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The effect of various levels of potassium fertilizers on the yield and the nutrient value of carrots… McNeill, Ronald James 1952

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THE EFFECT OF VARIOUS IEVELS OF POTASSIUM~ FERTILIZERS ON THE YIELD AND THE NUTRIENT VALUE OF CARROTS AND RADISHES fey Ronald James McNeill, B.S.A. A thesis submitted in partial fulfilment of the requirements for the degree of Master of Science in Agriculture in the Department of Horticulture (Plant Nutrition) We accept this thesis as conforming to the standard required from candidates for the degree of Master of Science in Agriculture Members of the Department of Horticulture The University of British Columbia April 1952 ABSTRACT THE EFFECT OF VARIOUS LEVELS OF POTASSIUM FERTILIZERS ON THE YIELD AND THE NUTRIENT' VALUE OF CARROTS AND RADISHES by Ronald. James McNeill, B.S.A. The welfare of mankind i s intimately bound up with the welfare of soils and plants as a l l of man's food comes, in the, fir s t instance, from plants. Much research has been done to increase yields but l i t t l e i s known of the nutrient values of plants. Since l i t t l e i s known about potassium's effect on the nutrient value of plants, and because carrots have a high Vitamin A precursor content and radishes have a higher Vitamin C content, the author decided to determine what level of potash fertilization should be applied for optimum nutrient value in carrots and radishes. His decisions were, that while the addition of potash to land containing sufficient readily available potassium appears to tend to reduce yields, i t does increase the mineral content of the produce. It also increases the total sugar up to a point after which i t inhibits the carbohydrate formation. The author also found that additional potassium has no effect on the nitrogen content and, while i t has no significant effect on the Vitamin A content i t does have a very definite upward trend to produce more with the increases of potassium applied. The addition of potash increases the trend to produce more Vitamin C to the extent that high and very high levels of potassium applications become significant. The author found that correlation exists between the application of potassium and the protective nutrient value in plants. ACKNDWEDGMENT The writer wishes to thank sincerely Dr. G.H. Harris, Professor, Department of Horticulture, University of British Coltxaibia, for his advice in the setting up of this experiment; for his assistance in getting the analytical work done, and for his helpful suggestions in planning and preparing this thesis. Sincere thanks are given also to Dr. A.P. Barss, Professor and Head of the Department of Horticulture, University of British Columbia, for his constant and kindly help and guidance. Thanks are also due to Dr. CA. Hornby, Associate Professor, Department of Horticulture, University of British Columbia, for his careful explanation of various statistical methods; to Mr. Robert J. Edgar, Laboratory Instructor (1952), Plant Nutrition Laboratory, Department of Horticulture, for his very valuable assistance with the analytical work on the radishes, and to Mr. Willard Mohr, Laboratory Instructor, Plant Nutrition Laboratory, Department of Horticulture, for his' assistance with the analytical work on the carrots. TABLE OF CONTENTS Introduction 1 Review of Literature 3i Materials and Methods 7 Carrots 7 Radishes . . . . . . 10 Analytical and Statistical Methods 12 Results 14 Carrots . . . . . . . . . . . . . 14 Radishes . . . 23 Discussion 27 Summary 37 Literature Cited 38 Appendix 42 - 1 -INTRDDUCTION The author has always taken a keen interest in the growing and handling of living plants and animals. It was not until some six years ago that the opportunity arose to attend the University of British Columbia and to make a more intensive study of these interests. With the passing of each successive university year a greater realization has grown upon the writer of| the fact that the welfare of mankind i s intimately bound up with the welfare of soils and plants. A l l of man's food comes in the f i r s t instance from plants. Our milk, fish, poultry and eggs arise from plant substances and the beef rancher i s in reality the manager and owner of the factory where plants are converted into more palatable forms for human use. Dairy products, leafy vegetables and vitamin-rich foods are well known to be fundamental for health but they s t i l l tend to be lew in the average diet as compared with diets that meet all-round nutritive needs. This i s particularly noticeable in hie diets of low-income groups in a l l highly industrialized countries. It has been said that a means must be found to bring these essential foods within the reach of everyone but how this i s to be done i s not yet apparent. The suggestion that a surplus of these protective foods might place them within the means of a l l induced the growers or producers to instigate research directed towards increasing yields, and much has been accomplished along these lines. - 2 -Although authorities agree that potassium as well as nitrogen and phosphorus i s of the greatest importance to plant growth, l i t t l e i s known about i t s nutrient effect on plants. This fact led the author to investigate how the nutrient value of plants would be affected by potassium. In order to make the experiments as simple as possible carrots QDaucus carota) having a high vitamin A precursor content, and radishes (Raphanus sativus) with a high vitamin C content, were chosen. The object of these experiments was to determine what level of potash fertilization should be applied for optimum nutrient value in carrots and radishes, and to ascertain i t s effect on total yield and on top and root growth. - 3 -REVIEW OP LITERATURE It i s known that carrots and radishes, in keeping with many other plants, require large amounts of potassium. The bulk of the potassium absorbed by a plant ordinarily moves into i t in the earlier stages of i t s l i f e history, unlike a l l of the other ash constituents required by plants i n appreciable amounts, potassium i s not definitely known to be built into organic compounds of