fiullelin 729 LIBRARY ' A mino Triazale and “ecivbri -- A New Alosciuion C/oenaical and Growth Inhibitor Cotton detolictted with Amino Triazole at the rate of 1.5 pounds per acre in 26 gallons oi water. equipment was used. Dark spots in the background are check plots that did not receive insecticides during the growing season. Ground Nwwém /954 TEXAS AGRICULTURAL EXPERIMENT STATION R. D. LEWIS. DIRECTOR, COLLEGE STATION, TEXAS SUMMARY Experiments were conducted with Amino Triazole, a new abscission-promoting but growth-' iting chemical, in the laboratory, greenhouse and in the field at College Station during 1952, 1953 1954. AT caused chlorophyll destruction and impaired chlorophyll synthesis in tissues formed at the or subsequent to the absorption of the chemical. The inhibition of chlorophyll synthesis was pr tional to the concentration and the age of the tissues at the time of treatment. The possibility the restriction of chlorophyll synthesis was due to immobilization of Mg, Fe, Mn, N, P or K by A z peared unlikely; the inhibitory effect appeared to be prior to the protochlorophyll stage. ’ Translocation experiments in the greenhouse indicated that AT is readily absorbed by the and aerial organs of the cotton plant and is mainly translocated upward. When applied to the w is absorbed by the roots and apparently moves upward in the xylem, but foliar applications a ently are transported in the phloem. Although the results were seldom as clearcut or striking,- observations generally confirmed the systemic action of AT noted in the greenhouse. Greenhouse and field tests demonstrated the effectiveness of AT as a cotton defoliant and a i i, pressant of secondary growth. It was compatible with other defoliants, increasing both defoli and regrowth inhibition. When applied at the normal time of defoliant application, detriment fects on seed or fiber properties were not observed. a Carbohydrate metabolism of AT-treated cotton plants was affected. Within 48 hours after fo application, the aerial organs lost approximately half of the original reducing sugars and sucr slight increase in starch was essentially balanced by an equivalent loss in the hemi-cellulose fra The result was a decrease in total carbohydrates. Fractionation of the treated plants showed tha uble sugars decreased in both the upper and basal shoot, but reserve carbohydrates increased in upper plant and decreased in the basal parts following treatment. changes in nitrogen, phosphorus and potassium in AT-treated plants, but calcium values were una ted. Reduction in stem height and other inhibitory effects were noted for cotton sprayed with A two stages of growth. Elongation of oat coleoptile sections was suppressed by all concentrations y 0.84 mg/L, the inhibition increasing with increasing concentration. The stimulatory effect of ,_i' acetic acid (IAA) on Avena section growth was further enhan-ced by the proper combination with» Relatively high concentrations of AT could relieve partially the inhibitory action of 10 mg./l. - hydrazide (MH) but higher concentrations of MH in combination with AT were mutually inhib' Below 21 mg/l., AT stimulated root growth but reduced hypocotyl growth at all concentrations \ tested by means of the cucumber or cotton seedling test; in combination, IAA and AT were inhib' to both root and hypocotyl growth. Competitive inhibition experiments showed that AT antago the effect of IAA in a manner qualitatively but not quantitatively expected of an anti-auxin. Itsi a action with auxin appears to be of practical significance. : AT increased respiratory rates of cotton leaf blades and oat coleoptile sections. The effect AT in combination with IAA and MH on respiration roughly paralleled their observed effects on gro A Preliminary experiments if ’ CONTENTS Page Summary ............................................................................... .. 2 Competitive Inhibition Studies _________________________ _, Introduction .......................................................................... -- 3 Effects on Respiration ................................. ........... .., Methods and Results .......................................................... _- 3 Cotton Leaves .............. .; ....................................... ..i Effects on Chlorophyll Destruction and Avena Coleoptile Sections................................