EFFECT OF GROWTH SUBSTANCES ON FLOWERING OF CUCURBITACEOUS PLANTS Thesis §or “10 Degree of DH. D. MICHIGAN STATE UNIVERSITY Irvin G. Hillyer 1956 This is to certify that the thesis entitled "1 effect of Growth Substances on Flowering of Cucurbitaceous flants presented by Irvin George Hillyer has been accepted towards fulfillment of the requirements for Eh . 1) degree inHor’ticulti I re Date August 3 1356 0-169 EFFECT OF GROWTH SUBSTANCES 0N FLOWERING OF CUCURBITACEOUS PLANTS Irvin G. Hillyer AN.ABSTRACT submitted to the School of Graduate Studies of Michigan State University of Agriculture and Applied Science in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Department of Hbrticulture Year 1956 ABSTRACT Greenhouse and field plantings of cucurbitaoeous crops were treated with many growth regulators during early growth for artificial induction of male sterility. Maleic hydrazide (250 to 1000 ppm) and alpha naph- thaleneacetic acid (100 ppn) used on several varieties and under various environmental conditions were most effective in suppressing staminate flower production and at the same time, permitting pistillate flowers to develop. Changes in flowering behavior externally visible, were re- lated to chanically induced morphological differences in stall spices and in flower initiation. Seedlings were started from seed in flats containing vemiculite and later transplanted to large clay pots in greenhouse studies or to the field. Chuical treatments as water solutions were applied by soaking, dipping or by spraying the plants. Available facilities en- abled a control of tauperature and photoperiod in the greenhouse studies. Field experiments were conducted during the sumsr seasons of 1951. and 1955. Plant tissue sections in the morphological studies were taken from greenhouse grown plants and prepared by standard histological procedures. Suppression was obtained of staminate flowers on Acorn squash by maleic manna. (25 or 350 ppm) applied during the first and mm at the fourth to fifth leaf stages of growth; also on Caserta with 350 ppm, applied when cotyledons were expanded and again at the sixth to seventh leaf stages of growth and, similarly, when applications were made at cotyledon expansion and again at the fourth to fifth and ninth to tenth leaf stages of growth. Maleic hydrazide concentrations effective for suppression of staminate flowers of Acorn and Caserta squash in the greenhouse were not effective under field conditions during the late spring and early manner of 1951. and 1955. However, complete suppression of staminate flowers on Acorn squash was achieved by maleic hydrazide at 750 to 1000 ppn in the field during the late sinner of 1955. The shorter photoperiod in late summer and early fall favored suppression of staminate flowers by the chanical as compared with longer photo- periods of late spring and early summer. Differences in varietal re- sponse to treatment with maleic hydrazide were apparent with Qgggghitg, 2132.. 29mm: mam. 9mm halo. and W m. Uhder controlled environments in the greenhouse, the greatest sup— pression of staminate flowers by maleic hydrazide (350 ppn) and alpha naphthaleneacetic acid (100 pm) on Acorn and Caserta squash resulted at low (60°F.) temperature and generally at the short (8 hour), com- pared with the long (16 hour) photoperiod. Pistillate flowers appeared after fewer nodes at 60 than at 70°F., irrespective of variety and champ ical treatment, and their numbers were also generally reduced at long photoperiods and high temperatures. Reduction in pistillate flower nmber caused by long photoperiod, was nullified by low temperature on Caserta squash whether treated or not treated with alpha naphthalene- acetic acid. Acorn squash not chuically treated and grown at 60’F. had more pistillate flowers preceding the appearance of staminate flowers, when flowering occurred, than at 70° F. Morphological studies showed that maleic hydrazide suppressed cell differentiation in apical meristems and the developnent of pollen grains in the androecia of staminate flower buds. A theory of auxin versus anti-auxin effects on successive phases of flower sex expression in Acorn squash is suggested as an explanation of the selective inhibition of staminate flowers while allowing for simul- taneous developnent of pistillate flowers. EFFECT OF GROWTH SUBSTANCES 0N FWERING OF CUCURBITACI‘DUS PLANTS By (5“ Irvin cf Hillyer A THESIS Submitted to the School of Graduate Studies of Michigan State University of Agriculture and Applied Science in partial fulfillment of the requirements for the degree of DOC'IOR OF Pl-lIIDSOPl-l! Department of Horticulture Year 1956 ACKNOWLEWWTS The author wishes to express his sincere appreciation to Dr. S. H. Wittwer, Professor of Horticulture, under whose direction this investi- gation was undertaken. Sincere thanks are also expressed to Drs. R. L. Carolus, S. T. Dexter, G. P. Steinbauer and 0. R. Megee as manbers of the guidance committee. The constructive suggestions of Drs. F. B. Widmoyer, Jr. and J. D. Downes are also appreciated. The author is grateful to the Naugatuck Chemical Company for supply- ing many of the chanicals used in the investigation and the financial support which made this study possible. LIST orm Page I. Staminate-Pistillate Flower Ratios as Influenced by Certain Chemical Growth Regulators Applied at Differ- ent Concentrations and Stages of Growth (Acorn Squash, Greenhouse, September 29 to December 15, 1953) . . . . . 21. II. Staminate-Pistillate Flower Ratios as Influenced by Several Growth Regulators Applied at Different Con- centrations and Stages of Growth (Acorn Squash, Greenhouse, JanuarthoHarch19,l95h). . . . . . . . 25 III. Stanimte—Pistillate Flower Ratios as Influenced by Chemical Growth Regulators Applied at Different Con- centrations and Stages of Growth (Acorn Squash, Greenhouse, December 30, 1951. to March 19, 1955) . . . . 27 IV. 'lhe Effect of Maleic We Applied at Different Concentrations and Stages of Growth on the Stainate- Pistillate Flower Ratios (Acorn Squash, Greenhouse, mn1umm,195h)eeeeeeeeeeeeeeee 29 V. The Effect of bleic Hydraaide Applied at Different Concentrations and Stages of Growth on the Staminate Pistillate Flower Ratios (Caserta Squash, Greenhouse, Septubor 29, 195‘) to Jam 8' 1955) e e e e e e e e e 33 VI. Staminats-Pistillate Flower Ratios of Varieties of W. as Influenced by Various Concen- trations of Elsie iiydrazide (Field, June 3 to August ”'19511.)eeeeeeeeeeeeeeeeeeeeeee 36 VII. Staminate-Pistillate Flower Ratios of Varieties of and mm as Influwccd by Various Concentrations of Haleic Hydroxide and Alpha Naphghaleneacetic Acid (Field, flay 16 to August 1., 1955 O O 0 C O O O O O I O C O O O O O O O O O C O O 0 (.0 VIII. The Effect of Different Concentrations of Dhleic do on Flowering of Acorn Squash When Applied at the First Leaf and Repeated During the Fourth to Fifth leaf Growth Stages (Field, July 23 to October “.1955)eeeeeeeeeeeeeeeeeeeeeee [‘2 X. XI. XII. XIII. The Nimber of Flowers and the Staninate-Pistillate Flower Ratios as Influenced by Pintoperiod, Tanpera- ture, Meic twenties (350 ppm) and Alpha Naphtha- leneacetic Acid (100 pp), (Acorn and Caserta Squash, Greeninuse, October 21, 1955 to February 25, 1956). . . . 1.8 The Node timber at Which the First Staminate and Pistillate Flowers Appeared as Influenced by Photo- period, Temperature, Maleic drazide (350 pm) and Alpha Naphthaleneacetic Acid (X) pm), (Acorn and Caserta Squash, Greenhouse, October 21, 1955 to Pebm25,1956)eeeeeeeeeeeeeeeeeeee52 The Huber of Days to Anthesis for the First Staminate and Pistillate Flowers as Influenced by Photoperiod, T-perature, Maleic ltdrazide (350 ) and Alpha Naphthaleneacetic Acid (100 ppm), Acorn and Caserta Squash Greenhouse, October 21, 1955 to February 25, 19565 The Huber of Pistillate Flowers Preceding the First Staminate Flower as Influenced by Photoperiod , Taiperature, Maleic Wdrazide (350 ppm) and Alpha Naphthaleneacetic Acid (100 pp), (Acorn and Gaserta Squash, Greenhouse, October 21, 1955 to February25,l956).................... 58 O O O C O O O O O O O O O O O 55 Stuinate-Pistillate Flower Ratios of Acorn Squash as Influenced by Various Concentrations of Haleic Wdrazide when Gram During Three Different Seasons in the f 131d 0 O O O O O O O O O O O O O O O O O O O O O O 73 l. 2. h. 5. 6. 7. 8. 9. 10. 12. LIST 0? FIGURE Acorn squish growing in the greenhouse, showing culture m ”mm mm 0 O O C O O O O O O O O O O O O O Acorn squash following treatment with 350 pm of mleic ludraside when the first leaf and the fourth to fifth laws 1“ dwelom '0 O O O O O O O O O O O O O O O O O "om-Acomathmteeeeeeeeeeeeeeee Acorn squash treated with 500 ppm maleic bydrazide (FidthD)eeeeeeeeeeeeeeeeee Acorn squash treated with 750 pp: maleic twdraaide (field mment D) O O O O O O O O O O O O O O O O O O Non-treated Acorn squash (Field Experiment D) . . . . . . Nunber of staminate and pistillate flowers as influenced by photoperiod night temperature and maleic hydrazine (Varietonorn..................... Node umber at which the first staninate and pistillate flowers appeared, as influenced by photoperiod, night temperature and maleic hydraside (Variety Acorn) . . . . Number of days required for the appearance of the first staminate and pistillate flowers, as influenced by photoperiod, night temperature and naleic hydraside v01“, Acom) O O O O O O O O O O O O O O O O O O O O 0 Huber of pistillate flowers preceding the first staminate flower, as influenced by photoperiod, night temperature and mleic wdnside (Variety Acorn) . . . . Camera Lucida drawing showing comparative longitudinal sections of saleic hydraside treated and non-treated terminal squash aeristus (Variety Aoom) . . . . . . . . Sta-inate flower buds showing comparative development of androecia of maleic ivdraside treated and non-treated M, (vmuy ‘com) 0 O O O O O O O O O O O O O O O I 31 32 #3 1.5 L9 53 56 59 63 65 13. 1h. 15. Page Pistillate flowers showing comparative ovary develop- ment of maleic hydrazide treated and non-treated plants(VarietyAcorn).................. 66 Photomicrograph of a longitudinal section of an androeciun from a staninate flower bud produced on non-treated Acorn squash. Note the norml pollen grains.......................... 68 Photomicrograph of a longitudinal section of an androeciun from a staminate flower bud produced on a maleic ludrazide (3 50 ppm) treated Acorn squash. Note the shnmkenprotoplasminthepollengrains . . . . . . . 69 TABLE OF CONTENTS Mont,“ ION O O O O O O O O O O O O O O O O O O O O O O O 0 mm OF LEE-AME O O O O O O O O O O O O O O O O O O O 0 General Relationships in the Flowering of Higher Plants Effects of Chemicals on Altering Flowering . . . . . . . General Effects or Meic I'Vdrazide on Flowering . . . . Morphological Responses of Plants to Maleic I-lydrazide Chemical Induction of Male Sterility in Plants . . . . . Chemical and Environmental Relationships in Flowering of Cucurbitaceae . . . . . . . THE PROBLEM FOR INVESTIGATION . MEI‘IDDS ............ Location.......... Plant Material and Culture . Chemical Growth Regulators . fiwiromnental Control . . . Morphological Treatment Evaluation . . . . mmmm O O O O O O O O O 0 Greenhouse Flowering response of Acorn and Caeerta squash as related to concentrations of various chunicals applied and as determined by the developmental stage of plants treated QQUIUUJH 10 16 17 l7 l7 l9 l9 8 Page EXPERIMENTAL cont. Field Flowering response of various varieties of cucurbitaceae as related to concentrations of chemicals applied and as determined by the develop- mentalstageofplantswhentreated. . . . . . . . . 31. Tauperature, Photoperiod and Chanical Interactions (Varieties, Acorn and Caserta Squash) Nunber of flowers and staminate-pistillate flower “tics O O O O O O O O O O O O O O O O O O O O O O O [*6 Node number at which the first staminate and pistillateflowersappeared. . . . . . . . . . . . . 51 Nunber of days required to anthesis for the first BWtempisti-uatanmrs eeeeeeeeee 5h Nunber of pistillate flowers preceding the first smte flower 0 O O O O O O O O O O O O O O O O O 57 lbrphological (Acorn Squash Haleic twdrazide effects on meristans . . . . . . . . 62 Maleic Indra-side effects on staninate flower bud fomtion C O O O O O O O O O O O O O O O O O O O O 0 61‘ DISCUSSION.......................... 70 SUMRY............................ 79 BIBLIOGRAPHY.........................82 APPENDIX............'