area f o r the c a r r y i n g on of photosynthesis, the foods formed being then c a r r i e d to and stored i n the tubers i n i t i a t e d when short day lengths were, begun. Bates (1935) and Werner (1934) found environmental f a c t o r s to be important i n r e g u l a t i n g the s i z e of the potato tuber, Werner obtaining maxium t u b e r i z a t i o n w i t h a low temperature, abundant ni t r o g e n and a short.day, which he modified i n 1935 to a low f l u c t u a t i n g temperature, r e s t r i c t e d nitrogen supply and a short day. With Cyperus es.culentus L. Karisnev (1957) found somewhat d i f f e r e n t e f f e c t s of the photoperiod on tuber formation. The short day i n t h i s case merely retarded the time of formation of the tubers, long day g i v i n g b i g g e r , heavier and more numerous tubers. - »** ., -P l a n of Procedure: To conduct an experiment of t h i s nature, the work would have to be done indoors under c o n t r o l l e d c o n d i t i o n s . Hence, arrangements had to be made i n the greenhouse to subject boxes of earth to d i f f e r e n t day lengths. A f i v e hundred watt bulb and r e f l e c t o r were to be used f o r lengthening the day, but as no f a c i l i t i e s were a v a i l a b l e f o r shortening the day, the p l a n t s would hare to receive j u s t normal day and night c o n d i t i o n s . In the s e c t i o n of the greenhouse, too, where the p l a n t s were to he pl a c e d , the temperature was u n c o n t r o l l e d , so some f l u c t u a t i o n s i n i t would he encountered. On March 29th, 191-0, twenty boxes s i m i l a r to those used i n the pH experiments, were f i l l e d w i t h s o i l obtained from a near-by compact heap, high i n organic matter, and brought into the greenhouse. In each was placed one of the c u t t i n g s that had been obtained November 24th, 1939, which were s t i l l i n the f l a t s of sand. S i x t e e n of these boxes were placed on the f l o o r i n one corner (southwest) of the greenhouse, the other four a c t i n g as checks being placed on the east bench along w i t h the pH boxes. Above the si x t e e n boxes on,the f l o o r , f o u r feet from them, was hung the f i v e hundred watt bulb and r e f l e c t o r . , The l i g h t was turned on every, n i g h t s t a r t i n g A p r i l 16th, 1940, from 5 p.m. t i l l 8 a.m., thus g i v i n g the p l a n t s continuous i l l u m i n a t i o n . Those on•the bench were protected from the lamp by a screen hung between and allowed to receive the normal day length. The temperature i n the greenhouse was the same as that outdoors, no heat being i n the s e c t i o n and the v e n t i l a t o r s i n the roof being always open. As the r e s u l t s of t h i s work i n d i c a t e d i t would be worth w h i l e to g i v e the p l a n t s a d e f i n i t e long and short day i l l u m i n a t i o n , hours of. sixteen and e i g h t d a i l y l i g h t p e r i o d were chosen as s u i t a b l e for t h i s . A s p e c i a l cage w i t h dark b l i n d s on three s i d e s and the top was b u i l t so th a t the short photoperiod could be p r o p e r l y regulated. The other side of the cage was b u i l t s o l i d , w i t h a shuttered opening placed i n i t to allow a f a n t o p u l l f r e s h a i r i n , and so keep the temperature i n s i d e and outside the cage constant. The s i x t e e n hour day was obtained by u t i l i s i n g the f u l l normal day to w i t h i n one-half hour of sunset w i t h e x t r a l i g h t provided i n the morning ,to complete the s i x t e e n hour i l l u m i n a t i o n . This extra l i g h t was the same f i v e hundred watt bulb and r e f l e c t o r p r e v i o u s l y used, hut now was connected to a time clock to insure i t coming on and o f f at the co r r e c t time. As the days lengthened l e s s a r t i f i c i a l l i g h t was needed so the time of coming on and o f f was adjusted each week. Thus, the 16-hour day was secured by u s i n g the a r t i f i c i a l l i g h t u n t i l one-half hour a f t e r s u n r i s e , p l u s the normal day length. The eight hour day was secured by l i f t i n g the b l i n d s on the cage every day at 8$30 a.m. and lowering them every day at 4:30 p.m. As i t took considerable time f o r the necessary m a t e r i a l to be gathered and the experiment set up, the a l f a l f a p l a n t s under continuous i l l u m i n a t i o n remained under t h i s day length u n t i l they could be incorporated i n t o the new experiment. This meant they were under a f u l l twenty-four hour d a y l i g h t treatment from A p r i l 16th, 1340, u n t i l the new experiment began on January 13th, 1941. At the end of December, however, a l l the p l a n t s were cut back to a height of eight inches. Thus a considerable photoperiodic a f t e r e f f e c t would be found i n the p l a n t s which were placed under the short day. This may have helped to e x p l a i n the