__.. Synthesis in Cotton .................................................. -- 3 Disottesion ______________________________________________________________________________ Absorption and Translocation Experiments ---------- -- 4 Effects on Chlgrgphyll _______________________________________________ s0i1 Application --------------------------------------------------- -- 5 Absorption and Translocation __________________________________ Leaf Application .................................................. -- 5 Defoliation and Regrowth Inhibition ______________________ __ ' Defoliation and Regrowth Inhibition ---------------------- -- 5 Effects oi, Chemioei Composition ____________________________ ___ Effects 0n Chemical Composition ____________________________ -- 6 Growth Effects and Competitive Growth Effects ............................................................ _- 7 IIIhibitiOH Studies .................................................... __ ' Cotton Plant .......................................................... .. '7 Respiratory Effects ................. ................................. Avena Coleoptile Sections ................................ .. 8 Acknowledgments _________________________________________________________________ _ Cucumber and Cotton Seedling Tests .............. .. 10 Literature Cited ____________________________________________ ___ ______________________ _ f N0 TRIAZOLE (AT) 1s A WATER SOLUBLE, t yclic compound composed of a five-mem- ‘iv ring with three nitrogen atoms. Its chem- tructure is: N C-NHZ or_ 3-Amino- l,2,lL-'1'r1az<>1e . N/ 1 oduced under the trademark name of AMI- Lit has a molecular Weight of 84.5 and ap- l: as transparent elongated white crystals (2). melting point is reported between 153-159° epending on the investigator. Amino Tria- ill react with most acids and bases to form p; it will react with ketones and aldehydes to many derivatives, and can be oxidized to "azotriazole although the triazole ring resists common oxidizing agents. Preliminary toxi- ‘studies indicate that AT is relatively non- to rats (2). T was first discovered to have defoliating egrowth inhibiting properties in tests with J conducted in 1952 by the Texas Agricul- Experiment Station (9, 10). Subsequent Yin Texas (22) and by others elsewhere (21) f that AT, alone and in combination with rd defoliants, possesses exceptional prom- . a cotton defoli_ant and as a regrowth and j l plant growth suppressant. AT has proved effective as a pre- and post- igence spray and as a selective herbicide T is the first defoliant reported to possess systemic action; all defoliation chemicals ,1 previousl have been of the contact type. ugh far rom being the ideal defoliant, the tial impact of AT on the defoliant field may "analgous to the discovery of DDT and its utionary effect on the field of insect control. is report summarizes experiments with AT tton and other plant tissues conducted in the tory, greenhouse and in the field at College on during 1952, 1953 and 1954. (pending on the concentrations used, AT, and in combination with other compounds, ses either stimulating or inhibiting proper- n several of the basic plant processes. Be- * of its unique effects upon plant tissues it j. unusual possibilities for future research in the basic and applied fields. ctively, professor, assistant professor, and Ander- ayton and Company research fellow, Department of Physiology and Pathology, College Station, Texas. i710 TTiflZ0l6 -- A New Ahscission Chemical and Growth I nhihitor WAYNE C. HALL, S. P. JOHNSON and C. L. LEINWEBER* METHODS AND RESULTS The pure form of Amino Triazole, supplied un- der the code name ACP-981 by the American Chemical Paint Company, was used in most of the experiments reported in this study. For a few of the more critical experiments the ACP-981 compound was re-purified and re-crystalized be- fore use. Efiects on Chlorophyll Destruction and Synthesis in Cotton It was noted in the early work with AT that localized destruction of chlorophyll and dehydra- tion of affected tissue often occurred when rela- tively high