doctoral D im n u im m m nn e s Lv- 1/ m m m c iim • m m : f; v i t i y J) » * ' y '''' V 4' ' ’ *v ... I*'/■ fC s?: ^ /: 7 6MHCfa1/ S/m M IINIVFRfilTYM fc/IISAftSMft6ML DATEM AUTHOR DEGREE Pit, PUBLICATION NO. m I ™ UNIVERSITY MICROFILMS i THE HERBICIDAL ACTION OP SODIUM TRICHLOROACETATE WITH SPECIAL REFERENCE TO TRI TI CUM VULGARE By Gurbachan Singh Rai A THESIS Submitted to the School of Graduate Studies of Michigan State College of Agriculture and Applied Science in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Department of Horticulture 1952 ACKNOWLEDG-f'E'TTS The author wishes to express his indebtedness and sincere appreci­ ation to Dr. C. L. Hamner for his guidance, encouragement and never fail ing help which made this investigation possible* Thanks are due to Dr. R* L. Cook for his advice and suggestions which are reflected in the presentation of this manuscript* Appriciation is due to Dr. B* H. Srigsby, for his constructive criticism and valuable suggestions, and Drs. H. B. Tukey, L. 14. Turk, H. M. Sell, S. J. Benne, and W. D. Baten for their advice* Thanks are also due to the Dow Chemical Company for a grant-in-aid to support the respiration studies which are included in this discourse. TABLE OF CONTENTS Pag® INTRODUCTION................................................... 1 REVIEW OF LITERATURE........................................... 4 1« G e n e r a l ............................................... 4 2. Mode of TCA Entry intotheP l a n t ..................... 8 3* Pre- and Post-EmergenceTreatments ................. 8 MATERIALS AND M E T H O D S ........................................... 11 EXPERIMENTAL RESULTS ........................................... 19 DISCUSSION OF R E S U L T S ........................................... 44 S U M M A R Y ......................................................... 57 LITERATURE C I T E D .......................................... 4 • • 59 LIST OF TABLES Page Table 1. The residual effects of soil applications of sodium trichloroacetate on the yield, fresh and dry weight of tops and dry weight of roots, of wheat grown on muck s o i l ................................................. 27 Table 2* The residual effects of soil applications of sodium trichloroacetate on the yield, fresh and dry weight of tops and dry weight of roots, of wheat grown on clay loam s o i l ............................................. 28 Table 3» The residual effects of soil applications of sodium trichloroacetate on the yield, fresh and dry welgit of tops and dry weight of roots, of wheat grown on Oshtemo s a n d ......................................... 29 Table h. Analysis of variance of wheat yield, fresh and dry weight of tops and dry weight of roots, in the split plot experiment....................................... 30 Table -A. summary of the yield data for all treatments, rates, times and s o i l s ....................................... 31 Table 6. The effects of soil applications of TCA on the nutri­ tional status of the soils during tne entire period of the e x p e r i m e n t ....................................... 32 Table 7» The effects of soil applications of TCA and fertilizer (10-10-10) on N, P, and K in plant tissue and on pH, F an d K contents of s o i l * ..........................33 Table 8* The effect of soil application of TCA on amino acid, nitrogen and protein contents of wheat leaves (includ­ ing s t e m s ) ........................................... 3^ Table 9. The effect of soil application of TGA on amino acid, nitrogen end protein contents of wheat r o o t s ..............35 Table 10. The effect of soil application of TCA on carbohydrates and ether extract contents of wheat leaves (includ­ ing s t e m s ) ........................................... 3b Table 11. The effect of soil application of TGA on carbohydrates and ether extract contents of wheat roots. ........... 37 LIST OF TA3LE5 (CO'TT.) Page Table 12. The respiration rates of plant materials as affected by growth regulators and TCA treatments applied to soil and foliage .................. . . . . . . . . 38 INTRODUCTION In the production of crops It is necessary to wage a continuous battle with weeds. The presence of weeds is undesirable because of their ill effects in the way of competition with the crops for the avail­ able food and water supply of the soil. ▲ plant of yellow mustard (Brasslca campestrls) needs twice the amount of nitrogen and phosphoric acid and four times the amount of potash and water as does the mature oat plant (57) • Consequently when one factor becomes limiting the others can not be used effectively; thus the yield of the crop is affected* It has been estimated (13) that in the United States, the yield of corn is reduced as much as ten percent by the presence of weeds. The total annual loss in the United States from weeds exceeds the combined losses due to livestock disease, plant diseases and insect pests (57)* It has been suggested that plants produce toxins in the soil which may affect the growth of the adjacent plants. Such a theory, if proved true, might furnish an explanation for the ecological plant associations as well as information for the detrimental effects of certain weeds on crops. Glie commonly U3ed systems of cultivation are usually sufficient to suppress weed growth. The operation, however, is most effective in seed bed9 and during the early stages of the crop growth. most harmful during this stage of crop growth (59)• TTeeds are usually Hoeing is another standard measure which can be used successfully with many shallow rooted and garden crops. In certain cases, for example, as is the case with charlock (Braesica slnapla) in cereal crops, where weeds propagate by seeds, the crop is harvested earlier than the ripening time of the weed seeds. Auto­ matic weed control is thus obtained b y normal cultural methods. However in certain cases such cultural means of control are not possible. Present agricultural practices, while embracing these old and ef­ ficient methods of crop production should include certain chemical weed control measures. The shortage of labor required in the mechanical methods of weed control has given further Impetus to the development of chemical methods which can be used successfully for weed control purpose During the last decade, among many other chemicals, acid arsenical spray, carbon disulphide, sodium chlorate, sulphuric acid, 2,4-dichlorophenoxyacetlc acid (2,h-D) have been employed with varying degrees of success for the control of annual, biennial and perennial weeds. None of the chemicals gave entirely satisfactory results with annual or per­ ennial grasses. Only recently sodium trichloroacetate (TCA) has come to the front as a useful herbicide in this respect. Hecommendations regarding the application and dosages involved have stimulated much interest among the farmers. They wish to know how long the herbicide persists in the soil and to what extent it is affected by the chemical and physical nature of the soil. From the point of view of the horticulturist, this information is important in order that he may modify cultural practices so that subse­ quent plantings may not be affected adversely. Moreover, in the case of pre-pianting or pre-emergence treatment this information would serve an a useful index In regulating the dosage of the her'olclde in relation to environmental factors and other situations which may demand consid­ eration in crop rotation. The purpose of this investigation was to attempt to answer certain of these questions dealing with the use of TCJL as a herbicide. REVIEW OP LITERATURE 1• General Plant growth Is Influenced by environmental conditions. A minor change in one sometimes starts a series of complex reactions which seriously affect the development of the plant* The sodium salt of trichloroacetic acid is a fairly stable compound and when certain concentrations are present in the root cone it will kill plants. Molecular weight of the compound is 185*37 and- the struc­ tural forsiula is given below:Cl Cl --- c — c I ^ 0- Na Cl A search of literature reveals little information pertaining di­ rectly to the herbicidal effects of TCA on wheat (Tritlcum vulgars). However, an attempt is made here to present the review of results which have direct or indirect bearing on the subject. The most comprehensive work of this nature is given in the reports of Weed Control Research Committees. The related references are included in this manuscript. The grass killing properties of trichloroacetates were established as early as 19^9 (^7). Sodium trichloroacetate, abbreviated as TCA in this discourse, has given satisfactory results for the control of grass 5 weeds (3, 17. 