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PUBLICATION NO. _ l|lll|lll|lllJtl|l|Til|l|T^|l|T |l|liTjj| r>p UNIVERSITY MICROFILMS ANN ARBOR - MICHIGAN SOME EFFECTS OF FOLIAR SPRAYS OF MALEIC HYDRAZIDE ON THE POST-HARVEST PHYSIOLOGY OF POTATOES, ONIONS, AND CERTAIN ROOT CROPS By Donald Robert Paterson 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 Year 195>2 SOME EFFECTS OF FOLIAR SPRAYS OF MALEIC HYDRAZIDE ON THE POST-HARVEST PHYSIOLOGY OF POTATOES, ONIONS, AND CERTAIN ROOT CROPS By Donald Robert Paterson AN ABSTRACT Submitted t.o 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 Year Approved 1952 Donald Robert Patersos Single aqueous sprays of 500, 1000 and 2500 ppm of maleic hydrazide, benzo-thiozole- 2-oxyaoetic acid and 2 ,4 ,5trichlorophenoxyacetic acid were applied to field plots of potatoes, onions and six root crops at different intervals before harvest in 1950 and 1951* mined, After yields were deter­ the various crops were placed in 35°» k $ ° » and 55° F storage rooms for several months* The potatoes and onions were analyzed both before and after this storage period for dry matter, total nitrogen, non-reducing sugar* starch, reducing sugar, and The amount of storage sprouting and breakdown as well as the loss in weight due to respiration, \ transpiration and other vital processes was determined at the end of the storage period for the various crops* Five hundred, 1000 and 2500 ppm of maleic hydrazide applied to the foliage of potato plants one to seven weelcs before harvest were effective in prolonging dormancy of Irish Cobbler, Pontiac, Russet Rural, and Sebago tubers held in storage for seven months at temperatures of i|5° i and 55 F. Complete inhibition of sprouting resulted from single ureharvest foliar sprays of 2500 ppm of maleic hydrazide applied four to seven weeks before harvest and the inhibition was more pronounced than that obtained with preharvest foliar treatments of 2,4.,5-triehlorophenoxyacetic acid or with post-harvest applications of the methyl ester of alpha-naphthaleneacetic acid. Maleic hydrazide induced sprout inhibition was accompanied by an absence of shriveling with little or no deterioration of quality and with no Donald Robert Pate( reduction in yield of U.S. No. I potatoes in 19£o. Re­ ductions in yield from the spray treatments x^ere detected, however, in 195>1 indicating the necessity for proper timing o.t application of the chemical if satisfactory results are to be obtained. Apical dominance of both tubers and individual sprouts on the tubers was destroyed. The per­ centages of reducing and non-reducing sugars were lower in maleic hydrazide treated potatoes stored at l $ ° P in 1 9 ^0 , while extensive storage studied of treated and non-treated potatoes held at 3 £ ° , k -S ° , and F the following year showed no differences in reducing sugar, non-reducing sugar or starch percentages. Early post-emergence sprays of maleic hydrazide at Z $ 0 0 ppm did not reduce storage sprout­ ing of potato tubers, and low concentrations of maleic hydrazide applied shortly before harvest stimulated sprout growth on potato tubers. Sprays of £00, 1000 and 2^00 ppm of maleic hydrazide applied to the foliage of onion plants seven to ten days before harvest resulted in marked reductions of sprout and root growth during storage. Foliage sprays of maleic hydra­ zide at 25>00 ppm applied three weeks or more before harvest resulted in an increase in storage breakdown of all onion varieties. There was a decrease in the percentage of reducing sugar in the control samples of Y-i+O onions over a four and one-half month storage period, while similar samples treated with a 2 ^ 0 0 ppm foliar spray of maleic hydrazide showed no decrease in reducing sugar. No alter Donald Robert Paterson ations in the amount of dry matter, total nitrogen, or non­ reducing sugar in the Y-ij.0 onions was induced by the maleic hydrazide treatments. The percentage of weight loss not resulting from sprouting, rooting or breakdown was nearly identical itfhen both treated and non-treated Y-I(.0 onion bulbs were held under bulk storage conditions. Preharvest foliar sprays of maleic hydrazide at 2500 ppm applied ten days before harvest reduced the amount of sprout growth of carrots, beets, rutabagas, turnips, and sugar beets held in storage at 55 F* ACKNOWLEDGMENT The author wishes to express his sincere appreciation and indebtedness to Dr. S. H. Wittwer for his encouragement, guidance and never failing help which made this investi­ gation possible. Appreciation is also rendered to the members of my guidance committee: Drs* Robert L. Carolus, William D, Baten, George P. Steinbauer, and Clive R. Megee and to Dr. Harold B. Tukey, Head of the Horticulture Department. Thanks are extended to Drs. Harold M. Sell, Erwin J. Benne and to Mr. L. E« Weller of the Agricultural Chemistry Department for assistance in the analytical phases. For their cooperation in the field studies, thanks are due to Dr. John F. Davis, and Professors James S. Boyd and Ernest J. Wheeler. The author is indebted to the Naugatuck Chemical Company for supplying the chemical maleic hydrazide and for giving financial support which made these investigations possible. TABLE OF CONTENTS Page I. INTRODUCTION............ T II e REVIEW OF LITERATURE ...................... Effects of maleic hydrazide on potatoes. . . . Effects of maleic hydrazide on onions..... £ Effects of maleic hydrazide on vegetable root c r o p s ............................ 7 Effects of maleic hydrazide on sugar beets . • III. EXPERIMENTAL............ 1 3 3 7 10 Potatoes A. The effect of concentration and time of application of preharvest foliar sprays of maleic hydrazide on the yield, sprout Inhibition and storage quality.............. Bo Yield, storage sprouting and composition of potatoes as affected by the time of application of foliar sprays of maleic hydrazide and the starch-sugar relation­ ships of the tubers subsequently stored at various temperatures < > . o . . o . . . o Co The yield and storage sprouting of three varieties of potatoes as affected by post­ emergence foliar sprays of maleic hydrazide Do Storage sprouting and quality of Sebago potatoes as affected by concentration of preharvest foliar sprays of maleic hydrazide and soil type . . . . o . o o o o Eo Yield of potato plants grown from tuhers which were harvested from plants sprayed with maleic hydrazide 10 19 28 30 3k- Onions A. The effect of concentration and time of application of preharvest foliar sprays of maleic hydrazide on the yield and storage sprouting and bi’eakdown of five onion varieties ......... B. The composition, yield and storage sprouting and breakdown of Y-i|.0 onions held under bulk storage conditions. . » . 0 38 I4J4. TABLE OP CONTENTS CONT Root Crops A« The effect of concentration and time of application of preharvest foliar sprays of maleic hydrazide on the yield at harvest and the storage sprouting and breakdown of sugar beets and five vegetable root crops, . . . . . . . o . . IV. V. VI. . DISCUSSION........... ....................... SUMMARY................. • „ . LITERATURE CITED .............................. 5>6 73 80 83 LIST OP FIGURES Figure 1 2 3 Page Uon-treated Sebago potatoes after six months storage at55°P 0 . . 0 . . . . . 0 Sebago potatoes treated with 2^00 ppm of maleic hydrazide seven weeks before harvest and after six months storage at 55° F . 32 . 33 Injury of Yellow Sweet Spanish onions caused by early foliar sprays of maleic hydrazide .............. [j. Non-treated Y-ij.0 onions after four months in common storage and three months at 55° F ....................... ............. 52 5 Y-I4.O onions treated with 2500 ppm of maleic hydrazide 18 days before harvest, and after four months in common storage and three months at 5 5 ° F * # * * * . * * * ® ij-3 53 LIST OP TABLES Table I II III IV V Page The yield of Irish Gobbler and Pontiac potatoes as affected by the concentration and time of application of maleic hydra­ zide and 2 ,ij.,5 -t richlorophenoxyacetic ................15 acid sprays. The effects of concentration and time of application of maleic hydrazide and 2 ,Lj.,5 trichlorophenoxyacetic acid on the sprout­ ing of Gobbler and Pontiac potatoes sub­ sequently held at storage temperatures of and 5 p P for 7 months 16 The sugar content of Irish Cobbler potatoes after 7 months storage at i $ ° and 55° F as affected by a preharvest foliar spray of maleic hydrazide. 17 The effects of foliar sprays of maleic hydrazide and 2 ,Ij.,£-tri chioroph.or.oxyacetic acid on the per cent fresh weight loss in storage other than from sprouting in Pontiac potatoes, . . • • • • • • • • • • » lQ Yield at harvest, and sprouting of Irish Cobbler, Sebago and Russet Rural potatoes after 6 months storage at 55° F as affected by the time of application of maleic hydrazide sprays • 23 Via The effect of maleic hydrazide on the composition of Irish Cobbler potatoes 25 days after harvest. VIb Vic VII 2l\. The effect of maleic hydrazide and temperature on the composition of Irish Cobbler potatoes after llj. weeks storage. . . . 25 The effect of maleic hydrazide and tempera­ ture on the composition of Irish Cobbler potatoes after 25 weeks storage. • • • • • • . 26 Summary of the effects of maleic hydrazide on the composition of Irish Cobbler potatoes after 25 weeks storage at 35, i+5, and 55° F ................. 27 4 LIST OP TABLES CONT. Table VIII IX X XI XII XIII XIV XV XVI Page The effects of post-emergence foliar sprays of maleic hydrazide applied approximately 4 weeks after planting on the yield at harvest and storage sprouting of potatoes after 6 months storage at 55 F, • • • • • • « 29 Sprouting of Sebago potatoes originally grownQon two soil types after 6 months at 55 P as affected by various spray concentrations of maleic hydrazide , , * , • , 31 The comparative yields of potato plants (1951) grown from Pontiac tubers, harvested from plants sprayed (1950 ) at various times and with various concentrations of maleic hydra­ zide and 2 ,4 >5 **trichlorophenoxyacetic acid • , 35 Yield at harvest and storage sprouting and breakdown of Brigham Yellow Globe, Downing Yellow Globe, Early Yellow Globe and Michigan State College Sweet Spanish onions after 8 months in common storage as affected by various sprays of maleic hydrazide, , « . , 40 The effects of foliar sprays of maleic hydrazide on per cent weight loss other than from sprouting in Early Yellow Globe onions held 8 months in common storage , , » « ilfL The induction of sponginess at harvest and the storage sprouting and breakdown of Sweet Spanish onions after 8 months in common storage as affected by concentra­ tion and time of application of maleic hydrazide sprays 42 Comparative storage quality of maleic hydra­ zide treated and non-treated Y-i|0 and non­ treated Downing Yellow Globe following ventilated bin and crate storage conditions, « 49 The effects of a foliar spray of maleic hydrazide on the keeping quality of onions, Variety Y-ilO, held in ventilated storage bins of 200 bushel capacity for months, • « 50 Yield at harvest and the keeping quality of onion, Variety Y-ij.0, after l± months In common storage and 3 months at 55° F as affected by maleic hydrazide sprays, , , , « « 51 LIST OP TABLES CONT. Table XVII XVTII XIX XX XXI XXII XXIII XXIV XXV Page The effect of maleic hydrazide on the composition of Y-1|.0 onions during I|.^ months of common storage • • < > • . . . . , > • 54 Storage bin temperatures of Y-lj.0 onion bulbs as affected by a foliar spray of maleic hydrazide................... 