concentrations were used, particular- ly under conditions of. high light intensity and temperature. Tissues formed at the time or sub- sequent to the absorption of AT were character- ized by chlorosis. The degree of chlorosis varied with the concentration of AT used and the age of the plant and affected tissues at the time of treat- ment. When sub-lethal concentrations were used the chlorotic tissues often remained alive and eventually regained their normal color, although other manifestations of growth inhibition some- times persisted for several months. To check more closely the effects at AT on chlorophyll synthesis, cotton seed was planted in soil in 4-inch pots and germinated in the dark at room temperatures. When the etiolated, chloro- tic seedlings had well-developed cotyledons they were thinned to four seedlings per pot and di- vided into six lots with five pots per lot. The six lots were sprayed in reduced light with the following concentrations of AT: 0.0 (distilled Wa- ter), 8.4, 84, 210, 420, 650 and 840 mg/l. Immed- iately after spraying, the seedlings were placed back in the dark for an additional 24 hours to permit absorption of the AT, then left in the dif- fuse light of the laboratory for another day prior to being placed in the greenhouse under normal conditions of light and temperature. The seedlings were observed daily and records kept on the number of days required for the coty- ledons to obtain the relative greenness of cotyle- dons of seedlings germinated under normal condi- tions of the greenhouse. The cotyledons of all treated seedlings, except those receiving 650 and 840 mg/l. AT, eventually became normal green in color. At the two higher concentrations the cotyledons were still chlorotic along the veins when the experiments was terminated. Growth of all treated plants was severely inhibited. Growth formed subsequent to treatment was en- 3 tirely chlorotic. Treated plants died erratically during the experiment; by the end of '6 weeks all plants except the controls appeared to be dead. The length of time for the cotyledons to obtain normal color is roughly proportional to the con- centration of AT applied (Figure 1). To determine if AT was enhancing the light- induced destruction of chlorophyll, a concentrated acetone extract from fresh cotton-leaf powder was prepared and 15 ml. aliquots pipetted into separate test tubes. Either 15 ml. distilled water or 0.5 or 1 percent AT solution was added to the tubes. They were then placed in bright light. After 3 days the chlorophyll solution was mostly oxidized in the distilled water control tubes, but it was still bright green in the tubes containing AT. Apparently, the effect of AT on chlorophyll destruction depends on the properties of living tissue. The possibility that the inhibition of chloro- phyll synthesis was due to immobilization of Mg, Fe, Mn, N, P or K by AT appears unlikely. Single node main-stem sections from fruiting cotton plants, each containing a mature leaf, were treat- ed by dipping the leaves momentarily into a 0.01 M AT solution. Control leaves were dipped in distilled water for comparison. The bases of the sections were immersed in a container of weak sugar solution containing sulfanilamide, being held upright in place by inserting the sections through large-meshed hardware cloth on the top of the container. The sections were placed on the laboratory bench in light. Forty-eight hours after treatment, the leaves were removed, forcing the axillary buds, which were chlorotic in the AT treated sections. As soon as the new growth 40- as» 0 ‘ ' a * Hi’ : : : : Q 5Q 9Q I00 20o 300 40o mqs)/Lifer Days for darkgrown cotton seedling cotyledons treated with varying rates of AT to obtain normal green color. 