...............87 INTRODUCTION Large scale production of first generation (F1) hybrid seed has stressed the need for natural or induced male sterility in many crop plants . In general, cucurbitaceae are prolific in the production of staminate flowers and tedious hand labor must be expended daily by the comercial seed grower for their runoval to insure quantities of true hybrid seed. The labor expense has tended to restrict the production of hybrid seed. A (chemical means for inducing male sterility in cer- tain cucurbitaceae would greatly reduce the present costly removal of the staminate flowers and alleviate the necessity of maintaining nat- urally occurring male sterile lines. The primarily monoecious cucurbitaceae family presents a particu— lar challenge in that it has been shown that the flower sex pattern can be altered by chemical treatments (25, 36, 39). These observations have suggested the possibility of suppression, of all staminate flowers in cucurbitaceae with chemicals. The resulting plants would ranain as funale functional plants with no staminate flowers. Accordingly, de- tailed investigations of the effects of various growth regulators with special emphasis on maleic hydrazidel (NH) were herein conducted, using the following cucurbitaceous crops: various varieties and lines of cucmbers (mm -mina). watermelon: (91m mimic). musk- melona (932m sole). ptmpldm and squash (W m).- Throughout 1 mammme salt of 1, 2-dihydropyridazine-3,6-dione. the investigation, Acorn squash was used as an experimental standard. because in its growth habit there is a single dominant runner with few side-shoots and because of its clearly defined monoecious flowering. Flowering response was studied as related to the concentrations of various chemicals applied and as determined by the stages of develop— ment of plants when treated. Special emphasis was given to the effects of photoperiod and tanperature when interacted with variety and chemical treatment on the formation of staminate and pistillate flowers. A com- parative morphological study was also made of the growing apices and early flower bud developnent on maleic hydrazide treated and non-treated Acorn squash. REVIEW OF LITERATURE Control of flowering of plants is of economic importance with such crops as carrots, beets, celery, cabbage, spinach and lettuce because these crops tend to bolt or develop premature seed stalks under certain environ- mental conditions which destroys their market value. Regulation of flowering is also important in economical seed production, in that uniform maturity should be attained to facilitate harvesting and storage. More precise methods of flower control would be welcomed by those en- gaged in the production of food crops, as well as by those who produce the seed from which they are grown. Certain theories relative to the mechanism of flowering in plants are reviewed briefly. Prominent in the theoretical discussions of Sachs (1.1) was the idea of a flower—inducing substance. However, the theories of Sachs at the time attracted little attention, as control of plant growth by the use of nutrients was then the dominant theory. This theory achieved its greatest popularity about 1918, when Kraus and Kraybill (23) Pub- lished the concept that flowering was related to a balance between the carbon and nitrogen nutrition of the plant. However, in 1920, Garner and Allard (12) established the fact that day-length controlled the flowering habit of tobacco. Subsequent investigations, by Gregory (15) and Garner and Allard (13) showed that flowering in many plants is con- trolled by the length of day. Temperature during one or more of the developmental phases of some plants may also determine the future flowering habit. A well known example is the vernalization of winter wheat as reported by Klippart (21). Another outstanding example is the tulip as reviewed by Went (1.8). However, Gregory and Purvis (16) have shown that cold temperature vernal- ization can be reversed by subsequent exposure to high temperature. Audus (1) suggests that a substance formed in the cold responsible for flower initiation is destroyed at the higher temperature; likewise, the production or non-production of flower-inducing substances at different day—lengths is explained. Gregory (15) in 1913, Proposed a hormone theory which gives the widest coverage to the whole range of flowering phenomena in higher plants. He suggested that the final flowering hor- mone is formed in the meristems from precursors carried there from the leaves. Although there is much indirect evidence that a flowering hormone exists, there is little positive proof. Hamner and Bonner (20) obtained transmission of a flowering stimulus from a cocklebur plant treated with short day-length to a receptor cocklebur plant grown in long day-length, through lens paper placed between the stock and scion. As there was no graft union, it was seemed that the stimulus was soluble in the water soaked up by the paper. Ulrich (1.6) in 1939, claimed a flowering hormone was found in an extract prepared from the stigna of the crocus. Roberts (AG) in 1951, reported that kerosine-oil extracts of the flower- ing cocklebur yielded a material which was able to induce flowering in a vegetative cocklebur plant. It is known that all plants have in their genetic background the potentiality of flowering, also, if during an appropriate developnental stage, flowering does not occur, some inhibitor may be present. Gregory (15) considered the problem of flowering as being a failure to flower instead of flower plomotion. It is understood from this viewpoint, that the effect of temperature or day-length may be explained by the des- truction of a flowering inhibitor instead of the production of a flower— ing promoter. W: A relatively new .10. proach to the problan of flower control is the study of the effects of various, externally applied chemicals. The purpose has been to discover some chemical growth regulator which would promote flowering directly or indirectly perhaps as an "antagonist" of a theoretical flowering in- hibitor. An example of a positive chemical effect was the use of ethylene and later alpha naphthaleneacetic acid on pineapple as report- ed by Clark and Home (1.) in 1942. Flowering was actually induced by the above chemicals. Van Overbeek used the Cabenzona variety of pine- apple and was able to control the time of flowering and also the size of the plants by using five to ten ppn of naphthaleneacetic acid (37). Again, the initiation of flower primordia was actually induced by the chemical. However, applications of naphthaleneacetic acid at higher levels tended to delay rather than promte flowering. Bonner and Thurlow (2) in 191.9, reported that flowering was delayed and even prevented in the cocklebur by sprays of either indoleacetic or naphthaleneacetic acid (50 to 500 pm) applied during the time of flower induction. Leopold and Thimann (30) in 191.9, working with Chalso teosinte and Wintex barley found that applications of solutions of naphthaleneacetic acid (0.01 to 400 plan) to the teosinte inhibited flowering, while 0.01 to l ppn on Wintex barley caused an increase in the total flower number, but there was a reduction in flowering at higher concentrations. The vegetative growth response of the plants was directly correlated with the auxin concentrations. This suggested that overall growth in gen- eral rather' than specifically flower formation was affected. Low auxin content and accelerated flowering was observed by Bentley and reported by Audus (1). Bentley reasoned that the high levels of ultra-violet light at high altitudes destroys the auxins of alpine plants and con- sequently they are dwarfed and flower early. Zinmermn and Hitchcock (52) in 191.2 reported that 2,3,5-triiodo- benzoic acid induced flowering in peculiar patterns in the tomato. When plants had four to 200 pm of 2,3, 5-trii0dobenzoic acid applied to the soil around the roots, or as a spray to the foliage, flower-clusters grew from the axillary buds, from which leafy shoots normally grew. Flower-clusters also terminated the main star on indeterminant varieties. However, Galston (11) in 191.7, stated the tomato was day-length in- sensitive and consequently the effect of 2,3,5-triiodobenzoic acid may only have been an acceleration of the developnent of flowers previously formed. Working with soya beans, Galston found 2,3, S-triiodobenzoic acid did not induce flowering with plants in a vegetative condition, but augnented the flowering response in day-lengths favorable for flowering. An effect somewhat similar to that of 2,3,5-triiodobenzoic acid on the tomato has been reported by Teubner and Wittwer (LA) with N-m-tolyl- phthalamic acid. This chemical promoted fruit set of the tomato; in- fluenced flower formation of later developing clusters and increased the flower number of the first clusters, if applied to the young tomato seedlings. Liabach and Kribben (2h, 25, 26, 27, 28) reported that naphtha- leneacetic acid increased the number of pistillate flowers on cucumber, but reduced the total number of flowers. The development of pistillate flowers was also stimulated at the first nodes of the cucumber seedlings with 0.1 per cent naphthaleneacetic acid in paste form. Wittwer, Coulter and Carolus (A9) reported that seedstalk elonga- tion of celery was inhibited by ortho-chlorophenoxypropionic acid (100 PP“) and accelerated by 2,l.-dichlorophenoxyacetic acid (50 ppn). How- ever, Clark and Wittwer (3) later observed that alpha-orthochloro- phenoxypropionic acid had no effect on celery seedstalk elongation and that 2,h-dichlorophenoxyacetic acid resulted in a slight retardation of the growth of seedstalks. Clark and Wittwer (3) sprayed lettuce plants (8 to 12 weeks in age) with 2,A—dichlorophenoxyacetic acid, para-chlorophenoxyacetic acid, triiodobenzoic acid, and naphthaleneacetic acid. They observed, in general, accelerated seedstalk elongation with the effect greater for repeated than for single applications. However, para-chlorophenoxy- acetic acid when applied to month-old plants, significantly reduced seedstalk elongation. WWW: Studies on the effects of maleic hydrazide on plant development are many and diverse. The more pertinent references are reviewed. According to Schoene and Hoffman (1.2) maleic turdrazide suppressed the growth of tomatoes, corn and turf. Leopold and Klein (29) stated that there are strong indica- tions that the inhibiting action of maleic hydrazide may be due to the suppression of the amdn present in the plant. Klein and Leopold (21) have further reported that maleic hydrazide completely inhibited the fomation of flower primordia in Wintex barley. The effective in- hibitory concentration varied with the age and size of the treated plants. With Biloxi soybean, a short-day plant, photoperiodic induction was somewhat inhibited by maleic hydrazide, but flower initiation was not completely suppressed. With foliar applications of maleic hydrazide to Wand peppermint plants, there was an inhibition of flowering in the terminal buds, but not in the laterals. They suggested that maleic hydrazide inhibited the production of flower primordia prim- arily through its inhibitory effect on growth, rather than by any specific action on the photoperiodic mechanism. Wittwer, a 5],. (51) reported that maleic hydrazide applied at different stages in growth of Cornell l9 celery, had a definite influ- ence on the growth of seedstalks. Applied at 50 to 100 ppn, to young plants having 8 to 10 true leaves before cold induction, flowering was induced in many plants which normally would have ranained vegetative. With applications at 500 to 1000 pm when 37 true leaves had developed; there was a retardation of the developnent of seedstalks. W: The effects of maleic hydrazide on the internal structure of a plant is of great importance in that the outward appearance is often a reflection of the effects of the chemical on cell division and growth. According to Naylor and Davis (35) many plants developed abnormal leaf shapes follow- ing treatment with maleic Indrazide. They worked with wheat, sun- flowers, Turkish tobacco, oats, red top grass, corn, peas, peanuts, cocklebur, tomatoes and cotton. The new leaves were abnomal in appearance but the meristans were not permanently affected as normal leaves were eventually produced. They also reported a more direct dosage response from maleic hydrazide in older plants than in seedlings. Effects of maleic hvdrazide in every species were: (1) cessation of activity in terminal meristems, (2) cessation of elongation of inter- nodal regions, and (3) increase in stem diameters. Rao (38) observed no cell division in onion bulb root primordia which had been harvested from plants which had received a preharvest foliar spray of 2500 ppn of maleic hydrazide. Maleic hydrazide was reported by Greulach and Atchison (17) to inhibit onion root cell division but not cell enlarge- ment at low concentrations. Both cell division and cell enlargement were stopped when high (1000 to 2000 PP“) of maleic hydrazide were applied. Similarly, inhibition of mitotic division of cells has been ob- served by Deyson and Rollen (9). They stated, "Haleic hydrazide in- hibits growth of vegetables by preventing the cells from entering into mitosis. Suitable concentrations of maleic twdrazide allow roots to continue to elongate for a certain time even though their meristus do 10 not show any signs of mitosis. The inhibiting action on cellular elonga- tion manifests itself at a later stage." In this connection, mg 1113 roots which were in water solutions above 0.0005 molar of maleic hydra- zide for 21. hours, gave no indication of mitosis as studied by Darlington and McLeish (8). Breakage