55 The effects of maleic hydrazide and benzothiozole-2-oxyacetic acid on the yield at harvest and storage sprouting and break­ down of Chantenay, Danvers, and Nantes carrots after 3 months at 55° F (1950) . . . Per cent weight loss other than from sprouting in Chantenay carrots during 3 months storage in 1950 as affected by foliar sprays of maleic hydrazide and benzo-thiozole-2 -oxyacetic acid (1 9 5 0 ) . 0 The effects of maleic hydrazide on the yield at harvest and storage sprouting of Chantenay, Danvers, and Nantes carrots after 11 weeks at 55° F (1951) • • • • • » • 60 6l 62 Yield at harvest and storage sprouting and -breakdown of Purple Top White Globe turnips after 2 months storage at 55° F as affected by maleic hydrazide sprays (1 9 5 0 ) 61}. The effects of maleic hydrazide on the yield at harvest and storage sprouting and break­ down of American Purple Top rutabagas held 3 months at 55° F (1950) ................ 65 Yield at harvest and storage sprouting of Purple Top White Globe turnips and American Purple Top rutabaga after 3 months storage at 55° F a.3 affected by foliar sprays of maleic hydrazide (1 9 5 1 )* • • • • • • • • • • 66 The effects of maleic hydrazide on the yield at harvest and storage sprouting of Detroit Dark Red beets after 3 months at 55° F (1950) 68 LIST OP TABLES CONT. Table XXVI Yield at harvest and storage sprouting of Detroit Dark Red beets after 3 months storage at 5-5 ° F as affected by foliar sprays of maleic hydrazide (1951)* • • •• • 69 XXVII The effects of time of application and concentration of maleic hydrazide sprays on the yield at harvest and storage sprouting of Hollow Crown Thick Shoulder parsnips after 3 months at F ............ 70 XXVIII Yield at harvest, storage sprouting and sucrose content of sugar beets after 3 months storage at 55° F as affected by foliar sprays of maleic hydrazide. 0 . .. . 71 XXIX The effect of maleic hydrazide treated potatoes on the partial pressure of carbon dioxide in pliofilm bags and the relationshi: of this altered carbon dioxide atmosphere to the sugar compo­ sition of the tubers after 6 weeks storage at l\.$° F ................... 72 I. INTRODUCTION Since antiquity, man has been dependent on a measure of control of temperature and humidity to prevent loss in tuber, bulb, and root crops held in storage* In recent years the subject of numerous investigations has been a more thorough analysis of these factors in controlling storage losses (1, 2, 3, 7, 9, 3k> 35, 39, k 9 , 55, 56, 56, 59, 8 2 , 83). In the last decade, chemical control of storage sprout­ ing of potatoes has been achieved since Guthrie (31) reported that the methyl ester of alpha-naphthaleneacetic acid or other growth substances was effective if applied to potato tubers after harvest* Subsequent workers have reported similar results (10, 11, 15, 16, 1?, I tf , 68 )* Progress in the chemical control of storage sprouting was evolved still further by Smith., Baeza, Ellison and McGoldrick (2i|., 25, 61^., 65) when they were successful in inhibiting the sprouting in storage of potato tubers harvested from plants sprayed In the field with various growth regulating chemicals. In 1950, Wittwer, Sharma et al (78 , 79, 80) found preharvest foliar sprays of maleic hydrazide* to be effective in pre­ venting the storage sprouting of onions and carrots» *Water soluble diethanol amine salt of 1 ,2 -dihydro- 3 »6pyri dazinedi one• 2 As the application of sprout inhibitors to growing crops is much simpler than treating the produce after harvest with crops that are ordinarily sprayed for the control of diseases or insects, and as maleic hydrazide has been demonstrated to be an effective sprout inhibitor on various crops (79 , 80 , 86 ), the effects of various con­ centrations and times of application of this chemical on the storage quality and chemical composition of potatoes, onions, and certain root crops were investigated. In some tests other chemicals in addition to maleic hydrazide, having proven sprout inhibiting effects, were included as control comparisons for maleic hydrazide in addition to the non-treated controls 0 4 II. REVIEW CP LITERATURE Schoene and Hoffman (62) first described maleic hydrazide as a unique growth regulant, and subsequent investigators have initiated many varied lines of investi­ gation with this chemical. Miller (i}.8 ) reported that maleic hydrazide can cause abscission of young flowers or fruits; Crafts e_t al (13) used it as a herbicide; Naylor (.60) stated that maleic hydrazide will shift the critical daylength of Xanthium; White (72) found that this chemical delayed the fruiting of black raspberries; and Naylor and Davis (5l) reported that maleic hydrazide produced sterile staminate flowers on Zea. Accordingly, the specific effects of this chemical on the plants used in this study are re­ viewed briefly. Effects of maleic hydrazide on potatoes Using maleic hydrazide as a herbicide on Netted Gem potatoes, Barnard and Warden (6 ) reported a slight increase in tuberization from 1000 ppm of maleic hydrazide applied two weeks after emergence and accompanied by a slight reduction in size. When 6000 ppm of maleic hydrazide were applied, tuber set was further increased but a smaller percentage of the tubers attained No. 1 size. growth and aerial tubers were formed. Many second Denison (11+) noted the effects of concentrations from 375 ppro to 6000 ppm on the Kennebec variety when applied as a herbicide on July 6 , July 20, and July 28, 1950. Yields of the early application showed a marked reduction increasing with concentration, while the second application gave a smaller yield reduction and the last application resulted in no significant reduction. No difference was reported in the specific gravity of tubers from treatments or dates of application. Marshall and Smith (1+6) have reported effective sprout inhibition from 2500 ppm of maleic hydrazide treatments to potato tubers when the material was injected into the tuber by sticking impregnated toothpicks in the tuber. Tubers immersed in a 2500 ppm solution of maleic hydrazide exhibited no sprout inhibition. "iickel (8 6 ) first reported that foliar applications of 3000 pom of maleic hydrazide seven weeks after planting prevented sprouting of potato tubers in storage. Kennedy and Smith (1+2) showed the effects of concen­ tration of 1 0 , 1 0 0 , and 1000 ppm of maleic hydrazide on the Sebago variety when applied at four dates during the growing season. A concentration of 1000 ppm of maleic hydrazide applied about the time of initial tuber set caused a large increase in the number of tubers formed, severe injury to formed tubers and curling and chlorosis of foliage accom­ panied by stunting of growth. Foliage and tuber injury decreased with later applications and with less concentrated 5 applications or maleic hydrazide. In general, a high con­ centration of maleic hydrazide early in the growing season caused vine and tuber injury, but applied late resulted in a reduction in amount of sprouting in storage, Salunkhe, Wittwer at al (61) reported that preharvest foliar sprays of maleic hydrazide (2^00 ppm) applied to Russet Rural, Irish Gobbler and Sebago potatoes resulted in a larger number of tubers in higher specific gravity groupings than was found in comparable tubers harvested from non-treated plants. Following harvest the color quality of chips processed from maleic hydrazide treated Sebago potatoes of the same specific gravity groupings as compared with control lots wa3 superior. Subsequent to five months storage at 37° F and again following lj.3 days of conditioning at ?8° F, Russet Rural, Irish Cobbler and Sebago potatoes harvested from vines sprayed with maleic hydrazide and placed in various specific gravity groupings were within each group given superior arbitrary chip color ratings. Effects of maleic hydrazide on onions Maleic hydrazide was first used on onions as an herbi­ cide. Harris (32) and Harris and Leonard (33) reported that young wild onions, Allium canadense, when sprayed on November llj., 19lp9 with 1.5>> 3> 6, and 12 pounds per acre of maleic hydrazide as a herbicide gave 98 per cent control at the 3 pound rats and approached eradication at the 12 pound rate. A second treatment in March showed excellent 4 6 control at all rates but the onions were not eradicated. No onion shoots developed on treated areas In the fall. Preisen and Howat (27) stated that maleic hydrazide applied one month after planting at 2500 and 5000 ppm had no apparent effect on onion plants. Greulach and Atchison (30) made the interesting obser­ vation that Southport Yellow Globe onions grown in a solution of one ppm of maleic hydrazide produced many more roots than comparable control bulbs indicating a possible root stimulating effect of maleic hydrazide. Wittwer, Sharma et al (76, 77> 78* 80) stated that maleic hydrazide inhibited sprouting of onions in storage when applied at concentrations of 2500 ppm when one-third of the tops were down, two weeks before harvest. There was a significant reduction in sprouting accompanied by a reduction in storage rots five months after storage when 500 ppm had been applied. Bulbs from plants treated with 2500 ppm of maleic hydrazide showed normal internal structure with no effect on flavor, color or odor. The onions were planted at the end of the five month storage period but remained dormant and sound for eight weeks* Johannessen and Oebker (3 8 ) observed that a preharvest foliar spray of 2500 ppm of maleic hydrazide applied to Early Yellow Globe and Brigham Yellow Globe onions reduced sprouting In a 16 week storage test at 32° and ipO0 F and also reduced sprouting under simulated retail store con­ ditions five weeks after this storage period. 7 Effects of maleic-hydrazide on vegetable root crops Barnard and Warden (5) applied maleic hydrazide at 1000 ppm one week after gemination of several vegetable crops and observed little effect on the yield of beets and carrots* Howat (36) observed that post-emergence maleic hydrazide sprays applied at 1*5, 3*0, and 6.0 pounds per acre did not effect yields and appearances of Detroit Dark Red beets* Freisen and Howat (27) showed that 5000 ppm spray of maleic hydrazide one month after planting reduced the yield of beets. Crafts _et al (13) observed that young vegetable crops such as carrots and lettuce are more susceptible to injury from maleic hydrazide sprays than are older plants* Wittwer, Sharma jet al (77, 1 8, 79, 80) reported that sprout growth of carrots held at 50° F for three months was almost completely inhibited by foliar 3prays of 2500 ppm of maleic hydrazide applied four days before harvesting* The maleic hydrazide produced no significant alteration in the amount of dry matter, carotene, carbohydrates, or Kjeldahl nitrogen in the stored carrots. Sprouting in these carrots was also significantly reduced by a foliar spray of 500 ppm of maleic hydrazide* Effects of maleic hydrazide on sugar beets Wittwer and Hansen (73, 7i|, 75) reported that sugar beets treated with a 2500 ppm spray of maleic hydrazide approximately 3 weeks before harvest and then stored for 8 35 days in bins of 5 ton capacity showed no change in sugar composition, while the average percentage of sugar in com­ parable non-treated beets was reduced by more than if per cent of the original. Corresponding weight losses were more than 9 per cent in controls, with, again almost neg­ ligible loss in the bin of treated beets. A loss of 13«06 per cent of the total original sugar, arising from sizeable losses in both total weight and composition was realized in the controls, compared with 0*72 per cent in the beets receiving the preharvest spray of maleic hydrazide. Practi­ cally all top growth, root growth and storage breakdown was eliminated in the roots from plants receiving the pre­ harvest foliage spray of maleic hydrazide. The average temperatures within the bin containing the beets treated with maleic hydrazide ran several degrees cooler throughout the 35 day storage, Peto ej; al (53) likewise reported that the temperature in a control bin of sugar beets rose to a minimum of 6° F above that of a similar bin of sugar beets sprayed with maleic hydrazide before harvest, and that treated beets exceeded the controls by 0*25 per cent sugar at the be­ ginning of storage and 0,38 per cent after 3i+ days storage, Ririe and Mikkelsen (57) found that foliar sprays of maleic hydrazide produced significantly higher percentages of sucrose in sugar beets but did not influence root yield. Contrary to the above, Stout (6 7 ) reported that 1250, 9 2.900 and £000 ppm of maleic hydrazide applied 13 days before harvest showed no significant difference between treatments in yield and sugar percentage* There wa3 no significant difference in respiration rate and sugar loss during the 38 day storage period at 72° F* III. EXPERIMENTAL Potatoes A* The Effect of Concentration and Time of Application of Preharvest Foliar Sprays of Maleic Hydrazide on the Yield, Sprout Inhibition and Storage Quality Procedure, Field tests were conducted on a productive Hillsdale sandy loam soil using certified seed of the Irish Gobbler and Pontiac varieties planted May 19, 195>0, in rows 36 inches apart and with seed pieces at 12-inch intervals. As outlined in Table I, single aqueous spraya 0 .,. 