75o l 50° eoo aoo 90° Figure 1. was visible it was sprayed daily with weak solutions of N, Mg, Fe, Mn, P and K. a Calcium nitrate, sodium nitrate, ammo sulfate, urea, magnesium sulfate, magn chloride, ferrous sulfate, ferric chloride, ma nese sulfate, potassium phosphate or potas sulfate did not prevent chlorosis, although c i tic growth generally became green at a faster‘ following applications of magnesium or potas salts. Regrowth from AT treated sections not obtain the greenness or size of control tions. A second set of single node main-stalk . tions, with leaves removed, were infiltrated Y 0.0025 M AT under vacuum. Following treat i they were sprayed daily with the various salt‘ lutions noted earlier. The results agreed with" first experiment involving leaf application at‘ Foliage application of most of these salts to in plants previously treated with AT did not pre, chlorosis. In vitro tests also showed that does not chelate iron or magnesium. Absorption and Translocation Experiments Preliminary experiments on the absorp and translocation of AT were conducted in 1 with Stoneville 2B cotton plants grown in greenhouse and observations were made in 1 on Deltapine cotton treated in the field. In initial work, mature, but physiologically ac plants, were treated by immersing one of the l’ er, fully-expanded main-stalks leaves per plan 1 M AT for 3 hours. The previously-menti, effect of AT in causing chlorophyll destruc and necrosis of affected tissues as well as chl sis in newly formed tissue was used as evid of the transport of AT to tissues remote from point of application. » Two to 5 days following treatment the ' treated leaf blades showed chlorotic and necri areas. At that time all main-stalk leaves w, removed to force axillary growth. The new gro that developed, both terminal and lateral, sho _-.‘_L-4A~n_|¢b-Jb-.I—l0?h(\fi varying degrees of chlorosis ranging from t, . albinoism in the upper plant to only slight chl, j sis at the base. Another preliminary translocation__experi I l was performed with mature cotton plants. l-i molar AT was applied by dipping one leaf l plant as follows: (1) a leaf blade on a vegetas, _ lateral; (2) a fully expanded main-stalk leaf cated on the middle of the stem; and (3) af i?" expanded main-stalk leaf located on the seco, node above the cotyledonary node. The apical meristems were excised and a plants were manually defoliated to force axillf growth 2 days after AT application. The pattern and extent of chlorosis that peared in the new growth indicated that: moved from the leaf treated on the vegetati r into the main stem and mainly upward; ment occurred to tissues located above and the treated middle stem blade as evidenced hlorotic growth; and transport Was mainly rd from the treated basal leaf. 'eld observations showed that AT is readily T bed by the aerial organs of the cotton plant. pature but physiologically active plants the ical is primarily translocated to the meri- ‘regions. When relatively high concentrations applied the pathway of transport was main- pward to the terminal meristem and young es; death of the terminal meristem occurred , followed by necrosis progressing downward 31 the stem. if Jsecond greenhouse study of translocation performed in 1953. Young vegetative plants e four to six-leaf stage and fruiting, but ac- _y growing plants, were cultured singly in 3- } jars containing fertile soil. The plants j used in the following series of experiments. ‘Application ‘o one lot of four young and four mature F s, 50 ml. of 0.1 M AT were added to the soil ch jar. Prior to application, 50 percent of lants were girdled by removing to the xylem -half-inch wide layer of bark just above the edonary node. ight hours after treatment both the young the mature plants, girdled and non-girdled, ed chlorotic and dried areas in the foliage, ting the absorption and translocation of At the end of 9 days all plants displayed ed leaf chlorosis and desiccation; new term- jand axillary growth was entirely devoid of ophyll; some leaves and all squares and. p; g bolls had abscised. The AT-induced symp- ~ were slightly more pronounced in the girdl- ants than in the ungirdled plants, and in the g plants than in the older ones. All plants tually died. p‘ . Application hree experiments were conducted on the ab- ion and movement of AT by dipping the leaf s in a 0.01M solution. The first two experi- ts consisted of four young and four mature 1' each. Only the four mature plants were ,_ in the third experiment. AT was applied to f‘ the two lower main-stalk leaves above the ledons or to the two first fully-expanded below the apical meristem. The treat- ~ were: (1) basal leaf treatment: young ‘s-girdled above the cotyledons, non-girdled; re