of chromosomes at mitosis rather than stoppage of mitosis was noted at lower concentrations. Maleic hydrazide has also been shown to influence the development of vascular systans of many plants. A cessation of cell division, collapsed phloem near the stem apex, and inhibited developnent of new vascular elements were observed by Girolami (lit) in the vascular system of flax following treatment. Currier, 93; £46) reported that as maleic hydrazide moves into the phloem of barley plants, it affects sieve tube differentiation. Struckmeyer (13) observed that Croft Easter lilies were inhibited in growth and failed to differentiate flower buds after a 0.2 per cent maleic hydrazide treatment. The leaves were thicker, cells were larger, and there was a loose arrangement of the spongy paren- chyma with large intercellular spaces. Phloem elements of the vascular bundles of both stems and leaves were comonly found in varying stages of collapse and the enlarged stems of treated plants were explained in part by an increase in size of the cortical cells. Watson (1,?) observed the abscission zone of petioles of maleic hydrazide treated Red Kidney bean plants were more advanced than plants not treated. Cell enlarge- ment was noted to be inhibited, but no abnormal cells were observed. Greulach and Atchison (18) also observed, as had Watson (1.7) that buds of bean plants treated with maleic hydrazide regularly abscised several weeks after treatment. They also reported inhibition of mitosis in the terminal buds after treatment with a 0.01 molar solution of maleic hydrazide. Chemical induction of Male Stegility in Elgntsz Other investi- gators have reported maleic hydrazide induced.male sterility in various plants. Naylor (34) in 1950, noticed that with corn plants sprayed with a 0.025 per cent solution of maleic hydrazide, the staminate flowers became sterile, while at the same concentration, there was no effect on the pistillate flowers, which would produce seed when cross-pollinated. It was also reported that when cocklebur plants were sprayed with maleic hydrazide (0.025 per cent) at the time of photo-induction, there was an inhibition of the flower buds. (Mollrath (31) in 1953, used single applications of maleic hydrazide in a range of concentrations of from 60 to 2000 ppn on grain sorghum. He found as much as 98 per cent male sterility could be attained in a milo variety with the higher dosages. It was also reported that with the high concentrations, there was approximately an 80 per cent re- duction in the stand of plants and the surviving plants suffered an extreme reduction in vigor. In some instances, however, the treatments resulted in a complete sterility of flowers. After continued experi- mentation, it was suggested that if maleic hydrazide was used in small- er dosages, at varying time intervals, relatively large total quantities could be applied without seriously reducing the vigor of the milo. With such applications, there was no significant difference in the time at which treated and non-treated plants flowered. It was noted that the developmental stages of the plants at the time of treatment proved to be important. A greater amount of sterility of plants was attained 12 if the treatments were initiated when the inflorescence was very small. It was also observed that treatments which gave only male sterility under field conditions in Texas, resulted in sterility of both staminate and pistillate organs under the greenhouse conditions at Chicago. McILrath also stated that different varieties of sorghum responded differently to a given concentration of maleic hydrazide. Consequent- ly, a separate procedure would have to beestablished for each variety as well as for each geographic location. Of special interest are the studies of maleic hydrazide induced male sterility in cucurbitaceae. Rehm (39) observed that with water- melons sprayed with 250 and 500 ppm maleic hydrazide, one week before the first flowers opened, there was a temporary inhibition of growth, afterwhich, the plants became fully fertile. Wittwer and Hillyer (so) in 1951., reported the suppression of staminate flower buds in Acorn squash for approximately three to four weeks in the greenhouse follow- ing treatment with maleic hydrazide (250 or 350 ppn) when the first true leaf was fully expanded and again when the fourth to fifth leaves had expanded. The induction of male sterility in egg plant has been studied by Nakamura (32). He reported pollen treated with the amine salt of 2.1+- dichlorophenoxyacetic acid (10 pm), lost most of its viability in three days. The fanale ovary remained fertile during the experiment and developed normal sized fruits containing seeds. However, leaves of treated plants were narrower, growth was inhibited, and the plants became prostrate and had more branches. 13 Chemicals other than maleic hydrazide, have been reported by various investigators to induce male sterility in cucurbitaceae. Rehm (39) reported complete male sterility for more than one week with the following treatments applied to watermelons beginning one week before the first flower Opened: (a) Triiodobenzoic acid (10 ppn), applied every week; (b) triiodobenzoic acid (50 ppn), repeated once after four weeks; (c) triiodobenzoic acid (250 ppn), applied once and (d) 2,1.- dichlorophenoxyacetic acid (5 ppm), applied every week. He also ob- served that the cucumber variety Early Fortune treated during full bloom with triiodobenzoic acid at 25 pm. PrOduced five staminate and seven pistillate flowers over a five day period. Nakamura and Terabun (33), created a partial male-sterility in cucumbers, using the amine salt of 2,4-dichlorophenoxyacetic acid at 50 and 100 ppm, and reported that treated cucunber plants had fewer staminate and more pistillate flowers at 50 ppn than at 100 ppn. Pollen from the treated plants was reported to be fully as viable as that from the controls. It was also observed that there was 'a decreased number of branches and flowers of a smaller size on the treated plants. Wittwer and Hillyer (50) observed that spraying young cucumber plants in the greenhouse after two to three true leaves had formed, with alpha naphthaleneacetic acid (100 Pm), or 2,3, 5-triiodobenzoic acid (25 ppn), reduced the staminate-pistillate flower ratios from approximately 23:1 to 8:1 in National pickling and from 14:1 to 2:1 in Burpee Hybrid varieties. Alpha naphthaleneacetic acid at 100 pm applied to Acorn squash grown in the greenhouse, when the first true leaf had expanded, resulted in a decrease in staminate- pistillate flower ratios from l.l,7:1 to 0.1,:1, with an occasional plant producing no staminate flowers. Nitsch, gt 3.1- (36) sprayed Acorn squash (with two developed leaves) with alpha naphthaleneacetic acid at a concentration of 100 mg. per liter, three times in a lO—day interval. They were able to induce one pistillate flower bud per plant at approxi- mately the ninth node in comparison with the non-treated plants grown under similiar conditions which did not form any pistillate flower buds until the twentieth node. Eh Re 0 in Flo e o u bigceog Plants: The effects of environment and chemical growth regu- lators separately and when interacting are varied, on the flowering of cucubitaceous plants. Tiedjens (1+5) observed that abundant light was favorable to the developnent of staminate flowers of the cucumber, while a reduction of light increased the number of pistillate flowers. He stated, however, that environment did not determine the flower sex; it produced conditions which made possible the expression of the potentiali- ties in the plant. Hall (19) working with mania m (gherkin) found that the peak of flower production occurred 15 days earlier in plants exposed to eight hour in contrast to 16 hour day-lengths. Approx- imately 50 per cent more flowers were produced in the short- as compared to the long-day lengths. He also observed that more pistillate than staminate flowers were produced by high nitrogen grown plants in both short- and long-day lengths. Danielson (7) reported maximm staminate flower production on W m (small gherldn) at eight hour day lengths and that stem elongation was also greatest during short- rather than long—days. Edmond (10) observed while working with different cucun- ber varieties, that from June 27 to September 6, the number of developed 15 pistillate flowers per plant varied from 1.37 to 8.78 and for a period from December 15 to April 15, 61.1, to 10h.83 pistillate flowers were produced. Nitsch, 93‘ 5;. (36) found that day-length and temperature influ- enced greatly the developnent of staminate and pistillate flowers of squash and cucumbers. They reported that high temperatures and long days tended to cause the vines of Acorn squash to produce staminate flowers while low temperatures and short days favored the develoment of pistillate flowers. Beginning from the first leaf, the following flower- ing sequence occurred: underdeveloped staminate, normal staminate, normal pistillate, inhibited staminate, giant pistillate and finally, parthenocarpic pistillate flowers. The authors proposed that climate factors modified the length but not the order of each phase of flower- ing. They also reported that 92% M L. variety Boston pickling cucunber, and M m L. (small gherkin) tended to produce staminate flowers at high temperatures and long days and pistillate flowers at low temperatures and short days. 16 THE PROBLEM FUR INVESTIGATION It is widely know that male sterility in crop plants is useful in the production of hybrid seed. A reliable chemical method of inducing .male sterility in certain cucurbits would.merit considerable attention because, daily hand renoval of staminate flowers on a large scale is an economical handicap and there is also much difficulty in maintaining naturally occurring male steril lines. Consequently, the problem for investigation included: (a) the effects of various chemicals on the flowering response of different cucurbitaceous varieties: (b) time of treatment and concentrations of chemicals necessary for elimination of the staminate flowers under different environments; and (c) an evaluation of certain morphological changes in the developing flower parts associated with chemical treat- ments favorable for induction of male sterility. l7 METHODS Logtion: All experiments were conducted in the horticultural field plots and greenhouses of Michigan State University at East Lansing, from July, 1953 to June, 1956. W: Various lots of seed were obtained from the Ferry ibrse Seed Company, Detroit and varieties are listed as follows : Squash (varieties); Caserta, Stock No. D9730 Zucchini (Dark Green), Stock No. 16136 Acorn, Stock No. 001.21 Pumpkin (varieties); New England Pie, Stock No. D3h09 Connecticut Field, Stock No. D1732 Watermelon (varieties): Congo, Stock No. D2504 Dixie Queen, Stock No. 77511. Muskmelon (varieties); Iroquois, Stock No. D3567 Resistant "1.5", Stock No. 15531. 18 Cucumber (releases) ; Pickle type F.M. 14312, mosaic resistant Pickle type F.M. 3204, mosaic resistant Pickle type, F.M5 751h7, scab resistant Slicer type, F.M. D3033, mildew resistant Slicer type, F.M. 01750, mosaic resistant In addition, two pickling types of cucumbers, mosaic resistant l7 and scab and mosaic resistant 12-9, were Obtained from the Associated Seed Company, New Haven, Connecticut. In the greenhouse experiments, all seedlings were grown in flats containing vermiculite, until their cotyledons had expanded, then trans- planted into four-and eight-inch clay pots filled with soil. For field plantings they were transferred to a ground bed or coldframe prior to setting in the field. Soil fertility was maintained at a high level in the greenhouse by periodic additions of a high analysis (10-52-17) water soluble fertilizer. For seed treatments, chemical growth regulators were applied by soaking the seeds in Petri dishes on two Whatman No. 1 filter papers, moistened with water containing the chemical. Seedling plants were treated by dipping the leaves for approximately five seconds in.a water solution containing the growth regulator and "Draft" (Proctor and Gamble) as a wetting agent at a concentration of 0.1 per cent. The field applications were made with a hand sprayer containing water solue tions of the chemical and "Draft". l9 Chemiggl Growth Regglgtorg: ,The following are the chemicals used in the various experiments and their abbreviations: 1,2bDihydropyridazine-3,6-dione (Maleic Hydrazide, MH) 2,3,5—Triiodobenzoic Acid (TIBA) Alpha Naphthaleneacetic Acid (NAA, NA, NAc) N-p-chlorophenylphthalamic Acid Alpha Cyano-beta-Z,4~dichlorophenyl Acrylic Acid (CDAA) Benzene Sulfonyl Hydrazide 2,4PDichlorobenzelnicotinium Chloride Alpha Methoxyphenylacetic Acid (MDPA) Nemeta-tolylphthalamic Acid (7R-5) Env e nt :_ Air temperatures were maintained in the greenhouse at night by thermostatic controls set at 70 and 60°F. Day temperatures averaged ten to fifteen degrees higher. Pbtted plants were placed on carts, moved into dark rooms for the designated photoperiods. The sixteen hour photoperiods were provided by extending