900, 1000, and 2S>00 parts per million (ppxa) of maleic hyir&zide" were applied to the foliage of the Irish Gobbler variety 37 days (Ja;.y 15>), 19 days (August 2), 10 days (August 11), or 2 days (August 19) before harvest. Plants of the Pontiac variety were treated similarly ij.9 days (July l£), 31 days (August 2 ) , 22 days (August 11), or 2 days (September 2) before harvest. in length. Treatments were replicated on rows 15 feet Three-gallon hand sprayers were utilized in applying the chemicals and the leaves were sprayed until the solution dripped from the leaves. ’’Draft” (Proctor and Gamble) was added at a concentration of 0.1 per cent as a ~'rWater soluble di ethanol amine salt of l,2-dehydro-3,6pyridazinedione « 11 wetting agent. At the earliest spray application on July 15 tubers of both varieties ranged from one-fourth to two and one-half inches in diameter. Forty-eight hours after the latest treating dates, August 19 for Irish Gobbler and September 2 for pontiac, the vines of all plots were cut off; and the tubers were harvested four days later. Three controls were included to determine the relative merits of the various preharvest foliar sprays of maleic hydrazide (Table II): 1. Successive sprays of 5>0, 100, and 200 ppm of 2,i|, 5>-trichlorophenoxyacetic acid were applied to both varieties on July l£, August 2, and August 11. This treatment was included because of favorable results reported by Marshall and Smith (U.1 ?) . 2. A post-harvest treatment with the methyl ester of alpha-naphthaleneacetic acid as a dust formulation, ’’Barsprout” (American Gyanamid Company, New York), was used. Approximately the equivalent of 0.9 grarn of the active ingredient was applied per bushel at the time the potatoes were placed in storage. 3. A third control received no chemical treatment. Harvests were made and the yields were recorded on August 25> for the Irish Gobbler variety and on September 9> 19^0 for the Pontiac variety. Immediately after harvest, duplicate 10-tuber samples were taken from the replicates of each treatment and placed in paper bags. With the Pontiac variety, individual tubers in all samples were labelled and initial weights recorded. One of the dupli­ cate 10-tuber samples from each of the two replicates of 12 all treatments of both varieties was then placed in a storage maintained at l\.$ + 2° F and the other at 5>5? + 2° F. On March 29> 19E>1> after approximately seven months, the potatoes were removed from storage, photographed, weighed, and desprouted. The weight of the sprouts for each sample of 10 tubers was determined,, Subsequent to the seven months of storage at lj..3 and ..o 55 F, samples of Irish Cobbler tubers harvested from plants sprayed with 2^00 ppm of maleic hydrazide on July 15, 1 9 ^ 0 , along with comparable non-treated control lots, v^ere analyzed for total nitrogen, starch, reducing and non­ reducing sugar (!}., 6 3 )« Results. Harvest records showed no reduction in the yield, size, or quality of potatoes within a given variety resulting from any of the chemical spray treatments. No (visible) tuber injury was evident in any instance. There was however, a difference in the productivity of the two varieties with a mean acre yield of 268 bushels of U.S. No. I potatoes for Irish Cobbler compared with 35 bushels for Pontiac (Table I). Data on the weight of sprouts in grams for 10 tubers after seven months storage at and 55° F for the various treatments applied to the two varieties are given in Table IIo The relatively greater effectiveness of preharvest foliar sprays of maleic hydrazide as contrasted with 2,i}.,5>trichlorophenoxyacetic acid and the post-harvest application 13 of the methyl ester of alpha-naphthaleneacetic acid Is apparent from the data. Especially striking were the . .o differences in sprout growth at 55 F. Applications of 2500 ppm of maleic hydrazide 19 to I4.9 days before harvest resulted in nearly complete inhibition of sprouting at both temperatures, while control lots sprouted profusely. Some reductions in sprout growth resulted when maleic hydrazide was applied 1^.8 hours before the vines were cut off. Greater dormancy resulted when the sprays were applied on August 11* This application date was approximately 10 days prior to harvesting Irish Cobbler and 22 days before harvesting the Pontiac variety. Tubers from plants receiving 2500 ppm of maleic hydrazide on either July 15 or August 2 were clean, bright, firm, and practically free from any evidence of sprout growth, even after seven months storage. The data In Table II Indicate that a spray of 1000 ppm of maleic hydrazide, if applied at the proper time, may be sufficient for the induction of dormancy. It also appears that 1000 ppm and even %00 ppm of maleic hydrazide compare favorably with 2,l4.,5-trIchlorophenoxyacetIc acid as preharvest foliage spray applications for inhibition of storage sprouting in potatoes. No differences were found in percentages of dry matter, starch, or other acid-hydrolyzable polysaccharides, total carbohydrate, or nitrogen (Kjeldahl). However, lower values were found for both reducing and non-reducing sugars In tubers stored at Ij-5° F which had received the preharvest Ik foliar spray of 2£00 ppm of maleic hydrazide 37 days before harvest. Similar, though less striking, trends were also evident when tubers were stored at 5£° F (Table III). Although initial and final weights after storage of ten individual tubers of the Pontiac variety were recorded for all treatments, there was no consistent reduction in average weight losses when tubers and the- attached sprouts were weighed together after storage at 1|.£ and ££° F for seven months (Table IV). Similar results for post-harvest treatments using the methyl ester of alpha-naphthaleneacetic acid on the Irish Gobbler variety have been reported by Gandarillas and Nylund (28)0 TABLE I v- i - ■■ THE YIELD OP IHISK COBBLER AND PONTIAC POTATOES AS AFFECTED BY THE CONCENTRATION AND TIME OF APPLICATION OF MALEIC -HYDRAZIDE AND 2 , k , 5-TRICHLORO PHENO.XYACETIC ACI D SPRAYS Spray treatments Days before Chemical pom harvest Cobbler Pontiac Maleic hydrazide 500 1000 2500 37 5 oo 1000 2500 19 300 1000 2500 Yield (Lbs*/l5 ft 9 row) Cobbler Pontiac 1+9 Treatment me an 2 3 .5 * 16.0 iif.5 2 5 .5 " 22 05 2I4.0 0 1 9 .3 1 9 .3 31 17.0 21.0 18.0 30.5 27.0 23.0 2 3 .8 2I4.0O 2 0 .5 10 22 16.5 1 1 .5 16.5 20.5 2 8 ,0 3 6 ,5 1 8 ,5 19.7 2 6 .5 500 1000 2500 2 2 1 3 .5 ii+ .5 18.0 3 0 ,5 2 7 .5 2 7 .5 2 2 .0 2 1 .0 2 2 .8 5-tri50 chloroohenoxyacetic 100 acid 200 37 lf9 19 31 10 22 1 3 .5 23.0 18.2 Control 18.5 3 1 .0 2L(..8 Variety means 16 06 2 6 .9 2 „ 2k* f “Each value represents means of samples harvested from two reolicates0 16 TABLE II THE EFFECTS OF CONCENTRATION AND TIME OF APPLICATION 0^ MALEIC HYDRAZIDE AND P.,If., 5-TRICHLORO PHENOXYACETIC ACID ON THE SPROUTING OF CO EULER AND PONTIAC POTATOES SUBSEOTJENTLf HELD AT STORAGE TEMPERATURES OF 45° ADD 55° F ■FOR 7 MONTHS Sprouting (Grams/lO tubers) Spray■ treatments Days before Chemical ppm harvest Cobbler Maleic hydrazide Cobbler 55° F 45° F Pontiac 1+5° F 55° f Pontiac 500 1000 2500 37 (July 15) 5oo 1000 19 (Aug# 2) 10 (Aug. 11) 9 .0 0 .0 1 1 0 .0 * 2 8.0 2 .0 31 17.5 lij..0 2.0 39.0 12.5 12.0 1 0 .5 3 .0 0 .0 40.0 3.5 0.0 22 27.5 15.0 7.0 66.0 37.0 30.5 I4.0 , 0 2 2.5 0 0.0 68 .0 2 4 .5 26.0 58.5 39.5 26.0 12 4 ,0 145.5 94.5 51.5 156.5 133.0 75.5 28.0 53.5 2 .0 47.5 Barsprout (post-harvest ariplication) 13.0 66.5 0 .0 56.0 Control (no treatment) 47 98.5 96.0 11 5 .0 5-9 2500 500 1000 2500 500 1000 2,500 50 tri­ chi orophen100 oxyacetic acid 200 2-sk-t 2 2 37 (July 15) 49 19 (Aug. 2) 31 10 (Aug. 11) 2.2 52.5'' 108.5 96.0 88.5* 9.5 1.0 n o . 5'* 5o.5 3.0 *Each value represents the means of samples harvested from two replications# '”~”r9oO grams removed from 2 tubers TABLE III THE SUGAR CONTENT OP IRISH COBBLER POTATOES AFTER 7 MONTHS STORAGE AT k$° AND 55° F AS AFFECTED BY A PREHARVEST FOLIAR SPRAY OF MALEIC HYDRAZIDE (Expressed as per cent of dry weight)*’ Treatment k$° Reducing sugar Replication II Replication I Non-reducing sugar Replication II Replication I F Maleic hydrazide 1.63 1 .6 ^ 0.69 0.76 Control 3.26 2,68 1.21 1.02 Maleic hydrazide 0.56 0 ,i|2 1.05 0.77 Control 0,62 0.52 1.63 1.25 gg° p 'Each value represents the mean of duplicate determinations f—1 18 TABLE IV THE EFFECTS OF FOLIAR SPRAYS OF MALEIC HYLRAZI.DE AND 2,14-,5-TRICHLOROPHENOXYACETIC ACID ON THE PER CENT FRESH WEIGHT LOSS IN STORAGE OTHER THAN GROM SPROUTING IN PONTIAC POTATOES Chemical Spray treatments Days before PPm harvest Maleic hydrazide 2,1).,£-tri chlorophenoxyacetic acid Control (no treatment) £00 1000 2^00 £-9 (July l£) £00 1000 2£00 31 (Aug. 2) £00 1000 2£00 OO (Aug. 11) Weig;ht loss (per■ cent) £5° f ll.£* 6 .£ 7.£ 10.0 8 .£ 8 .£ 9.0 12.5 9.0 9.0 9.0 9.5 11.0 •10.5 9.0 7.£ £00 1000 2£00 2 (Sept. 2) £0 (July l£) 100 31 (Aug. 2) 200 22 (Aug. 11) io.5* ii.5 1Q.£ 10.£ 10.0 12.£ 12.£ 11.0 6.5 8.5 10.0 13.0 "'‘"Each value represents means of samples harvested from two replicationso 19 B « Yield, Storage Sprouting and Composition of Potatoes as Affected by the Time of Application of Foliar Sprays of Maleic Hydrazide ana the Starch-Sugar Relationships of the Tubers Subsequently Stored at Various Temperatures Procedure« Certified seed of the Irish Cobbler, Sebago, and Russet Rural varieties were planted May 2lj_ on a Hills­ dale sandy loam soil in rows 36 inches apart and with seed pieces at 12-inch intervals. 