plants—girdled above cotyledons, non- ed; (2) upper leaf treatment: young plants dled above the cotyledons, non-girdled; ma- [plants—girdled above the cotyledon, non- d; and (3) girdled at the middle of the main stem: lower leaf treatment, upper leaf treat- ment. The girdles were made by removing a one- half-inch wide layer of bark to the cambium. Some of the plants showed the effects of treatment when observed 8 hours after the AT application. Nine days after treatment both young and mature plants receiving the basal leaf appli- cation showed typical AT-induced symptoms in parts above the girdle. The most marked chloro- sis and necrosis occurred in the upper plant parts. Plants receiving the top-leaf treatment show- ed the most accentuated effects in the apical mer- istem region, but some chlorosis and desiccation were apparent to the base of the plants or to the girdle. Abscission of squares, young bolls and affected leaves was noted in all plants. In the plants of the first two experiments the cotyle- dons abscised only in the non-girdled plants. The effects of AT generally were not apparent below - the girdles. In a few of the girdled mature plants, necrotic bark tissue immediately above and be- low the girdle suggested a possible slight carry- over across the girdle, but typical AT symptoms- were not apparent below the girdle. Deioliation and Regrowth Inhibition Several experiments were conducted in the greenhouse with Stoneville 2B cotton and in the field with Deltapine 15 cotton to ‘test the effects of AT, singly and in combination with commercial. defoliants, on defoliation and regrowth inhibition. The cotton was mature and over 50 percent of the bolls open at the time of treatment. The sprays were applied with a hand sprayer to the green- house-grown cotton to wet thoroughly the foliage, but without runoff. All materials were applied inthe field with a Hahn high-clearance self-pro- pelled sprayer at the equivalent rate of 26 gallons of spray to the acre. Table 1 summarizes the results of a represent- ative greenhouse experiment. The percent defol- iation was determined by counting leaves before and 10 days after application. All unabscised leaves, including those on unsprayed controls, were then removed and the amount of regrowth produced after 35 days was rated in terms of the control plants being 100 percent. One percent AT c gave excellent defoliation and completely check- ed regrowth. As an additive to cyanamide sprays, AT also increased defoliation and greatly reduced regrowth. Table 1. Effects of Amino Triazole on defoliation and re- growth inhibition of Stoneville 2B cotton grown in the greenhouse Concen- Deiolia- Relative re- Treatment tration. tion. growth after % ‘X, 35 days. ‘Y, Controls — — 100.0 Amino Triazole 1.0 90.4 None Monosodium cyanamide 2.0 62.8 200.0 Potassium cyanamide 2.0 95.7 120 Monosodium cyanamide + AT 2 + 0.25 80.7 l0 0 Potassium cyanamide + AT 2 + 0.25 100.0 5 0 Results 0f several field experiments conducted in 1953 0n the Main Station Farm and. on the Brazos River Valley field laboratory are given in Table 2. The amount of defoliation was de- termined 8 to 9 days after spraying and the rel- ative regrowth rated 21 days after application. AT gave acceptable defoliation over the range of 0.5 to 1.5 pounds per acre. Other field results in 1953 (22) show that 1.5 to 2.0 pounds of AT per acre gave more consistent results. The lower rates in the present experiments were used in relatively small cotton growing on theiMain Sta- tion Farm. AT was found to be compatible with three chemically-different commercial defoliants. Acceptable inhibition of regrowth was obtained only with the higher rates of AT. Seedlings ger- minated from seed collected from AT-sprayed plants were normal unless the bolls were imma- ture at the time of spraying. Effects on Chemical Composition The effects of AT on the carbohydrate com- position of mature fruiting Deltapine cotton grow- ing in the field on the Brazos River Valley Lab- oratory were determined as follows: Table 2. Effects of Amino Triazole, alone and as an addi- tive with defoliants. on defoliation and regrowth inhibition of field-grown Deltapine cotton ' Av. de- Relative Rate folia- regrowth Treatment per acre tion. after 21 Remarks % days. % Control i- —— 100.0 . . . . . . . . . . . . . . . . . . Amino Triazole 0.25 lb. 49.8 80 Only slight effect on regrowth, slightly chlorotic Amino Triazole 0.5 lb. 87.6 45 Basal chlorotic regrowth Amino Triazole 0.75 lb. 88.6 30 Regrowth chloro- tic, dead termi- nals in some plants Amino Triazole 1.0 lb. 90.6 20 Slight. chlorotic regrowth, mostly basal Amino Triazole 1.5 lb. 80.0 15 Most unabscised leaves dried. Re- growth chlorotic and basal. About 50% of plants eventually died Endothal control 5 qts. 85.1 90 Almost complete re-foliation Endothal + AT 5 qts.