fundamental physiological significance. It occurs in plants almost solely as soluble inorganic salts. Potassium salts of organic adds also occur in plant cells. In spite of this fact potassium is an indispensable element and cannot be completely replaced even by such chemically similar elements as sodium or lithium. The young and active regions of plants, especially buds, young leaves, root tips, etc. are always rich i n potassium. Older tissues in which relatively few living cells remain contain relatively l i t t l e potassium. Internal redistribution of this element occurs readily and continuously during the l i f e history of the plant. The exact physiological role of potassium in plants i s largely unknown. Since i t i s apparently not used in any necessary plant cell constituent i t s role i s probably a regulatory or catalytic one. It i s possible that i t may influence enzymatic activity. Certain results of a deficiency of potassium upon plant metabolism are recognized. Dolan and Christopher recognize that potassium appears to be necessary for (a) carbon dioxide assimilation, (b) the synthesis of simple sugars and starch, (c) translocation of carbohydrates, (d) nitrate reduction in the plant, (e) meristomatic activity, and (f) normal c e l l division; while, on the other hand, in some cases i t (a) delays maturity, (b) decreases total dry weight, and (c) depresses total yield. (13) The potassium ion i s usually the most abundant univalent cation in plant cells, and undoubtedly exerts important effects upon such phenomena as the permeability of the cytoplasmic membranes and the hydration of the protoplasm. Much has been learned about the effects of various fertilizers on the yield of both fruit trees and vegetables. It has been found that persistent increase in the amount of potash may depress yield due to nutrient unbalance, and that increased yields are dependent on the harmonic balance of nutrients. (13, 17) The balancing role has been attributed to potash. It has also been found that the plant content of any single element may be largely influenced by the application of some other element to the soil. A number of cases have been reported where nutrient element deficiency symptoms have been increased in severity by the use of chemical fertilizer. (10) Comparatively l i t t l e has been done to determine the effect of fertilizers on the food value of crops. Perhaps this has been the direct result of pressure from the producer since he i s primarily interested in increased yields and the consequent increased returns rather than the actual nutritional value of his crop. Potassium i s found both i n the organic matter and in the mineral matter of soils but occurs chiefly in the mineral matter and becomes available to the plants by solution in the soil water. A l l soils, except mucks and peats, contain relatively large amounts of "total" potassium, but the amount available to the plants in any one soil may be low, especially in sandy soils. A limiting quantity of potassium in the soil causes marked disturbances in plants, but, unless the potassium supply i s very low the effects are not clearly visible, and may be confused with other nutrient deficiencies. Potash starvation reduces the vigor of the plant and makes i t more susceptible to attack by insects and disease. It i s known that a plant i s capable of absorbing a nutrient to the best advantage at certain optimal levels, and that for any given nutrient the cr i t i c a l level may be defined as that range of concentration at which the growth of the plant i s restricted in comparison to that of plants growing at a higher nutrient level. (18) Few vegetable crops use more than ninety pounds of available potash per acre and where more than this value i s supplied i t i s probable that a reserve of potassium is built up. (17) An average crop of snap beans removes from sixteen to twenty pounds of available potash from each acre and beans have been found to f a i l to respond to additional potassium and yields were actually reduced in direct proportion to increases in the amount of available potash supplied. (17) However, Cain drew the conclusion that leaf injury normally attributed to a deficiency of magnesium might actually be the toxic effect produced by an excess of potassium. (9) Dunbar and Anthony found that potassium had a blocking effect on nitrogen. (14) Jenkins found a decided decrease in the yield of snap beans from plots which had received potash applications and concluded that on some soils the addition of potash was of doubtful value. (17) Dolan and Christopher found that high potash applications very significantly increased the yield of celery but the yield of tomatoes was similar with both h i ^ i and low applications of potash. (13) Jenkins showed that potassium reduces yields (17) and Dolan and Christopher state that i t usually gives the least response of any of the three major plant nutrients. (13) If this i s true, i t would appear desirable to determine whether the lower yields would be offset by a higher nutrient value of the produce. MATERIALS AND METHODS Carrots A 5x5 Latin Square was laid out in the front yard of the author's home in the spring of 1950, on land which had previously been lawn but which had become very run down. This "burned out" lawn had patches of bare soil and was over-run with couch grass (Agropyron  repens), rib grass (Plantago lanceolata) and a l l the assorted weeds generally found on waste land. This yard had been dug over, screened, and raked some two months previous to the laying out of this experiment and great care was taken to remove a l l the root pieces of the couch grass. The s o i l was a red, sandy loam only two feet deep, overlaid on an impermeable blue clay hardpan. The reaction of this soil was about pH 6.0. As a basic treatment 5-10-0 fertilizer was broadcast at the rate of 1000 pounds per acre on May 17, 1950 and raked lightly into the top soil before the seed was planted. This was to compensate for any s o i l deficiency that mi$it have existed. To get the exact ratio of fertilizer required for this experiment, several lots of fert i l i z e r were made up from ammonium nitrate (33$ nitrogen), superphosphate (19$ phosphoric acid), and