r e s u l t s that were obtained. As exact times of i l l u m i n a t i o n were to be run i n t h i s e x p e r i -ment other s t r a i n s and species of rhizomatous types of a l f a l f a were secured and some grasses a l s o used, i n order to give a more complete p i c t u r e of day length and rhizome grov/th. The f o l l o w i n g s t r a i n s and species, t h e r e f o r e , were procured and included i n the work: Medicago g l u t i n o s a . - from an increase block of seed ' k i n d l y sent by Dr. W. J . White, Officer-in-Charge of Dominion Forage Crops Laboratory, Saskatoon, Sask. Dr. White mentions these p l a n t s i n t h i s group t o c o n s i s t of a great v a r i e t y of d i f f e r e n t types, a -60-considerable proportion-'-being rhizomatous, some very strongly creeping'. Dr. Brink of ladison, Wisconsin, from whom, the seed was originally obtained, says t h a t this alfalfa was not rhizomatous under Wisconsin conditions, the crown being much spread out and broad. It was introduced 'into Wisonsin from the E. Caucausus region of U. S. S. H. Medicago falcata - under the strain nuDiber;,S-T-33--l9 also obtained from Dr. White of Saskatoon, t h i s strain of Ml falcata was noted t o be quite strongly creeping, particularly when kept c l i p p e d .or mowed. The parent p l a n t of this strain was found growing- in a Kentucky Bluegrass. lawn on the University of Saskatchewan p l o t s and had spread over an area of four feet in diameter. M»- falcata - S. P. I, 75,745 obtained through the courtesy of Dr. H. L. Vie stover, Senior Agronomist, Di vi si on of Forage Crops and Diseases in the Bureau of Plant Industry, U. S. Dept. of Agriculture. In his letter, Dr. Westover mentions this and the next two strains, S. P. I. 35,087 and 42,715 repre-sent early introductions of pure M. falcata, the germination of the seed sent being extremely low. The seed i t s e l f was 60 per cent of a brown coloration and of small size. M. falcata - S. P. I. 35,087 bbtained from Dr. Westover and i s pure falcata. It also is small seeded with 70 per cent brown coloration. M, falcata - S. P. I. 42,715 obtained from Dr. westover and i s falcata also with small seed, 80 per cent brown. M. falcata - S. P. I. 111,614 from Dr. We stover who mentions i t i s a more recent introduction but may show - c on si der ab 1 e crossing with. M. sativa. This seed sent was yellow with 60 per cent brown. M. falcata - S. P. I. 115,364 from Dr. We stover who mentions i t too to be a later introduction and li k e l y to have crossed with M. sativa. It has very small seed, 60 per cent of which is brown. M. gaetula - S. P. I. 26,590 from Dr. Westover who states i t i s from Algeria, northern Africa, but he is uncertain as to i t s trueness to type. The seed is plump, medium to large, and yellow-brown in color. Oliver (1915) on p. 27 of his bulletin mentions this same strain number where he was using i t in his crosses, claiming i t i s quite hardy, has a vigorous lot of rhizomes deep in the s o i l , these -61-being developed early i n autumn. M. gaetula - S. P. I. 7292 from Dr. Westover and intro-duced from Algeria, "but doubt as to i t s trueness to type again mentioned. This seed was not threshed, the pods being spirally coiled, wound two to four times with an open centre and scattered pubescence over the reticulum. Three to four well developed seeds were found per pod, the seeds being well f i l l e d , yellow and a few brown. M. gaetula - S. P. I. 88,950 from Dr. Westover and .originally from Africa with doubt, too, as to type adherence. Here again the seed was unthreshed, the pods being fattened, coiled two to three times with a fine, sparse, spiny pubescence on them. The seed was large, w e l l - f i l l e d and had five per pod. Agropyron repens — (Couch grass) obtained in the form of a four inch t a l l three-bladed young plant and trans-planted into pots in the greenhouse. Poa pratensis - (Kentucky Bluegrass) - obtained as seed by Dr. ¥. C. Brink from Kamloops, B. C., where he noted i t s abundant rhizome growth when growing there. The U. B. C. alfalfa already mentioned as obtained from cuttings November 24th,.1939, a l l belonging to one mother plant and having been under continuous illumination since April 16th, 1940. A l l plants except U. B. C. alfalfa and Agropyron repens were grown from seed. This seed was germinated in petri-plates in the laboratory the latter part of December, 1940. The seedlings were then transferred to flats of sand in the greenhouse. On January 30th, 1941, when the f i r s t t r i f o l i a t e leaves had appeared, the plants were transplanted to pots of earth obtained from the same p i l e as that in the boxes of a l f a l f a . As already mentioned, the U„ B. C. alfalfa began the light treatments January 13th, eight boxes being placed in the short day conditions and eight i n the long day. On January 22nd the Couch Grass from the f i e l d was brought in, three plants being