22) and, by contact, broad-leaved weeds as well (47). It caused a severe stunting in Russian thistle (Saulsola toll) and red root pigweed (Amaranthua retroflexua) (22) and inhibited the growth of many other plants (36)• It has been found that the soil, atmospheric conditions, variety or species of the weed plants, and their stage of growth influence the rate of the herbicidal action of TGA (3. 4, Si). However, the rates of applications for different environmental conditions are not established as yet. The experiments, concerning TCA treatments on quack grass, have shown that the percentage of kill was proportional to the rate of appli. cation of TCA (3?. 3^. 35. 33, 40, 41, 42, 43, 53, 80, 81). However, heavier rates of application were required to produce a complete kill (35. 55. 66). No resprouting w^s observed at any application of 150 pounds per acre (3, 20, 35)* Fiesen (22) applied 20:. 40, 80, 100 and 160 pounds per acre, TCA prior to heading of the grass. growth of the grass. All rates of application killed the top However, root kill was incomplete (22, 27, 35, 6b). There was a 5 to 15 percent recovery, depending upon the rate of applica­ tion, in almost all treatments after a period of 8 weeks. were further corroborated by Havlychento (5^» 55) These results Slife and Fueljtman (65) who used different amounts of the chemical in their experiments. In another series of experiments McDonald et al. (39. **0. 41, 42, 45) obtained inconsistent results when they applied 10, 20, 30. ^0 , 60 and SO pounds of TCA in 3? 1 /2 gallons of water per acre. The spray ap­ plications were made during the second week of June under similar conditior that Is, nature of soil, soli moisture and stage of grass development were practically the same in all the cases* Soil sterility caused by application of TCA appeared to be terapor^ ary. Crops such as oats, alfalfa (33) ernd corn (75) g**ew normally on the treated plots. to T h e ^ x i c conditions of the soil lasted only for 60 90 days (*+7)* Experiments (80) showed that soil moisture had a greater significance, within the range of applications used, of application* than did the actual rate or date In another series of the experiments high moisture con- tent of the soil led to inferior results (5» 19)• However, best results were obtained on a moderately dry soil with scant to moderate rainfall during a one month period following the spray (5)» Watson (7*0 found a direct correlation between rainfall following spray an d degree of quack grass control* fall, It was further pointed out by him that sufficient rain, following soil application of the chemical, was necessary to get the material into the root zone* Tillage operations when combined witn TCA treatments gave a better control of weeds (9» 19* b5) • However, Chadwick et al* any such evidence from their experiments. (15) did not find Watson (7*0 found plowing with a mold-board plow prior to TCA treatments greatly enhanced the effective­ ness of the chemical and proved to be a good effective treatment in quack grass control* In another series of experiments such cultural operations made up for low rates of TCA applications (o, 11, lh, 3 b ) . Barrons and Watson (5) further suggested that during a period of low carbohydrate content the grasses are more easily controlled* Treat­ ments at this stage may be combined with tillage for the best results* 7 In another series of experiments McCall and Zahnley (4g) applied 50* 75* 100 and 200 pounds of TCA in 109, 218 and 436 gallons of water per acre; the latter application proved to he more effective because of the soil penetration by larger volumes of water. The volume differ­ ences were most notable at 50 pounds per Acre application which ml^it be a border line for grass control. They further suggested that there was practically no difference in results with ammonium or sodium salts of trichloroacetic acid (46, 48). Livestock did not show any aversion to the sprayed vegetation (24), Alfnlfa sprayed with 120 pounds per acre made a vigorous regrowth but at the end of six weeks began to die and appeared to be completely killed (24). Crop tolerance studies made by Barrons (4) might be useful in de­ vising pre- and post-emergence treatments of TCA. His observations are summarized as follows: Tolerant group, not effected at 5 or 10 pounds per acre and which showed apparent recovery from 20 pounds, included crops such as peas, lettuce, tomato, pepper, egg plant, tobacco, carrot, parsnip, celery, cabbage, kale, cauliflower, turnip, broccoli, mustard, radish, flex, beet and swiss chard. Intermediate group, showed no appreciable effect at 5 pounds and were apparently recovered from any effect noted at 10 pounds, included crops such as alfalfa, Ladino clover, oats, cotton, okra, asparagus, gladiolus, sweet potato, onion, spinach, potato, strawberry, muskraelon, cucumber, pumpkin, squash, watermelon, and peanut. Susceptible group, showed a marked effect at 5 pounds and severe 8 clover, alslice clover, Korean lespedeza, corn, sorghum, sudan grass, Kentucky blue grass, seaside bent grass, red top grass, German millet, timothy, orchard grass, rice, rye, barley and wheat* 2* Mode of TCA Entry Into the Plant Review of literature does not lead to any conclusive Information on this point* Plowing prior to the application of TCA has proved to be an efficient method in quack grass control (11, 21, Jb) which might suggest that roots serve as an important avenue to the entry of the com­ pound* Further support of this assumption comes from experiments in which a better kill was obtained in up-turned qua degress sod than when the foliage was sprayed (6), No systemic TCA response was noticed when primary leaves of kidney beans were dipped in TCA solutions (7)* The physiological action of TCA on plants is not well understood* It is stated that trichloroacetates, when applied to soils, are absorbed by the roots (1) and are carried to all parts of the plant through the xylem which is mainly a dead tissue. The rate of tr&nslocatlon is slow, however, in case of foliage application as the phloem, tissue involved in such translocation is killed (l)* 3* Fre- and Fost-Emergence Treatments* Fre—emergence treatments have aroused considerable interest because they are the only type of treatments, thus far developed, which control both broad-leaved annuals and weedy grasses such as crabgrass and foxtail (78). Here, however, one is primarily interested in the elimination of undesirable effects rather than eradication or a high percentag* kill 9 of the weeds. Such soil treatments with TCA prevent emergence of grass seedlings and thereby help in conservation of soil resources that can be us6d advantageously by the crops. Sufficiently favorable results were obtained to warrant the belief that TCA can be used successfully with certain crops e.g., pea, tobacco, beet, eggplant, tomato, pepper, and flax (4). However, it is not cer­ tain with which crops pre-planting or post-planting treatments should be used. The safe rates and methods of application in relation to en­ vironments have not yet been established. Pre-emergence treatments with TCA were impossible on soybeans and proved to be injurious to crucifers (79) «uad onions (5^) even at the low rate of 4 pounds. per acre (67)- All corn plants were killed at 10, 20, and 30 pounds Rates higher than 20 pounds severly injured beets (25, 2b) but weed control was good (28, 70)• Forty pounds of TCA, as immediated post-emergence treatment to flax, proved to be of marginal utility in control of gree foxtail (lo) and wild oats (58). At low rates of ?, 4, 8 and 12 pounds acid equi­ valent, there was no injury to flax (18, 1?). lowered significantly at 20 pounds (33)• The yield of flax was There was no control of the wild oats growing in the flax plants treated with 40 pounds; the flax showed signs of injury after 20 days from the date of seeding (lb). The surviving plants