the natural light with 150-watt photoflood lamps, which gave an average of 30 foot-candles at the leaf surface of the plants. Photoperiods were extended in other studies with fluorescent lamps pro— ducing approximately 90 foot-candles of light at leaf surface. Field experiments were conducted during the summers of 1954 and 1955. Thus, differences in temperature and length of day were en- countered as compared with the greenhouse tests. Morphologigl Studies: Plant material was fixed in a FAA solution and dehydrated with butyl alcohol. The tissues were imbedded in paraf- fin, sectioned with a rotary microtome, and stained with safranin and fast green. WM: Randomized blocks or split plots were used in the experimental designs in the greenhouse and field with the analysis of variance to evaluate mean differences of treatmwt effects. Replications comprised of single plants per treatment were used in greenhouse studies and one field study, with replications of five plants per treatment in other field experiments. In some instances no statistical evaluations were made since the nature of the results made such testing unnecessary. The following measurements were made in all experiments: (1) the number of flowers appearing, (2) the node nunber at which, and the number of days to anthesis of the first staminate and pistillate flowers, (3) the number of pistillate flowers preceding the appearance of the first staminate flower and (4) the staminate-pistillate flower ratios. Node number was determined by starting from the cotyledons. EXPERIMENTAL Greenhouse Stgggg: Preliminary studies were conducted in the greenhouse to determine the effect of various chemical growth regulators on the flowering response of Acorn and Caserta squash. The effective- ness of several concentrations of chemicals applied during various de- velopnental stages in growth were first ascertained. Experiment A: Seed of Acorn squash were planted in the greenhouse on September 29, 1953 and after 12 days the geminated seedlings were transplanted into four-inch clay pots of soil. The plants were later transferred to 8-inch clay pots and placed on a ground bed (Figure 1). Boards were placed beneath the pots to prevent the roots from growing into the ground soil. Some plants were treated once when the second to third leaves had developed. Others, treated twice, first when the second to third true leaves had developed, and again approximately two weeks later when five to six leaves had expanded. Five chemical growth regulators were used at the following concentrations: W W 2,3 ,S-Triiodobenzoic Acid 25, 50, 100, 250 ppn Alpha Naphthaleneacetic Acid 25, 50, 75, 100 ppn N-p-chlorophenylphthalamic Acid 25, 50, 75, 100 ppn Maleic Hydrazide 25, 50, 100, 250, 500 ppn Alpha-cyano-beta-Z, h-dichlo ro- phenyl acrylic Acid 25, 50, 100. 250, 500 ppm Daylength was extended to 16 hours by the use of artificial lighting. .393 deco-tau. s: .85.- ?azuo .55.. .3385 as 5 Hush all: In: A chat _ .. L p . ,...m......_.,r..v. . a Ill" . .. .u. .5 Irwiuuuia... 111 — at .4, T. _ I... A u..." ,I, .1 ._ ; .. .1. 23 It was found that 250 ppm of maleic hydrazide (Table 1) applied when the second to third leaves had expanded and again two weeks later, resulted in a 0.1. staminate-pistillate flower ratio with no serious in- jury to the plants. Plants not treated had a 3.5 staminate-pistillate flower ratio. Alpha cyano-beta-2,h-dichlorophenyl acrylic acid and 2,3 ,5-triiodobenzoic acid were not consistent in their effects on the staminate-pistillate flower ratio and n-p-chloropherwlphthalamic acid actually increased the staminate-pistillate flower ratio as the con- centrations were increased (Table 1). Alpha naphthaleneacetic acid significantly reduced the staminate-pistillate flower ratios when applied twice but only a slight reduction occurred from single appli- cations (Table 1). Studies were continued on the flower response of Acorn squash as related to various chemicals applied, and as determined by the develop- mental stage of the plant when treated. Experiment B: Acorn squash seed were sown January 8, 1951. and the resulting plants treated with benzene sulfonyl hydrazide, n-meta- tolylphthalamic acid, 2,l.-dichlorobenzelnicotinimn chloride, and alpha- cyano-beta-2,l.-dichloropherwl acrylic acid at concentrations of 100 and 500 ppn. One treatment was made when the first leaf had expanded and the second when the first leaf appeared and repeated when the fifth to sixth leaves were expanded. When the chemical growth regulators were applied only at the first leaf stage at concentrations of 100 and 500 ppm, there was an increase in the staminate-pistillate flower ratios at the 500 ppn (Table II), ahead 343:3 3.5338 couscous 35.8 1* £23 £8: u fine. 8.. sounds. as 853 m 3. m 8s. 835 z. fiancee a... 823a n 3 a 5s: 8334 .. a...” 338$ 85 Hanson m.m $0.0 «loom Tm To Son 5.“ 0.0 46 163 m6 o.m o.~ 3mm 1m 0.? .12 To Tm 18H o.m 4.3 «A Nam Tm *8.“ H33 0.0 . at: mé. gm *3. m.m ma o3 m6 m.m ton 2 >6 Tm flu N3 #3 mi 14 «.m To Nam .13 «.m ma mé TN o.m *3 738.3%.“ using named» 23..“ no :35 m3! unbo< Agofiog 33 039% 33 38:3 33 038: 3383: 35 Li .mufimsnog an: 115%? quluz tvodsal . 3.. 1.533%... 2a: 3on aoaaasamoaoo 2an .3 39839 on on usfilfiom 53250.6 .sndsum 500$ 5.3.5 uo nowdam one 3838.53 Icoo 95.3.3.3 as vofiaa< snowed—mom 5.3vo 13326 Soc .3 anaconda «4 3.34m $3on oaoaaudmloadqaam Hg 25 n... $33.“. 85 H838 o.~ QH e 3 m in H m .« 1N H 30¢ ogoggabsfioauflm: o.~ m.m o co m sea H «.0 H.o a ofle< oHHhuo< Hhconaouoansauna.un¢¢onloanhatdana< m.« as o 3 m an. H «.0 «.4 H .333 SgssHaHonfipZoHfioSus§ TN «A e 3 m B. H m .m a .m H 33 02:33.. H33 38.12 Tm s 3 m as H «H m... H 835% H.353 .855 Amovcoaon acad— oamfiu 3.3 «o 505 -§EBm , 2433 8.5 o 8 8&5 3 .1088 33H .mH 332 3 m 23.3. 33388... 3333 8.83 5.6.5 co 895m 8. 33s 183.88 gauche a. 83%: 233mg 533 Hun-8m .3 Ragga 2 83.5 ease osaHdfiHmtaaHaSm dug 26 with the exception of benzene sulfonyl hydrazide which severely stunted the plants. In many instances, the plants not treated had a lower staminate-pistillate flower ratios than the plants treated at the first leaf stage. In contrast, when the chemical treatments were applied at the first and again at the fifth to sixth leaf stages a lower staminate- pistillate flower ratios generally resulted, in comparison with plants not treated. This was especially true when a concentration of 500 ppn was employed. In all instances, at the 500 ppm concentration, a re- peated application was the most effective in reducing the staminate- pistillate flower ratio (Table II). Experiment C: The effects of additonal concentrations of chemicals applied at various stages of growth was next determined. Acorn squash seed were sown December 30, l95h and the resulting plants treated with maleic hydrazide at concentrations of 100, 250, 350 and 500 ppn; and alpha naphthaleneacetic acid and n-p-chlorophenylphthalamic acid at concentrations of 25, 50 and 100 ppm. The chemical treatments were applied at eight different stages of growth, consisting of (1) seed, (2) emergence of cotyledons, (3) cotyledons expanded, (A) first leaf expanded, (5) second to third leaves expanded, (6) fourth to fifth leaves expanded, (7) second to third leaves expanded and repeated at two weeks and (8) six applications at seven day intervals, beginning .at emergence of cotyledons. In all instances (Table III), there was a lower staminate-pis- tillate flower ratio in the chemically treated plants as compared with those not treated. In general, the higher concentration (100 P1111) as 27 60260.5 8030C oz .1 60260.5 23on mpg» 02 * Tm “cops: 85 H828 «H «.0 «.o 38338 no 8838.. e. 33599 «H.533 .3. a. as 33.335. “an A8 8393 N no condom: use To 3...... .56 o.H Ensues nossH 2m 3 Boson MS TH TH 2o m6 flu To 38.98 853 an 3 grass 3 m.~ m.H ad o.H «.0 9o Recess uo>8H Em 3 28% RV Tm m.~ .3 «.m io 06 88.98 3H 3.5 3 fin a.« o.« n.m «.H .3 82.98 88358 3 Ya Nam Tu in «4.. H.~ 803138 as 38325 3 .3 «4 pH TH ed o.H econ d Anon—coach «:13 0.353 256 no :35 02 on 3 8H on 3 8m omm one 8H an in in noaaooam< as 5396 we 03m 33 masfisHeofiBoHfiAuz 33 afloococoHBafiwz .3595 3.3. «RS .mH :93: 8 43H .8 casinos .Safiaoouo 38:8 283 size no $me e5 33» 189888 €28an a. 3354 stooges sfifiu H835 B 88.33 3 834m 3.58 Bananas-guise HHH an. 28 compared with 50 ppm of n-p—chlorophenylphthalamic acid applied at each of the stages of growth resulted in an increase in the staminate- pistillate ratio except at stages (2) and (6) (Table III). with maleic hydrazide treatments, the higher compared with the lower concentrations at the (2) and (6) stages of growth resulted in an increased stamdnate- pistillate flower ratio. Alpha naphthaleneacetic acid treatments at the (l) and (2) stages of growth resulted also in an increased staminate- pistillate flower ratio with the higher concentrations compared with the lower (Table III). Maleic hydrazide at 350 ppm applied when the second to third leaves had expanded and again two weeks later, resulted in completely male sterile plants (Table III). No staminate flowers were produced. At 500 ppm.of maleic hydrazide there were neither pistillate nor staminate flowers (Table III). Six applications at seven day in- tervals beginning at the emergence of the cotyledons, greatly reduced the staminate-pistillate flower ratios with all chemical growth regu— lators as compared with the plants not treated (Table III). Considering all chemicals evaluated, reduction of the staminate-pistillate flower ratios of Acorn squash was accomplished to the greatest degree with maleic hydrazide. Experiment D: Further studies were conducted with maleic hydra- zide to ascertain its effects on flower developnent in Acorn squash. Seed was sown March 1, l95h in the greenhouse. In Table IV are shown the effects of various concentrations of maleic hydrazide applied at the following stages of growth: (1) seed, (2) emergence of cotyledons, (3) cotyledons expanded, (A) second to third leaves expanded, (5) fourth 826$ 34333 323338 383:. 33.... 83398 8.53 .23 3 etude M3 Beaded 853 22... 3 808m 3 need-98 wood the M3 Yugo 833.38 c * 0.0 33.029 no.5 H8300 ed $66 .166 3 30 me me .3 3 3 do M3 3 3 do *3 3 3 3 «.0 m.0 4.0 30588 meshed 5.3% 3 £938 3. m6 m6 Reg 82.3 EH» 3 Sodom 4.0 Meo Moo 60% Ed #5 m.0 m .0 «.0 no? 330.1300 5.0 0.0 4.0 0.0 3003300 no 028985 flow To ad 3. Row on 3303.30.“ acad— odwcdm 05.“ no :35 000A 03. 00m 0mm 03 00a A33 0359?»: can; no cowagpaoocoo defianefldfi a. 5:20 we amuse 33H .m... .3 3 H no.3: 3325.20 336m 583 new»; 830E decadent fig usage on... do 5395 .3 835 e5. afiezefieeoo antenna a. 8334 3355 3.3. .8 team 2:. 30 to fifth leaves expanded; and combinations of the following: (1) cotyledons expanded, (2) first leaf expanded, (3) second to third leaves expanded and (A) fourth to fifth leaves expanded. With seed treatments complete inhibition of germination occurred at 1000 ppn (Table IV). Maleic hydrazide applied at either 250 or 3 50 ppn when the first leaf had expanded and repeated when the fourth to fifth leaves had expanded resulted in plants producing exclusively pistillate flowers (Figure 2), as compared with plants not treated (Figure 3, Table IV). Maleic hvdrazide at 500 ppm applied at the above stages of growth resulted in flower ratios similiar to plants not treat- ed (Table Iv). Experiment E: That varieties within W m might be evalu- ated as to the effects of maleic hydrazide on the suppression of stem- inate flower buds, the variety Caserta was studied \mder greenhouse conditions. Maleic hydrazide was applied at concentrations 100, 250, 350, and 1.50 ppm (Table v). Stages of growth when treated included: (1) the cotyledons expanded and repeated at the fourth to fifth leaf stage, (2) the cotyledons expanded and repeated at the sixth to seventh leaf stage, (3 ) the cotyledons expanded, and repeated at the fourth to fifth and the ninth to tenth leaf stages. (1.) the first leaf expanded, and repeated at the fourth to fifth leaf stages, (5) the first leaf ex- panded, and repeated at the sixth to seventh leaf stages, and (6) the first leaf and repeated at the fourth to fifth and the ninth to tenth leaf stages. Figure 2. Acorn sqush plant grove: in the greenhouse following treet- Ient with 350 pp of Isleie wax-aside when the first leaf hed expendedaldeuiluhenthe fourthtofifthleeves hsdexpended shoving We. of flown-1h“ flowers with suppression of the statute (loves-ea. Theplant is Isle sterile figure} lonelAeomequeshplentgz-ewninthe weds-ism We s of staminate flowers at the lower nodes. 33 .3onoono Bored oz n... .8252 Sana henna? Bodega .5 n .2 333a. 35 afioeoo 82.3 £89 3 nofiz 8.53 53 3 esteem it! no mo 3.. m .23 no.5 $0 notion £86m 3 some do o4 «A no“ a 3 n22 3 8.53 55 on steam o4 no do as a 3 find 3 853 £89 3 £52 nee-3 £5 3 season in... too on «.o m eoeoafieo 5 no too «A o4 m 853 £85m 3 £58 nannies 3 do o4 do no u 853 names 3 stone noeoiooo a Amoveoaoh $5.3 0.35.» 25% mo Q35 one 3 m one ooa 83.3433 8334 83 one; many o3; 3nd: one; 383 antennae o o Mo non-52 no.5 neweum 5320 .33 .m gene 3 $3 .ou engineer. 