muriate of potash (50$ potassium). The treatments were designated A, B, C, D, and E and were made up as shown on the following Table 1 :-Table 1 Fertilizer Application Showing Potassium Treatment Treatment % $ % Potassium Designation Nitrogen Phosphorous Potassium Level A 5 10 0 N i l B 5 10 3 Low C 5 10 5 Medium D 5 10 10 High E 5 10 20 Very high Seed of the Imperator variety of carrot was sown in rows 12 inches apart. On June 18, 1950, when the f i r s t true leaves were appearing, the young plants were dusted with benzene hexachloride (.5$ Gamma Isomer) at the rate of 1 pound for every 200 feet of row as a deterrent against the Carrot Rust Fly (Psila rosae). This dusting was repeated on September 1, 1950, to catch the third brood of the Carrot Rust Fly which was then emerging. The crop was harvested on November 4 and 5, 1950. The tops and roots were twisted apart and weighed immediately to give an estimation of total yield and top/root ratio. A representative sample was then chosen at random and taken to the University of British Columbia for nutrient analysis. Figure 1 Layout of Plots in the Form of a Latin Square 25' : B 1 : DI ; [ EI : AI : 1 CI : 0 2 \ ! A2 : ! B2 i f E2 . ! D2 I D3 ! 1 C.3 ' : A3 ! ! B3 ! ! E3 ! E4 ! B4 : c4 | D4 ! A4 : A 5 : E5 : D5 : C 5 ! 1 ; B5 5' ! 1 - 10 -MATERIALS AND METHODS Radishes In early December 1951, soil was transported-from- the site of the previous experiment to the greenhouse at the University of British Columbia where i t was placed in 30 eight-inch pots. The pH of this soil was 6.1. A 5-10-0 fertilizer was broadcast on the pots at the rate of 1000 pounds per acre as a basic treatment and the pots received the varying amounts of potassium as planned for in this experiment. The fertilizers were raked lightly in the top half-inch of s o i l and the pots were watered. Then, for an additional control, six pots were f i l l e d with John Innes greenhouse soil and added to the experiment so that the whole was carried out in six randomized blocks. This soil also had a reaction of pH 6.1. See Appendix for composition of this soil. Approximately 20 seeds of radish (Raphanus sativus) were sown in each pot on December 20, 1951. Because of the general lack of light during January and early February,, the plants became etiolated. At the beginning of February they began to show signs of "damping off", and approximately one inch of clean sand mixed with a small amount of Arasan was put into each pot to combat this disease and to support the plants. On the week-end of March 21 to March 24, 1952, the greenhouse was allowed to become extremely hot. -11 -Figure 2 Arrangement of Radish Pots on the Greenhouse Bench. — East West —> IV I III VI II K K K K K K K K K ^ K K K K „ K T T K 20 3 5 3 10 20 10 5 0 J ± 0 20 5 0 d l 0 J 1 20 K K ^ K ^ K ^ K K K K K K K K K K K 10 0 0 d X 5 0 1 3 20 3 10 5 3 20 10 10 5 3 The peak of the greenhouse roof, which extends from north to south, ran directly across the center of this bench. - 12 MATERIALS AND METHODS Analytical and Statistical Methods Immediately upon harvesting, the carrots were weighed to obtain the fresh weights for the yield data. The tops were twisted off and the roots and the tops were again weighed separately in order to determine the top/root ratio. A representative sample was chosen at random and transported to the Plant Nutrition Laboratory of the University of British Columbia where the remaining determinations were carried out. A sample was weighed and dried at 50° C. and reweighed for the percentage dry matter. This sample was then ashed at 600° C. and reweighed for percentage ash over dry matter. Another sample was pulped and juiced, and an aliquot was used to determine conductivity by means of a "Solu-bridge" conductivity meter. Further aliquots were used to determine total sugars by means of the Brix Spindle and Refractcmeter. Nitrogen was determined on the fresh material by the Kjeldahl method A.O.A.C. (2) Carotinoids were determined by Booth's method. (6) This i s essentially a cold extraction method using a petroleum ether-acetone mixture and a colorimetric estimation of carotinoids with a 0.02$ potassium dichromate as a reference standard. The radish yield data was obtained from the fresh weights, - 13 -however dry weights were used to obtain top/root ratio becauseof the condition which the plants were in due, largely, to the overheated condition of the greenhouse on the week-end of March 21 to March 24, 1952. The Vitamin C content of the radishes was determined on the roots by the method of Bessey and King. (5) Nitrogen was determined on the dry material by the Kjeldahl method A.O.A.C., and the total sugars were determined by the Lane and Eynon method A.O.A.C. (2) A l l statistical methods used by the author were those of Paterson. (21) The data on the carrots has been considerably reworked since f i r s t accumulatedand particular attention has been paid to the various trends which appear in this work. RESULTS Carrots On harvesting, the carrot tops and roots from each of the plots were weighed immediately. They were then taken to the Plant Nutrition Laboratory at the University of British Columbia where the remaining determinations were carried out. Complete results are shown below. Table 2 The Effects of Treatments on a l l Factors Analysed (5 replications) Factor Reps Treatment A B C D E n i l a> 5 10 20 Yield of (1) 7.20 5.90 11.71 8.10 11.71 Roots per acre (tons) (2) 8.76 8.60 10.40 13.10 9.74 (3) 11.54 11.29 8.60 7.94 13.51 (4) 17.07 9.66 10.81 9.43 10.81 (5) 12.85 18.91 9.91 9.43 12.20 Top/Root (1) .2500 .2777 .2587 .2222 .1958 Ratio (2) .1666 .2381 .2440 .2312 • .2353 (Fresh Weight) (3) .2500 .2173 .2380 .2577 .2121 (4) .2296 .1778 .2348 .2413 .1893 (5) .1783 .1428 .2066 .2671 .2214 Dry Weight (1) 14.625 13.700 13.725 14.500 13.975 (percentage (2) 13.750 14.400 14.250 14.275 13.550 Fresh Weight) (3) 13.675 15.075 15.525 15.625 13.650 (4) 13.000 13.425 15.225 13.575 14.025 (5) 12.825 13.925 13.075 15.525 14.025 - 15 -RESULTS Table 2 (cent) Factor Reps Treatment A B C D E n i l 3 5 10 20 Ash Weight (1) 9.075 10.238 10.198 13.185 13.057 (percentage (2) 9.824 12.132 10.965 10.621 12.951 Dry Weight) (3) 11.402 11.269 13.022; 11.469 13.415 (4) 9.873 8.757 