put under the long day and three under the short day. On February 2nd, two of each type of the seedling a l f a l f a were put under the long day and two under the short day. The Kentucky Bluegrass was included at this time as well. Observation of Results: The f i r s t observations of the results of the exposure of the alfalfa plants to varying light conditions were made on the normal and twenty-four hour day plants. On June 6th, those plants under the twenty-four hours daily light exposure were seen to be starting to bloom. These plants were three feet t a l l , whilst the controls under the normal day length had only made a growth of one foot* On June 17th plants under the light were cut back to a height of four inches. About July 18th the plants again came into flower, the checks making very l i t t l e growth and showing no signs of flowering. By July 27th the illuminated plants were in one-quarter inch bloom, having made a growth of about two and one-half feet, but producing very slender stems and rather sparse foliage. The check plants s t i l l showed no sign of flowering, were only seven inches high, and the growth, though a more luscious green than the continually illuminated plants, was not very heavy. By August 15th the illuminated plants were well past f u l l flowering. On October 15th the plants from the two light treatments were examined to see what effects the treatments were having on rhizome formation. A striking difference was observed* On November 20th photographs were made of some of the roots which had been washed clean. The plants under continual illumination showed absolutely no sign of rhizome initi a t i o n , whilst those under the normal day length gave very pronoxmced growth. On some plants the rhizomes had grown out ten inches and were very numerous, whilst on others they were short and few. The top growth in the twenty-four day plants was -63-much t a l l e r and heavier than i n the normal day ones. The f o l l o w i n g photographs show these e f f e c t s very c l e a r l y : Figure 12 Photograph t o show e f f e c t of photoperiod on top growth. Normal day p l a n t s to the l e f t twenty-four hour day p l a n t s t o the r i g h t . Figure 13 Figure 14 Photograph to show e f f e c t of photo-p e r i o d on rhizome and root production. Normal day le n g t h to the l e f t , twenty-four hour day t o the r i g h t . Note heavier and t h i c k e r r o o t s i n short day plant w i t h abundant rhizome growth. Photograph of centre p l a n t s i n Figure 13 taken c l o s e r to give d e t a i l s of rhizome growth more cle a r l y . The more branched and f i b r o u s roots of short day, and slender, thinner tops of long day p l a n t s are w e l l seen. On November 20th, 1940, the weight of the top growth of the plants under the two light periods was taken. The results, which are given in Table IF, emphasize the differences already observed in the photographs. : Table W Weight of Top Growth of Alfalfa used in the Summer's Photoperiodism Experiment Weights (Green) taken November 20, 1940. | Plants under j t .' Continuous Illumination j Plants under Normal Day Length Plant Weight .' Plant Weight-! Plant j Weight 1 24.6 2 58*6 3 46.3 4 107.7 5 142.1 6 31.4 7 41.5 8 36.1 1 :" 9 • 5U7 10 63.6 I 11 • 156.1 12 56.6 • 13 36.2 14 , 15 31.9 16 29.1 i 1 . 30.5 ' .. 2 .' 33.1 ' 3 j 16.3 | 4 j 23.2 1" -The effect of the light treatment of eight hears and sixteen hours per day was seen to be very similar as regards top growth to that previously observed of the normal and twenty-four hour light exposures. However, no rhizome, growth was noticed on the plants at any time. Several times before the end of the experiment the plants had been examined for rhizome development but no evidence for rhizome in i t i a t i o n was found. The long day plants grew much more quickly in a l l cases than the short day, the Couch Grass in particular making very rapid growth. On February 26th a spike was seen appearing on the Couch Grass under the sixteen hour day which, by February 28th, had emerged two inches, with one on another plant also showing. It took this f i r s t spike •until March ,16th to begin flowering, and by March 21st a l l the spikes were in f u l l flower. The Kentucky Bluegrass did not grow as t a l l as the Couch Grass and showed no sign of flowering during this time, under either sixteen or eight hour daily light treatment. March 4th was the earliest time of flowering of the alfalfa, one flower opening under the sixteen hour day on plant 14. This plant had six flowers March 12th. Plant 9 began flowering on the same date. March 19th showed a third a l f a l f a to be flowering, with the f i r s t plant having four racemes open and the second, three. By March 27th five plants were seen to be flowering, the f i r s t group being in half-bloom. Hone of the plants included in the eight hour day showed any indication of flower buds beginning to appear during this same period, nor up to the end of the experiment. The time i t took the various plants to flower can be readily seen from Table .T. Table V Time Required for the Different Plants to Flower Under Sixteen Hour Day r - ' • : - * . ; l •• Plant fbighfc Treatment ! • . 