68928.6 .533 stondov 3.23m .832 33:95 tong—3n 2:. no dozen... on 83$ on» 8335588 gong no canon: on: use; we team one >5 34 At growth stages (2) and (3) above (see also Table V), only pistillate flowers formed when 350 ppn of maleic hydrazide was used. For treatments (1), (1.), (5) and (6), there was a decrease in the stamimte-pistillate flower ratio as compared with the plants not treat- ed (Table V). In all instances, the staminate-pistillate flower ratios were significantly less on treated than on non-treated plants with the exception of 100 pm of maleic l'wdrazide at stage (A), and 250 ppm of maleic hydrazide applied at stage (3) (Table V). W Field experiments were next conducted to evaluate the effects of outdoor environment on the response of different cucur- bitaceae to the chemicals used successfully to suppress staminate flower production under greenhouse conditions. Again, various concentrations of chemicals were applied at different stages of growth. Experiment A: On June 3 , 1951. seed of the following: Cucumber (releases) 3 (1) mosaic resistant l7 (2) scab and mosaic resistant 12-9 (3) pickle type PM. 11312 (1.) pickle type F.M. 3201. (5) pickle type Fun. 7511.2 (6) slicer type m1. 01750 (7) slicer type RM. D3033 Muskmelon (varieties) ; Mildew resistant "1.5" Iroquois 35 Squash (varieties; Caserta Dark Green Zucchini Acorn Punpldn (varieties); New England Pie Connecticut Field were sown in flats of vermiculite and the seedlings transplanted two weeks later to field plots. Five single plant replicates were used with the plants spaced in the "hill" system six feet apart. The plants were treated with maleic hvdrazide (100, 250, 350 and 500 ppm) in the green- house when the first true leaf had developed. A repeat treatment was applied to the plants in the field with a hand sprayer when the fourth to fifth leaves had expanded. Rotenone (l per cent dust) was applied weekly, to control squash vine borers (W W) and striped cucunber beetles (LBJ-221m): Flowering records for each of the cucurbitaceae varieties covered approximately a three week period initiating with the anthesis of the first flowers. The staminate-pistillate flower ratios in pickling type cucunbers (l), (2) and (3 ) listed above, were reduced as the maleic hydrazide con- centrations were increased (Table VI), except for (3) at 250 ppn. The lowest staminate-pistillate flower ratios occurred at 500 ppn. With pickling type cucunbers (A) and (5), the staminate-pistillate flower ratios were the highest at 250 ppn; but lower at 500 pm than those of plants not treated. Slicer type cucumber (6) also produced the highest 36 .HH .H one: area? 8» parades ”83.33. ten .83. as: fine 3 £58 23 e. :19. B- the or... e. 83%: 2.559 e h on. on 0.4 5.2 «.3 3.8 303888 m4 e; 0.4 «.4 on .5 35 .5: 3 3V GU32 e.« 4.... H4 9m eé 584 4A 04 m.« To 4.« 2235 580 3.25 ed m .o «d «.0 m .o 3.33 a av £33 0.3 «.3 «AN 4.3 oéu soosa 3H3 and ed. m.4« 4.? o.e4 ones 3 g codeine»; 5;. 4.3 mg. 44. mg. 39694 4.m H24 0...” .14 his 89?. #5330." Suva a «.333 84.6.3: o4. 2. 5.3 44. 5. among a: 25 .831... AS ed .4.“ o.m «3 as 03.3 .xd 85 arena 3V may .3 1m 3. 2 35. .2..— 25 33E 3 ea 4.« «.m or» ea 40% a: 25 cued 4v .3 «.4 «A me «.m «£3 a: 0&3 open 3 «.4 o; o.m ma «.4 T3 233...... 338 can seem «v as “A m.« «3 as S €338.“ e13. 5 33V teases . 333%?” Ba 33.? m we 53$ 30.23:. 35 8“ own 3« 8H Hananoo .x. o 0 ago o 00 4mm: .8 one»: o... m as; .33.. negate»: anode: Me Seaeflefieeeo 33.3 a g a e n “.8533 3 an «as «dug a _ .33 «mag no Savage .3 839m eased eefldfifluoesqfiem Hbg 37 staminate-pistillate flower ratio following treatment with maleic hydra- zide at 250 ppn but lower ratios, when 350 or 500 ppn were applied in comparison with plants not treated. With the slicer type cucumber (7) no significant reduction in flower ratios was apparent from use of maleic hydrazide at any concentration (Table VI). The muskmelon varieties Mildew Resistant "AS" and Iroquois had reduced staminate-hermaphroditic flower ratios as concentrations of maleic hydrazide were increased up to 350 ppn; however, at 500 pm a sharp increase in the ratios occurred (Table VI). Similarly, both watermelon varieties were irratic in their response to treatments of maleic hwdrazide, with no consistent trend in staminate pistillate flower ratios as concentrations varied (Table VI). Caserta squash had consistently low staminate-pistillate flower ratios which were not greatly altered as the concentrations of maleic hydrazide were increased. Flower ratios for maleic hwdrazide treated Dark Green Zucchini were lower than for plants not treated, but with no consistent trend as the concentrations of the chemical were increased. Contrary to all greenhouse tests, Acorn squash staminate-pistillate flower ratios were not reduced by treatment with maleic hydrazide at amr concentration (Table V1) with all ratios of treated plants, irrespective of concentrations, being higher than those of plants not treated. The punpldn variety, Connecticut Field, showed a general reduction in staminate-pistillate flower ratio in response to increased maleic hydrazide concentrations, with lower ratios at 350 and 500 ppn than for those plants not treated. Maleic hydrazide at 500 ppn significantly 38 reduced the staminate-pistillate flower ratio of New England Pie pumpkin in comparison with the control plants (Table VI). Treatment and variety separately as well as chanical treatment and varietal interactions were found to be highly significant in reducing number of staminate and pistillate flowers on varieties of Mt; 129.129.. m.2at_oim-ma eels. and mm (Appendix Tables I, II). Experiment B: During the summer of 1955 a second field test was conducted again with several varieties of cucurbitaceae to further evaluate the effects of various concentrations of chemical growth regu- lators on staminate and pistillate flower production. Seed of Acorn and Caserta squash, New England Pie pumpkin, Marketeer cucumber and the cucumber HR 12-12 were sown May 16, in flats containing vermiculite and the seedlings were transplanted seventeen days later to field plots. Three replications of five plants per treatment were used, with the plants again spaced in the "hill" system, six feet apart. Flowering records for each variety of cucurbitaceae covered a period of two weeks. Irrigation water was applied when necessary. The mean temperatures for June and July respectively were 67.1. and 71.1°F. Acorn and Caserta squash were treated with maleic hydrazide at 350, 1.50 and 650 pm; New England Pie pumpkin with 350, 500 and 750 pun: and the Harketeer and MR 12-12 cucumbers with 500, 750 and 1000 ppn. Alpha naphthaleneacetic acid was applied to the five varieties at 100 ppn. All varieties except Caserta squash were first treated when the first and again when the fourth to fifth leaves had expanded. Caserta squash treatments began 39 when the cotyledons were expanded, repeated at the fourth to fifth leaf and again at the ninth to tenth leaf stage of growth development. The data in Table VII show that for Acorn squash treated with 3 50 ppm maleic hydrazide, the staminate-pistillate flower ratio was slightly higher than for the control plants; at 1.50 and 650 ppn the ratio was significantly less. Caserta squash treated with maleic hydrazide pro- duced lower standnate-pistillate flower ratios at all concentrations as compared with the non-treated plants. New England Pie pumpldn showed an increase in staminate-pistillate flower ratio for all concentrations as compared with the controls. The staminate-pistillate flower ratios for both cucumber varieties were reduced as the maleic fwdrazide con- centrations increased, being lower than the control at 1000 ppn for Marketeer and at 650 and 1000 ppn for MR 12-12. Effects of alpha naphthaleneacetic acid at 100 ppn varied for the different varieties. Staminate-pistillate flower ratios were reduced for Acorn squash and the cuctmnbers, while with Caserta squash and New England Pie pumpkin, higher ratios occurred as compared with thom for the controls (Table VII). Appendix Table III shows a highly significant difference for the number of staminate flowers produced, as influenced by effects of maleic hydrazide treatments, while with the number of pistillate flowers pro- duced the maleic hydrazide treatment effects alone were not significant (Appendix Table IV). Since maleic hydrazide under field conditions did not suppress staminate-pistillate flower production of Acom squash, the results in the greenhouse were not confirmed, and therefore, an 1.0 .3” .HH «0.33. 5.93%: coo ”8.3330 3339.0: pom .vnoa League .3 some... “84 5:3 3 55: 23 3.. :32 3 4.58 23 a. 3d? £38.98 Severance a. nausea It. Sees—league no one... .23 eta 3. 5.38 of e. 54? e5 .23 the on... .3 Sag .. 4.« «A a; no 2. $33.5. 35 48....8 o.« m.« 9m 4.4 me 84 33 eateseegafiuz and «A 4.4 o84 4.4 m.“ 94 one . m6 me 93 a.« as «.m 8w 4.0 1m 84 Tm 4.o «.3 an .333. 3.1: $38342 23% m 8.3» no :85 Menage non—525 c.3955 cam seesaw 5425 an 13.4550 *«73 m: 18.3.3. avenge 3.: $3.88 *284 32A .4 3&3 3 3 .22 .335 33 afloeseegafiez and B. 843.6% 3.34 no 83.5....888 33”.”; .3 63533 as 3.3-” 3 en.- ddufl g .«o noaaoane> no 331m .83on oaéanfllougm HH> an. additional experiment with higher concentrations of maleic hydrazide was conducted during the late sunmer and early autumn. Experiment 0: Acorn squash seed was sown July 23, 1955 and the resulting plants treated with maleic hydrazide at concentrations of 500, 750 and 1000 ppn in the greenhouse when the first leaf had develOp- ed; with the repeated applications made after the plants were trans- planted to the field and after the fourth to fifth leaves had expanded. Three replications of five plants per treatment were used with the plants again spaced six feet apart in the "hill" system. Flowering re- cords were kept, covering a three week period beginning with the first anthesis. The mean temperatures for August, Septanber and October, 1955 were 69.0, 61.8 and 50.5‘F., respectively. The increased number of days required for the appearance of the first staminate flowers was highly significant as the maleic twdrazide concentrations were increased, while those for pistillate flowers were significantly increased (Appendix Tables V, VI). Plants not treated produced pistillate and staminate flowers at an earlier date than plants treated with maleic hydrazide (500 to 1000 pm) (Table VIII). Maleic hydrazide also significantly increased the node number at which the first staminate flower occurred (Table VIII, Appendix Table VII). . There were no significant treatment effects on node numbers at which the first pistillate flower appeared (Appendix Table VIII). Highly significant suppression of staminate flowers (Appendix Table X) was obtained with 500 ppn (Figure I.) and 750 ppn maleic hwdrazide (Figure 5). as compared with plants not treated (Figure 6, Table VIII), while .3 29.85 s 83.2. 58284 8. 8331.5 33.33. 8a .3803 33:23 575335 833.3 395 5.... .226: 3:553 e. .2232 scans .. seed 3.5.3. ten .5 0.0 >.m H.o 4.0 wndvooeaa eaosodu caeaadaofim 0.H ***0.0 H.0 . «.0 .uaesoam o.aa 4.5 III. n.m 0.H H.m m.m m.oa oaeafldeafin 0» soundness no odpem .vonuogge naezoam Amy use Amv m.a 0.¢H Ito: N.HH 0.m 0.ma 0.4 0.0H anawu ono.no«:3 we genes: eeoz .uozoau Amv one Amv pmafiu no .7? 0.3 I... 5.3 oi. «.3 0.3 93 8g. s8 .3 co 83 Anopeoaanoa ocean m eons» no neozv m a m a F F m a in i . as g 5‘. flmddw. 833.: .342: Honnsoo o o oo 033 .fi .8338 3 ma 3:. .Boév 33$. 5.596 3 sea 3 £58 23 93:5 898a; e5 .35 the on» s. 83.5 5.; €33 58¢ ca 3.23.» so 3283 3.1: no 23.38.88 gotcha «o tote 2; HHH> mqmda .3 2312.3 335 taxed 343.3.— 3 :33: 5 head 3.5.3. no 8:16 8.5 in. .8 nfififlufifi 8». 3... So: its“ no 8.3.. ~45 sad 3. 5.58 .5 an 3.8%.. us. 35 on... a. .3332 3.1- IE 8“ 5.? 3.8.3 €39 933 z. 582 of Mo 11.