3-12-12 fertilizer was applied in bands on either side of the seed piece at 800 pounds per acre. In one treatment, an aqueous spray of 25>00 ppm of maleic hydrazide was a rolled to the vines of the three var­ ieties 6I4. days before harvest (July 19). A second treatment consisted of a similar aoplication to vines of all three varieties 50 days before harvest (August 2). The third treatment consisted of a control in which no chemical was applied (Table V). A split plot design was employed. Each of the four replicates consisted of two ?3 foot rows each of the three varieties. As in 1930, the plants were sprayed to run-off with the appropriate solution of maleic hydrazide and a 0.1 per cent concentration of "Draft" was used as a wetting agent. At the July 19, 19f?l spray application, tubers of the Irish Cobbler, ''ebago, and Russet Rural varieties ranged in size from three-fourths to two inches in diameter. This date also coincided with the end of blossoming of the potatoes. On August 2, £0 days prior to harvest, the vines of all varieties were still green when sprayed with maleic hydrazide. Harvesting was completed and the yields were recorded on September 21, 1951. The potatoes were held in common storage for 25 days to allow for suberization of the peri­ derm of the tuoers injured in harvest before being placed in thermostatically controlled storages at 35, 1+5, and 55° F. On October 16, 1951, triplicate 1+0-tuber samples of the Irish Gobbler variety were taken from the replicates of each treatment and placed in 5 0 -t>ound mesh onion bags for later chemical analyses. In addition, triplicate 10-tuber samples of all varieties were taken from each of the repli­ cates of each treatment and placed in paper bags for observing the growth of sprouts when stored at 55° F. One of the triplicate 1+0-tuber samples from each of the four replicates of the three treatments of the Irish Coboler variety along with one of the triplicate 10-tuber samples from each of the four replicates of the three treatments of all varieties was then placed in each of three storages maintained at 35 + 2° F, at 1+5 + 2° F, and at 55 + 2° F, respectively. On April 1+, 1952, after approximately six months, the potatoes were removed from storage and desprouted, and the weight of the sprouts for each sample of 10 tubers determined. Twenty-five days after harvest, and subsequent to 11+ and 25 weeks of storage at 35, 1+5, and 55° F, samples of Irish Gobbler tubers harvested from plants sprayed with 2500 ppm 21 of maleic hydrazide 6I4. and 50 days before harvest; along with comparable non-treated control lots, were analyzed for total nitrogen, starch, reducing and non-reducing sugar (1|, 63). Results. Harvest records showed a reduction in yield significant at the one per cent level with the plants of all three potato varieties sprayed 6J4. days before harvest (July 19) with 2500 ppm of maleic hydrazide in comparison with the control and a reduction in yield significant at the five per cent level between the plants of all three potato var­ ieties sprayed 50 days before harvest (August 2) with 2500 ppm of maleic hydrazide in comparison with the control (Table V)# However, the low average yield per acre of potato tubers likely caused in pact by poor soil drainage leaves doubt as to whether this experiment was an adequate test of either the effects of maleic hydrazide on the yield of potatoes or of the yielding ability of the three potato varieties involved,, The weight of sprouts in grams per 10 tubers after six months storage at 55° F was many times higher for the non­ treated control samples than when the plants were sprayed either 6ip or 50 days before harvest with 2500 ppm of maleic hydrazide (Table V). There was no difference in sprout inhibition at the two dates of spraying# Tables Via, VIb, Vic, and VII show a highly significant decrease in percentage dry weight between potatoes sprayed July 19 with 2500 ppm of maleic hydrazide and the non-treated 22 controls and a significant decrease in percentage dry weight between potatoes sprayed August 2 with 2300 ppm of maleic hydrazide anu the controls. There was a significantly higher percentage of total nitrogen in the tuoers harvested from plants sprayed August 2 than from those harvested from the plants sprayed July 19 and the controls. No differences were found in percentages of starch, reducing or non-reducing sugars °rom treatment with maleic hydrazide (Table VII). At the 33° P storage temperature the percentage of reducing and non-reducing sugar was higher than at the lp3 and 35>° F temperatures. Again at the 35° F storage temper­ ature the starch percentage was lower than in either the 4-5 oh 3 3 ° F storage. A similar starch-sugar relationship was observed between the lp3 and 35° storages but was less pronounced. These results are in agreement with numerous reports in the literature (3, 18, 20, 21, 22, 33, ip9, 38, 39, 8 3 ) . The lower sugar and the higher starch percentages at the 23-week sampling as compared with the li^-x^eek sampling in the 3^° F storage (Tables VTb and VIc) were in part due to a mechanical failure of this storage one week before the potatoes were prepared for analysis on April I4., 1932. The degree of control of these storages (+ 2° F) permitted at least a significant difference in the sugar values since Denny and Thornton (20) observed that a + 1° C difference gave a significant change in percentage total sugars and sucrose. 23 TABLE V YIELD-AT HARVEST, AND SPROUTING OP IRISH COBBLER, SEBAGO AND RUSSET RURAL POTATOES AFTER 6 MONTHS STORAGE AT 55° F AS AFFECTED BY THE TIME OF APPLICATION OF MALEIC HYDRAZIDE SPRAYS Spray treatments Days before harvest Yield of tubers Lbso/l^O ft. row Sprouting Grams/ 10 tubers Chetni cal ppm Maleic hydrazide 2500 6ii. (July 19) 10ij..2 1.83 2500 30 (Aug. 2) 113.9 2.08 130.3 132.30 Control Treatments LSD 5 per cent LSD 1 per cent I6 .6I4. 22.79 TABLE Via THE EFFECT OF MALEIC HYDRAZIDE ON THE COMPOSITION OF IRISH COBBLER POTATOES 25 DAYS AFTER HARVEST j{, (Expressed as per cent dry weight)" Treatments Days before harvest Treated 61}. (July 19) 50 (Aug. 2) Control Total N Starch 20*514- 1.53 69*98 0.93 i.it5 20.8i| 1.56 70.05 0.53 0.91 20«6ii 1.55 67.28 0.80 0.95 Dry weight Reducing sugar Non-reducing sugar 'Each value listed represents an average of samples from four replications* TABLE VIb THE EFFECT OF MALEIC HYDRAZIDE AND TEMPERATURE Oil THE COMPOSITION OF IRISH COBBLER POTATOES AFTER 14 WEEKS STORAGE (Expressed as per cent dry weight) Treatments 35° F Treated Total N 64 (July 19) 50 (Aug. 2) 19.19 19.48 19.95 1.6 4 1.66 1.6 4 56 . 4 6 58.75 58.76 15.77 13.31 13.04 4.28 3.59 3.94 64 (July 19) 50 (Aug. 2) 19.70 19.30 19.77 1.53 l.5o 68 .98 68 . 6 3 68.01 2.42 2.52 2.44 0.73 0.72 0.77 21.IQ 19.59 19.74 1 0UP 1.66 1.54 69 »46 67.57 0.38 0.33 67.69 0 .61 0.36 0,62 0.53 Control 55° F Treated Control Non-reducing sugar Dry eight Control Treated Reducing sugar Days before harvest 64 (July 19) 50 (Aug. 2) 1 .6 4 Starch *Each value listed represents an average of samples from four reolications. ru vn TABLE Vic THE .EFFECT OF MALEIC HYDRAZIDE AND TEP-TPZRATURE OH THE COMPOSITION OF IRISH COBBLER POTATOES AFTER 25 WESTS STORAGE ressed as per cent dry weight) Treat-merits 35° F Treated Days before harvest 64 (July 19) 30 (Aug. 2) Control Dry weight Total N Starch 19.37 19.70 19.32 1.77 1.72 1.69 59.96 60.6l 59.23 19.50 19.93 20.59 1. 6? 2 0 .1 8 21.72 23.19 Reducing sugar 0.80 ion-reducing sugar 9.06 3.10 2.72 2.89 1.52 6i|.*91 66.15 65 0DP 3«30 2.94 3.46 1.19 1.18 1.20 1. 6l 1.72 1.57 6 9 .8i+ 70.03 68.75 0.18 0.30 0.19 1.08 0.74 1.17 . 9.63 45° F Treated 6i| (July 19) 50 (Aug. 2) Control 1.77 55° P Treated Control 64 (July 19) 50 (Aug..2) ‘ 'Each value listed represents an average of four replications. ru .n TABLE; VII SUMMARY OP THE SPPEOTS OF MALEIC HYDRAZIDE ON Till COMPOSITION OF IRISH COBBLER POTATOES AFTER 25 WEEKS STORAGE AT 35, 45, AND 55° F (Expressed as per cent dry weight) Treatments Days before harvest Treated Control LSD 5 per cent LSD 1 per cent Dry -weight 6ij. Oh n Q 5o Total N Starch Reducing sugar 1.39 65.65 4 .8k 20o22 1.65 65.9? 4 .2 2 2 0 .8 1 1.59 65.00 G-o 2p 0 ,4 6 0.62 0.058 Non-reducing sugar JL • { Li. 1 .63 No Significant Differences 0 .0 7 9 fN "l IJ 28 C. The Yield and Storage Sprouting Three Varieties of Potatoes as Affected by Post-Emergence Foliar Sprays of Maleic Hydrazide Procedure. Since young potato tubers were already initiated before the time of spray application in the pre­ vious two experiments, it was suggested that foliar sprays of maleic hydrazide be applied to the potato vines on emer­ gence from the soil to determine whether such early spray applications would effect the yield or storage sprouting of the potato tubers. Accordingly, such a single aqueous spray of 2500 ppm of maleic hydrazide was applied to the foliage of the Irish Cobbler and Sebago varieties on June 1 5* 195>1* Plants of the hUsset Rural variety were similarly treated on June 20, 195>1* Treatments were replicated on rows 15 feet in length. Harvests were made and the yields were recorded on September 18, 1951* Ten-tuber samples were taken from the replicates of each treatment and placed in paper bags which were then placed in storage at 5 5 + 2 ° P. On April \±, 1952, after approximately 6 months, the potatoes were removed from storage and desprouted. The weight of the sprouts for each sample of 10 tubers was determined,, Results. Post-emergence sprays of maleic hydrazide at 2500 ppm significantly reduced the yield of Irish Cobbler, 29 Sebago and. Russet Rural potatoes out did. not signif .i-canbly affect th© weight in grams of sprouts per 10 tubers between maleic hydrazide treated, and comparaole non-treated sarripl.es after six months storage at 55° F (Table VIII)* TABLE VIII THE EFFECTS OF POST-EMERGENCE FOLIAR SPRAYS OF MALEIC HYDRAZIDE APPLIED APPROXIMATELY 1+ MEEKS AFTER PLANTING ON THE YIELD AT HARVEST AND STORAGE SPROUTING OF POTATOES AFTER 6 MONTHS STORAGE AT 55° F (MEAN VALUES FOR IRISH COBBLER, SEBAGO AND RUSSET RURAL) Treatment Yield Pounds of tubers per l5 foot row Sprouting Grams of sprouts per 10 tubers t Maleic hydrazide (2500 ppm) 11+.8 80,5 ^Control 20 0^ 103*5 LSD 5 per cent LSD 1 per cent i f . 86 8.91 No Significant Diff, 30 D. storage Sprouting and Quality of Sebago Potatoes as Affected by Concentration of Preharvest Foliar Sprays °f Maleic Hydrazide and Soil Type Procedure. Single aqueous sprays of y00, 1000, and 25>OQ ppm of maleic hydrazide were applied August 10, 1951« to the foliage of the Sebago variety grown both on mineral and muck soil. These treatments were replicated on five hill plots on the two soil types. Harvests were made on September 30, 195>1> and tentuber samples were taken from the replicates of each treat­ ment and placed in paper bags which were then placed in storage at 55 + 2° p. On April ip, 1952, after approxi­ mately 25 weeks storage, the potatoes were removed from storage, photographed and desprouted. The weight of the sprouts for each sample of ten tubers was determined,, Results. Foliar sprays of maleic hydrazide at 500, 1000, and 2500 ppm applied approximately seven weeks before harvest on the Sebago variety grown on either mineral or muck soil resulted in a reduction in weight of sprouts when any of the three spray concentrations were compared with control samples (Table IX, Figures 1 and 2). No differences were noted as to any possible influence of soil type and the effectiveness of the three concentrations of the chemical used. However, the non-treated potatoes on the mineral soil had fewer sprouts than those grown on muck soil. 31 TABLE IX SPROUTING OF SEBAGO POTATOES ORIGINALLY GROWN ON TWO SOIL TYPES AFTER 6 MONTI-S AT 55° F AS AFFECTED BY VARIOUS SPRAY CONCENTRATIONS OF MALEIC HYDRAZIDE Treatments Grains of sprouts per 10 tubers Muck soil Mineral soil Mean Treated 500 ppm 1000 ppm 2500 ppm Control Feans 7o5 0.0 7.5 0.5 0.0 7.5 3.8 0.0 I3 8 0 O 60.5 99.2 7o0 38 .1 17.1 .32 Figure 1* Non-treated Sebago potatoes after 6 months storage at £5° F 33 Figure 2* Sebago potatoes treated with 25>00 ppm of maleic hydrazide seven weeks before harvest and after six months storage at 35° F 34 7* Field of Potato Plants Grown from Tubers Which Were Harvested from Plants Sprayed with Maleic Hydrazide Procedure. Since approximately five per cent of the annual 375 million bushel potato crop in this country is used for seed purposes { ) , any chemical that retards sprouting or growth of potato vines poses the question as to the effect of this chemical on seed stock potatoes. Therefore, tubers of the Pontiac variety harvested from plants, the vines of which were sprayed with the maleic hydrazide concentrations in 1950 as outlined in Table X, were planted May 5» 195lj on a productive Hillsdale sandy loam soil in twice replicated 10-tuber rows. Results. Prom Table X it can be seen that concen­ trations of 1000 and 2500 ppm on July 15, 1950; 500, 1000, and 2500 ppm on August 2, 1950; and 2500 ppm of maleic hydrazide on August 11, 1950, resulted in no yield or a marked reduction in the harvest of tubers in comparison with comparable non-treated control samples. Five hundred ppm of maleic hydrazide applied September 2, 1950, I4.8 hours before the vines were cut off, increased the yield of tubers in the 1951 crop aoout 90 per cent as compared with non-treated control samples. The 2,4,5-tri- chlorophenoxyacetic acid treatments resulted in a reduction in yield approaching the five per cent level of significance. 