1 Began First J Days Day of i to Flowering' j Flower r • • i • • ~ jU. B. C. Alfalfa j January 13th) Grown | j ) from •Couch Grass j " 22nd)Cutting: March 4 j 50 - • - - I i i March 16 j 53. . . . . . . . . . . j Kentucky Bluegrass j February 2nd) Medicago gaetula (3 strains) " " ) Medicago falcata (S strains) " " 5 Medicago glutinosa (1 strain) " " ) — • -66-Thus i t is seen that the Couch Grass and alfalfa took about the same period of time to flower, the other plants showing no indication whatever of flowering. On April 6th the plants were photographed, two plants from each type, one long day, one short day, being used. On April 10th the roots of each of these were washed clean to show any rhizome growth appear-ing. In only two cases did they appear, in both cases these being the grasses and under the sixteen hour day. The rhizomes of the Couch Grass were about six inches and twelve inches long, that of the Kentucky Blue-grass eight inches. The roots of the U. B. C. alfalfa under the 8-hour day, although showing no rhizome response, were much heavier and more branched than those under the sixteen hour day, indicating less drain on their reserves. The following photographs illustrate some of the results that were attained. Figure 16 The two alfalfas obtained from Saskatchewan M. glutinosa were considered as having a considerable portion rhizomatous. The strain of falcata shown was noticed as quite strongly creeping. The falcata under the 8-hr. day was eaten off by sowbugs. -67-Figure 17 The M. gaetula on the l e f t i s one of the o r i g i n a l s t r a i n s O l i v e r mentions as coming from A l g e r i a , that on the r i g h t a f a l c a t a Westover mentions as perhaps crossed w i t h s a t i v a . Figure 18 Two of Dr. Westover's f a l c a t a s . That on the l e f t a pure s t r a i n of e a r l y i n t r o d u c t i o n , that on the r i g h t a f a l c a t a perhaps crossed w i t h s a t i v a . -68-Figure 19 Two more of B r . Yi'estover*s p l a n t s . On the l e f t another pure f a l c a t a , on the r i g h t M. gaetula introduced from A l g e r i a and true to type. Eight hour p l a n t eaten by sowbugs. Figure 20 On the l e f t another pure f a l c a t a from Dr. Westover and a M. gaetula of true type from A f r i c a . Eight hour p l a n t eaten by sowbugs. 69 -Figure 21 Note the great v a r i a t i o n , i n r e s -ponse t o long day and short day i n the two grasses. Figure 22 Note d i f f e r e n c e i n type of growth i n t h i s U.3.C. a l f a l f a . That on the l e f t i s the 16 far. day and i f i i n flower, on the r i g h t i s the 8 hr. day p l a n t w i t h no sign of f l o w e r i n g . Figure 23 Showing the root growth of the TJ.B.C. a l f a l f a under 16 hr. and 8 h r . day. The 8 hr. day p l a n t had heavier and more abundant growth. -70-Figure 24 I l l u s t r a t i n g the e n t i r e l a c k of rhizome growth i n both the seedlings. A much more vigorous p l a n t was formed under the sixt e e n hour day. This i s a s t r a i n of Dr. Westover's impure "Medicago f a l c a t a . Figure 25 A view of the "cage" used i n o b t a i n i n g an eight hour day. The b l i n d s shown were l i f t e d at 8:30 a. m. and lowered at 4:30 p.m. each day. -71-Conclusion: The lack of rhizome production in the alfalfa plants exposed for eight hours was rather surprising . The gradual change of daj length to which they were exposed "before in the normal day length, in contrast to the limited eight hour day in the fin a l experiment, certainly cannot have been the cause of the rhizome growth. As alfalfa is a long day plant the extreme period of time when continuous light was given to the plants con-ceivably may have carried over and stopped initiation of rhizome growth. From the discussion of the literature already given, this after-effect of the. long day's exposure must be discounted. The results given there would seem to indicate that i f any effect were to be noticed, i t would only be a delaying or hurrying-up process of the rhizome initiation and not a cessation of their growth altogether. Season conceivably may have had an effect on their lack of initi a t i o n , alfalfa being known to begin rhizome growth in the f a l l . However, i f conditions in the greenhouse had be en suitable for their growth, they would have formed. Hence, conditions must not have been suitable. The only remaining logical reason why the rhizomes were not produced was that there was a difference in the temperature in the two sections i n which the plants were grown. Otherwise, conditions were very similar. As already mentioned, the f i r s t experiment was carried on in a section where a continuous exchange of air within and without