+0.25 lb. 92.0 75 Checked regrowth slightly Endothal + AT 5 qts.+0.5 lb. 93.3 60 Regrowth partly chlorotic Regrowth mostly chlorotic Some regrowth Endothal -|- AT 5 qts.-|-1.0 lb. 83.6 30 Monosodium cyana- mide control 4 lbs. 36.9 150 initiated before application Monosodium cyana- Upper regrowth mide + AT 4 lb.+0.25 lb. 55.0 85 chlorotic Monosodium cyana- Upper regrowth mide + AT 4 lb.+0.5 lb. 70.4 55 chlorotic Monosodium cyana- mide + AT 4 lb.+0.75 lb. 72.6 40 Regrowth chlorotic Monosodium cyana- Regrowth mostly mide + AT 4 lb.+1.0 lb. 81.8 30 basal Monosodium cyana- Regrowth mostly mide + AT 4 lb.-|-1.5 lb. 90.3 25 basal Shed-A-Leaf-L Conditions favor- control 6 qts. 78.5 85 able for regrowth Conditions favor- able for regrowth Conditions favor- able for regrowth Conditions favor- able for regrowth Shed-A-Leaf-L + AT 6 qts.-|-0.25 lb. 97.0 70 Shed-A-Leaf-L + AT 6 qts.-|-0.5 lb. 96.2 55 Shod-A-Leaf-L + AT 6 qts.+l.0 lb. 84.6 40 Six rows, 100 feet long, in a uniform bl a1 cotton were selected for the test. Sixteen p, sampled at random from the block as co _ were used to determine the original carbohy composition of the plants at the beginning u; experiment. Immediately afterwards at 10" AT at 0.1, 0.25 and 0.5 percent concentr was applied to alternate rows with a 2-gallon '_ w, sprayer. The sprays were applied to wet E oughly the foliage, but without excessive ru 1G1 .. ta: Twenty-four and 48 hours after applica 16 plants were collected at random from eac the three treatments. All sampled plants f fractionated immediately following harvest, “k lower, middle and upper thirds; these sa |= were composited into blades, petioles and s The composite samples were dried in a It e draft oven at 80° C. After drying to con weight, the samples were ground to pass anl} mesh screen. . The analytical methods used for deter j m tion of carbohydrates are given in detail elsewi (5). The sugars were extracted from ‘oven samples in a Soxhlet apparatus with 80 pe , ethanol and determined by the semi-micro me of Wildman and Hansen (23). Sucrose was termined by inverting an aliquot of the et extract with concentrated HCl and computi 4 the usual manner. Starch contained in the Y T let residue was determined by combined dias p- and acid hydrolysis. The starch-free residue S, hydrolyzed by autoclaving with HCl and th t, ducing values determined expressed as hem' ulose. The results are given as percentage dry W in Table 3. The 0.25 and 0.5 percent AT =1 samples collected at 24 hours were not anal- Results with 0.1 percent AT are generally re sentative of the changes occurring with the p er concentrations. Figure 2 shows the percen crease or decrease in carbohydrates from the? tial control levels during 48 hours for this centration only. I Within 48 hours after application of 0.1 i cent AT, the aerial organs of the cotton lost approximately half of the original redu sugars and sucrose; an increase in starch con‘ was essentially balanced by an equivalent‘? crease in the hemicellulose fraction. The r was a slight decrease in total carbohydrates y whole plant basis within 48 hours after the? plication of AT. In general, the upper plant l» (blades, petioles and stems) showed a net f. crease in soluble sugars after 48 hours, whe the reserve carbohydrates were increasing these organs (Figure 2). On the other h basal plant parts showed a net decrease in ‘ soluble and insoluble carbohydrate fractions. V only deviation from the general trend was re ted in the sucrose fraction; slight increases shown by the upper and basal blades and l stems. These deviations in sucrose, howeverg _..-...