on the treated plots, at the time of harvest, were b to 7 inches shorter, and sickly in appe-ranee, in comparison to plants on check plots (lb)• Setaria Sp. in flax seemed to be easily susceptible to TCA applica­ tion. Five to 10 pounds of TCA in 10 to 20 gallons of water gave good 10 control of weeds without injury to flax (37* *+4) • Higher rates reduced flax yields and did not result in effective control of grassy weeds (31) • In another experiment, 4 pounds TCA in 50 gallons of water resulted in 25 percent control of crabgrass (72) in Alaska peas* warren and Singletary (73) found that 44 pounds of TCA gave good control of weeds without lowering the yields of direct-seeded tomatoes. In another experiment the yield of Alaska peas was not affected by use of TCA at rates up to8 pounds per acre*(10). On the other hand, the yield of Tellow Jersey sweet potatoes was reduced signigic&ntly by 2 to 4 pounds of TCA when applied in 50 gallons of water (72), the control of crebgrass in the crop was 85 percent* MATERIALS AND METHODS Soil conditions play an important role in the determination of the satisfactory agricultural practices which are to he followed after the application of the herbicide* In order to determine the residual effects of TCA in relation to crop growth on different types of soils, an experi­ ment in a split plot design, was arranged at the Plant Science Green House, Michigan State College, East Lansing, Michigan. Equal Tolumes of soils- Oshtamo sand, Brooketon clay loam and muck weighing 4,000 grams, 3,700 grains and 1,700 grams respectively, were mixed with amounts of TCA corresponding to the rates of 15* 30 and 60 pounds per acre and placed in number 10 cans* The calculations were based on the surface area of the cans and rates are expressed on the acid equivalent basis. The mixing operations were done on 21, 42, bh and 108 days before the soring date of the crop. Wheat was used as a test plant as it is m o w n to hrve sensitivity to TCA at rates as low as 5 pounds per acre (4). seeded to Henry spring wheat on July Q, The cultures were 1950; 20 seeds were placed in each can at a depth of 1/2 to 1 inch. To each can of Oshtemo sand was added 500 ml, of distilled water. Each can of clay loam and muck soil recieved J00 ml. of water* These quantities of water were considered to be enough to raise tne moisture levels of the soils to their optimum moisture-holding capacities* During the entire period of the experiment the cans were weighed frequently. Sufficient water was added to each pot to bring the ::ioisture 12 content bacK to its original level* The losses of water were due to the surface evaporation and transpiration toy wheat plants* There was no loss because of leaching as the cans were water-tight* In order to find the relationship, if any, between TGA applications to soils and their nutrient status, the soil samples were taken by a specially designed soil sampling tube which was inserted to the bottom of the cans* These samples were taken on April *+, April 18, May 2, May o lb, June 21, and August 23, 1950 a«d were dried in an oven at 60 C* Lots of 12, 40, and 50 grams of e rch treatment were put aside each time for soil analysis work* for analysis were put back into therespective cans. pH and mineral The pH of Q u a n t i t i e s of soils in excess of those needed Determination of nutrient levels were made* the soil samples was determined by the pH meter.Nitrate nitrogen and available phosphorus and potassium determinations were made by a revised Spurway method which makes use of a colorimeter. Calcium, magnesium, ammonia and nitrite nitrogen were determined by the standard Spurwey methods (oS). In ranking use of the colorimetric procedures, the standard curves, given on pages 13, lh, end 15. for N, F f and K, were constructed. The values of unknown soil solutions were determined from these standard curves. The data, averaged for all dates of sampling, are presented in Table b. Plant growth was considered to be a direct measure of toxicity of the compounds (57)* With this in mind the data were recorded for rate of growth, fresh weight of the roots. of the tops, dry weight of the tops and dry weight mhe data are given in Tables 1, growth is shown by Figures 1, 2 and 3* 2 and 3* ^h© rate of STANDARD CURVE FOR \ RARTS PET? /iA/L L /O/V { R P JA j NO-N O /o SO 30 50 PERCENT 40 3T4NQAFQ CURVE FOR PHOSPHOROUS 0 /O P O 30 40 SO PERCENT STANDARD CURVE FOR POTASSIUM 0 10 JO JO 40 50 PERCENT 16 The main crop was harvested on August 23, 1950* The plants grow, ing in soils which recieved the largest applications of TGA just 21 days before the sowing of the crop were harvested earlier as they would have been dead by August 23* The second series of the experiments were designed to confirm the theory that the death of the plants which hAd been injured by TCA was due to unbalanced nutrient uptake. In this case, lb and 30 pounds per acre applications were made on Oshtemo sand only. The corresponding amounts of TGA, size of the cans, mixing operations and moisture level conditions were the same as given in the preceeding pages. F-K treatments were included in the experiment. However, N- The fertilizer was fur­ nished by applying l.b grams of a mixture of a m ionium sulfate, super­ phosphate and muriate of potash mixed in such a way as to make a 10-1010- fertilizer. The mixture was added as a band application, at the outer edge of the soil surface. Just prior to the date of sowing which was March 9, 1951 I** this case. The crop was harvested on April b, 195^-» Tlae soil samples were taken and were analyzed for pH, N, 3F and X in the manner described in the preceding pages. The plant tissue was analyzed for total nitrogen and phosphorus by methods given in methods of analysis, A.O.A.C. (3 ) • Fotassium was deter­ mined by the Flame Photometer using lithium as the internal standard. The data are given in Table 7* /mother experiment w e s arranged to determine the effect of TCA upon the metabolism of plants. Seeds of spring wheat (var. Henry) were selectee for maturity and planted in flats, containing 3,000 grams of 03htemo sand. The flats were lined with oil paper to prevent leaching. contained hoo plants* Bach flat ""wo replications of 2,000 plants each were used from which to obtain material of the treated and non-treated plants* Applications of TCA (jO%) - at the rate of 30 pounds, acid equi­ valent, per acre were made to the soil prior to the sowing of the seeds. The pH of the soil was adjuster to b*5 toy the addition of lime* The application of TCA did not appreciably chan g e the pH of the sand* The soil was maintained at its water holding capacity for the duration of the experiment. The flats were placed in a greenhouse at temperatures ranging from J0° - 75° F. during the day and 65° F. at night. plants were harvested fourteen days after sowing. The The plant material was dried in the dark at 30° C. for seventy-two hours and then segregated into root and leaf (including stem) tissue* After drying, the material was ground to pass a 60 mesh sieve and stored in glass Jars until needed. Amino acids were determined microbiologically with the organisms Lactobacillus arablnosua. Streptococcus faecalis and Leuconostic meaenteroides. The media used in the various determinations were essentially the same as those described by Sauberlich and Baumann (60). Samples were prepared for assay by the method described by Stokes et.al. (69) with the exception of the tryptophane samples which were prepared ac­ cording to the method of Wool ay and Sebrell (3?). Carbohydrates were determined by the procedure outlined by Sell ot al. (61). The method of analysis for netrogen and ether extract were those given in A.O.A.C. 18 Respiration StudiessThe rate of oxygen uptake was determined in a standard Warburg apparatus in 0.02 M pH 5»7 phosphate buffer (bh, 71). The treatments considered are tabulated in Table 12. In experiment 1 , TGA (70*) *t the rate of 3° pounds per acre acid equivalent, was mixed thoroughly with 8,000 grams of Oshtemo sand* The treated soil was trans­ ferred to wooden trays lined with oil paper to prevent leaching* Seeds of Henry spring wheat were sown in the wooden trays on July 18, 1951 and the crop was harvested to the ground level after 10 days. In experiment 2 and 3 (Table 12) h week old cauliflower, tomato, sugar beet and bean plants were completely saturated with a 5*000 ppm TGA spray* The respiration studies were conducted on these plants in the 3rd week of July, 1951* *he plants were 5 weeks old at this time. A sample of 1 sq. cm. in area was taken from the central portion, along the mid-rib, of the treated and untreated leaves. In experiment U- (Table 12) one gram of 3-P-chlorophenyl 1,1-dimethylurea (CMU) was dissolved in absolute alcohol and volume was made up to 100 ml* with distilled water; 5 of this solution was further diluted to 100 ml. thus giving 509 ppm of the compound* The same procedure was adopted for iso propyl !T-phenyl carbamate (IPC) which was also insoluble in water* These solutions were employed to moisten the filter papers placed at the bottom of the hetri-dishes. During the entire period of the experiment uniform moisture conditions were maintained. 