the greenhouse o o could take place. The temperature thus was about 50 - 60 F. The later experiment was conducted in a different,heated section. Here the tempera-ture was between 70° - 80° F. This never varied very much between these figures, perhaps going higher but certainly not lower than this. The f i r s t section both rose and f e l l from the 50° - 60°F. temperatures mentioned. -72-Q ? h u s » n i n u s t 1 3 6 concluded that the failure of the U. B« C. alfalfa to produce rhizomes was that the temperature was above the optimum for their " growth. Other observations have been made of similar effects. Dr. Woe (1928) found, upon transferring this U. B. 0. alfalfa to Ithaca, Hew York, that a decided drop in rhizome production occurred. He concluded the environ-ment was responsible for this effect. From the results obtained here we may conclude day length and temperature were mainly responsible. Few York has warmer and longer days than Vancouver during the time that rhizomes should be forming, which must have be en above the limits necessary for rhizome growth. It was amply demonstrated from the work just condticted that al f a l f a needs cool, short days in a soil above pH 6 for production of rhizomes. A further example of this limitation of rhizome growth i n a l f a l f a w i l l be given by reference to growth noticed in the Agronomy plots at the University of B r i t i s h Columbia. Here, upon examination of the F 4 progeny of the U. B. C. strain of alf a l f a quite a striking effect in the manner of spread of each individual plant was noticed. The side of the plant (i.e. the north side) away « / from the sun was found to have spread eight to ten inches from the main j root system, whilst that on the sunny side (south side) had no spread whatsoever. Thus, even at Vancouver the effect of the increased warmth from the sun's rays striking the crown of the plant more directly, was sufficient to prohibit rhizome growth on that side, normal spread occurring where the warmth was less, from the rays striking more obliquely. Purer (1936), i t w i l l be remembered, found the rhizomes of Convolvulus soldanella L. responding very markedly, too, to a change in temperature. A rise i n i t causing the rhizomes to grow upwards, and a decrease in i t causing them to grow downwards. i: O***^; -73-From the results obtained here i t is seen that in order to produce rhizomes, different plants certainly need widely varying conditions. Alfalfa requires cool, short days in order to initiate and form extensive rhizome growth. The grasses studied here, that i s , Couch Grass and Kentucky Bluegrass, both need long days. The temperature levels for these grasses were not-obtained in this experiment. The other alfalfas studied produced no rhizomes under either the short or long day because they were too immature. IT. CONCLUSION The results obtained i n this study have helped considerably to limit the conditions jshich (must occur before) rhizone s w i l l form i n a l f a l f a . High temperature is a very important factor limiting their growth. Soils which are too highly acid w i l l also prevent their occurrence. From the results of other workers, i t has been found that too severe and too frequent removal of the top growth w i l l also cause cessation of rhizome formation. For abundant growth of rhizomes in alf a l f a , then, the plants need to be left uncut in soil well above pH 6, and grown in a climate where cool, short days occur. From the f i e l d studies, no conclusive results could be drawn. The effects of cutting practices on rhizome formation was obtained from previous workers. The effects of f e r t i l i z e r s on rhizome production was not found. The hay yields from the variously treated plots were obtained, but no reliance could be placed in any significant differences obtained. However, differences were noticed. The complete f e r t i l i z e r , phosphorus, potassium, and sulphur appear to be beneficial, at least to the top growth and nitrogen and excess lime may be detrimental. -74-v. SUMMARY 1. Rhizomatous strains of al f a l f a require rather exacting environ-mental conditions for optimal rhizome growth, their genetical makeup alone not being sufficient to assure this, 2. A pH of 6 is very detrimental to rhizome growth in alf a l f a in some cases prohibiting i t , A pH brought up to 7 by the use of lime was beneficial, abundant rhizome growth occurring® 3. For optimum rhizome product ion in the U. B. C. strain of al f a l f a , cool, short days are essential, the plants being grown in soil above pH 6, 4. Maximum spread of a l f a l f a in the f i e l d was observed in the undipped plants, • 5. 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Thesis/Dissertation
eng
Agricultural Economics
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Graduate
Rhizome development in plants with special reference to alfalfa (Medicago sp.)
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