“ If. reputed gt. tho ton-tn to am: 1:: am» prone-mm; mm». (mm upon-m. c). l S i E .9: fi 3 g E B 3 .3 31.3. no 3553803 $533. vand— Ag- E84 333130: .0 0.3»: 1.6 the nunber of pistillate flowers was increased as compared with non- treated plants (Table VIII, Appendix Table IX). As indicated in Table VIII, treatment. with 500 pm maleic hydrazide reduced the staminate- pistillate flower ratio to 0.2, while no staminate flowers developed when 1000 ppm was applied. in average ratio of 1.6 occurred in the con- trol plants. The mean differences in numbers of pistillate flowers preceding the first staminate flower were highly significant, as the maleic hvdrazide concentrations were increased from 500 to 1000 ppn (Appendix Table XI). The greatest numberof pistillate flowers pre- ceding the first staminate flower, occurred with the 750 ppn maleic hydrazide (Table VIII). W: A final greenhouse study was initiated October 21 , 1955 and continued through February 25, 1956. Acorn and Caserta squash plants were grown in 10- inch clay pots filled with soil, placed on movable carts and exposed to 8, 12 or 16 hour photoperiods at night temperatures of 60 or 70°F. The plants were treated twice with maleic hydrazide at 350 ppn or alpha naphtlnleneacetic acid at 100 ppn with additional plants not treated left as control comparisons. The first chunical treatment was applied at the first true leaf and the second, at the fourth to fifth leaf stages. Flowering responses as influenced by chemical treatment, photoperiod, and temperature were evaluated for the two varieties in the usual manner. Some interesting relationships occurred in pistillate flower pro- duction on the two varieties. Acorn squash grown at 70°F. (night A7 temperature) and treated with maleic hydrazide, produced a smaller number of pistillate flowers than the plants not treated at each of the respective photoperiods (Table IX, Figure 7 A). At 60°F. pistil- late flowers were produced only during the 12 and 16 hour photoperiods on plants treated with maleic hydrazide (Table Ix, Figure 7 B). At 70°F. Acorn squash treated with alpha naphthaleneacetic acid did not produce any pistillate flowers during the 16 hour photoperiod, while at 60°F., following treatment with alpha naphthaleneacetic acid, neither staminate nor pistillate flowers were produced at any of the photoperiods. For the variety, Caserta grown at 70°F., the number of pistillate flowers on plants treated with maleic hydrazide decreased as the photo- period increased, while the number of pistillate flowers on plants treated with alpha naphthaleneacetic acid increased (Table Ix). No pistillate flowers were produced on Caserta treated with.maleic hydra- zide and grown at 60°F., while with plants treated with alpha naphtha- leneacetic acid the pistillate flower number was increased as the photoperiod increased (Table IX). The number of staminate flowers on.Acorn squash grown at 70°F. (night temperature) whether treated or not treated with maleic hydrar zide, increased as the photoperiod increased with the number of flowers on the treated plants being smaller than on the control plants at the respective photoperiods (Table IX, Figure 7 C). Alpha naphthaleneacetic acid treated Acorn plants produced staminate flowers only during the 8 and 16 hour photoperiods at 70°F. For plants (Acorn) grown at 60°F. 1.8 .33 .5” 23a. fined? 8. 833.36 483303. 3a .voosooue 0.3.3.3 oz u... :83on spends-am a... .uexofln saga-E * 0.o o.o 0.0 4.0 0.0 o.o «.4 «.5 ...- 0.0 0.« 5.4 04 0.« 0.« 0.4 .... m.« 03.60 3.830 4.0 ..- o.o ... o.o ... ca 0.« .......- I! 0.0 .... ...- ..... Tm .... .... .393 E84 33 39885339.: and 0d ... 06 I. 0.0 ..- «.4 «.5 ..-- -... m.« 5.4 -..- -..- m.« 0.4 .1..- .... sang 3.808 4.0 o.o o.o o.o o.o ... oA 0.« II o; 3.. Tm -... o; -..- «.0 I 533 E84 835% 3.1: _ otsaaonela $.00 5.0 5.« a.« «an 04 «.m 0.4a 0.4 4.0 o.« 0.3” o.4 o.“ 0.4 0.0 0.0 «.4 04 £33 £86 0;. 322E H.« o.o 0.4 o.o o.4« 0.« «.3 ...- 4.o« 04. ...- 0.« «.5 4.a o4 «4 save £84 33 03.33.3302 3a: 5.« «.m o.« 5.« 0.4 0.4 0.4a o.4 o.4 0.4 0.3 o.4 0.4 04 0.0 0.0 0.4 0.« 00:60 588 0.50 0.0 H.« 0.0 04 0.0 o.4« 0.« 4.4a 04 4.8 0.0 0.0 0.0 «.4." 44. o.m «.0 53$ £84 34933: 3.03. 838.989 $.05 $33.5”qu panda edge 03“ Ho :35 0 a m a 0 a m a 0 a 10 i 0.03:. 82 0.08; 03.3.4. so: 03.8.4. 0385 so: 808:. ...lldunfllqfl.‘ (Illa? ..Illdaflllllllm '( t “Ha 30$ .0« Eustace 3 33 .H« 3038 60202530 53:00 33:63 ecu 58$ AER 003 304 owaoosocodwnvfiez 9342 one Anne 33 cognate»: 303 .ohsaetoaaon. .uouaoaoaonm .3 anaconda no 330m 33on oagdanfllopefiagm 23 use 303on no pea—52 one 1+9 6333—5. 30d:- 13 33809!» 4.3: {fix—38.— 5.. 38843 3 €89. 884 a. 82:5 333435 05 3.5.3. «o 80.5 .5 250: 3309a :28: on a 348.: so: I 34.554 3.1: as can § 84.233. 8.2.3385 03.333. vofla39a .304 33.30 .304 .33 .30 £04524 .2. .204 .234 .20 I. 2 2 . i ,. o i T ”4.. 1.4 L 1” .fi 04 .8. .4« .‘ .5 .3 . .5 .05 .u .3 4. .05 3.5.30«. 3.5.3005 133-4.... .3443 “and” Jo .toqmu 50 and not treated with maleic hydrazide, staminate flowers were produced only during the 16 hour photoperiod, in comparison with.maleic hydra? zide treated plants which produced no staminate flowers at any photo- period (Table IX, Figure 7 D). At 60°F. alpha naphthaleneacetic acid treated Acorn squash produced neither pistillate nor staminate flowers (Table IX). For the variety, Caserta grown at 60°F., no staminate flowers were produced from.plants treated with maleic hydrazide; however, staminate flowers were produced during the 12 hour photoperiod on plants treated with alpha naphthaleneacetic acid (Table IX). At all photoperiods and at 70°F. the staminate flower numbers from Caserta plants treated with maleic hydrazide and alpha naphthaleneacetic acid were smaller than those on nonstreated plants (Table IX). In all instances, the staminate-pistillate flower ratios for maleic hydrazide treated Acorn and Caserta squash grown at 70°F., increased as the photoperiod increased and were generally lower or the same as those of plants not treated, with the exception of Caserta at the 8 hour photoperid. The staminate-pistillate flower ratios for Acorn squash grown at 70°F. and treated with alpha naphthaleneacetic acid were smaller than those of non-treated plants except during the 16 hour photoperiod (Table IX). The staminate—pistillate flower ratios for Caserta squash grown at 70°F., and treated with alpha naphthalene- acetic acid was greater than the plants not treated, except during the 16 hour photoperiod (Table IX). The staminate-pistillate flower ratios for Caserta squash grown at 60°F. and treated with alpha naphthalene- acetic acid, were lower than the plants not treated at all photoperiods (Table IX). 51 The node at which the first staminate and pistillate flowers appeared on Acorn and Caserta squash was also influenced by photoperiod, temperature and the chemical treatments utilized. Pistillate flowers on maleic hydrazide treated and non-treated Acorn squash grown at 70°F. appeared at a significantly higher node than those on plants grown at 60°F. (Table X, Figure 8 A,B). At 60°F. the node at which the first pistillate flower occurred from maleic hydrazide treated plants was lower than those of plants not treated at the 12 and 16 hour photoperiods (Table X, Figure 8 B). Pistillate flowers on maleic hydrazide and alpha naphthaleneacetic acid treated and non—treated Acorn and Caserta plants grown at 60°F., appeared at significantly lower nodes than those grown at 70°F. (Table X). At 70°F. the node number at which the first stami- nate flower occurred on maleic hydrazide treated Acorn squash was re- duced as the day-length was increased (Table X, Figure 8 C). Acorn squash not treated with maleic hydrazide and grown at 60°F. produced staminate flowers during the 16 hour photoperiod at a higher node number than those staminate flowers produced on plants grown at 70°F. (Table X, Figure 8 D). With respect to the variety Caserta grown at 70°F., pistillate flowers on plants treated with maleic hydrazide, appeared at approxi- mately the same node as the non-treated plants irrespective of photo- period, while the staminate flowers appeared at a much higher node (Table X). Staminate flowers on Caserta grown at 70°F., and treated with alpha naphthaleneacetic acid, appeared at a lower node than those on plants treated with.maleic hydrazide, while in contrast, the 52 .ex .55 33a gee? 8. e303? 33.33. tee 60269:“ 32.5.: oz :8on opaque-am .1. dosed season * o; «.5 .3- «.5 4H «.5 90 4.0 0« 6.0 3.. 6.5 533 £38 6.3 4..H« 3..- 33 33 o.o 3.33 33 «.5 -.3 3.- £360 £84 33 eateuoSgfieez 334 GA «.5. 33. It... 4.." 0.5. .33 ed 0.0 0...... 3!. season «£03 6.3 4A« 3.. o.o ..3 o.m 33m.5 3.- m.5 ..3 .3. e33 584 33351 3.3. 95.790959 .578 on 6.3 m5 o.4« o4 0:2 m.“ 0.8 «A 4.3 . m.“ 5.0a :36... £38 m3 6.: 05 .3. «.« «.2 339.: 0.n 0AA ed” «.«H seesaw 884 304 eaeoeaoeoafiefiez 934 on o.oa m e «.3 64 “A.” «#92 «A 4.: «.m «fl ensue 3.86 ««H 9% 00 3: «.« «.«H 55. 0.3 0.m 0.: 0.2 «.2 :53 E84 0353 393. 838.989 $.65 Anopeoaop 0.53 0.35» 25d no 505 0 a m m m m m e m a in em vegans 902 @9329 gauche 902 voodofl. con-ions voz condone . 303 .m« ghee 3. mama ..n« 3836 8.338810 £330 £38 e5 E8: AER 8d 33 eapeeueeegfieazfiefi 8. Ana 603 338e,»: 3.1: 6.898359 .eefloeeeefi B 88825 8 83234 2.32 scanner e5 3.553 the 23 £2: a. ..352 28: 2a. fig 53 gigo-x 3&5 .304 .3«« 3o R RR RR .h .8 Iain fl 63.83. aid... I... teens—Ia 3m? .eetleefie 3 c.8255 8 3.3.3. need 33%. 3.84 34:33.3 8. .353. the 3.3.. a. tale .8: .m 9333 32253.. .30” .3«H 3o .h .2. 0&3 o 38.3. a... I 3fl&3e£ .3 0H .3 «a .3 .m .8 0% I .3353 3.3 Is Rm 5 vets—3.5 30H .3«a 3o .u .2. on? 4 43 .3” .8 run .10qu epofi 5h pistillate flowers appeared at a higher node on plants treated with alpha naphthaleneacetic acid as compared with those treated with maleic hydrazide (Table X). The time, in days, required for the appearance of the first staminate and pistillate flowers of Acorn and Caserta squash was also influenced by the various photoperiods, temperatures and chemical treatments applied. The number of days required for the appearance of the first pistillate and staminate flowers on.maleic hydrazide treat- ed Acorn plants was significantly greater at all photoperiods and temperatures than plants not treated, except during the 16 hour photo- periods, during which the plants not treated either required.more or approximately the same number of days to produce pistillate flowers (Table x1, Figure 9 A, B, c, D). Plants of both varieties treated with alpha naphthaleneacetic acid and grown at 70°F. required more days for the pistillate flowers to appear than did those treated with.maleic hydrazide (Table XI). Caserta at 70°F. and treated with alpha naphtha- leneacetic acid, produced staminate flowers after fewer days than plants treated with maleic hydrazide. The number of days required for the appearance of the first staminate flowers of either variety grown at 70‘F. and treated with either chemical, decreased as the photo- period increased (Table.XI). The number of days required for the appearance of the first pistillate flowers on non-treated Caserta squash grown at 70°F. was greater at the 12 hour than at the 8 or 16 hour photoperiods (Table XI). At 60°F. the number of daYs required for the appearance of the first pistillate flowers on Caserta, not .5: .Hi 838. .3893 8. 5331... 33.33. .8 602693 93.53 02 £252 3.5.3.... r. £2.63 3.33...." .. 0.2. 0.2. .I- 0.2. o... m... 0:5 33 ..8 o... .I. 33 :36... 3.8.8 93.“ 0.8." II .I. I... “A. ..I II II o... III. .333 E... 3.4 .3....=.3£a.z sad 0.? oi. ...I II o... m... I s... can III- .36... 3.3.8 Sad .63 II o I. «é .I. .33 -I- a... .I. I... €33 E... .338? 33.: 05593939 $.00 33 ...m You o n. a S o.$ c Q. o... .6“ .13 0.2. o... :38. 5.3 .12 «A. 93. I «m can .I. m... 0.3 o4. 9.... 9.3 :36... E84 3.. 3.888152%: £34 0.3 a... “.2. 3.. 4.3 03 as“. mé. o.o. ..S in. ode :36... 3.8.8 .33 $3 ..3 new. «A. can o3. .3. can 93 can. .28 e353 584 .33.; 3.1: .éafioeia .92. Aeovsaoa $5.3 edge 023 no 505 m a m a m a m . m m . a re a 8.3a. ..z 9...; 8.3.9 ..2 8......“ 3.8.3. no: 8.8.9 Jflaall'llgudll .llllluuaawlnlll I1 [I A33 .3 ESE... 3 33 .N .338 6828.5 3.33 3.8.3 use 5005 Anna 8.3 304 03333133; 392 nee mag 33 03.5.8.9 30.1: 3.5.7598." 622.9305 .3 8.552 .. 2.33m Saga .5 Sana-am .25 .5 .8 3.3.5 o... .58 a. .352 .6. Hung 56 63552 3.1.. 3. 5.8.9.... £3. aqua—38.. 3 3.8.55 3 a}... £84 a. 22:5 ...Adaqu 3.. 3.5-3. .5» a» u. 8i. .3 .5 3c: .3. u. .215 2.2.98 225......» .3363. adding—Rn ! 3.3395 £3 .afi he. xx xx. .h .8 Gain a Eta; .3 ma .3 3 a...» .u .3. 3...!» o 38.8 a... I Efifiofifl 3...: Ema h; cad—Hug m gasfim .33” haw." nab oh .2 3% 4 $953..— Im Jo Jam 57 chemically treated, was less during the 12 hour and greater at the 8 and 16 hour photoperiods (Table XI). The number of days required for the appearance of the first staminate flower on Caserta squash not treated, decreased at both temperatures respectively, as the photo- period increased (Table XI). With Acorn plants grown at 70’F. and 60°F, and not chemically treated, the number of days required for the appearance of the first pistillate and staminate flowers was the great- est during the 16 hour photoperiod. Pistillate flower numbers preceding the appearance of the first staminate flowers of both varieties was also altered by photoperiod, temperature and chemical treatments. ‘Where flowers were produced, the number of pistillate flowers preceding the appearance of the first staminate flower of nonstreated.Acorn squash plants was greater at 60'F. than at 70°F. (Table XII, Figure 10 A, B). No pistillate flowers appeared before the appearance of the first staminate flower on Caserta treated with alpha naphthaleneacetic acid at 70°F., while at 60°F. there was significant increase in number over those on plants not treated as the-photoperiod was increased. Acorn plants grown at 70°F. and treated with maleic hydrazide, had the greatest number of pistillate flowers preceding the appearance of the first staminate flower, during the 8 hour photoperiod. Maleic hydrazide treatments induced more Pistillate flowers to appear before the first staminate flowers on Acorn plants than did alpha naphthaleneacetic acid at both temperatures, except during the 12 hour photoperiod at 70°F. 58 ASE 3.3 €83 8» “33315 10332.: 8a 602603 32.63 oz .83on 33.9.33 * oz... o.m m6 b.~ o.o m.N season gonad o.~ II in II 0.4 ll :33 803 32 0388832“; 2&4 00H I “00 i 0.0 ell-III sad—flaw §0Q6 o.~ o; man 04 0.4 ll :33 £02 335% 303 Eugene-we Amoco o.o o.o o.o o.o o.o o.o :33 «£38 o.o o.o o.o m.