35 TABLE X THE COMPARATIVE YIELDS OF POTATO PLANTS (1951) GROWN FROM PONTIAC TUBERS, HARVESTED FROM PLANTS SPRAYED (1950) AT VARIOUS TIMES AND WITH VARIOUS CONCENTRATIONS OF MALEIC HYDRAZIDE AND 2,4, 5 -T R ICHLOROPHENOXYACMTC ACID Spray treatmenbs Chemical Maleic hydrazide 2 ,4 ,5 -trichlorophenoxyacetic aci d Control PPm Days before harvest Yield Lbs./lO hills 5 oo 1000 2500 49 (July 15) 2 8 .0 4-5 Jo 0 5 oo 1000 2500 31 (Aug. 2) 1 .5 0 .0 0 .0 500 1000 2500 22 (Aug. 11) 1 9 .5 1 0 .0 0.0 <00 1000 2500 2 (Sept. 2) 4 o .5 3 0 .0 2 1 .0 5o 49 100 31 200 22 1 1 .0 21.0 36 Onions A • The Effect, of Concentration and Time of Application of Preharvest Foliar Sprays of Maleic Hydrazide on the Yield and Storage Sprouting and Breakdown of Five Onion Varieties Although both sprouting and rooting of onion bulbs can be controlled by low temperature at a low humidity (39* 32), most of the northern onion cron is held in common storage. Depending upon the variety, location, and the weather, commercial onion producers can expect a 5 to 50 per cent loss in the storage of their harvested crop (7 , 12, 26, 29, [p., 70) . Snrouts and root growth account for approxi­ mately 85 per cent of this loss according to Gaylord (29)* The successful use of maleic hydrazide as a sprout inhibitor by Wittwer et al (78, 79, 80) made it desirable to find out the optimum concentration and time of appli­ cation for applying this chemical to a commercial onion crop. Accordingly, the following experiment was designed. Procedure . ' On May 8 , 19.50, seed of Brigham Yellow Globe, Early Yellow Globe, Downing Yellow Globe and Michigan State College Sweet Spanish onions was planted in ll).-inch rows on Carlyle muck soil and fertilized with 1000 pounds of a 0-20-20 fertilizer plus 25 pounds of copper sulphate per acre. As outlined in Table XI, single aqueous sprays of 500, 4 37 1000, and 2300 ppm of maleic hydrazide were applied to the foliage of the four onion varieties at 29, 11, and 2 days before harvest. in length. Treatments were replicated on rows 13 feet Three-gallon hand sprayers were utilized in applying the chemical. The leaves were sprayed to run-off. Triton B 19.36 (Rohm and Haas, Philadelphia, Pa.) was added at a concentration of 0*1 per cent as a wetting agent. The Early Yellow Globe and Brigham Yellow Globe var­ ieties were pulled and piled in windrows to cure on August 31, and the Downing Yellow Globe and the Michigan State College Sweet Spanish -varieties on September 1. On Sep­ tember d and 9 all four varieties were hand topped and the yields were recorded. After approximately three weeks of field curing in bushel crates, 10-bulb samples were taken from the replicates of each treatment and placed in paper bags on September 23. W5 th the Early Yellow Globe variety, Individual nulos in all samples were labelled and. initial weights recorded. The bagged onion samples were then placed on shelves in a common onion storage. Yellow Sweet Spanish onions were grown from green­ house plants seeded March 1 and transplanted into a field of productive mineral soil the second week in ivay, 1930. . l As outlined in Table XIII, single aqueous sprays of 300, 1000, and 2300 ppm of maleic hyarazide were applied to two 13 foot row replicates at ig3, 11, and 2 days before harvest in a manner similar to that already described for the onions grown on muck soil. The samples were field cured, topped and yield data recorded as previously descri _>ed. On September 20, 10-bulb samples were taken from the repli­ cates of each treatment ana placed in paper bags. These samples were then placea in common stora e along with the four other onion varieties. On May 19, 1951, after approxi- mately eight months, the five onion varieties were removed from storage, weighed and the oer cent of sprouting and breakdown determined for each 10-bulb sample. Results. Harvest records showed no reduction in the yield of onions resulting from any of the spray treatments (Table XI). The. per cent sprouting- for 10-bulb samples after eight months common storage for the various treatments applied to the four varieties grown on muck soil is given in Table XI • All treatments gave a reduction in per cent sprouting with the exception of 500 ppm of maleic hydrazide applied 48 hours before the onions were pulled. Twenty- five hundred ppm of maleic hydrazide -applied 29 and ,11 days before harvesting gave complete sprout inhibition (Table XI). There was no difference in the per cent break­ down of the four onion varieties for any spray treatment applied 2 and 11 days before harvesting or for the 500 ppm of maleic hydrazide applied 29 days before harvesting* Both the 1000 and 2500 ppm concentration of maleic hydrazide applied 29 days before harvest resulted in marked increases in per cent breakdown when compared with comparable non­ treated samples (Table XI)* Although initial and final weights after storage of individual bulbs of the Farly Yellow Globe variety were recorded for all treatments, there was no significant reduction in weight losses when bulbs and the attached sprouts were weighed to ether (Table XII). with the Yellow Sweet Spanish variety, a preharvest foliar spray of maleic hydrazide applied days before harvest not only resulted in from 9*5 to 62.0 per cent unmarketable spongy onions at harvest (Figure 3) but also greatly increased the breakdown of these onions in storage (Table XIII). TABLE XI YIELD AT HARVEST AND STORAGE SPROUTING AND BREAKDOWN OP BRIGHAM YELLOW DOWNING YELLOW GLOBE, EARLY YELLOW GLOBE AND MICHIGAN STATE COLLEGE 31 SPANISH ONIONS AFTER 8 MONTHS IN COMMON STORAGE AS AFFECTED BY VARIOUS SPRAYS OF MALEIC HYDRAZIDE Spray treatments Yield (Lbs»/l5 ft, row) Sprouting (Per cent) B re akdow: (Per oen Chemical ppm Days before harvest Maleic hydrazide 5oo 1000 29 16 .8 " 16.5 15.1 5oo 1000 2500 11 15*9 16.3 32.5 21.3 0.0 6.25 1.25 7.50 5oo 1000 2500 2 16.1]. 13.6 16.1 56.3 35.0 20.0 ■3aV1P 9 3.75 2.5o 15.9- 68.8 5.00 2500 Control 5.0* 2.5 0.0 8.75' 22.50 25.00 tv 'Each value represents the mean of samples harvested from two replications. ■oP" TABLE XII THE EFFECTS OF FOLIAR SPRAYS OF MALEIC HYDRAZIDE ON PER CENT WEIGHT LOSS OTHER THAN FROM SPROUTING IN EARLY YELLOW GLOBE ONIONS HELD 8 MONTHS IN COMMON STORAGE Spray- treatments Chemical Maleic hydrazide m -^ Days before harvest 500 1000 29 4.3 7.1 7.5 ii 8,5 5.8 5.3 2 7.5 7.5 7.6 2500 5oo 1000 2500 ■ 500 1000 2500 Control (no treatment) Treatments LSD 5 per cent LSD 1 per cent Per cent fresh weight lost per 10 bulbs 9.1 No Significant Dif'f. TABLE XIII THE INDUCTION OP SPONGINESS AT HARVEST AND TK'S STORAGE SPROUTING AND BREAKDOWN OF SWEET SPANISH ONIONS AFTER 3 MONTHS IN COMMON STORAGE AS AFFECTED BY CONCENTRATION AND TIME OF APPLICATION OF MALEIC HYDRAZIDE SPRAYS Spray treatments Chemical >00 1000 Days before harvest kS 9.5"”’ 62*0 hi ^ '4-0Jt> 11 0.0 0.0 2500 5oo 1000 2500 500 1000 2500 O 0.0 0.0 0.0 0.0 Breakdown (Per cent) 60.0* 0.0 0.0 25.0* 85.0 85.0 3 0 .0 15.0 15*0 5oQ 10.0 15.0 55.0 10.c 1 5 .0 25.0 10.0 5.c 0.0 O' Control 0 .0 Sprouting (Per cent) 0 . 0 Maleic hydrazide ppm Sponginess (Per cent) Each value represents the mean of samples harvested from two replications. k3 Figure 3, Injury of Yellow Sweet Spanish onions caused by early foliar sprays of maleic hydrazide. Left, normal control bulbs; right, spongy bulbs resulting from maleic hydrazide applied too early as a foliage spray B, The Composition, Yield and Storage Sprouting and Break­ down of Y-I4-Q Onions Held, under Bulk Storage Conditions Many recently Introduced high yielding hybrid onion varieties have poor keeping qualities, Foskett _et al (26) and Wittwer and Paterson (??)o The possible use of these high yielding onion varieties in combination with the control of sprouting of onions established by Wittwer et_ al (76, 77, 78» 79, BO) and verified by Johannessen and Oebker (38 ) suggested the following experiment in which the hybrid onion variety Y-1|.0 was given a preharvest foliar spray of maleic hydrazide and then held with comparable controls under bulk storage conditions* Procedure* On May 9» 1951 > Y~l\.Q hybrid onion seed (Associated Seed Co,) was planted in lip-inch rows on Carlyle muck soil and fertilized with 1000 pounds of I4.-IO-2O fertilizer plus 25 pounds of copper sulphate per acre, A single aqueous spray of 2500 ppm of maleic hydrazide was applied to the foliage of the Y-ij.0 onions 21 days before harvest. This treatment was replicated I4.O times on 1/113 acre four row beds* Forty adjacent and paired non-treated beds served as controls. Three-gallon hand sprayers were utilized In applying the chemical and the leaves were sprayed to run-off. of spray were used per acre, Approximately 226 gallons Triton B 1956 was actded at a concentration of 0,1 per cent as a wetting agent. On August 8 , at the time of the spray application, the tips of the onion leaves were dead and about one-third of the tops had fallen over. One week after the spray application, Blast was rapidly spreading throughout the field and over one-half of the onion tops were dead. On August 29, the treated and non-treated onions were harvested with a Chickering vegetable harvester and the yields for II4. treated and ll}. non-treated plots were recorded. At the time of harvest, 10-bulb samples were taken from the ij.0 replicates of each treatment and placed in paper bags. These 10-bulb samples were held four months in common storage and three months at 55 + 2° F, On March 21, 1952, the 1 O-bulb samples were removed from storage and the per cent of sprouting and breakdown and of marketable onions was determined. Immediately after harvest, weighed samples of both treated and non-treated onions were placed in venti­ lated bins (8 ) of approximately 200 bushels capacity. In addition, weighed crate samples of both treated and nontreated onions approximating a total of 500 pounds of each were placed in common storage after curing in the field. Both the bin containing the maleic hydrazide treated onions and the bin containing the non-treated onions were equipped with thermocouples installed at two, four and onehalf, and seven feet from the bottom of each bin to record the temperature within the separate bins during the storage period. On January 17, 1952, after approximately four and one-half months in common storage, the two bin and crate 46 samples of Y-4° onions were graded and