11.495 11.119* 12.892* (5) 8.494 9.894 8.300 13.802 11.276 Conductivity (1) .180 .160 .176 .160 .192 (per cent (2) .180 .168 .156 .172 .200 NaOH) (3) .176 ".144 .160 .160 . .168 (4) .192 .112 .148 .132 ".128 (5) .172 .160 .132 .172 .172 Total Sugar (1) 9.7 9.3 10.2 11.0 10.1 (Refractameter (2) 7.8 9.7 9.0 10.9 10.1 percentage Fresh Weight) (3) 7.1 10.1 11.5 11.1 " 8.8 (4) 7.8 - 7.7 9.3 - 9.1 8.3 (5) 8.2 9.6 9.0 10.0 10.9 Total Sugar (1) 10.4 12.0 12.8 14.3 12.4 (Brix Spindle (2) 8.8 11.2 11.2 13.2 12.8 percentage Fresh Weight) (3) 7.2 12.8 14.8 14.4 12.0 (4) 9.6 10.4 11.6 12.0 11.2 (5) 10.4 12.4 " 12.0 12.4 13.6 - 16 -Table 2 (cont) Factor Reps Treatment A B C D E n i l 3 5 10 20 Nitrogen (1) .2122 .1809 .2313 .1905 .2047 (percentage (2) .1985 .2182 .2345 .2390 .1917 Fresh weight) (3) .2398 .2383 .2431 .2143 .2039 (4) .2571 .2102 .2066 .1861 .1933 (5) .1953 .2321 .1972 .2734 .1974 Carbohydrate/ (1) 45.7 51.4 44.1 57.9 49.3 Nitrogen Ratio (2) 39.4 44.5 38.3 41.4 52.6 (3) 29.6 42.4 47.3 51.9 43.1 (4) 30.3 36.7 44.9 48.9 43.0 (5) 42.0 41.4 45.7 36.6 55.3 Carotinoid (1) 6.7734* 5.5968 6.7416 7.3140 10.0170 Pigments (mg/loo gm juice) (2) 2.9256 5.1198 6.5508 8.8404 7.6320 (3) 7.3776 7.2504 7.5048 7.6320 7.4412 (4) 7.8864 6.6144 8.5860 7.9500 6.9960 (5) 8.9040 10.4940 6.7416 8.0772 7.7592 «• Calculated by averaging other four replications. The above complete data is summarized below. - 17 -Table 3 The Effect of Treatments on Yield Treatments A B C D E Gen Sig.Dif. Mean 5$ Average Yield Tons/Acre 11.48 10.87 10.28 9.60 11.59 10.76 1.85 Percent Mean 106.7 101.0 95.5 89.2 107.7 100.0 17.2 From the above i t can be seen that both the control (no potash -Treatment A) and the 20$ potash treatment (E) gave a higher yield than the 10$ potash treatment (D). There was no difference due to the other treatments. Table 4 The Effect of Treatments on Top/Root Ratio Treatments A B C D E Gen Sig.Dif. Mean 5$ Average Per Plot . .215 .211 .236 .243 .211 .223 0.051 Percent General Mean 96.24 94.36 105.87 109.22 94.40 100.0 23.01 There was no significant difference in the top/root ratio due to treatments. However, i t would appear that as a result of both treatments C and D there was a tendency for root growth to be reduced relative to top growth. - 18 -Table 5 The Effect of Treatments on Total Minerals as Reflected in the Ash Weight Treatments Gen. 5$ A B C D E Mean S.D. Mean Ash Weight (on dry weight) 9.734 10.458 10.796 12.039 12.718 11.149 2.414 Percent General Mean 87.30 93.30 96.33 107.98 114.07 100.00 21.65 The very high (20$) treatments significantly increased the ash weight in comparison to the control treatment. There was a tendency for the ash content to be progressively increased with increasing levels of potash. Table 6 The Effect of Treatments on Minerals as Determined by Conductivity (per cent NaOH) Treatments Gen. 5$ A B C D E Mean S.D. Mean Conductivity .180 .149 .154 .159 .172 .163 .028 Percent General Mean 110.42 91.41 94.47 97.54 105.52 100.00 17.17 The addition of 3$ potassium depressed the minerals in the roots when compared to the mineral content of the roots from the control treatment. There is a tendency, however, for the minerals to increase with increasing levels of potash, but the increases were lower than the control treatment. - 19 -Table 7 The Effect of Treatments on Dry Weight Treatments A B C D E Average Per Plot 13.575 14.105 14.360 14.700 13.845 Percent General Mean 96.16 99.91 101.72 104.13 98.07 100.00 8.38 The several levels of potassium had no significant effect upon the dry matter produced in the roots. There was a tendency for the dry matter to increase with increasing potash up to the 10$ level of application with a decrease in dry matter with the very high (20$) application. Table 8 The Effect of Treatment on Total Sugar as Shown by the Refractometer Mean Total Sugars (percentage fresh weight) Percent General Mean 85.80 98.51 103.81 110.16 101.69 100.00 19.38 The total sugar was higher in the carrots which received the high application (10$) of potassium when compared to the control treatment. There was an apparent trend towards increased sugar with increasing amounts of potash up to the 10$ level, with a decrease of sugar at the 20$ level. Gen S.D. Mean 5$ 14.117 1.184 Treatments - c n b c D e ££. §: 8.1 9.3 9.8 10.4 9.6 9.44 1.83 - 2 0 -Table 9 The Effect of Treatment on Total Sugar as Shown by the Brix Spindle Treatments Gen S.D. A B C D E Mean 5$ Mean Total Sugars (percentage fresh weight 9.3 11.8 12.5 13.3 12.4 11.86 2.83 Percent General Mean 78.41 99.49 105.39 112.14 104.55 100.00 23.86 The total sugar as measured by Brix Spindle was significantly higher in the carrots receiving 5$, 10$ and 20$ potassium when compared to the control treatment. There was an apparent trend towards increased sugar with increasing amounts of potash up to the 10$ level, with a decrease of sugar at the 20$ level. Table 10 The Effect of Treatment on Nitrogen (Percentage Fresh Weight) Treatments Gen S.D. A B C D E Mean 5$ Mean Nitrogen .221 .216 .222 .221 .198 .216 .034 Percent General Mean 102.31 100.13 103.20 102.36 91.92 100.00 15.63 The potassium treatments did not significantly affect the nitrogen. However, there was an apparent tendency for a lower nitrogen content in the roots of the carrots under the very high (20$) potash treatment when compared with the control treatment. - 2 1 -Table 11 The Effect of Treatment on Carbohydrate/Nitrogen Ratio (Total Sugar by Refractometer) Treatments Gen S.D. A B C D E Mean 5$ Mean Carbohydrate/ Nitrogen . * Ratio 37.40 43.28 44.06 47.34 48.66 44.15 9.39 Percent - - • • General Mean 84.71 98.02 99.79 107.22 110.21 100.00 21.26 The high and very high levels of potassium (10% and 20% respectively) gave a higher carbohydrate/nitrogen ratio when compared with the control treatment (no potash). There was an apparent tendency for higher carbohydrate/nitrogen ratios with increasing increments of potash. Table 12 The Effect of Treatments on Carotinoid Pigments (mg/lOO gm juice) Treatments Gen S.D. A B C D E Mean 5$ Mean . . . . . Carotinoid Pigments 6.773 7.015 7.225 7.963 7.969 7.389 2.074 Percent General Mean 91.66 94.93 97.77 107.76 107.85 100.00 28.07 There was no significant effect which could be attributed to the