~ To 04 nausea 883 33 oapmogemgpfiaz 3a: o.o To to oé o.o m6 533 33nd o.o o.o o.o fa To 03 egg 584 033.8% 303 232033 ...rR Ammpdoaou 9.3.3 can 03“ we 505 m m m m m l 8.5.89 82 espouse €2.89 32 e38; 8.3a 82 emanate Illldufllom 3.. i _. ..IIIJHQMHIIII Jam... mini! 3an .mu magma 3,33 .Q “338 .omsozeemeo Begum 3.830 and 53$ ARE 00.3 33 0300353»an use: 93 Anna Ommv 3.3865: 30.32 .onsadaoeeua 60.309305 .3 3059.35 3. Agog oagm 992E 2.3 meadoooam £93on 09333 no .3852 one HHM an. m... m . m m m .m W m. w. a o m.» w mam. , . .m w mm W W... M m h i L... . x mm“ g Goad-n HO hoia 60 The results of a statistical evaluation of the temperature, photo- period and chemical effects on the various indices of flowering re- spone of Acorn and Caserta squash are listed below with tables in the Appendix. Concerning the total number of staminate flowers produced, photo- period showed no significant effects, while temperature and chemical treatment singly, and the interactions of chanical treatment with tanperature, chemical treatment with photoperiod and chemical treat- ment with variety, were highly significant on influencing the number of staminate flowers (Appendix Table XII). The total number of pistillate flowers produced was not signifi- cantly affected by photoperiod or temperature separately. The inter- action of chemical treatment with photoperiod was significant. Chemi- cal treatment singly, and the interaction of chemical treatment with temperature and chemical treatment with variety were highly significant (Appendix Table XIII) . The node number at which the first staminate flower was produced was not significantly influenced by photoperiod singly, or the inter- action of chemical treatment with temperature. Temperature and cheni- cal treatment singly, and the interaction of chanical treatment with photOperiod and chemical treatment with variety were highly significant in influencing the node number at which the first staminate flower was produced (Appendix Table XIV) . Concerning the node number at which the first pistillate flower was produced, tmperature or photoperiod singly, or the interaction of chemical treatment with photoperiod showed no significant effects. Chanical treatment alone was highly significant, as were the inter- acting effects of the chemical treatment with temperature and chemical treatment with variety (Appendix Table XV). The nunber of days required for the appearance of the first staminate flower was not significantly affected by photoperiod. Tempera- ture and chemical treatment singly, and the interaction of chemical treatment with temperature , chanical treatment with photoperiod and chemical treatment with variety were highly significant, however (Appendix Table XVI) . The number of days required for the appearance of the first pistillate flower was not significantly influenced by photoperiod or temperature singly or by the interaction of chemical treatment with photoperiod. Chemical treatment alone, the interaction of chemical treatment with temperature and the chemical treatment with variety were highly significant (Appendix Table XVII). The number of pistillate flowers preceding the first staminate flower was not significantly influenced by photoperiod singly, or by the interaction of chemical treatment with temperature, and chemical treatment with photoperiod. Temperature was significant, while chemi- cal treatment and the interaction of chanical treatment with variety were highly significant (Appendix Table XVIII). It should be noted that the many significant interactions make it difficult to asign any definite results to any one factor used in the experiment . 62 WW Although many effects of maleic hydrazide on the gross morphology of plants have been described, there is little information on internal cellular structure. Consequently, a study was conducted to relate internal histological changes to external evidences of reduced staminate flower production. Samples of buds and apices from Acorn squash plants were collected at intervals of three days beginning May 3, 1955, following treatment with 350 ppn maleic hydrazide when the first leaf and repeated when the fourth to fifth leaves had expanded. It was previously determined that this treatment would normally result in a complete suppression of staminate flower buds. Buds and apices were also collected at corres- ponding intervals from plants not treated with maleic hydrazide. The samples were fixed in a FAA solution and dehydrated with butyl alcohol, imbedded in paraffin (melting point 53 to 55°C.) and then sectioned with a rotary microtome at 15 microns in thickness and stained with safranin and fast green. Detailed camera Lucida drawings were made to one scale for the comparative materials to give identical enlargement . The comparative rather than the absolute measurements were used to stress the nature and extent of the time response to maleic hydrazide. The morphological structure of the terminal meristem (apices) from plants treated and not treated with maleic twdrazide are shown in the camera Lucida drawings (Figure 11). Three days after treatment, the apex was inhibited in growth as compared with the non-treated apices (Figure 11, tOp, left). Cell differentiation of the staminate flower 63 .. 3.41: . 1 i D "p: *p . ’ ."e' ‘ .Q 3 "I ”It. ‘ 5) o . 1...... ‘ ’ O 1. .- 5.«. at: r-‘w ’. ' . ...:-h .- \ffil . . ' J“!- VJ': '3'... e“ o r. . ' 9..'.’. -' 10...! o ..o ‘0 ' ~ ‘ a... ‘s ‘ "I.“ a. 0:! d 55:1... ." 0.. ”.39. '. ’3".'..' . 3:2. - " . 2...! : o . .9 "S a . a ...mi. A.“ o a..- 2‘.‘ 'I .v- I l 3" f. ‘ I ' pb 3“ 1" ‘- - . ~ ‘3 . ’- I {F -' ‘4'": ‘ ‘ . . 44‘ ' - 3r . 5‘ . c ..J n 3 . . ‘ t 9 ° ' ,. A .- " fi' ‘ .{ . . t ' . g. r < . ' . a 4!...1.‘ .. . ., (“L g'.‘ I a. '. ' z . . - . 3".5. ' .51" ‘ $15- 9 “ 3327;, . .9z;§’ . 9.. J ‘ e sf? 3-. ". £§'fl; .- 9 I. ’ . w h ( .. ‘ ‘ ‘ Q ~ 1 2‘. 3‘ ‘ n . . ‘ A " 'v-z' ’. 5' . o o;: a,' 5 ~' : 0.." ..' £~ '3: ' ). " q, ._ s l V)‘ . . . . . o t 4 - .' A“ .l .0 ’ - ' 0 1‘ a .' o n' . . .0 .f.‘ 1": " 's ’1 - ‘1‘ -\ . ' . G . . - ‘ A fit ‘. 9 :96 ~ . A .- . . ‘ . ”WV-.9 ~. ' - v - . ~ I " .e: L ‘ ' ‘1'”? 22‘.P.... -.' . 9 .. . - . A . -.. w- ~‘ . " - ‘z' I If: . fi‘ \ A" s. ' ". . ' . . 5' ..‘f ..t.‘ ° " l o ‘ . ' ‘ 0 ,. ‘fl . .u 7‘ . I . ' O . . : if" *:.00 . ° "~ ) .‘. . o . . _\ rm . ;~.. 3;: ' .53 -- “$43“: .. o , . 9 o o Jrr”; ‘ r ‘ . ' ‘;.. "’1."- ‘5 ° 9 ' .gnd. ".4 ‘“ ° ‘ n o l r a ‘ ‘ J H. 1‘ ‘ h 3- ' '1' s" H 0.. r g o . o 9 "4*“. a: T. '° . ‘n'r" I at -- 9 ' 2'. ° 9 e... . 'mfe‘; -.~ f.“ ' ‘ \ . 0 g ,. u ' - - .9. “:9. ..-.-= - - . a... ‘ '0 .9N'" I . . . .0. 1 ’ ..o’ . c ' ' .0 . . ‘ 5" ‘1 o I . ’ o n’ . o . ° '0. I \ I . "’ \o... . . o.. o . . I ‘ . ’ . O. c - .I o . . . . . I . . ' c O . 0 o . . . . Pinon. Mammotluutwuctiomoftoninal m of Acorn squall. Loft—top to bottu: Ion-treated plant m-m3,fl,and3lhysfmti-offirstomimtion MWMWNWM. Right—topto mun Wowtmtdplnttmurist-s 3, fl, dnmfmtinoffthmmnhibitionofflom bunt-pica]. develop“. (W 1.691). bud was almost completed for the non-treated plants, while plants treat- ed with maleic hydrazide showed an inhibition of cell differentiation in the stem apices. With all apices of maleic hydrazide treated plants there was no formation of staminate flowers and tissue differentiation was greatly reduced as compared with the controls. As the time from the first collection date increased, the plants not treated with maleic hydrazide, gradully shifted from the initiation of exclusively staminate flowers to both staminate and pistillate flowers (Figure ll, left, t0p to bottom). Approximately 23 days from the time of the first examina- tion the treated plants began to initiate pistillate flowers (Figure 11, right, center) in contrast to plants not treated with maleic twdrazide, which initiated pistillate flowers approximately 31 days from the time of the first examination (Figure 11, left, bottom). The gross morphology of staminate and pistillate flower buds har- vested from Acorn squash plants treated and those not treated with maleic hydrazide is illustrated in Figures 12 and 13. The staminate flower buds from control plants had fully developed androecia in com- parison with staminate flower buds from treated plants, which exhibited elongated, widened, leaf-like sepals and undeveloped androecia. The pistillate flower buds from plants not treated with maleic hydrazide had fully developed corollas and ovaries, while pistillate flower buds from the treated plants were shown to have elongated ovaries and twist- ed, shrunken coroL‘Las. Such flowers, however, when pollinated with viable pollen, produced normal fruit with seed, which upon gemination produced normal appearing plants. longitudinal sections of staminate 65 Staninete flower showing undeveloped androecia. Sta-inate a O 2 In 5 c i; i 3 2 a right : right 8 Figure 12. 66 elongated ovaries and when pollinated twisted, undeveloped corollas. Such flowers, however, ed produced usual fruit and so . loml pdstillate flowers Abnonal pistillate Figure 13. Pistillate flowers of Acorn squash. Top: showing fully developed corolla and ovary. Bottom: flowers from Isleio ”dz-aside treated plants showiu 67 flowers harvested from maleic hydrazide treated Acorn squash are shown in.Figures 1h and 15. Pollen grains were normal in the androecium of staminate flowers harvested from plants not treated with.maleic hydra- zide as compared to the shrunken protoplasm in the pollen grains of androecium from.treated plants. 9‘ ,I‘Qfi I e ‘ '. . I ' ' . 1‘ ‘\> \ ' . \ s ‘ x U 2:. ‘5 ~ ’ x“ - ‘ . A . m . "‘ :r‘k .‘ ‘ ‘ .“ ‘\‘ ‘ 5' s Figure 11.. Photenicregreph of a lengitulinal section of an androecia. Ir. a staminate flower bud produced on non-treated Acorn squash. lete the usual pollen grains. (Magnification 2801). 0‘ . (Jinn-Mm Acernsqush. letetbshr-IQMa-iaponeapdas. (leanification 280K) Wefaleu‘ltuflaalsectienofanaadreeeiufm DISCUSSION Considering all the chemicals evaluated, the reduction of the staminate-pistillate flower ratio of Acorn squash was accomplished to the greatest degree by maleic hydrazide in the greenhouse and field studies. The stages of growth of Acorn squash, as related to the best time period for application of maleic hydrazide was found to be after the first and again after the fourth to fifth leaves had expanded. Poor staminate flower suppression was obtained at stages in plant growth when there were few or no leaves present. This was probably the re- sult of inadequate absorption of the chemical. Relatively low con- centrations had to be used to prevent direct foliage injury and yet in quantities absorbed, they were likely inadequate for the inhibition of staminate flower production. Repeated but not single applications of maleic hydrazide at 250 to 350 ppn prevented staminate flower production of Acorn squash under greenhouse conditions. Single applications may have not provided a sufficiently long period for absorption of the relatively low concen— trations of maleic hydrazide, while high concentrations applied once were injurious. Repeated applications with other chemicals also proved to be more effective than single applications in reducing the staminate- pistillate flower ratio. In the fore-mentioned studies, Acorn squash was utilized because its growth habit made easy training of the plants 71 in the greenhouse. However, studies with the variety Caserta, showed that 350 ppn of maleic hydrazide also resulted in complete male steril- ity. Suppression of the staminate flowers was obtained with triple applications of maleic hydrazide, applied when the cotyledons, fourth to fifth leaves and ninth to tenth leaves had expanded. The chemical at this concentration and at repeated applications apparently was sufficient in quantity to continue the suppression of staminate flowers through the experimental period. Although.many varieties of the cucurbitaceae family, grown in the field, had their staminate-pistillate flower ratios reduced at most of the concentrations of maleic hydrazide employed,no complete sup- pression of staminate flower initiation was attained except with Acorn squash. The lack of suppression was probably due to improper timing of chemical application, as there were great differences in varietial responses, even with types closely related. A comparison of all vari- eties indicated that no two varieties responded alike to chemical treatment, and it is evident that for each variety, the optimum stage of growth and chemical concentrations would have to be determined, if complete male sterility is to be attained for practical hybrid seed production. In other studies, it was found that for a given physiological re- sponse that higher concentrations of chemicals were required with plants grown in the field than those grown in the greenhouse. Al- thought 250 and 350 ppn of maleic hydrazide were effective in sup- pressing flower production in the greenhouse, they actually increased 72 the staminate-pistillate flower ratios of Acorn squash under field conditions (Table VI). This may have been due to dilution of the chemical by resulting dews prior to the absorption, or the leaves may have developed thicker cuticles more resistant to penetration of solutes in comparison to greenhouse plants. Also, a lower relative humidity may have reduced the absorption rate of maleic hydrazide as reported by Zukel (59), whereas under greenhouse conditions the relative humidity was generally higher. In addition, the longer photoperiods and higher temperatures in the field favored production of staminate flowers, whereas somewhat lower temperatures and shorter day-lengths ‘were more conducive to pistillate'flower production in the greenhouse. This influence of environment on sex expression of other cucurbitaceae has been reported by Edmond (10), Danielson (7), Hall (19), Nitsch'gt 3;, (36) and Tiedjens (AS), and confirmed by the present studies. Suppression of staminate flowers of Acorn squash with maleic hydrazide was excellent, in comparison with plants not treated during the final field experiment conducted from July 23 to October 1A, 1955. As the days became shorter and the night and day temperatures cooler, a greater degree of femininity (36) was exhibited by all plants. The longer photoperiod was prObably the deciding factor in influencing the great difference in staminate flower suppression during the early summer of 1954 as compared with the staminate flower suppression ob- tained during the late summer of 1955, as temperatures were approxi- mately the same for all field experiments (Table XIII). This was con- finmed by the greenhouse studies (Table IX), where short photoperiods 73 s.H m.m a.