weighed. Five comparable bushel crate samples were removed from both the treated and the non-treated bin as they were unloaded for grading. The per cent of sprouting and breakdown of market­ able onions was determined. At the time of loading the bins on August 29, 195l* and subsequent to the four and one-half months of common storage on January 17, 1952, samples of marketable Y-ij.0 onion bulbs from plants sprayed August 8 , 195l> with 2500 ppm of maleic hydrazide along with comparable non-treated control lots were analyzed (I4., 8I4., 85 ) for total nitrogen, reducing and non-reducing sugar. Per cent dry weight was determined by evaporating 100-gram samples of onion tissue preserved in 80 per cent ethyl alcohol to dryness, then drying the residue for five hours at 100° C before weighing the tared flasks for a final weight determination. Results. Both the bin and crate samples of Y-lj.0 onions sprayed with maleic hydrazide before harvest had a higher percentage of marketable onions than did comparable control samples; although neither had as high a percentage of marketable onions as did the wnbcoated Downing Yellow Globe variety held in a comparable bin storage (Table XIV), The untreated Y-I4.O onions had a higher percentage of rotting and sprouting in both bins and crate samples than did the maleic hydrazide treated Y-I4.O onions. There was, ^however, a lower percentage of rotting as well as sprouting in the Downing kl Yellow Globe non-treated onions than in either the treated or non-treated Y-lj.0 onions. The per cent weight loss not due to sprouting or rotting; was nearly identical for both the treated and non-treated bin samples of Y-lj.0 onior.s. An analysis of four random ^0-pound samples in both the treated and non-treated bins of Y-lj.0 onions showed a highly significant increase in the per cant of marketable onions, per cent breakdown of onions and a definite decrease in the per cent sprouting of the maleic hydrazide treated onions as compared with compara ;le non-treated control samples (Table XV). Harvest records showed no reduction in the yield of the Y-lj.0 onion variety resulting from the preharvest spray of maleic hydrazide (Table XVI)* As in the bin and crate samples, the per cent market­ able onions and per cent breakdown of onions in the 10bulb samples held four months in common storage and three o months at F, was greater for maleic hydrazide treated onions when compared with comparable non-treated control samples. Also there was a decrease In the per cent sprouting of maleic hydrazide treated onions in comparison with nontreated samples (Table XVI, Figures If. and £), No differences were found in percentage dry matter, total nitrogen, or non-reducing sugar. However, a signifi­ cantly higher value was found for reducing sugar in the control sample of Y-ij.0 onions when compared with maleic hydrazide treated onions immediately after harvest (Table 1*8 XVII). At the end of the four and one-half month storage period, there was a highly significant decrease in reducing sugar in the control sample of Y-lfO onions compared with almost no decrease in the maleic hydrazide treated sample over the same storage period. Although periodic temperature determinations in both treated and non-treated bin storages showed no significant differences between the temperature in the maleic hydrazide treated bin of onions and the comparable non-treated bin, Table XVIII shows that the control bin averaged a warmer temperature than the treated bin and also that the nontreated bin got progressively warmer from top to bottom while the bin containing onions treated with maleic hydra­ zide evidenced no such temperature gradient from top to bottom (3), I 49 TABLE XIV COMPARATIVE STORAGE QUALITY OP MALEIC HYDRAZIDE TREATED AND NON-TREATED Y-l+O AND NON-TREATED DOWNING YELLOW GLOBE FOLLOWING VENTILATED BIN AND CRATE STORAGE CONDITIONS* Treatments Condition after 4lr months storage Marketable Rotting and sprouting Shrinkage (per cent by weight) (Per cent (Per cent by weight) by weight) Y-40 Maleic hydrazide Bin 61.31 Crate 74.61 26.95 13.97 1 1 . 4 2 Y-ij-0 Control Bin Crate 50.24 20.11 11.77 16.71 13.40 5.71 14.26 9.00 37.99 63.18 Downing Yellow Globe Control Bin 72.34 Crate 85.29 11.74 *Data for Downing Yellow Globe onions provided by Boyd arid Davis (8). I TABLE XV THE EFFECTS OF A FOLIAR SPRAY OF MALEIC HYDRAZIDE ON THE KEEPING QUALITY OF ONIONS, VARIETY Y-lj.0, HELD IN VENTILATED STORAGE BINS OF 200 BUSHEL CAPACITY FOR MONTHS Detailed Analysis of Random Samples Average of k. random 50-pound samples in each bin Treatment Marketable (Per cent by weight) Sprouting (Per cent by weight) Breakdown (Per cent by weight) Sprouting and rotting (Per cent by weight) Treated 68.23 11.50 20 .2? 31.77 Control I4.8 .I4.2 36.56 15.02 51.58 8*20 12.72 2.93 8.19 LSD 1 per cent TABLE AVI AT HARVEST AND THE KEEPING QUALITY OF ONION, VARIETY Y-ij.0, AFTER ij. MONTHS IN COMMON STORAGE AND 3 MONTHS AT 55° P AS AFFECTED BY MALEIC HYDRAZIDE SPRAYS YIELD Treatment Yield (Lbs. per Marketable'*' Sprouting-'" (Per cent) (Per cent) Bre akdown"'r (Per cent) 1/113 A) Treated 396, ij. 78,66 1.84 1 9 .5 0 Control 382,6 6.85 88.15 5.00 '‘Each value represents the mean of four samples, 4 52 Figure Ii, Non-treated Y-lbO onions after four months in common storage and three months at 55° F Figure 5> Y-ifO onions treated with 2f>00 ppm of maleic hydrazide 18 days before harvest, and after four months in common-storage and three months at F 51 TABLE XVII THE EFFECT CP MALEIC HYDRAZIDE OH THE COMPOSITION OP Y-l+O ONIONS DFRINO- i+f MONTHS OF COMMON STORAGE (Expressed as per cent dry weight) Dry weight Total N Reducing sugar Non-reducing sugar Treated ?o?0 2.71 1+2.Ok 13.06 Control 7.35 2.76 i|5.5i 16.13 Treated 7.30 1.91 1+2.13 12.1+0 Control 7.1+9 2.22 39.37 12.21+ Treatments Before storage After storage LSD 5 P®f cent LSD 1 per cent No significance 3.08 p.ll No significance 55 TABLE XVIII STORAG-E BIN TEMPERATURES OP Y-ij.0 ONION BULBS AS AFFECTED BY A FOLIAR SPRAY OF MALEIC HYDRAZIDE o *3 Treatments Treated Non-treated (Average of 17 temperature determinations) o *1 Height of the m o couples in storage bins (feet) 2,0 52.53 52.91 ii-»5 52.29 53.50 7.0 52.45 5 4 . 4 4 Means 5 2 .I4 . 2 53.61 56 Root Crops A. The Effect of Concentration and Time of Application of Preharvest Foliar Sprays of Maleic Hydrazide on the Yield at Harvest and the Storage Sprouting and Break­ down of Sugar Beets and Five Vegetable Root Crops Although vegetable root crop storage is not as important in the northern states as the storage of potatoes and onions, still food processors have to hold such crops as carrots and sugar beets for some time after the peak of harvest, and storage losses from sprouting may be excessive (60, 73, 74* 75) • Also home gardeners may desire to store root crops for several months in the Pall and Winter. The successful use of a 3prout inhibitor such as maleic hydraside would represent a great saving in such stored produce. As Wittwer e_t al (76 , 77* 78* 79* 80) have shown maleic hydrazide to be an effective sprout inhibitor of such crops as onions and carrots, it was suggested that maleic hydra­ zide could also be used as a sprout inhibitor on other vegetable root crops. The following experiment was con­ ducted to find outthe effect of concentration and time of application of maleic hydrazide on carrots, rutabagas, turnips, beets, parsnips and sugar beets. Procedure. The crops were planted on a productive Hillsdale sandy loam soil in 1950 as follows: Parsnip, variety Hollow Crown Thick Shoulder - June 5 Carrot, varieties Chantenary, Danvers, and Nantes - June 6 57 Sugar beet 3 - June 9 Rutabaga, variety American Purple Top - June 1 $ Beet, variety Detroit Dark Red - July 3 Turnip, variety Purple Top White Globe - July ll| As outlined in Tables XIX, XXTI, XXIII, XXV, XXVII, and XXVIII, aqueous sprays of various growth substances were applied to the foliage of these root crops at definite intervals before harvest in the same manner as previously described for potatoes and onions. Treatments were repli­ cated twice on rows 15 feet in length. Prom October 7 to October 28, these root crops were harvested and the yields recorded. Duplicate 10-root samples were taken from the replicates of each treatment for each variety of each crop and placed In paper bags. With the Ghantenay carrot variety, Individual roots in all samples were labelled and initial weights recorded,. One of the duplicate 10 -root samples from each of the two replicates of all treatments of all crops was then placed in storages maintained at 45 + 2° F and 55 + 2° F* At harvest, the three carrot varieties were observed to have a heavy infection of Aster Yellows, Although only sound-appearing roots were selected In sampling, many of these roots developed typical Aster Yellows symptoms in storage. On January 6, 1951# after approximately three months, the produce was removed from the 55° F storage, weighed and desprouted. The weight of sprouts for each sample of 10 58 roots was determined* Subsequent to the three months of storage the sugar beets were analyzed for sucrose* In 1951, this same work was repeated with the following exceptions: Sugar beets were not included* A single aqueous spray of 2500 ppm only of maleic hydrazide was applied ten days before harvest to the foliage of the various root crops. Treatments were replicated on three row plots IS feet in length. All crops were stored at 55 + Results* In 1950 and 1951 harvest records showed no reduction in the yield, size, or quality within a given variety of any crop resulting from any of the maleic hydra­ zide spray treatments (Tables XIX, XXI, XXII, XXIII, XXIV, XXV, XXVI, XXVII, XXVIII). However, the September 6, 1950, application of 1000 ppm of benzo-thiozole-2-oxyacetic acid resulted in a highly significant decrease in yield (Table XIX). The carrot roots from this spray application had a white corky area on the shoulder. In general, spraying the various root crops in 1950 and 1951 with maleic hydrazide resulted in a reduction of sprouting. This chemical did not seem to pr event the breakdown in s torage of any of the root crops except carrots, while the benzo-thiozole-2-oxyacetic acid resulted In a greater storage loss of carrots. The specific response of the individual crops are as follows: Carrots: The Increase in the sprouting of the carrots sprayed September 6, 1950, with 1000 ppm of maleic hydrazide approached statistical significance and there was a signifi­ 59 cant Increase In sprouting with those sprayed September 30 with 500 ppm of maleic hydrazide, otherwise, there was no difference on any of the spray treatments or the controls (Table XIX). The September 30 spray of 2^00 ppm of maleic hydrazide gave a highly significant decrease in per cent breakdown when compared with the control samples. The October 5> spray of 25)00 ppm. of maleic hydrazide resulted in a significant decrease in per cent breakdown during storage (Table XIX)0 A significant increase in storage breakdown resulted when the three carrot varieties were sprayed ’ with 1000 ppm of benzo-thiozole-2-oxyacetic acid September 30, 1950 (Table XIX). Although Initial and final weights after storage of Individual roots of the Chantenay variety were recorded for all treatments, there was no apparent reduction in weight losses when roots and the attached sprouts were weighed together (Table XX). In 1951* there was a pronounced reduction (Table XXI) In the sprouting of carrots sprayed 10 days before harvest with a 25)00 ppm concentration of maleic hydrazide as com­ pared to non-treated samples (79* 80). The various treatments of the different root crops In the F storage responded similarly to the treatments O _/o In the 55 F storage except that sprouting at the Ip F temperature was reduced. at all was evident* In some instances no sprouting THE EFFECTS OF MALEIC HYDRAZIDE AND PHNZ0-THI070LE-2-GXYACETIC ACID ON THE YIELD AT HARVEST AND STORAGE SPROUTING AND BREAKDOWN OF CHANTENAY, DANVERS, AND NANTES CARROTS AFTER 3 MONTHS AT 55 F (1950) Yield (Lbs, A 5 ft. row) Spray treatments Chemical Maleic hydrazide ppm 500 1000 2500 5oo 1000 2500 500 31 (Sept, 6) Control LSD 3 oer cent LSD 1 per cent 7.5 io,5 9.0 35.0 23.3 12.3 9.6 5.3 20 •0 23.3 11.7 15.3 15.0 8.5 7.5 6.5 3 0 ,0 16.7 8,2 2.5 8-5.0 m Q J. d j ^ 16,8 , 17.3 6 (Sent. 30) 1 9* -i-S. J$J 16.7 15.3 2 (Oct. 5) 2500 1000 Breakdown (per cent) DaJ s before harvest 1000 Benzo-thiosole-2oxyacetic acid Sprouting (Per cent) 31 (Sept. 6) 16.8 20.0 31.7 1000 6 (Sent, 30) Ik.8 2.3 60,0 1000 2 (Oct, 5) 16.8 k.8 83.3 15.2 5.5 36.7 5.84 17.07 23.95 i!