50 wheat seeds (var. Henry). Each Petrl-dish contained Respiration studies were made on these seeds. The same procedure was adopted in experiment 5 (Table 12), with the exception that the solutions concentrations of TCA were different in this EXFERIMEIITAL RESULTS Yield The effect of sodium trichloroacetate on the growth of wheat plants is shown by the data in Tables 1, 2 and 3* It clear from the recorded observations that the amount of growth, recorded as fresh weight of tops, dry weight of tops and dry weight of roots, was directly related to the amounts of TCA applied. For instance, the fresh top-growth, where wheat was planted on muck soil 21 days after TCA was applied at the rate of bO pounds per acre, amounted to 0.4b grams per pot as compared to 1.50 grams per pot where the rate was 15 pounds per acre and 14.00 grams per pot where the chemical was not applied. Similar results were obtained where TCA was applied on clay loam and sandy soils where the elapsed time between treatment and planting was 21 days. The residual effect of TCA was less in the sandy soil than it was on the muck and clay loam. This is shown by the results obtained when the elapsed time between treating with TCA and planting of wheat was 42 days. In the case of sand, where 15 pounds per acre of the chemical was applied, the wheat was not appreciably injured and only slight injury resulted where the applications were 30 pounds per acre. At oO pounds per acre application wheat yields were reduced from an average of 19*33 grams to 10.bb grams per pot. In contrast to the results obtained in the sandy soil all applications of TCA on clay loam and muck soils caused pronounced injury to wheat plants where the elapsed time between applica­ tion of TCA and planting of wheat was 42 days. 20 Where the elapsed time between treatment and planting was 64 days the results show that wheat grown on the sandy and clay loam soils was not injured when the applications of TGA were as high as 60 pounds per acre. On the other hand the residual effect of TGA was quite pronounced on the muck soil even 103 days after application of the chemical* The growth rate curves shown in Figures 1, 2 and 3 show graphically the variations which existed in the results obtained from different soils* It may be seen from Figure 1 that on muck soil 13 pounds of TCJL per acre significantly affected growth where the elapsed time was 21 or 42 days but had little effect where more than 42 days elapsed. Where the rate of application was higher, 30 o r oO pounds per acre, growth was affected even when 108 days had elapsed* It can be seen from the curves representing the plant growth rate for clay loam soil. Figure 2, that the growth of wheat was not depressed in the pots where planting had occurred 64 or 108 days after the applica­ tion of 1*5, 30 or bO pounds TCA per acre* The growth curves for these ti me periods are almost identical with those for the controls, thus in­ dicating quite clearly that the toxic or residual effect disappeared after b4 days from the time of application* The depression of growth was pro­ nounced only where planting was done 21 or 42 days after the chemical was applied* The effect of TCA application on sandy soil can be seen in Figure 3« This shows that growth was only depressed by the 15 pound rate of TGA application where the elapsed time period was 21 days. No appreciable depression of growth was observed at the lower rate where the elapsed tirue period was longer than 21 days. For the two heavier rates, depression 21 of growth occurred where elapsed time was either 21 or 42 days* The plants in figures 4 and 5 show the effect which TCA applica­ tion to the soils had on the growth of wheat plants* figure 4 shows the contrast between the plants grown in untreated muck and plants grown in muck treated with TCA where the elapsed time, after application, was 108 days. A similar growth trend for the plants grown on clay loam soil (S2) can be seen where the elapsed period after application was 21 or 42 days in contrast to two longer periods of b4 and 108 days. It may also be observed from Figure 4 that plants grown in sandy soil show a marked contrast between control plants and treated plants where the elapsed time, after application, was only 21 days. figure 5 shows the same relative differences as shown in Figure 4 with the exception that the picture was taken 30 dAys after planting instead of 20 days, as was the case in Figure 4. The results are soma, what more striking. The data recorded, in Tables 1, 2 and 3* show that the dry weight of the tops would lead to exactly the same conclusions as have been drawn from fresh weight of tops. weights. Some inconsistencies do exist in the root The data indicate, however, that the inconsistencies are the results of experimental errors. For instance, the dry weight yield of wheat plants was greater from 30 pounds per acre application of TCA than from 13 pounds on the sandy soil where the time interval was 4? days. The same thing occurred on muck soil where the time interval was bh days. Such results were probably due to loss of roots in the washing process or to the fact that some soil may have remained on some of the roots. 22 In general, the conclusions to be drawn from the dry root weights are not unlike those already discussed for the fresh top yields* The analysis of variance presented in Table h shows that hi^ily significant differences occurred between times (elapsed time from the date of application to the date of planting), rates of applications, and soils. It is interesting that second and third interactions are alBO significant* For instance, consider times and soils. The injur­ ious effects of TGA disappeared sooner in the sandy soil than in either of the other two soils and lasted longer in the muck. Some injurious effect persisted in the muck even to 108 days* One would expect the interaction between rates and times to be significant. Such was the case, particularly on the two mineral soils. The significance of the soils and rates interaction is explained by the fact that rates made more difference, in the 21 days time inter­ val, in the sandy soil than in the other two soils. In the clay loam and muck the three treatment rates, 15. 3° and &0 pounds per acre ap­ plications, produced results which were similar and of greater magnitude than those obtained in the sand. considered, the opposite is true. On the other hand when final time is Sixty pounds of the chemical still caused a pronounced injury in the muck soil but 15 pounds per acre ap­ plication was not injurious. With the other soils, at that time inter­ val, none of the applications were injurious. By referring to Table 5 ** times, and soils. possible to see the effects of rates, In each case the other variables are averaged. For all times of application and all soils, significant differences in the fresh weight of the tops but not in the dry weight of tops resulted from 23 ▲ consideration of time, including all rates and soils, shows that significant differences resulted in all three yield categories. Like­ wise, the same was true of the differences caused by soils when all times and rates w3re thrown together. 