potassium treatments. There was, however, an apparent trend towards higher carotinoid concentrations with increasing amounts of potassium. - 22 -Table 13 Summarized Table of Values in Order of Yield for the Average for Each of the Various Treatments. Yield Tons Treat-ment T/R Ratio Treat-ment % Dry Weight Treat-ment 11.59 E .244 D 14.700 D 11.48 A .236 C 14.360 C 10.87 B .215 A 14.105 B 10.28 C • .211 E 13.845 E 9.60 D .211 B 13.575 A Total Sugar Treat-ment Total Sugar Treat-ment Cond. Treat ment 10.4 D 13.3 D .180 A 9.8 C 12.5 C .172 E 9.6 E 12.4 E .159 D 9.3 B 11.8 B .154 C 8.1 A 9.3 A .148 B Caro-tene Treat-ment Ash weight Treat-ment Nit-rogen Treat, ment 7.969 E 12.718 E .223 C 7.962 D 12.039 D .221 D 7.225 C 10.796 C .221 A 7.015 B 10.458 B .216 B 6.773 A 9.734 A .198 E - 2a -RESULTS Radishes The radishes were taken from the greenhouse to the Plant Nutrition Laboratory where these determinations were carried out. Complete results are shown below. Table 14 The Effects of Treatments on a l l Factors Analysed (6 replications) Factor Reps j . l . A n i l B 3 Treatments C 5 D 10 E 20 Weight of (1) 80.00 11.90 33.54 33.11 30.03 49.08 Harvest (gms/pot) (2) (3) 73.40 58.96 32.60 23.59 72.40 20.95 44.00 22.27* 51.40 2.30 43.70 32.22 (4) 178.45 30.75 30.00 47.84 33.00 18.30 (5) 44.56 ' 25.28 24.90 43.95 ' 24.45 19.28 (6) 44.25 1.40 47.14 12.84 . 16.44 25.90 Top/Root Ratio (Dry Weight) (1) (2) (3) 3.190 9.264 2.897 3.142 3.643 3.419 2.689 2.939 5.501 2.828 12.118 7.280* 1.804 8.931 13.733 1.618 6.074 2.265 (4) 1.164 4.363 7.372 4.471 2.259 9.206 (5) 7.015 6.672 6.174 9.909 9.410 6.109 (6) 4.658 4.247 2.800 4.812 3.444 5.787 Total Nitrogen (percentage Dry Weight) (1) (2) (3) (4) 2.077 3.210 4.327 2.392 2.565 1.888 2.612 2.596 2.140 2.203 3.210 2.801 2.895 " 3.084 . 3.344* 2.376 2.911 2.093 1.253 1.228 4.689 2.549 5.004 2.226 (5) 1.810 2.596 2.423 2.282 2.832 1.747 (6) 3.792 1.281 3.462 2.219 2.612 2.565 - 24 -Table 14 (cent) Factor Vitamin "C" Treatments Reps J.I. A B C D E n i l 3 5 10 20 (1) 9.60 7.47 22.51 16.66 21.56 14.96 (2) 13.36 8.09 13.46 13.08 14.26 18.98 1 (3) 12.17 12.07 16.84 14.62* 15.46 19.70 (4) 17.60 11.11 23.37 11.40 18.97 18.97 (5) 18.63 15.06 11.17 11.03 24.96 16.19 (6) 23.14 9.28 8.93 21.33 6.73 14.33 Invert Sugar (1) 15.666 5.000 6.366 10.152 9.138 7.835 (2) 9.460 5.356 15.596 12.746 5.250 14.806 (3) 13.113 6.934 12.353 13.587* 10.135 11.693 (4) 14.568 10.920 13.826 16.260 13.000 8.519 (5) 13.926 4.965 8.960 12.186 3.500 7.720 (6) 7.000 7.815 11.677 11.797 15.346 10.953 # Found by Paterson's Missing Plot Technique (21) The above complete data i s summarized in the following tables. Table 15 Average Yield gms/pot Percent General Mean The Effect of Treatments on Weight of Harvest Treatments J.I. A B C D E Gen Mean S.D. 5$ 79.94 20.92 38.16 34.00 * 26.27 31.41 38.45 28.17 207.90 54.40 99.24 88.42 68.32 81.69 100.00 73.26 There was no significant difference in harvest due to treatments. But the second control (J.I.) was highly significant over the f i r s t control (A.), and a l l potassium treatments (B, C, D and E). - 25 -Table 16 The Effect of Treatments on Top/Root Ratio Treatments Gen S.D. J.I. A B C D E Mean 5$ Average Per Plot 4.698 4.248 4.579 6.903 6.597 5.176 5.165 3.385 Percent General Mean 90.95 82.24 88.65 133.64 127.72 100.21 100.00 65.53 There was no significant difference in the top/root ratio due to treatments. However, there was a tendency for root growth to be reduced relative to top growth in treatments C and D. Table 17 The Effect of Treatments on Total Nitrogen (Percentage Dry Weight) Treatments J.I. A B O D E Mean Nitrogen (percentage Dry Weight) 2.935 2.256 2.707 2.700 2.155 3.130 2.647 1.018 Percent General Mean 110.88 85.22 102.26 102.00 81.41 118.24 100.00 38.45 Gen S.D. Mean 5$ There was no significant difference in nitrogen due to treatments. However, i t would appear that there was a tendency for the 3$, 5$ and 20% levels of treatment to increase the nitrogen but this tendency was broken at the 10% treatment level. - 26 Table 18 The Effect of Treatments on Vitamin "C" Treatments r c T> 15.75 10.60 16.05 14.69 16.99 17.19 15.21 6.058 Percent General Mean 103.55 69.69 105.52 96.58 111.70 113.01 100.00 39.82 The high (D) and very high (E) levels of potassium were significant over control (A) but no treatment was significant over the second control (J.I.). The trend toward greater Vitamin "C" increases through potassium levels 3, 10 and 20, but at the 5$ is down. Table 19 The Effect of Treatments on Invert Sugar Treatments Gen S.D. J.I. A B C D E Mean 5$ Average Yield Invert Sugar mgs/100 gms 12.289 6.832 11.463 12.788 9.395 10.254 10.504 3.729 Percent -General Mean 116.99 65.04 109.12 121.74 89.44 97.61 100.00 35.50 The 3$ and 5$ treatments (B and C) were significantly higher than the control treatment (A). The second control (I.I.) was significantly higher than the f i r s t control (A). A tendency was apparent for the trend to increase with the low (B) and medium (C) treatments and then to drop off with treatments D and E. Average mgs/100 gms - 27 -DISCUSSION Much of the results obtained from the radish section of these experiments would seem to be at variance with the results 1 obtained from the carrot experiment. It might be well to remember that Dolan and Christopher (13) obtained very different results with crops of celery, tomatoes and peppers. High potash very significantly increased the yield of celery but not of tomatoes and reduced the yield of peppers. Jenkins (17) states that beans failed to show an increase in yield from any of the potassium treatments and actually reduced yields occurred in direct proportion to the increases in the amount of available potash supply. Jenkins concluded that the difference in yield was due to the toxic effects of potassium salts and, further, that on some soils the addition of potash was of doubtful value as far as yield was concerned. Boswell and Beattie (7) state that Schermerhorn, Robbins and others showed that the shape of the sweetpotato root as well as the yield was very markedly influenced by differences in potash supply. However, Boswell and Beattie conducted their own experiment in another part of the Atlantic . Coastal area and concluded that increasing the