-.A>-¢|-+-. r-vtqt-v-z-rr-rctdffltzWfi i.’ i3. Effects of Amino Triazole on carbohydrate composition of field-grown cotton plants as percentage dry weight after 24 and 48 hours Blades Petioles Stems E95? Top Middle Bottom Top Middle Bottom Top Middle Bottom m n ' ° 24 48 24 48 24 48 24 48 24 48 24 48 24 48 24 48 24 48 Control 0.77 0.56 0.44 1.46 1.42 0.92 2.05 1.52 1.58 0.1 A 0.07 0.18 0.12 1.16 0.10 0.34 0.54 0.67 0.44 0.50 0.63 0.48 1.80 1.65 0.95 0.61 0.85 0.06 0.25 AT 0.12 0.70 0.84 0.78 0.40 0.76 0.69 0.38 0.32 0.40 0.56 0.29 — 0.23 — 0.37 — 0.50 0.5 AT 0.34 0.54 0.76 1.11 0.52 0.82 0.20 0.48 0.59 0.44 0.42 0.38 — 0.45 —— 0.32 — 0.69 " Control 0.26 0.34 0.35 1.74 1.66 1.13 1 84 2.19 1.40 0.1 AT 0.57 0.46 0.49 0.00 0.59 0.53 2.21 1.12 0.43 0.43 0.21 0.08 2.00 1.00 1.36 0.75 1.50 1.55 0.25 AT 0.44 0.22 0.83 0.42 0.21 0.36 0.52 0.19 0.36 0.58 0.76 0.44 — 0.90 — 0.81 — 0.70 0.5 AT 1.15 0.15 0.50 0.32 1.11 0.41 3.51 0.47 1.32 0.46 0.94 0.46 ——— 0.58 — 0.79 — 1.50 r Control 4.48 0.82 2.20 2.68 3.90 2.25 .35 2 5 2.57 .1 AT 8.04 6.28 3.09 1.48 5.44 1.54 5.78 4.75 1.50 3.00 3.12 1.68 340 3.07 1.95 1.15 2.21 1.99 0.25 AT 5.07 6.67 2.38 1.98 1.80 1.52 1.32 2.70 2.79 1.71 2.57 2.69 — 0.81 — 1.01 — 1.53 0.5 AT 1.58 5.66 2.20 2.45 1.77 2.10 3.81 3.25 3.40 3.44 2.15 3.40 -— 1.68 — 1.84 — 1.68 . Control 3.94 4.45 6.76 .13 15.59 17.46 16.25 16.25 16.25 '_-'§ 0.1 AT 7.27 7.18 4.49 5.94 4.99. 6.08 5.91 13.96 14.06 13.54 15.22 17.00 16.20 16.13 14.40 11.33 13.60 7.33 1- 0.25 AT 5.21 7.39 5.83 6.95 4.79 5.46 14.18 14.78 15.46 16.48 15.40 6.75 i- 14.4 i- 12.48 ——- 8.16 0.5 AT 4.49 7.18 4.97 6.22 5.40 5.98 14.08 2.18 14.25 8.04 14.08 15.13 ——— 15.05 —— 14.20 ——- 13.61 tly can be explained by examining the cor- 7nding fluctuation in reducing sugars in these preliminary experiment was conducted t0 ine the effects of AT on the inorganic ‘up of Stoneville 2B plants. The plants were v d with 750, 1,500, 3,000 and 6,000 mg/l m.) AT. The blades were harvested 24 and lurs after treatment and analyzed according Methods and procedures previously summar- _;(11). Potassium, phosphorus and calcium 2 determined colorimetrically or turbidmetri- following wet-ashing with H280, and H202. N was determined by the micro-Kjeldahl ure. Unsprayed plants growing on the i bench were harvested as controls at the» sampling intervals. ompared with the controls, the K content de- “ed in the 750 and 1500 mg/l treated tissues, sed at the 3,000 mg/l level but decreased ly at the 6,000 mg/l concentration. Phos- ,_ s content increased slightly but consistently ‘ the 3,000 mg/l treatment. Total nitrogen V, sed slightly up to 1500 mg/1 concentration ecreased slightly at 3,000 mg/l and dropped 7 low level in the 6,000 mg/l treated tissues. _;calcium content remained fairly constant in _ treated and untreated plants. ue t0 the limited number of plants available, al data are not presented for this phase. The ts are considered preliminary and no con- on can be made at this time. A more com- '_ nsive study of the effects of AT on the in- ic makeup of the cotton plant is now in -ess (14). Growth Effects Plant toneville 2B cotton was grown in the green- Te in 2-gallon jars containing fertile soil. When ~ lants were growing vigorously and were at t 10-leaf stage they Were divided into '12 lots ' ee plants each. On July 25, 1953, they were ~ ed with the concentrations of AT shown in Table 4. They were observed weekly until Sep- tember 25 when the main stems were measured and other pertinent information recorded. The growth of the main stem was reduced as the concentration of AT was increased. Other symptoms of inhibition were recorded, particu- larly at the higher concentrations of AT (Table 4). A similar experiment was conducted on July 30 with younger cotton at the four-true-leaf stage of growth. All plants eventually died at concen- trations above 625 mg/1. The effects of AT other- wise were comparable with the results with the older plants shown in Table 4. -415 -418 -926 Reducing Sugors M +482 .12 "51 -<— —3|.| L Starch —- Hemicellulose Total Percentage change in carbohydrates on the dry weight basis of leaf blades, petioles and main stalk of cotton after 48 hours following treatment with 0.1 percent AT. Plant frac- tionated into upper, middle and basal thirds. A plus value indicates an increase from the original content, a minus value a decrease in content. Figure 2. 