8oil Nutrients The data presented in Table 6 Indicate that the nutritional status of soils, including pH, and amount of available N, F, K, Ca, Mg, NH^ and NOp was not affected by the different treatments considered in this in­ vestigation. In many instances, the results varied more widely between replicates than between treatments. not consistent with the time. Furthermore, the differences were For instance, where the time was 21 days (T^) the nitrate content of soil (muck) seemed to increase with rate. Such was not the case, however, where longer time was involved nor did it hold for soils 2 and 3* other constituents. Similar instances could be pointed out for The potassium content of the soil 3 (Oshtemo) seemea also to increase with the rate of application of TCA for the 21 days time interval but did not 30 increase where longer time was involved. The other soils did not behave as did Oshtemo. However, differences in nutrient contents of the soils can be con­ sidered natural due to differences in the nature of the soils. indicated that F, NH and Tests were present only in traces in all the soils used in this experiment. ror that reason, the results are not presented. luring the progress of this study an experiment w?.s set up to de­ termine the effect of fertiliser on the action of TCA. Wheat was grown 2^ in Oshtemo soil. Treatments included a control and tiro rates of TCA, 15 and 30 pounds per acre applications, with and without 10-10-10 fer­ tiliser* The data presented in Table 7 show that fertilizers increased the NO^, F and K content of the control soil and total N and K content of the plants hut did not increase the phosphorus content of the plants* Nitrates were increased to high levels on the TCA treated soils which caused a considerable increase in the total nitrogen content of plants from TCA treated soil. Such plants showed an arrested growth indicating some interference in the metabolic activities of the plants* plants could not use the nitrate nitrogen present in them. Thus the However, potassium in the plants did not increase when the plants were stunted by the TCA treatments. On the contrary there was a marked decrease in the potassium content of the injured plants* Metabolism of the Plants Y/heat plants in TCA treated soil showed marked metabolic changes ascan be seen from Tables 8, 9, 10 and 11. Each entry is recorded as a single determination on each replicate* The data in Tabic 8, expressed as percent amino acid in the sample, show the following trends: The leaf tissue of the treated plants contain­ ed more protein and arginine than that of the controls. of tryptophane was less in the treated plants. The percentage Slight differences were noted for methionine, lysine, valine, leucine, histidine, and phenyl­ alanine. The percentage of isoleucine and threonine did not change* 25 Expressing the data in Table 8 a 3 percent of amino acids in crude protein, a somewhat different pattern was observed* The leaf tissue of the treated plants contained slightly less lysine, valine, leucine, his­ tidine, phenylalanine, isoleucine, threonine and tryptophane than did the controls. Approximately the same percentage of methionine and ar­ ginine was observed in both treated and non-treated tissue* The data presented on the basis of percentage of protein in the sample Indicate that there is an accumulation of protein* The differ­ ences in amino acids are not as pronounced as was noted in the tissue treated with 2,4-D (52, 77) • The results expressed as percent amino acid in the crude protein suggest that the nature of the protein has changed since the percentage of amino acids are as a rule less in the treated tissue than in the controls* This would indicate that the TGA ha8 an effect on proteolytic enzymes* The data presented in Table 9 show only a slight increase in the percentage of protein and amino acid in the root tissue of the treated plants* When expressed as percentage of the crude protein, little dif­ ference was observed in most of the amino acids with the exception of histidine which was slightly greater in the treated samples* The data expressed in Table 10 show a slight increase in the per­ centage of reducing sugar and acid hydrolyzable polysaccharides in the leaves of the treated wheat plants* However, a tremendous decrease was noted in the percentage of non-reducing sugar, ether extract, unsaponifiable material and fatty acids. A slight difference was observed in the percentage of starch* In the root tissue (Table 11) of the wheat plants there was a higher percentage of reducing sugar and starch in the treated plants. Little 26 difference was noted in the percentage of the non-reducing sugar and ether extract in "both the treated and non-treated plants* Only slight reduction was observed in the acid hydrolyzable polysaccharide of the treated plants* The large increase of the reducing sugar and starch in the root tissue and the accumulation of protein in the leaf and root tissue of the TCA treated plants suggests that the large depletion of the percent­ age of non-reducing sugar in the leaves is due to the conversion of part of the sugar to protein and to translocation of the remainder to the root tissue, in the form of reducing sugar, where it is stored as starch* Respiration Studies The application of TCA to soil and foliage caused an increase in the respiration rate of plant tissue. The data reported in Table 12 show that wheat seeds showed the greatest respiration activities during the first 24 to 48 hours after which the rate became slower* The experiment also indicated that 3-p-chlorophenyl 1,1-dimetcylurea (C W ) , isopropyl phenylcarbamate (I1C) and sodium salt of 3»b-endoxohexahydro phthallic acid (Endothal) were inhibitory to respiration more than TCA. Foliage treatments with 5*000 ppm solution produced results in treated plant species* Sugar beet was most tolerant followed by tomato and cauliflower while beans were least tolerant* 27 Table 1 The residual effects of soil applications of sodium trichloroacetate on the yield, fresh and dry weight of tops and dry weight of roots, of wheat grown on muck soil. Treatment Fresh wt- of tops Yield per pot in grams* Dry wt. of tops Dry wt. of roots Time 1 (applied 21 days before planting) 15 lbs TCA 1.50 0.36 30 lbs TCA O .70 0.33 0.13 60 lbs TCA 0.46 14.00 Control 4.53 Time 2 (applied 42 days before planting) 15 lbs TCA 30 lbs TCA bO lbs TCA Control 3.33 3.33 0.93 11.00 0.76 0.46 0.23 2.96 0.47 0.30 0.27 1.23 0.60 0.40 0.23 0.67 Time 3 (applied o4 days before planting) 15 lbs TCA 30 lbs TCA 60 lbs TCA Control 12.00 10.66 9.00 12.00 3-06 2.30 2.10 2.90 0.60 1.07 0.63 1.10 Time 4 (applied 108 days before planting) 15 lbs TCA 30 lbs TCA oO lbs TCA Control 12.33 IO.60 9« 66 12.66 * Average of three replications. 3.13 2.86 2.7o 3-63 0.87 0.93 1.13 1.13 28 Table 2 The residual effects of soil applications of sodium trichloro— acetate on the yield, fresh and dry weight of tops and dry weight of root8, of wheat grown on clay loam soil* Treatment Fresh wt* of tops Yield per pot In grams* Dry wt. of tops Dry wt. of roots Time 1 (applied 21 days before planting) 15 lbs TCA 30 lbs TCA 60 lbs TCA Control 2.00 1.00 0.86 18.33 0.93 0.63 0.33 H .90 0.43 0.20 0.17 1.17 Time 2 (applied 42 days before planting) 15 lbs TCA 30 lbs TCA 60 lbs TCA Control 4.66 1.00 0.90 24.00 1.20 0.20 0.26 6.16 Time 3 (applied o4 days before planting) 24.00 6.06 15 lbs TCA 22.00 30 lbs TCA 5*93 6.50 bO lbs TCA 24.66 Control 25.33 7.13 Time 4 (applied 108 day s before planting) 15 lbs TCA 30 lbs TCA 60 lbs TCA Control 22.33 23.00 20.33 19.33 5-56 6.66 5.13 4.86 0.67 0.27 0.10 1.90 1.70 1.50 1.30 1.73 1.50 i.4o 1.47 1.30 * Average of three replications. A 29 Table 3 The residual effects of soil applications of sodium trichloroacetate on the yield, fresh and dry weight of tops and dry weight of roots, of wheat grown on Oshtemo sand* Treatment Fresh wt. of tops Yield per pot in grams* Dry wt. of tops Dry wt. of roots Time 1 (applied 21 days before planting) 15 lbs TCA 30 lbs TCA 60 lbs TCA Control 4 . 6b 2 . bb 1.46 1.10 0.40 b.83 lS .b b 0 .b 3 0.30 0.33 O .23 2.63 Time 2 (applied 42 days before planting) 15 lbs TCA 30 lbs TCA 60 lbs TCA Control 18.00 lb.OO 10.6b 19.33 b.bb 5.46 2.30 0.S6 1.63 2.57 1.40 2.17 Time 3 (applied 64 days before planting) 15 lbs TCA 30 lbs TCA bO lbs TCA Control 24.00 26.33 8.23 2 2 .6 b 8.30 24.00 8 .0 b 9 .1 0 2.71 3.13 2.50 2.97 Time 4 (applied 108i days before planting) 15 lbs TCA ■*0 lbs TCA 60 lbs TCA Control 23.33 26.33 23.33 21.33 * Average of three replications* 7.23 8.30 7.40 7.30 2.67 2.67 2.50 2.70 Analysis of variance of wheat yield, fresh and dry weight of tops and dry weight of roots, in the split plot experiment Fresh wt. of tops Sources of variations D.F. S.S* M.S. Dry wt. of tops c e Oewe M.S. Dry wt. of roots S.S. M.S. 8.R4 7.31 3.65 1.24 0.62 175b.3*>** 4ib.50** 138.83** 33.13 11.04* 4.94 17.98 2.99 O.85 0.14 Replications 2 17.09 Time s 52&9.08 Error 6 29.b4 11 53i5.