potash content had no important effect on total yield, yield of top grade, or on the shape of sweetpotatoes. Carolus (11) found that either liming or manuring increased the effectiveness of potash fertilization. - 28 -Painter, Drossdoff, and Brown (20) state that the source of potassium had no influence on the potassium content of tung tree leaves grown on a fine, sandy loam. They also make the statement that the potassium content of the leaves was lowered by increasing the amount of nitrogen supplied. Dunbar and Anthony (14) found that potassium had a blocking effect on nitrogen. Lilleland (19) states that there can be l i t t l e doubt that the potassium had gotten into the plant from a soil in which the potassium content had been raised materially. The above findings indicate what widely divergent results have been obtained by others from different crops. Yield Under the conditions of this experiment the carrots showed that the no potash treatment (A.) and the wry high potash treatment (B) were both significantly higher than the high potash treatment (D). There was no difference due to the other treatments. From the radish data i t may be seen that the second control (j.l) was highly significant in relation to the f i r s t control (A.) and a l l treatments (B, C, D and E). There was no significance between the control (A) and any potash treatment (B, C, D and E). It i s assumed that these results reflect the moisture holding capacity of John Innes greenhouse soil compared with the moisture - 29 -holding capacity of soil from the author's frait yard. John Innes greenhouse soil contains one part in four by bulk of peat, which i s recognized as a useful soil adjunct because of it s water holding capacity. This additional water holding capacity undoubtedly was of great benefit to the radish plants which tended to dry out in the pots between waterings during the latter stages of their development. It appears to the author from the results of his experiments and i n the scope of his experiments, that the application of potash has a tendency to reduce yield when applied to a soil which has a sufficient supply of readily available potassium. However, he i s reminded that high levels of potassium have frequently been suggested to increase the resistance of plants to disease, and that there may be the possibility of ahigher nutrient value being produced in vegetable crops which w i l l offset this tendency to reduced yields. Top/Root Ratio No significant difference was found in the top/root ratio due to the treatments. It appeared that there was a tendency for root growth to be reduced relative to top growth in both radishes and carrots at the 3% and 10% levels of potassium treatment. This would seem to contradict the findings of Waugh and Cullinan (26) who make the statement that neither cultural treatments nor potassium application seem to have a significant effect on nitrogen content, but would agree with the findings of several other investigators (20, 14). - 30 -Total Minerals as Reflected in Ash Weight and i n Conductivity Owing to the time of year and other conditions beyond the author's control there was insufficient material harvested from the radish experiment to make ash and conductivity determinations. In the carrot experiment the very high potassium treatment 03) significantly increased the ash weight i n comparison to the control treatment (A). There was a tendency for the ash content to be progressively increased with increasing levels of potash. This would seem to coincide with the findings of Cain who states that in one-year-old Mcintosh apple trees as the potassium supply was increased, the dry weight, stem elongation and the potash content increased ... (9). Cain drew the interesting conclusion from his experiment that leaf injury normally attributed to a deficiency of magnesium might actually be the toxic effect produced by an excess of potassium. In the conductivity determinations the addition of 3$ potassium (B) significantly depressed the minerals in the roots when compared to the mineral content of the roots from the control treatment (A). Carolus states that the plant content of any single cation may be as largely influenced by the application of some other cation to the soil as by the addition of the one determined. (10) From this i t would appear that there was sufficient available potassium in the so i l for the plant's normal growth, and that this addition was sufficient to affect the calcium, magnesium and possibly - 31 other mineral contents of the plant. The tendency i s again noted for the minerals to increase with increasing levels of potash, but even at the very high (20$) treatment level these increases were lower than the control treatment. Dry Weight Because of conditions beyond the author's control, the radish crop had become partially cooked about a week before harvest. The wilted and dried tops precluded any attempt to obtain a dry weight as a percentage of the fresh weight. In the carrots the several levels of potassium had no significant effect upon the dry matter produced in the roots. However, there was again a tendency for the dry matter to increase with increasing potash up to the 10$ level of application, with a decrease in dry matter from the very high (20$) application. This agrees with Cain's statement (9) that the growth response to potassium i s slightly greater in height than in dry weight, indicating a primary response in stem elongation. Cain also states that both calcium and magnesium decrease sharply with increasing potassium but not in exact chemically equivalent amounts. Total Sugar Total sugar found in the carrots by both the Brix Spindle and - 32 -the Refractometer had the same seemingly apparent trends. The Brix Spindle results were significantly higher in the carrots receiving 3%, 10% and 20% potassium (C, D and E) when compared to the control treatment (A), while the Refractcmeter only showed the 10% application (D) to be significantly higher than the control treatment (A). However, Lilleland (19) found that the sugar content of the flesh of fruit was not altered by relatively large applications of potash and he states that undoubtedly other factors than potash influence the sugar content