-.77 6.J+0 7.30 TABLE XX PER GENT WEIGHT LOSS OTHER THAN FROM SPROUTING IN CHANTENAY CARROTS DURING 3 MONTHS STORAGE AS AFFECTED BY FOLIAR SPRAYS OF MALEIC HYDRAZIDE AND BSNZ0-THI0Z0LE-2-0XYACETIC ACID (19£0) Spray treatments Chemical Maleic hydrazide Renzo-thiozole-2oxyacetic acid Control ppm Days before harvest Per cent fresh weight loss per 10 root Storage at ££^ F Storage at 1|.£^ F £00 1000 2£00 31 14*9 14.7 11.1 17.9 l4*l 14.7 £00 1000 2£00 6 i£*4 11.8 10.7 14.8 14.4 19.6 £00 1000 2£00 2 12.3 18.2 1000 10,4 16.9 14.8 14.2 31 18,9 19.3 1000 6 19.0 18.8 1000 2 14.9 17.4 10.8 13.9 62 T ABLE XXI THE EFFE CTS OF M A LB I C H Y D R A 21 BE ON THE Y I E L D AT H AR V ES T A N D ST O RA G E SPROU TING OF CHANTENAY, DANVERS, A N D NANTES CARROTS A FT E R 11 W EEKS AT 55° F (1951) Tre atment Yield (Lbs./lp f t * ' r o w ) Sprouting (Gms./lO roots) *p m T re a t e d l 6 o0‘:‘ Control 1 5J+ 2*Ij. 17.0 '"Each value repre sents the me a n of two replications* 63 Turnip: I n 1950, th ere w e r e no a m o n g any of the t r e a t m e n t s , in s p r o u t i n g or b r e a k d o w n .aowever, t h e r e w as from plants less s p r o u t i n g of the r o o t s h a r v e s t e d s p r a y e d w i t h 25>00 p p m of m a l e i c h y d r a z i d e 2ij., 6 a n d 2 d a ys b e f o r e h a r v e s t ever, 13 jo'iples apparent reductions times the w e i g h t as c n c o m p a r a b l e (Table X X E I ) . T h e r e was, how­ of s p r o u t s o n the n o n - t r e a t e d roots from plants s p r a y e d 1 0 days b e f o r e h a r v e s t w i t h 2 5 0 0 p p m of m a l e i c h y d r a z i d e i n 1951 (T a b l e XX I V ) . Rutabaga: a p p l i e d 31 > 7> in a d e c r e a s e controls hydrazide Th e 2,900 p p m an d 2 days b efore h a r v e s t I n 1 9 5 0 r e s u l t e d in s p r o u t i n g (T ab le X X I I I } * a p p l i e d 31 s p r a y of m a l e i c h y d r a z i d e in c o m p a r i s o n w i t h n o n - t r e a t e d The 1.000 p p m and 2 days the 5 0 0 p p m o f m a l e i c h y d r a z i d e harvest gave bagas a decrease in In comparison with as a o o l i e d 7 days be f o r e those not treated. (Table XXIII). treatments There was more prevented any a c c u r a t e a n d the c o n t r o l samples (Table t h a n 1 0 0 t i m e s the w e i g h t of s p ro u ts o n the n o n - t r e a t e d r o o t s olants as w e l l of the c o m p a r i s o n of b r e a k d o w n b e t w e e n any of the maleic hydrazide XXIII). be f or e h a r v e s t s p r o u t i n g of the t r e a t e d r u t a ­ V a r i a t i o n i n the p l a n t m a t e r i a l analysis spray of m a l e i c as on those roots h a r v e s t e d fr om s p r a y e d w i t h 2 5 0 0 p p m of m a l e i c h y d r a z i d e 10 days b e f o r e h a r v e s t i n 1951 (Table XXIV)* YIELD AT HARVEST AND STORAGE SPROUTING AND BREAKDOWN OP PURPLE TOP WHTTZ GLOBE TURNIPS A.FTER 2 MONTHS STORAGE AT 55 P AS AFFECTED BY MALEIC HYDRAZIDE SPRAYS (1950) vi d (Lbs,/l5 ft, r■ow ) Spray treatments Chemical Maleic hydrazide Control ppm Days before harvest 500 1000 2500 Zk 500 1000 2500 900 1000 2500 Sprouting (Gms./lO roots) Breakdown (Per cant) 27.5* 30.0 27.0 21. 0* 61.0 13.0 75.0* 35.0 60.0 6 31.0 35.5 31.0 15.Q 2l|.«0 15.5 70.0 55.0 35.0 2 25.0 rjr' r-' 28.0 29.5 16.5 21.5 35.c 55.0 65.0 22.5 35.5 55.0 *Each value represents the means of samples harvested from two replications® TABLE XXIII THE EFFECTS OP MALEIC HYDRAZIDE OH THE YIELD AT HARVEST AND STORAGE SPROUTING AND BREAKDOWN OP AMERICAN PURPLE TOP RUTABAGAS HELD 3 MONTHS AT 55° F (1950) Chemical Spray treatments Day's before ppm harvest Maleic hydrazide 500 1000 2,900 9oo 1000 2500 *i7 Sprouting (Grins ,/l0 roots) 74.0* 39.0 ii-9.5 27.5 47*0 48 *5 55.0 1.5 5 0 .0 5 ,o 15.0 5o,5 0.0 15.0 35.0 5.0 6.5 L\Z .p 2500 kl.O 8 2 ,0 36.5 7.5 42,5 106,5 2 Breakdown (Per cent) -x50.0 46.0 1)4,0 1000 500 Control 31 Yield (Lbs0,/l5 ft. row) 0.0* 30.0 5o. c "’Each value represents the means of ssrniples harvested from two replications cr- mt TABLE XXXV YIELD AT HARVEST AND STORAGE SPROUTING OF PURPLE TO? WHITE GLOBE TURNIPS AND AMERICAN PURPLE TOP RUTABAGA AFTER 3 MONTES STORAGE AT 55 F AS AFFECTED BY FOLIAR SPRAYS OF MALEIC HYDRAZIDE (1951) Turnip Treatments Yield of roots (Lbs<,/l5 ft. row) Treated 69.0* Control 69.7 Sprouting (Oris./lO roots) 12.0* 160.0 Rutabaga Yield of roots Snrouting (Lbs./l6 ft. rovr) (0ms,/l0 roots) k k .7 * 60.7 '"'Each value represents the mean of samples harvested from two replications* 1.0* 101.0 67 Beets: The 2500 ppm spray of maleic hyarazide applied September 20, I960, resultea in a decrease in sprouting of beets when compared with comparable non-treated samples (Table XXV) o In 1951 there was a reduction in sprouting of best roots from plants sprayed with maleic hydrazide in comparison wit h non-1 re at ed samole s (Table XXVI). Shriveiln< was pronounced in all stora-.e tests# Parsnip: There was no reduction of sprouting in storage between roots from treated and non-treated. plants (Table XXVII)• In both 19.50 and 1951 the parsnip roots shriveled badly while in storage (1, 9, 5h» 57). Sugar beet: The 2500 ppm spray of maleic hydrazide applied 50, 6, and 2 days before harvest resulted In a decrease In the sprouting of sugar beet roots in comparison with roots from non-treated control samples (Table XXVIII) (73, Yk-t 75, 77) o There was no significant difference in the per cent sucrose between any of the treatments (Table XXVIII)* TABLE XXV THE EFFECTS OF MALEIC HYDRAZIDE OF THE YIELD AT HARVEST AND STOP.A OF DETROIT DARK RED BEETS AFTER 3 MONTHS AT 55° F (1?50) Spray treatments Chemical Maleic hydrazide ppm 500' 1000 Days before harvest 2if (Sent, 20) 2500 5 00 6 (Oct, 3} 1000 2500 500 Control 2 (Oct. 12) Yield (Lbs./l5 ft, row) Sprouti ng (Gris ./lO roots) 16.5" 25.0 20.0 7.5* it-05 17*5 21.0 26.0 11.5 ij-.O 1.5 31.0 0 .5 1000 22.0 1 2 ,0 8 .0 2500 23*0 5.5 22.0 5.5 Each value represents the mean of samples harvested from two replications« ON (JO 69 TABLE XXVI YIELD AT HARVEST AND STORAVE SPROUTING OP DETROIT DARI RED BEETS AFTER 3 MONTHS STORAGE AT 55° F AS AFFECTED BY FOLIAR SPRAYS OF MALSIC HYDRAZIDE (19^1) Treatment Yield (Lbs./l5> ft. row) Treated 10.7* Control 9.3 Sprouting (Gms./lO roots) 0.3* ‘Each value represents the mean of samples harvested from t '70 r eplications• TABLE XXVII THE EFFECTS OF TIME OF APPLICATION AND CONCENTRATION OF MALEIC HYDRAZIDE SPRAYS ON THE YIELD AT HARVEST AND STORAGE SPROUTING OF HOLLOW CROWN THICK SHOULDER PARSNIPS AFTER 3 MONTHS AT 55° F Spray treatments Chemical Maleic hydraside Control -* >pm Days before harvest Yield (Lbs./l5 it. row) Sprouting (Gms •/10 roots) 3 0 .o’" 2?.5 25.0 5.0* •'+.5 3.0 5>00 1000 2500 5o 500 1000 2500 6 3 0 .0 26,0 31.5 14.5 7.5 7.0 5oo 1000 2500 2 32,0 29.0 •3A E 13.0 6.0 12.5 29.0 Each vali’.e represents the mean of samples bar zested from two replications, TABLE XXVIII YIELD AT HARVEST, STORAGE SPROUTING AND SUCROSE CONTENT OF SUGAR BEETS AFTER 3 MONTHS STORAGE AT 55° F AS AFFECTED BY FOLIAR SPRAYS OF MALEIC HYDRAZIDE Spray treatments Chemical Maleic hydrazide Control ppm Days before harvest 500 1000 2500 50 5oo 1000 2500 6 5oo 1000 2500 2 Yield (Lbs,/l5 ft, row) 4 4 .o* 44.5 Sprouting (Gms./1 0 roots) 73 .5* 64.5 Sucrose (per cent fresh w t .) 15 .8* 14.5 15.7 42.0 11,0 48.5 1 2 0 .0 15.2 5i.o 38.0 53.5 17.5 14.9 15.5 40.0 40.0 4 6.5 45.5 42.5 32.0 15.7 21.0 15.6 15.6 76.5 15.7 ^Each value represents the mean of samples harvested from two replications. TABLE XXIX THE EFFECT OF MALEIC HYDRAZIDE TREATED POTATOES ON THE PARTIAL PRESSURE OF CARBON DIOXIDE IN PLIOFILM BAGS AND THE RELATIONSHIP OF THIS ALTERED CARBON DIOXIDE ATMOSPHERE TO THE SUGAR COMPOSITION OF THE TUBERS AFTER 6 WEEKS STORAGE AT k $ ° F Treated Control Reducing sugar (Per cent fresh w t .) Non-reducing sugar (Per cent fresh wt.) Carbon dioxide (Per cent) Oxygen (Per cent) 7/19/51 0,00 12.1 1.67 0 .14-7 8/ 2/51 1.00 18.1 1.66 0 .S14- 1.85 10.0 1.36 0.32 Treatments IV. DISCUSSION Potatoes Several chemicals (11 , 16 , 65) have been suggested as effective for the inhibition of sprouting of potatoes during storage. Applications of sprout inhibitors to growing crops may have distinct advantages with crops that are ordinarily sprayed for the control of diseases and insects. The rela­ tive effectiveness of the chemical may be much greater on growing crops because of the rapid absorption, penetration, and translocation to the desired plant organs, which usually occurs with foliar applications to growing crops as con­ trasted with post-harvest treatments which may fail unless special provisions facilitating penetration are provided (25, i+6 ). Formulations of alpha-naphthaleneacetic acid and 2 ,ij.,5 -trichlorophenoxyacetic acid, when sprayed on growing potato plants to reduce or inhibit subsequent sprouting during storage, have frequently resulted in tuber injuries and in a reduction of quality (25* 6I4., 8l). In this connection, maleic hydrazide induces no apparent abnormalities or loss of quality if the chemical is applied at the proper time and at concentrations which effect per­ manent dormancy. Prolonging dormancy with maleic hydrazide is unique in that apical dominance is apparently destroyed In both the tuber and in the potential individual sprouts on the 1 Ik tuber. Unlike the knobby suppressed sprouts which may eventually develop on the apical ends of tubers following treatments with the methyl ester of alpha-naphthaleneacetic acid and 2 ,14-,5-trichlorophenoxyacetic acid, maleic hydra­ zide inhibits completely the apical region of the potato and growth, when it occurs, is initiated at the basal end of the tuber* Several economic problems exist in the storage of potatoes. At relatively low temperatures (32 to I4.50 P) a degradation of starch occurs and sugars accumulate resulting in a sweetened product of poor quality for dehy­ dration, chip manufacture, and ordinary table use. Con­ versely, if relatively high (above I4.O0 P) storage tempera­ tures are utilized, losses from sprouting and shriveling occur along with rapid deterioration of edi die quality. According to Arreguin-Lozano and Bonner (3)» the regulation of starch degradation and sugar synthesis by temperature in potato tubers resides in a powerful phosphorylase enzyme rather than an amylase system. At least three reactions are involved in the temperature effects: (1 ) regulation of the amount of phosphorylase enzyme inhibitor which is produced at high temperatures, (2 ) regu­ lation of the activity of the glucose-fructose intercon­ verting system which is increased at low temperatures, and (3 ) regulation of the activity of the sucrose synthesizing enzyme which is increased in amount at low temperature storage# According