*l Soils 2 24b1.72 1230.87** 3b0.13 180.06** 45.61 22.80** Time x Soils b 821.1b 136.8b** 94.9b 15.82** 7.5b 1.26* Error lb 237.04 14.81 13.92 5.32 O.43 Sub-group (?) 35 8835.73 Rates 3 1294.22 431.UO** 128.49 42.83** 10.15 3-38** Rates x Time 9 1351.83 150.20** 130.33 14.48** 7.26 0.80** Soils x Rates b 161.47 2b.91** 7.27 1.21* 1.87 0.31** Rates x Time x Soils 18 3b0.93 20.05** 41.94 2.33** 7.44 0.41** Error 72 319.bO 4.43 30.73 0.42 6.75 0.09 Total 143 12323.78 Sub-group (l) 441.79 35.22 0.87 910.80 * Significant at % level* 1249.5b 93.71 127.lg 31 Table 5 A sumiaary of the yield data for all treatments, rates, times and soils. Rates- including all times and soil8 Fresh weight of tops* Dry weight of tops Dry weight of roots *4 L.S. D.** 5* 1* *1 *2 12.68 11.98 IO.38 18.33 0.977 1.297 0.37 0 .3b 0.30 0.55 0.299 0.397 0.l4o 0.186 R3 1.23 1.23 0.99 1.72 Times- including all rates and soils Ti T2 Fresh weight of tops 5*30 9.43 19.72 18.72 1.280 1.384 Dry weight of tops 1.79 2.80 5.81 5.40 0.99b 1.509 Dry weight of roots 0.64 1.05 1.79 l.bS 0.203 O.307 1.6b4 2.292 Fresh weight of tops t4 T3 Soils- including all times and rates s2 S1 s3 14.62 17. b5 7.7b Dry weight of tops 2.04 3.90 4.05 0.403 0*555 Dry weight of roots 0.7b 1.05 2.07 0 .27b 0.380 * All data expressed in grams per pot. ** Least significant difference The effects of soil applications of TCA on the nutritional status of the soils during the entire period of the experiment Treatments PH m "1 *n ”2 h h2 r3 H4 11.6 11.8 Mg pH 6.6 10.0 ic. 3 11.0 147.0 117.0 5.3 4.0 113.0 11.0 130.0 4.3 4.0 O.b 13.7 10.9 6.5 6.6 0.6 17.6 20.4 21.4 10.0 109.0 11.0 10.6 b.5 15.0 b.5 6.7 6.6 6.6 Soil2 (Clay loam) Ca K H0? Mg 8.4 4.0 8.0 5.2 7*2 4.3 7.8 5.0 Soil} (Oshtemo sand) Ca Mg m3 I PH 3.0 4.2 63.O 78.0 3.7 3.0 b.6 1.8 2.2 1.4 5.0 53.0 3.3 6.7 1.1 6.5 53.0 3.3 77.7 90.0 72.0 2.2 2.0 2.1 95.0 10b.0 4.6 4.0 b.5 6.4 90.0 83.O 3.7 4.0 0.5 11.2 4.2 78.0 4.2 6.3 3.0 109.0 100.0 3.8 3.8 3.5 6.5 b.5 13.5 11.5 3.3 4.5 72.0 104.0 3.7 3.9 6.5 6.4 2.0 1.6 3.7 4.4 4.8 11.5 170.0 3.4 6.5 10.8 2.3 89.0 3.2 6.5 1.7 3.7 50.0 2.2 16.8 10.4 152.0 b.b 9.1 5.8 79*0 4.0 4.6 80.0 2.2 12.4 149.0 b.b 7.2 73.0 6.5 3.5 4.9 69.0 2.4 S3 11.8 150.0 4.7 6.5 9.7 13.6 4.3 4.1 6.5 6.5 20.1 6.4 16.6 5.2 4.2 93.0 2.0 21.0 10.9 153.0 4.9 6.5 11.6 93.0 6.5 6.4 3-2 51.0 b.5 3.9 4.2 2.9 S4 7.1 o.c 3.2 3.8 55-0 2.2 h 6.3 12.8 12.1 150.0 4.5 6.5 10.6 4.4 71.0 4.8 6.2 4.0 2.5 50.0 1.5 0.4 16.7 10.9 140.0 5.0 9.6 4.2 80.0 4.6 6.2 4.0 2.6 43.0 1.8 0.4 IB.3 1C.0 157.0 3.7 6.5 6.4 10.5 4.2 82.0 6.2 4.0 15.3 9.0 149.0 5.0 0.5 10. b 3.9 68.0 b.2 4.6 3.3 2,2 43.0 1.7 o*5 4.5 4.4 *1 R? r3 *4 *1 R? T3 6.7 6.6 0.0 Soil, (rauck) K Ca R0? *5> S3 a4 38.0 1.8 * All data, except pH, expressed as ppm* w 33 Table 7 The effects of soil applications of TCA and fertilizer (10-10-10) on N, P f and K in plant tissue and on pH, NO,, P and K contents of soil* Treatments PH Soil analysis P« p.m. P n03 0.6 2.8 K N 4.2 2-75 0.492 2.00 1.7 29*2 5.15 0.488 4.53 13*9 T 50.0 8.48 0.460 1.56 5-5 19.5 1.2 50.5 9.53 0.593 1.86 5.7 15.3 B 26.5 9.03 0.528 0.90 C 6*3 CF 5.9 *1 5-7 R^F *2 Legend: C CF *1 RJF *2 Plant analysis percent P K No treatment* Fertilizer only. 15 lbs TCA per acre. 15 lbs TCA per acre and fertilizer. 30 lbs TCAper acre 3^ Table 8 The effect of soil application of TCA* on amino acid, nitrogen and protein contents of wheat leaves (including stems). Non-treated In the sample Replications 1 trogen Treated In the sample Non-treated In crude protein Treated In crude protein 1 2 1 2 1 2 1 2 % 4 4 4 % 4 * % 5.39 t>•37 Protein (N 6.25)33.69 33-56 6.67 6.65 41.69 41.56 Methionine O .35 0.36 0.39 0.40 1.03 1.07 0.94 0.96 Lysine 1.^3 1.43 1.5* 1.51* 4.24 4.2b 3.75 3.71 Valine 1.92 1.9^ 1.83 1.82 5.09 5-78 4.39 4.38 Leucine 1.77 1.77 1.83 1.89 5.25 5.27 4.39 4.55 Arginine 1.61 1.62 1.99 2.07 4.78 4.83 ^•77 4.98 Hi stidine 0.70 0.73 0.78 0.80 2.08 2.18 1.87 1.92 Phenylalanine 1.21 1.24 1.35 1.33 3.59 3* 69 3.24 3-20 Isoleucine 0.68 0.68 0.67 0.67 2.03 2.03 1.61 1.61 Threonine 1.27 1.29 1.27 1.27 3.77 3.84 3.05 3.06 Tryptophane 0.59 0.58 0.40 0.36 1.75 1.73 0.96 0.87 * J>0 pounds TCA/A to Oshtemo sand. i 35 Table 9 The effect of soil application of TCA* on amino acid, nitrogen and protein contents of sheat roots* Non~treated In the sample Replications Nitrogen Treated In the sample Non-treated In crude protein 1 2 1 2 1 % % % * % 2.92 Protein (w 6.25)19-31 18.25 3-39 1 2 % % 3-30 21.19 20.63 Methionine 0.17 0.16 0.20 0.19 0.8S 0.88 0.94 0.92 Lysine 0.67 O.bl 0.72 0.66 3.60 3*34 3*40 3.20 Valine 0.94 O.93 1-03 1.01 4.87 5.10 4.8b 4.90 Leucine o .s q 0.81 0.96 0 * O 3-09 2 Treated In crude protein 4.61 4.44 4.53 4.3b Arginine 0.85 0.76 1.06 0.94 4.40 4.16 5.00 4.56 Histidine 0.23 0.21 0.32 0.32 1.19 1.15 1-51 1.55 Phenylalanine 0.50 0.47 0.57 0.60 2-69 2.S8 2.b9 2.71 Iaoleucine 0 K\ • O 0.34 O .36 0.33 1*55 1.8b 1.70 1.60 Threonine 0.73 O.ob 0.75 0.69 3-78 3.62 3-54 3-3^ Tryptophane 0.17 0.16 0.20 0.19 0.88 0.88 0.94 O .92 * 30 pounds TCA/A to Osht erno sand. i 36 Table 10 The effect of soil application of TCA* on carbohydrates and ether extract contents of wheat leaves (including stems)* Non-treated Replications 1 2 Treated 1 2 Reducing sugars^ 2*90 2.93 3*20 2.58 Non-reducing S.20 8.49 2.74 2.92 Starch 0.65 0.72 1.04 1.26 Other polysaccharides 9.20 8.b2 10.83 10*72 Ether extract 5.37 5.37 2*33 2.47 IJnsaponifiables** 1.02 1.05 0.51 0.54 Fatty acids** 1.57 1.27 0.84 0.83 $ * 30 pounds TCA/A to Oshtemo sand ** Chlorophyll free. I 37 Table 11 The effect of eoll application of TCA* on carbohydrate and ether extract contents of wheat roots* Non-treated Treated 1 2 1 2 Reducing sugars 3*32 3*S3 b. b3 7.86 Non-reducing 3.09 3*44 3.37 3.^5 Starch 2*51 1.67 4.59 5-^1 20*95 21.05 16.89 16.24 2.86 3.02 2.18 2.33 Replications Other polysaccharides Ether extract * 30 pounds TCA/A to Oshtemo sand* Table 12 The respiration rates of plant materials as affected by growth regulators and TCA treatments applied to soil and foliage. Expt,. Gr. regulators no. 1 2 Concentration used .... 3 ___ Flant materials used k Micro liter of O^/hr. . . . Untreated -5 Treated 229.71 1 TCA 30 lbs/A Wheat foliage 2 TCA 5,000 ppm Cauliflower foliage 35«72 Tomato foliage 23 A 40.1 Sugar beet foliage 20.3 30.7 Bean foliage 40.4 b5*6 3 TCA 5,000 ppm 636.51 50.02 as affected by time 2 k hrs 48 hrs k TCA CMU IPC Sndothal 500 ppm 500 ppm 500 ppm 500 ppm Control Wheat Wheat Wheat Wheat Wheat seeds seeds seeds seeds seeds 15.53 h i 10.7 5.7 14.8 47.13 7.1 18.5 5*7 48.7 5 TCA 5,000 ppm 1,000 ppm 500 ppm Control Wheat Wheat Wheat Wheat seeds seeds seeds seeds 7.9 3.6 Ik.k 9.1 23.3 35.0 31.3 49.1* I. per gram of foliage; 2. per sq. cm. of foliage; _J2 hrs 6.7 2.2 k .k 3.9 3* per seed. VjJ OS RATE OF GROWTH MUCK S0I1.(S|). 6OLBS.R3 30 LB S .R 2 I9LBS. R, 4 0 .0 S J 1 3 0 .0 r r o UJ r • 20.0 .•* y y s LEGEND;. *• CONTROL 21 0 AYS A 10.0 ---9 o- 4 2 DAYS _____ 8 4 0 AYS 108 DAYS - A . ----- 9.-----o ----- »----- 9 2I DAYS 1 28 21 28 DAYS THE EFFECT OF RATE AND DATE OF APPLICATION OF TCA ON THE RATE OF GROWTH OF WHEAT ON MOCK SOIL 21 DA YS 28 RATE OF GROWTH CLAY LOAM (S£). 60LBS. 30LBS. Rg 19 LBS R 40 0 2 o 1 30.0 * ........ X UJ X 20.0 / /' // O' /// J/ // // / / // // /// 'v & .00 --------------- . LEGF. CONTROL 21 DAYS 4 2 DAYS r 640AYS _____ vO— ------ -0 I0 8 0 A Y S ,----------------------- --------------- -•---- -i . 21 DAYS FIG 2 - 28 7 21 28 7 DAYS 21 DAYS THE EFFECT OF RATE AND DATE OF APPLICATION OF TCA ON THE RATE OF GROWTH OF WHEAT ON CLAY LOAM S O IL 28 RATE OF GROWTH SANDY SOIL (S3). 30LBS.R2 I5LBS. R, 6 OLBS.R3 4 0 .0 I 2 0 1 30.0 H X o Ui X / / / r /j /. LEGEND - / / / / / / 20.0 CONTROL 21OAYS / / 7 / ,* / / r.* / '/ / © / / 10.0 42 DAYS 0 4 DAYS IO0OAYS 0 c 1 ----- 2 PAYS FIG. 3. 28 21 28 DA YS THE,EFFECT OF RATE ANO DATE OF APPLICATION OF TCA ON THE RATE OF OROWTH OF WHEAT ON SANOY SOIL d :. a -o 21 20 ri d a y o l d o f {.lantin*;. wheat j * ant s. II o » t i 1~. 