of prunes; and that size of crop and climatic conditions must be considered. Statistical analysis of the effects of treatments on invert sugar in radishes showed only the 3$ and 3% treatments (B and C) as significantly higher than the control treatment (A). The second control (J.I) was significantly higher than the f i r s t control (A). There was an apparent trend towards increased sugar with increasing amounts of potash to about the 10% level. From that point on, the decrease in sugar was rather marked in both carrots and radishes, which appears to show that potassium acts in some favorable way in aiding the formation of sugars up to this point. Total Nitrogen Potassium treatments did not significantly affect the nitrogen content of either crop. However, there was an apparent tendency for a lower nitrogen content in the roots of both radishes - 33 -and carrots under the very high (20$) potash treatment when compared with the control treatment. The fact that the tendency was broken at the 10$ treatment level in the radishes might be laid to experimental error. Carbohydrate/nitrogen ratio In the carrots the high and very high levels of potassium (10$ and 20$ respectively) gave a significantly higher carbohydrate/ nitrogen ratio when compared with the control treatment (no potash). There was an apparent tendency for higher carbohydrate/nitrogen ratio with increasing increments of potash. No determinations of carbohydrate/nitrogen ratio were made on the radishes since the potassium treatments had no significant effect on the nitrogen content. Carotinoid Pigments There was no significant effect which could be attributed to the potassium treatments. There was, however, an apparent trend towards higher carotinoid concentrations with increasing amounts of potassium, in the carrots. Radishes, having a white flesh and red skin, showed none of the orange pigmentation characteristic of the carotinoid pigments in - 34 -their edible portion or roots and consequently were not tested. They are shown as containing no Vitamin A precursor in the "Handbook of Chemistry and Physics" (Hodgman, Charles D. 16), but carotene i s found i n a l l green tissues and undoubtedly the presence of this pigment could be demonstrated in radish leaves. However, radish leaves are not used as a food for man and therefore this determination would be outside the scope of this thesis. The apparent trend towards higher carotinoid concentration with increasing amounts of potassium suggests to the author that further correlation studies should be made on this subject and would prove extremely interesting to the researcher engaged in this work. Vitamin C Radishes alone were tested for Vitamin C. The high CD) and the very high (B) levels of potassium were significant over the control (A) but no treatment was significant over the second control (J.I.) Radishes are listed as good sources of Vitamin C in the "Handbook of Chemistry and Physics" (Hodgson, Charles D. 16), and are listed as containing an average of 26 milligrams per 100 grams of the edible portion in "Elements of Food Biochemistry" (Peterson, et al . 22). The author assumes that approximately one-half of the potassium which enters a plant's roots comes from the soil water and the balance i s taken up by "solid phase feeding". On this assumption - 35 -rests the explanation for 1he fact that two of the treatments were significant over the control (A) but that no treatment was significant over the second control (J.I.). As explained before, the John Innes greenhouse soil contains one part in four of peat which i s noted for i t s high water-holding capacity and this would account for the average higher moisture content noticed i n the (J.I.) control. Yet, apparently, the lessened chance of these plants wilting from a lack of moisture did not affect them advantageously in their ability to obtain a greater amount of potassium. The over-all trend appears to be towards greater Vitamin C content as the potassium levels rise. However, not one of the pots of radishes reached the content of Vitamin C as given in Peterson et a l (22) and thus i t would appear that the upward trend occasioned by the addition of potash had not, under the conditions of this experiment, reached the optimum level of potassium for the production of Vitamin C. This theory does not allow for the low light-intensity and the short day duration of light which existed in the months of January and February 1952, and which undoubtedly had a bearing on the plants' manufacture of Vitamin C, but i t does satisfactorily explain the fact of seme treatments being significant over control A but not over control J.I. Here again there is a trend towards higher vitamin content which differs only from the carotene trend in that i t i s increasing at a greater rate and thus breaks into the levels of significance sooner. As mentioned above, the author believes that further intensive studies -36 -should be made on the correlation between the potassium level and the vitamin content of plants. In the layman's language we might say that the addition of potash to a soi l in which the potassium i s not readily available for the plants to use, would increase yields; but the addition of potash to soil which would release i t in sufficient quantities far normal plant growth, would appear to reduce the yield. However, the addition of potash to soil increases the mineral content of the crop grown and increases the total sugar content up to the maximum, but further applications have an inhibiting effect on the carbohydrate. While Vitamin A is not increased in carrots, Vitamin C i s definitely increased in radishes by increased applications of potassium. There appears to be a huge field open here for further research. SUMMARY The effect of varying levels of potassium fertilizer is :-1. On land containing potassium readily available for plants, additional potassium appears to have a tendency to reduce yields. 2. Additional potassium appears to increase the mineral content. 3. Additional potassium has no effect on the nitrogen content. 4. Additional potassium increases the total sugars up to a point after which i t inhibits the formation of carbohydrate. 