to Denny and Thornton (18, 20, 22), the browning of potato chips is essentially a carmelization of sugar; while Patton and Pyke (52) reported in 19ij.6 that this browning is not caused solely by the presence of reducing sugar but by the combined effect of reducing sugar and amino acids# The results of Salunkhs and W i t t w e r (6l) tend to support the hypothesis of Patton and Pyke, since potatoes treated with maleic hydrazide in the field gave superior quality chips yet there w a s no difference in the reducing sugar of treated and non-treated tubers (Tables VI and VII) . The differences found in both reducing and non-reducing sugars between maleic hydrazide treated and control potatoes in the 1950-51 storage p e r i o d but not in 1951-52 m a y have resulted from the use of different types of containers in the two storage experiments. I n 1950-51 the potatoes were h e l d In kraft paper bags, while in 1951-52 they were held in open m e s h onion bags. There has b e e n assembled consider­ able evidence that maleic hydrazide is a selective respira­ tory Inhibitor (37 > 6 6 ). I n this connection it should be emphasized that the carbon dioxide content of the atmos­ phere surrounding non-treated tubers in pliofilm bags increased to nearly two p e r cent over a six weeks period, while no carbon dioxide could be detected w i t h a Haldane gas analyzer in pliofilm bags containing potatoes treated w i t h the early application of maleic hydrazide (Table XXIX). Therefore, during the seven months storage period in 1950-51 76 a difference in the partial pressure of carbon dioxide of the atmospheres surrounding the treated and non-treated tubers in kraft paper bags could have influenced the relative amounts of reducing and non-reducing sugars in the treated and non-treated samples of potato tubers. Such conclusions are reasonable in view of the reports of Denny and Thornton (19, 21, 23), Thornton,(69) and Kardas and Blood (l+O). Although there is a considerable latitude in the time during the growing season that maleic hydrazide can be applied with effectiveness and in the concentrations which can be used, this chemical will decrease the yield of U.S. No. 1 potatoes if applied too early in the growing season as is shown in Table V and has been reported elsewhere (6, llj., l\.2). Sprays of maleic hydrazide at 2^00 ppm applied soon after the potato vines have emerged from the soil significantly depressed the yield of potatoes but did not significantly decrease sprouting in storage. The sprouts of potatoes treated at this early date were normal in appearance as contrasted with the sprouts shown in Figure 2 when the same concentration of chemical was applied seven weeks before harvest. Apparently, the maleic hydrazide spray has to be applied after the young tubers or the buds on the young tubers have been initiated to give effective sprout inhibition. One of the interesting effects of maleic hydrazide is the stimulation of plant growth at low concentrations. 77 This effect has previously been noted by Greulach and Atchison on onion roots (30). As shown in Table II, the 500 ppm concentration of maleic hydrazide, applied 2 days before the vines were destroyed, stimulated subsequent sprout growth on both Pontiac and Irish Gobbler potatoes in storage. This same spray treatment resulted in 90 per cent increase in the yield of Pontiac potatoes grown from tubers harvested from plants treated the previous year with Ioiat concentrations ( 5 0 0 ppm) of maleic hydrazide shortly before digging (Tables II and X). Onions Although concentrations of maleic hyurazide ranging from 500 to 2500 ppm will prevent sprouting of onions in storage, the 2500 ppm concentration is necessary for total sprout inhibition at the storage temperatures employed, Maleic hydrazide should be applied not earlier than two weeks before harvest, otherwise there is danger of increas­ ing breakdown of the onion bulbs in storage. As shown in Figure 3, the maleic hydrazide stops the initiation of new * leaves of the onion plant, while the leaves already formed continue to grow which results in a "spongy" elongated bulb. Secondary organisms already present or later gaining entrance into this spongy bulb will cause early decay and breakdown (Table XIII and Figure 3)* Zeller (85) has demonstrated that onions with a low percentage of sugars, especially non-reducing sugars, have 78 p o o r k e e p i n g qualities* Prom Table XVII It can be seen that the relative proportion of non-reducing sugar in the Y-I4.O onion is relatively low in comparison w i t h the percent­ age of r e d ucing sugar* Tables XIV, XV, and XVI show this variety to be a poor keeping onion. A l t h o u g h only marketable Y-I4.O onion bulbs were used for the various chemical analyses, all of the non-treated samples w e r e rooting profusely by the end of the four and one-half month storage period. I n addition, cross sections through the non-treated bulbs in every case revealed the presence of leaf and flower priraordia. In contrast, the maleic hydrazide treated bulbs did not show the presence of either roots or sprouts (Figure 5 )* The highly signifi­ cant decrease of reducing sugar in the non-treated Y-lj.0 onions over the storage period, this rooting, sprouting, is probably in part due to and other metabolic processes w h i c h occurred in the non-dormant onion bulbs* Root Crops Maleic hydrazide at 2500 ppm proved to be an effective sprout inhibitor on all five vegetable root crops and sugar beets at 55 ° F storage temperatures. I n 3-950, the three carrot varieties did not show any sprout inhibition because a h e a v y A s ter Yellows virus infection promoted a rapid break­ down of carrots In all treatments. In 1 9 5 1 > the three carrot varieties behaved as in 19ij-9 as reported by WIttwer, Sharma et al (78 , 79* 80). Maleic hydrazide gave no control over 79 the shriveling of beet and parsnip roots in storage at £5° F. As to the possible mechanism involved in maleic hydraside induced sprout inhibition in the crops studies, Leopold and K l e i n (ij-3) have demonstrated that an antagonism exists b e t w e e n m a l eic hydrazide and auxin in two ways: First, the inhibi t i o n of growth resulting from low concentrations of ma l e i c hydrazide can be overcome completely by the addition of auxin; and second, the inhibition resulting from excessive concentrations of auxin can be overcome by the addition of maleic hydrazide. The stopping of sprout initiation of potato tubers, the prolonging of the dormancy of onion bulbs, and the sprout inhibition of the several root crops could i n part be explained by this antagonism since auxin is n e e d e d to promote growth in meristematic tissues (71) • According to Pincus and Thiman (5i+)» a respiratory enzymatic reaction is an integral part of the growth process and auxin in some way accelerates or acts as a coenzyme for this reaction. If maleic hydrazide antagonizes auxin as noted above, this would help explain the highly signifi­ cant reduction in reducing sugar in the storage bin of nontreated onions since simple carbohydrates such as reducing sugars may be used in the process of respiration to furnish energy for various metabolic processes, Isenberg et al (37) have actually found that maleic hydrazide affects the respiration of onion tissue through the partial inactiva­ tion or inhibition of one or more of the dehydrogenases* V. SUMMARY' Some effects of preharvest foliar sprays of maleic hydrazide oh sprout inhibition, storage quality, and chemical composition of potatoes, onions, sugar beets, and vegetable root crops were determined# With potatoes in tests applied to crops grown in 1950 and 1951, sprays of 500, 1000, and 2500 ppm of maleic hydrazide applied to the foliage approximately one to seven weeks orior to harvest were effective in prolonging dormancy i of Irish Cobbler, Pontiac, Russet Rural, and Sebago tubers subsequently held in storage for seven months at tempera­ tures of h$ and 55° F# Complete inhibition of sprouting resulted from single preharvest foliar sprays of 2 5 0 0 ppm of maleic hydrazide applied four to seven weeks before harvest and the inhibition was more pronounced than that obtained with preharvest foliar treatments of 2,l+>5-trichlorophenoxyacetic acid or with post-harvest applications of the methyl ester of alpha-naphthaleneacetic acid# Maleic hydrazide induced sprout inhibition on potatoes was accompanied by an absence of shriveling with little or no deter­ ioration of quality and with no reduction in yield of U.S# No. 1 potatoes in 1950# Significant reductions in yield from the spray treatments were detected, however, in 1951 indicating the necessity for proper timing of application of the chemical if satisfactory results are to be obtained. Apical dominance of both tubers and individual sprouts on the tubers was destroyed* The percentages of reducing and non-reducing sugars were lower in maleic hydrazide treated potatoes stored at F in 19^0, while extensive storage studies of treated and non-treated potatoes held at 3£, and 55° P the following year showed no significant differences due to chemical treatment in reducing sugar, non-reducing sugar or starch percentages. Post-emergence sprays of maleic hydrazide at 25>00 ppm did not reduce storage sprouting of potato tubers, while low concentrations of maleic hydrazide applied shortly before harvest stimulated sprout growth on potato tubers* Sprays of 500, 1000, and 25>00 ppm of maleic hydrazide applied to the foliage of onion plants seven to ten days before harvest reduced or completely eliminated sprout and root growth during storage. These same treatments did not increase the breakdown of onions in storage. The 2500 ppm concentration of maleic hydrazide gave complete Inhibition of sprouting while the lower concentrations, although highly effective, did not show the same degree of complete sprout inhibition. Foliage sprays of maleic hydrazide at 2500 ppm applied three weeks or more before harvest resulted In an increase in storage breakdown of all onion varieties. Lower concentrations gave decreasing amounts of storage breakdown. Although marketable bulbs from maleic hydrazide treated 82 Y-i+O hybrid onions were increased by approximately 2^ per cent, the storage quality was not equal to non-treated Downing Yellow Globe onions, Tnere was a highly significant decrease in the per­ centage of reducing sugar in the control samples of Y-<+0 onions over a four and one-half month storage period, while similar samples treated with a 2^00 ppm foliar spray of maleic hydrazide showed no decrease in reducing sugar. Maleic hydrazide produced no significant alteration in the amount of dry matter, total nitrogen, or non-reducing sugar in the Y-i+O onions. The percentage of weight loss not resulting from sprouting, rootijgg, or breakdown was nearly identical when both treated and non-treated Y-l+0 onion bulbs were held under bulk storage conditions, preharvest foliar sprays of maleic hydrazide at 2^00 m m applied 10 days before harvest reduced the sprouting of carrots, beets, rutabagas, turnips, and sugar beets in storage. This same spray treatment resulted in marked reauctions in the storage breakdown of three varieties of carrots. vith the other root crops, there was no difference between any of the treatments in the percentages of storage breakdown other than from sprouting. Preharvest foliar sorays of maleic hydrazide did not prevent excessive shriveling of either parsnips or red beets held in storage# VI. LITERATURE CITED 1. Aldrich, P. H, The winter storage of roots. Agr. Exp. Sta. 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