'The e f f e c t o f T C A o n g r o w t h Ihornlcal a p p l i e d o n t h e d a y of of day old planting. wheat f lant*. SUMMARY The sodium salt of trichloroacetic acid was applied at three rates (1*5, 30 and bO pounds per acre) to pots containing much, clay loam, and sandy soils* Treatments were made 21, 4-2, 64 and 108 days before wheat seeds were planted. Thus it was possible to determine the effect of soil type, rate of application, and time between application and plant­ ing on the growth rate and appearance of wheat seedlings. The results of the study may be summarized as follows: 1. TCA proved very effective in suppressing the growth of wheat plants* This was borne out by fresh and dry weight of tops, dry weight of roots, and periodic rate of growth of plants* 2. The extent of injury was related to the rate of application of the compound, the bO-pound applications being the most injurious of all. The greatest suppression of growth resulted, irrespective of the nature of the soil, when TCA was applied 21 days before the sowing date of the wheat seeds. Crop injury was in proportion to the amounts applied* 4. In the second period, where the application was made 42 days before the sowing time, there was little evidence of TCA injury to plants growing in Bandy soil while those growing in muck soil were badly injured. The injury to plants grown on clay loam was intermediate* Crowth behavior of the crop as measured by yield data was signifi­ cantly different on each type of soil* 5* In clay loam and sandy soils the dissipation of TCA, as shown by wheat yields, was well under way by the time 42 days had elapsed and was complete by the end of 64 days. However, this did not hold true with muck soil where injury occurred even after 108 days* b. Soil nutritional levels, including pH, for available IT, P, K, Ca, Mg, HH^, and NO^ were not affected by different treatments considered in this investigation* 7* The leaves of wheat plants treated with TCA contained a larger per­ centage of protein, arginine, reducing sugar and acid hydrolyzable polysaccharide* and starch. Slight difference was noted in other amino acids A tremendous decrease was observed in the percentage of non— reducing sugar, ether extract, unsaponifiable material. The crude protein showed approximately the same amount of methionine and arginine and slightly less of the other amino acids* 8* The roots of TCA treated plants showed a slight Increase in the per­ centage of proteins and amino acids and also an increase in reducing sugar and starch. Little difference was noted in the other amino acids (expressed as percentage of crude protein), with the exception of histidine which was slightly greater in the treated plants, and in the percentage of non-reducing sugars and ether extract. 9* TCA injury to wheat plants was not the result of changes in the nu­ trient status of the soils but it was rather due to direct changes in the metabolic activities of the plants* 10* TCA treatments to plant tissues resulted in an increase of respira­ tion rate. 11* Respiration studies with treated foliage of various plants indicated that sugar beet was most to3.erant followed by tomato and cauliflower, while beans were least tolerant of all the plants studied. LITERATURE CITED Ahlgren, G.H., Klingman, G. C., Yfolf, D.E. trol* Principles of Weed Con­ John Wiley and Sons, Inc., 308 pp. 1951« Association of Official Agricultural Chemists. tive Methods of Analysis. Sixth Edition. 2o-27: 50^ pp. 19**5* Association of Official Agricultural Chemists. Analysis. Official Methods of Seventh Edition. 910 pp. 1950 Barrons, K.C. to Earth, Official and Tenta­ Relative tolerance of crops to sodium TCA 90$. Down b: No. h. 8-9 . 1951. Barrons, K.C., and Watson, A.J. with sodium TCA. Factors affecting field results North Central Weed Control Conference, Research Report. p. 43. 19^9. ___________ . ___________________ • Increasing the effectiveness of sodium TCA by combining with tillage. North Central Weed Control Conference Research Report, p. ^3» 19^9• Barrons, K.C., and Hummer, R.W. derivatives of TCA. Breakey, W.J. Some basic herbicidal studies with Publication, Dow Chem. Co. Feb. 1951. Eradication of quack grass or twitch grass (Agro- pyron repens) with sodium trichloroacetate (TCA 60$)• North Cen­ tral Weed Control Conference Research Report, p. 43. 19^9* Buchholts, K.F. treatments. p. 9. 1950. The response of quack grass to TCA and cultural North Central Weed Control Conference Research Report, o0 10. Buchholtz, K.P. Response of canning peas to applications of TCA, maleic hydrazide, and IPC. North Central Weed Conference Research Report, p. 121. 1950. 11 . Carder, A. C. Treatment of couch grass with TCA alone and in com­ bination with cultural means. North Central Weed Control Conference Research Report, p. 10. 1950. 12 . . The selective control of wild oats in flax by IPC, TCA and Chlorosol-A. North Central Weed Control Conference Research Report, p. 80. 19^9* 13. Cates, A.C. Year Book U.S. Dept. Agric. 205 PP« 1917* 14. Chadwick, L.C., and Dickinson, C. Discing necessary to control weed growth in nursery fields treated with sodium trichloroacetate (TCA) to control quack'~graas. North Central Weed Control Conference Research Report, p. 10. 1950. . 15. The control of quack grass in nursery fields with sodium trichloroacetate. North Central Weed Control Conference Research Report, p. 10. 1950. lb . Chubb, W.O., and Mackey, E.M. Effect of TCA on fibre flax. North Central Weed Control Conference Research Report, p. 89. 1950. 17. Coupland, R.T. Response of couch grass (Agropyron repens) to sodium trichloroacetate. North Central need Control Conference Research Report, p. 1+4. 1949* 18. _____________ . Response of flax and rape to sodium trichloroacetate. North Central Weed Control Conference Research Report, p. 82. 1949. 61 19* Dutton, W.C. Investigation to determine possible uses and develop­ ment methods of application of new herbicide. North Central Weed Control Conference Research Report, p. ISO. 19^9* 20. Friesen, H.A. repens). Effect of sodium TCA on quack grass (Agropyron North Central Weed Control Conference Research Report. p. 11. 1950. 21. . Effect of sodium TCA and tillage on quack grass (Agro- pyron repens)• port. 22. North Central Weed Control Conference Research Re­ p. 12. 1950. _________ . Effect of TCA on perennial grasses. North Central Weed Control Conference Research Re^rt. p. 44. 1949. 23. Green, K.R. TCA- a promising new weedicide for gras3 control. Agr. Gaz. N. S. Wales bl: 455-45b. 1950. 24. Grigsby, B.H., and Farewell, E.D. Studies on toxicity of herbi­ cides to livestock grazing on pastures sprayed for weed control. North Central Weed Control Conference Research Report, p. b4. 1949* 25. Grigsby, B.H. Herbicides for pre-emergence use on sugar beets. North Central Weed Control Conference Research Report, p. 69* 19^9* 26. Helgeson, E.A. Effect of herbicides in growing crops. tral Weed Control Conference Research Report, p. 6J . 27. Helgeson, E.A., Konzak, R. , and Thacker, R. icldal action of TCA sodium salt. North Cen­ 1949* Studies on the Herb- North Central Weed Control Con­ ference ftesearch Report, p. 4*3. 1949* 2S. Helgeson, E.A., Konzak, R., and Stahler, L.M. Pre-emergence chem­ ical weed control in sugar beets at Fargo-Moorhead. :-eed Control Conference Research Report, p. 09. 1949. North Central 62 29* Jones, M.S. The influence of 2,4— dichlorophenoxyacetic acid on nitrate formation in a prairie soil* J* Am. Soc. Agron., 40: 522- 526* 194S. 30* Kmtochvil, D.E. Determination of the effect of several herbicides on soil microorganisms, 31. Y/eeds. 1 :25-31. 1951* Krotochvil, D.E., Derscheid, L.A., and Stabler, L.M. The effect of treating wild oats (Avena futna) seeded with flax with TCA at four rates of application and TCA- 2,4-D mixture at two rates of applica­ tion at Broolcings. North Central Weed Control Conference Research Report, p. So. 1949. 32. ______________ . Effect of treat­ ing quack grass (Agropyron repens) with several herbicides. North Central Weed Control Conference Research Report, p. 45. 1349. 33. Kratochvil, D.E., Derscheid, L.A., and Stabler, L.M. Effect of var­ ious chemicals at several rates of application applied as pre-emer­ gence sprays on flax at Brookings. North Central Weed Control Con­ ference Research Report, p. 121. 