5. Additional potassium has no effect on Vitamin A content but a very definite upward trend follows the increasing levels of potassium applied. 6. Additional potassium increases the trend to produce more Vitamin C to the extent that high and very high levels of potassium applications become significant. - 38 -LITERATURE CITED 1 Anderson, W.S. The influence of potash on grade and shape of Triumph sweetpotatoes in Mississippi. Proc. Amer. Soc. Hort. Sci. 35: 709-711 1937 2 Association of Official Agricultural Chemists Official and Tentative Methods of Analysis 6th ed. Washington, D.C. 1945 3 Baker, Clarence E. The effectiveness of some organic mulches in correcting potassium deficiency in peach trees on a sandy soil. Proc. Amer. Soc. Hort. Sci. 51: 1-11 1948 4 Beach, George, and August Mussenbrock. Effect of nitrogen and potash fertilizers on Patrician carnations in soil. Proc. Amer. Soc. Hort. Sci. 52: 487-489 1948 5 Bessey, D.A. and King, C.G. The distribution of Vitamin C in plant and animal tissues, and i t s determination. J. Biol. Chem. 103: 687-698 1933 6 Booth, V.H. Simplified technique far estimation of total carotinoids in carrots J. Soc. Chem. Ind. 64: 194-195 1945 7 Boswell, Victor R., and J.H. Beattie. Grade and shape of sweetpotatoes in response to potash i n South Carolina. Proc. Amer. Soc. Hort. Sci. 34: 451-454 1936 8 Brown, G.B. The effect of maturity and storage on the carotene content of carrot varieties. Proc. Amer. Soc. Hort. Sci. 50: 347-352 1947 - 39 -9 Gain, John C. Some interrelationships between ealcium, magnesium and potassium i n one-year-old Mcintosh apple trees grown in sand culture. Proc. Amer. Soc. Hort. Sci. 51: 1-11 1948 10 Carolus, R.L. The relation of potassium, calcium and sodium to magnesium deficiency. Proc. Amer. Soc. Hort. Sci. 33: 595-599 1935 11 Carolus, R.L. Calcium and potassium relationships in tomatoes and spinach. Proc. Amer. Soc. Hort. Sci. 44: 281-285 1949-50 12 Culbert, John R., and E.I. Wilde. The effect of various amounts of potassium on the production and growth of Better Times roses under glass. Proc. Amer. Soc. Hort. Sci. 52: 528-535 1948 13 Dolan, D.D., and E.P. Christopher. Effect of modified fertilizer ratio on yield of vegetables. Proc. Amer. Soc. Hort. Sci. 53: 402-406 1949 14 Dunbar, CO., and R.D. Anthony. Two cases of potassium deficiency in peach orchards in South Central Pennsylvania. Proc. Amer. Soc. Hort. Sci. 35: 320-325 1937 15 Frear, D.E.H., R.D. Anthony, A.L. Haskins, and F.N. Hewetson. Potassium content of various parts of the peach tree and their correlation with potassium fertilization. Proc. Amer. Soc. Hort. Sci. 52: 61-74 1948 16 Hodgman, Charles D. ed Handbook of Chemistry and Physics 20th ed Chemical Rubber Publishing Company Cleveland, Ohio 1514-1536 1948 - 40 -17 Jenkins, J. Mitchell Jr. Some effects of potassium on yields of snap beans. Proc. Amer. Soc. Hort. Sci. 34? 471-472 1936 18 Kitchen, H.B. Ed Diagnostic Techniques for Soils and Crops, American Potash Institute Washington, D.C. 1948 19 Lilleland, 0. Does potassium increase the sugar content of prunes? Proc. Amer. Soc. Hort. Sci. 27: 15-17 1930 20 Painter, John H., Matthew Drosdoff, and Ralph T. Brown. Responses of bearing tung trees on Red Bay fine sandy loam to potassium and nitrogen. Proc. Amer. Soc. Hort. Sci. 52: 19-24 1948 21 Paterson, D.D. Statistical Technique in Agricultural Research 1st ed. McGraw-Hill Book Co. Inc., New York-and London 1939 22 Peterson, William H., John T. Skinner and Frank M. Strong Elements of Food Biochemistry Prentice-flall, Inc., New York - 1946 23 Sitton, Benjamin G. Response of bearing tung trees to nitrogen, phosphorus, and potassium fertilizers. Proc. Amer. Soc. Hart. Sci. 52: 25-38 1948 24 Spurway, C.H. Soil Testing Technical Bulletin 132 (3rd Revision) June 1944 Michigan State College Agricultural Experiment Station, East- Lansing, Michigan p. 12 25. U.S. Department of Agriculture Circular No. 750 July 1946 Washington, D.C. - 41 -26. Wander, I.W., and J.H. Gourley. A study of lateral movement of potassium and phosphorus in an orchard soil. Proc. Amer. Soc. Hort. Sci. 46: 305-306 1945 27 Waugh, J.G. and P.P. Cullinan. The nitrogen, phosphorus, and potassium content of peach leaves as influenced by soil treatments. Proc. Amer. Soc. Hort. Sci. 38: 13-16 1941 APPENDIX Composition of John Innes Greenhouse Soil By bulk - 3 parts peat 2 parts sand 7 parts loam By weight - 3 oz chalk per bushel 4 oz John Innes Base per bushel John Innes Base By weight - 2 Hoof and Horn -13$ Nitrogen 2 Superphosphate Lime -16$ Phosphorus 1 KSOo - 48$ Potassium - 43 -Calculations for Significance of Top/Root Ratio The following i s derived from data talcing an assumed mean of .2400. Row. Columns Row Totals - 1 .+ . - 2 + , - 3 + -. 4 + - 5 + + B D E A C I .0377 .0178 .0442 .01 .0187 o0040 n C .0040 A .0734 B .0019 E .0047 D .0088 .0848 i n D .0177 C .0020 A .01 B .0227 E .0279 .0249 IV E .0507 B .0622 C .0052 D .0013 A .0104 .1272 V A .0617 E .0186 D .0271 C .0334 B .0972 .1838 Total -.0530 -.1740 -.0142 1 -.0495 -.1256 Grand total -.4163 Treatment totals A = - .1255 B = - .1463 C = .0179 D + .0195 E - .1461 - 44: -An Analysis of Data of the Latin Square The data was multiplied by 10000 to remove decimals. (1) Total S.S. 142129 + 31684 + 195364 + 10000 + 34969 + 1600 + 538756 + 361 + 2209 + 7744 + 31329 + 400 + 10000 + 51529 + 77841 + 257049 + 386884 + 2704 + 169 + 10816 + 380689 + 34596 + 73441 + 111556 + 944784 = 3,338,603 - (CP.) 693204 - 2,645,499 (2) Row S.S. 1600 + 719104 + 62001 + 1612900 + 3385600 = 1016241 5 -,- (C.F.) 693204 = . 323,037 (3) Column S.S. 280900 + 3027600 + 20164 + 245025 + 1587600 . g = 1032258 - 693204 = 339,054 (4) Treatment S.S. 1575000 + 2161600 + 32041 + 38025 +2134500 g = 1188255 - 693204 = 495,051 (5) Error S.S. Total S.S. - (Row S.S. + Column S.S. + Treatment S.S.) = Error S.S. 2645499 - (323037 + 339054 + 495051) = l;488,357 - 45 -Analysis of Variance Factor S.S. Beg. of Freedom Variance F calc Total Row Column Treatment Error 2645499 323037 339054 495051 1488357 24 4 4 4 12 80759 84763 123763 124029 0.65 0.69 0.99 L.S.D. Treatment means error variance x 2 x t v/ n t.05 <n = 8> = 2- 3 0 6 124029 x 2 x 2.306 514. Divide by 10 4 to replace decimal «\ L.S.D. = 0.0514 

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