7 "2! E Ion nation -42 ‘lo -84 p p. —2|o so -42o — 840 — 8,400 \ . Concentration Amino Triazole — mqs/ L. Figure 3. Mean growth of Avena coleoptile sections (as percentage elongation) as a function of AT concentration. 25- 20— t: I5- .9 ‘s; c -|o 1A 2 Lu IO- °\., <10 1A 42 AT no 1A 5_ 2|o AT |o 1A e40 AT Q. Treatment Concentration —. mas/L. Figure 4. Effect of AT on IAA-induced growth of Avena coleoptile sections. Table 4. Effects of Amino Triazole on growth of the 1 treated at the 8 to 10 leaf stage 2 months treatment - Concentra- Average tion height main g WW Remarks AT. mg./ 1. stern; inches l _ , i- _ 0 (controls) 52.2 9 51.0 19 51.6 Cotton normal for spring-summer ~- house-grown cotton. L Plants normal in color. fruiting. bra and other growth characteristics. f Plants normal in color and fruiting. .1 tative and fruiting branches less controls. j Plants apparently normal except forf of axillary branches. i. Size reduction noticeable. otherwise, mal vegetatively and reproductiv Sparse branching at base of -~~ Old leaves with necrotic areas. othe _ plants almost normal except duced size. ‘ Old leaves partially mottled. Newl , smaller and lighter colored than w? shortened internodes in upper -i Fruiting slightly inhibited. Old foliage partially mottled and -- New leaves almost normal in color, reduced in size. Reduced flowering, fruiting only at top of plant. Old leaves partially mottled and - New leaves small in size but ~~ normal in color. Growing point r and axillaries chlorotic. Small. -- mal fruiting at top of plant. Most of old leaves had abscised. q" or dried. Growing point inactivok tremely short internodes. w 'te ies. Leaves small and abnormal“ Elongation 39 48.0 78 45.0 % 156 42.0 312 36.4 625 36.0 1250 31.0 2500 27.6 flowering or fruiting. , Terminal meristem dead. axillaries " and dead. Little growth after ap tion. Main stem still alive at baso‘ intact fruits. Squares abscised. ‘ Terminal meristem dead and main ', dead almost to base. Axillaries ' and dead. Leaves and squares abs Plant practically dead for all pur 5000 24.0 Avena Coleoptile Sections Seed of the Victory variety of oats were s face sterilized and soaked for 1 hour in disti water. They were germinated in stainless st trays containing moist sterilized vermiculite. a mination and growth of the seedlings took pl in the dark or under weak red light at 25 to 1. C. and a relative humidity of 85 to 90 percei When the coleoptiles were 2.5 to 3 cm. in len usually 80 to 84 hours after planting, unifo coleoptiles were selected and a single section mm. long was cut 2 to 3 mm. from the tip with? double-bladed tool. All sections were composi and lots of 20 sections distributedto sterile dishes containing 20 ml. of the test soluti _ Thirty sections were selected at random aff cutting and their lengths measured with a wi field binocular microscope fitted with an f 0' piece micrometer to determine the average ini if length and accuracy of cutting. All soliitions W41 adjusted to either pH 4.5 or 5.0 and buffered wi ~ 0.03 M phosphate buffer. The sections werei cubated in the dark at 25 to 26° C. for 16 hou Each treatment consisted of 40 to 60 sections; The final lengths of the sections were determined, under a microscope at the end of the incubating period. The mean growth of the sections is e pressed as percentage elongation and compar with the distilled water controls (Figures 5, 6, and 8). A The effects of AT on the elongation of Ave q sections were tested in serial concentration fro‘ 0.84 to 8,400 mg/1. (Figure 3). Compared Wi croTQJooQ IO IA <84 AT Treatment Concentration - mgs. L. Effects of AT, IAA and MH, alone and in combination, on growth of Avena coleoptile sections. {d Water controls, all concentrations inhibi- iWth; the inhibition increasing with increas- g A centration. the second experiment, IAA-induced section h, alone and in combination with AT, was i, ed With distilled water controls (Figure 4) . jmulating effect of IAA alone on Avena A ile section growth was demonstrated. Com- on of IAA with AT further enhanced elon- , . . e -r+=. 3O IA T:L*%?-Tl‘ <42Q AT \‘ 3O IA