19^9• Lee, O.C. Effect of TCA on Johnson grass, fcorghmi halepense) North Central Weed Control Conference Research Report, p. 50. 1949. 35. ____ . of TCA. Response of quack grass (Agropyron repens) to treatment North Central Weed Control Conference Research Report, p. 4o. 194p . 36. Leggett, H.W. The effect of trichloroacetate (TCA) on couch grass ''Agropyron repens). North Central We-d Control Conference Research Report, p. 13-14. 1950. 63 37* MacDonald, W.F., Zlnter, C.C., Slough, A.T. Application of TCA for control of annual grasses in flax in 1950 Dakota* Milbank, South North Central Weed Control Conference Research Repot p. 55. 1950. 3 8 * ________________________ ___________________ . Treatment of quack gras8 with TCA in 1949 at Baldwin, North Dakota* North Central Weed Control Conference Research Report, p. 9-7* 1949. 39* MacDonald, W.P., Zlnter, C.C., and Slough, A.T* Treatment of quack grass with TCA in 19**9 ®-t Stark Weather, North Dakota* North Cen­ tral Weed Control Conference Research Report, p. 46-47. 1949* 40*________________________________ • Treatment of quack grass with TCA in 1949 at Breckenridge, Minnesota. north Central Weed Control Conference Research Report, p. 47* 1949* 41. __________________________________________ _* grass with TCA, # 1 Treatment of quack fuel oil, chlorosal-A, and general chemical 7B-D in 1949 at Halstand, Minnesota. North Central ‘ Weed Control Conference Research Report, p. 4S. 1949. 4 ? . ________________________ _ _______ • Treatment of quack grass with TCA in 19^9 a-tWarren, Minnesota. North Central Weed Control Conference Research Report, p. 47. 1949. 43 . ________ ___________________________________ • Treatment of quack grass with TCA in 19i+9 Redwood Ralls, Minnesota. North Central Weed Control Conference Research Report, p. 47. 1949. + . ______________ _________________. 41 Application of TCA for the control of annual grasses in flax in 1950 at Danvers, Min­ nesota. North Central Weed Control Conference R-search Report, p. 93. 1950. 64 MacDonald, W.F., Slough, A.T., and Zlnter, C.O. grass with TCA In 1949 at Huron, South Dakota. Treatment of quack North Central Weed Control Conference Research Report, p. 4b. 19494b. McCall, G-.L., and Zahnley, J.W. The effectiveness of various exper­ imental chemicals for the eradication of grass, worth Central Weed Control Conference Research Report, p. 194. 1949* 47• ___ ____________________________ . with trichloroacetate*. Control of noxious perennial grasses Kansas State College, Agri. Exp. Sta. Cir. 255s Sp. 1949. 48. _______________________________ • The relationship between spray volume and the effectiveness of TCA as a grass killer. North Cen­ tral Weed Control Conference Research Report, p. 193* 1949 • *9. Millar, C.E., and Turk, L.M. Edition. so. Fundamentals of Soil Science. Second John Wiley and Sons, Inc. 510 pp. 1951* Newman, A.S. Ihe effect of certain plant growth-regulators microorganisms and microbial processes. on soil Soil Sci. Soc. Am. Froc. 12:217-221. 1948. 51. Norman, A. G., and Newman, A.S. Persistence of herbicides in soils, proceedings of the North Eastern States Weed Control Conference Research Report, p. 7*12. 1950* 52. Nylund, R.E. A study on the control of weeds in onions by pre-emer­ gence application of herbicide. North Central Weed Control Confer­ ence Research Report, p. 132. 1949* si. Favlychexuco, T.K. treatment 1949. Response of quack grass (Agropyron repens) to TCA North Central Weed Control Conference Research Report, p. 48. 1949. 65 54. Pavlychenko, T.K. Effect of ACF grass killer (TCA 90^) on quack grass (Agropyrons repens) sprayed on foliage at the heading stage, July 28th, 1950. North Central Weed Control Conference Research Report, p. 14. 1950. 55. _______________ • Respons of quack grass (Agropyron repens) to ACP grass killer (TCA) treatment 1949* Results taken I949 and 1950. North Central Weed Control Conference Research Report, p. 14—15. 1950. 5b. Rebstock, T.L., Hamner, C.L., Luecke, R.W., and Sell, K.M. The effect of sodium trichloroacetate upon the metabolism of wheat seed­ lings. 57. Flant Physiology. (In Press)• Robbins, W.W., Crafts, A.S., and Raynor, R.N. Weed Control. First Edition, McGraw-Hill Book Co., Inc. 543 PP* 1942. 58. Roe, J.F. Trichloroacetic acid as a pre-emergence to control wild oats in flax. North Central Weed Control Conference Research Re­ port. p. 91. 1950. 59. Russell, J.S. , Sir. Soil Conditions and Flant Growth, 8th Edition, Longmans, Green and Co., 635 PP* 1950. 60. Sauberlich, H.E., and Baumann, C.A. The effect of dietary protein upon amino acid excretion by rats and mice. Jour. Biol. Chem. lbb: 417. 194b. bl. Sell, H.M., Johnston, F.A., and Lagasse, F.S. Changes in the chem­ ical composltion of the tung fruit and its component parts. Jour. Agr. Res. 73: 319-334. l°4b. o2. Sell, H.M., Luecke, R.W., Taylor, B.M., and Hamner, C.L. Changes in the chemical composition of the red kidney bean plants treated with 2,4— dlchlorophenoxyacetic acid. Plant Physiol. 24 : 295—299* 1949. 66 63* Smith, N.R., Dawson, V.T., and Wenzel, M.E. herbicides on soil microorganisms. The effect of certain Soil Sci. Soc. Am. Proc. 10: 197-201. 1946 o4. Smith, F.0-., Hamner, C.L., and Carlson, R.F. Changes in food re serves and respiratory capacity of bindweed tissues accompanying herbicidal action of 2,4-dichlorophenoxyacetic acid. Plant Physiol. 22: lhi. 1945. 6^* Slife, F.W., and Fuelman, R.F. malic hydraride. Control of quack grass with TCA and North Central Weed Control Conference Research Report, p. 15* 1950. bb. . repens) with TCA. Control of quack grass (Agropyron North Central Weed Control Conference Research Report* p. 4S. 1949. b7« . control in corn. Chemicals for Pre-emergence weed North Central Weed Control Conference Research Report, p. 115» 1949. 68. b9. Spurway, C.H., and Lawton, K. Soil Testing. Tech. Bui. 132. (4th Revision) March 1949. Mich. Sxpt. Sta. Stokes, J.L., Cunness, M., Dwyer, I.M., and Caswell, M.C. methods for the determination of amino acids. Microbial Jour. Biol. Cnem. 160: 35. 1995* 70. Swanson, C.R., Helgeson, 3.A., Konzak, R., and Stahler, L.M. Pre­ emergence chemical we^d control in 3ugar beets at Fargo-Moorhead. ■orth Central Teed Control Conference, p.113. 1949* 71. Uw'orsit, W.tf., Burris, R.H., and Stauffer, J.F. niques and Tissue Metabolism. Manometric Tech­ Burgess Publishing Co. 22Jpp* 1951* 67 72. Warren, GhF., and Singletary, C.C. potatoes. Crabgrass control in sweet North Central Weed Control Conference Research Report. P. 57. 19^9. . 73. direct seeded tomatoes. ssarab Report, 7*. Pre-emergence weed control in North Central Weed Condrol Conference Be­ p. 132. 19^9. Watson, A.J. Effect of soil moisture following applications of sodium TCA on the control of quack grass (Agropyron repens). North Central Need Control Conference Research Report, p. 16. 1950. 75. _________. Residual effect of s o d i u m TCA on a succeeding corn crop. North Central Weed Control Conference Research Report, p. I03. 1950. 76. _________ . sodium Effect of several tillage treatments in combination with TCAin controlling ouack grass (Agropyron repens). North Central Weed Control Conference Research Report, p. 16. 1950. 77. Weller, L.E., Luecke, R.W., Hamner, C.L., and Sell, H.M. Changes in the chemical composition of leaves and roots of red kidney bean plants treated with 2,4-dichlorophenoxyacetic acid. Plant Physiol. 23: 289-293. 1950. 7S. Willard, C.J. Weed Control. Ohio Agr. Ext. Ser. Bull. No. 293* gp. 1948. 79 . Willard C.J., and Warren, C.S. cides on soybeans. The value of pre-emergence herbi­ North Central Weed Control Conference Research "sport. p. 120. 1949* 30 . Wood, H.E., Bourns, J.J., and Mather, H.J. Eradicating quacK or couch grass with sodium trichloroacetate (TCA). North Central Weed Control Conference Research Report, p. lo-17» 1950. A 68 SI. Wood, W .E. , Bourne, J. J. , and Mather, H.J. Eradicating quaclc or twitch grass with sodium trichloroacetate (TCA) and chlorosol-A. North Central Weed Control Conference Research Report, p. U9» 19*+9 82* Wooley, J. &., and Sehrell, W.H. Two micro-biological methods for the determination of l(-) tryptophane in protein and other complex substances. Jour. Biol. Chem. 157s 1^1 • 19^5*