~ Assamese eozv Hoeeeoo o.o 83 o.o OS. m.m 03 To .3 8m N.m One ads as 0mm in 0mm . o.m ooa 5 2.2 ...H was .5 3:: ...H SQ. .5 R1: ..i new and .uaduuqaqdam .oEos «HMHMMdegM .osme .dmduumdqdnm. IlldmmmHll oeflumpehm owoamz aqua 5.82 s38 :3: 35d use: edema use: has new: 33 use: we 80385828 ca .900 on MM Hmmw mmma mo museum oped e . «I; s a $2 .8 553 seem on 434 8. Miami. $2 .3 55% 1" 1' .eamfim on» cw meommom economuwm omega moweda assoc can: oewumnem: afloamz mo mGOfiumnpmoocoo escapes me emocozHHcH no nmmqum cooo< mo moaned nozoam oudaaaumfimtopmeflsepm HHHX mqmde 71. and low tauperatures definitely favored production of pistillate flowers in comparison with high tauperatures and long photoperiods, which favored staminate flower production. Similarly, Kitsch, fl. ‘1. (36) reported that low tanperatures and short days favored pistillate, while high temporatares and long days favored staminate flower pro- duction in Acorn squash. They also reported that low temperatures favored pistillate flower production, and increasing the photoperiod at the same time, retarded the production of pistillate flowers, in- dicating that the effects of light may reduce the effects of tapere- ture on pistillate flower production of Acorn squash. Many of the above relationships can be explained by the final ex- periment conducted in the greenhouse where tuperature, photoperiod and chanical effects were evaluated for both Acorn and Caserta squash. Treatments of 350 pun of maleic ludraside applied to Acorn and Caserta squash completely inhibited the production of both staminate and pistillate flowers during short (8 hour) days at 60'P., however, as the day-lengths were increased, pistillate flowers were produced on Acorn but not on Caserta squash plants, thus, indicating that the two varieties differed in response to chasical treatment, photoperiod and temperature; also, that the effects of tuperature may have re- duced the effects of photoperiod on pistillate flower production of Acorn but not on Caserta squash. The increased nuaber of days re- quired for the appearance of the first stuinate and pistillate flowers on Acorn squash plants treated with maleic hydrazide, grown at 60°F. and subjected to various photoperiods, suggested that 60?. us too low for flowering. 75 The appearance of the first pistillate flower on Acorn squash at a lower node on maleic hydraside treated plants grown at 60°F. , than those plants grown at 70’P., suggests that maleic twdraside as well as the interaction of maleic hydrazide and low taperatures were favorable for the initiation of pistillate flowers. The node at which the first pistillate flower appeared on plants not treated with maleic tum-aside and grown at 70'1’. increased as the photoperiod increased, indicating an enviroment not favorable for initiation of pistillate flowers (Table X) . The favorable interaction effect of naphthaleneacetic acid and low taperature on initiation of pistillate flowers may also be suggested when referred to the node nunber at which the first Caserta squash pistillate flower occurred, which as lowered by alpha naphtha- leneacetic acid (100 pm) at 60°F. in comparison with those plants treated at NW. The fact. that the first staminate flower appeared at an earlier node as the day-length was increased from 8 to 12 hours, but not from 12 to 16 hours for Acorn squash not treated with saleic hydrazide and grown at 70’1". (m1. x) m. be explained. At 70'P. the first staminate and pistillate flowers appeared at a relatively constant node number as the photperiod was increased from 8 to 16 hours for Caserta squash not treated with maleic twdmide, while with saleic hvdraside treated plants, there were large differences in node umber, which suggests again a differential response to photoperiod, tapere- ture and cheaical treatment. A photoperiodic inhibition of pistillate flower production or developent was suggested when at 70°F. the nuaber of pistillate flowers from maleic moraside treated and control Acorn 76 and Caserta plants generally decreased as the photoperiod increased: with the treated plants having fewer flowers (Table 11). Some interesting interactions of tuperature, day-length and treatment with alpha naphthaleneacetic acid on Acorn and Caserta squash may also be mentioned. Varietal response was exhibited when the staminate-pistillate flower ratio for Acorn squash grown at 70'?. and treated with alpha naphthaleneacetic acid, was much higher during the 16 hour that at the 8 hour photoperiod, while the staminate-pistillate flower ratio for Caserta squash was smaller at the 16 hour than at the 8 hour photoperiod (Table IX). Illustrating again varietal response to different chuicals, alpha naphthaleneacetic acid caused Caserta sqmsh grown at 70'F. to produce pistillate flowers at a higher node and the staminate flowers at a lower node than those plants treated with maleic hydrazide (Table X). In contrast, Acom sqmsh plants in general were similarly affected by both maleic hydrazide and alpha naphthaleneacetic acid as to the node umber at which the first stalli- nate and pistillate flowers appeared. Morphological studies revealed that one of the significant re- sponses following treatment with maleic hydrazide was cessation of mitosis in meristanatic tissue. The typical alteration of plant tissue by maleic tmdraside is the inhibition of growth of stem apices, which are characterized by lack of meristnatic growth (Figure 11). The neristenatic growth in the apex neristens apparently ceased after treatment with maleic deside. The absence of neristelatic growth has also been reported by Greulach and Atchison (18), studying the 77 mitosis of terminal buds of beans after treatment with maleic hydra- side. Struclmeyer (A8) also mm .hxdnaideoansingiailme of Croft Easter lilies to differentiate flower buds. The inhibitory action of maleic bydrazide may also explain the presence of the mnerous underdeveloped pollen grains in staminate flower buds found on maleic - hydraside treated Acorn squash plants as compared with staminate flower buis from plants not treated (Figures 1h,15). The action of maleic Indraside on suppressing the production of staminate flowers, may be explained in part by its growth regulating characteristics, which cause the selective inhibition of neristmtic tissue of the teminal growth of Acorn squash, as shown in Figure 11. Leopold and Klein (33) have also reported maleic worsens as an anti- auxin in studies related to the standard pea and Anna growth tests. Such anti-auxin effects, as reviewed by Audus (,1). nay be thought of as an attainment of a definite ratio of the natural auxin to anti- auxin within the plant. The critical balance differs for species and at least two groupings of plants are acknowledged. The "auxin plants" are those which require a high ratio of auxin to anti-auxin and which therefore can be induced to flower by auxin applications (pineapple). The "anti-auxin plants" are those which require a low ratio of auxin versus anti-auxin (cocklebur, soy bean) in which flowering is induced by lowering the auxin content or by increasing the anti-auxin. The inhibition from applied anti-auxin (maleic hydraside) apparently placed the Acorn squash plants in a stage of growth (36) unfavorable for staninate flower production but still capable of for-ing pistillate flowers. 78 The inhibition of staminate flowers by short photoperiod and low temperatures may be explained in part as to their effect on the sane biochanical processes within Acorn sqmsh plants which are illportant in the initiation of flowers. Nitsch 9t ‘1. (36) reported that during the growth period of the Acorn squash a definite sequence of flower types is produced. They are listed as follows: (1) underdeveloped staminate flowers, (2) normal staminate flowers, (3) normal staminate and pistil- late flowers, (1.) giant pistillate and inhibited staminate flowers and (5) perthehocerpic pistillate flowers. Currence (5) also reported that as cuctnbsr plants grew older, there no a change from a strongly stallinate conditions to a strongly pistillate condition. Since low tesperatures caused an increase in nmber of pistillate flowers at the expense of staminate flowers, it could be asst-ed that the Acorn squash plants were probably inhibited in growth free: a reduction of auxin and that a stage of growth was reached, which favored the production of pistillate flowers es described by Nitsch st. g. (36). The plants were also inhibited to a great extent by the action of the anti-auxin, nleic hydrazide, when staminate flowers are normally produced and then a decreasing inhibition, which allowed for production of pistillate flowers at later growth periods when conditions within the plants were still not favorable for staminate flower production. 79 SUMRI AND WNCLUSIONS Treatment with chemical growth substances, stage of plant growth at which applications were made, plant growing temperatures and day- length separately and when interacting, influenced pistillate and staminate flower production of various varieties of cucurbitaceae as measured by date of appearance of node ‘ntnber of,and total nunber of staminate and pistillate flowers. Preliminary studies indicated that a solution of maleic mdraside (250 ppm) applied to Acorn squash when the second and third leaves had developed and two weeks later was effective in suppression of staminate flowers. Further greenhouse studies showed that maleic Ivdraside at 250 or 350 pp! applied when the first leaf and again when the fourth to fifth leaves tad “painted reduced the staminate-pistillate flower ratio of Acorn squash to zero. Such plants were male sterile. Alpha cyano-beta-z, h-dichlorophemrl acrylic acid, benzene sulfonyl hydrazide, n-meta tolylphthalamic acid, 2, lt-dichlorobensel- nicotinim chloride and alpha nethozryphenylacetic acid at 500 ppm when applied to Acorn squash at various stages of growth, either resulted in injury to the plants, increased the staminate-pistillate flower ratios or were not as effective as mleic lwdraaide in suppressing staminate flower production. Maleic tum-aside (350 pm) also effectively suppressed staminate flower production in Caserta squash if applied when the cotyledons had expanded and again when the sixth to seventh leaves had expanded. Effective suppression occurred likewise, if the chemical was applied when the cotyledons had expanded, and again when the fourth to fifth and ninth to tenth leaves had expanded. The maleic murazide concentrations (250 to 350 ppm) effective for complete suppression of staminate flower production of Acorn and Caserta squash mder greenhouse conditions were not as effective in the field. Great varietal differences were in evidence with mm mm Wm Wuhan treated with maleic hvdraside in the field. Complete suppression of staminate flowers was achieved by using maleic hydrazide (1000 ppm) applied to Acorn squash grown in the field during the late stmer of 1955, but not during the late spring and early owner of 1951. and 1955. The shorter photoperiods during the late smsr favored suppression of staminate flowers by the chanical under field conditions as compared with those of late spring and early sulner. Under controlled environments in the greenhouse, the greatest suppression of staminate flowers by maleic hydraside (350 ppm) end alpha naphthaleneacetic acid (100 ppn) on Acorn and Caserta squash resulted at low (60°F.) compared with bish(70°r.) temperature end generally at the short (8 hour) coupered with the long (16 hour) photoperiod. Pistillate flowers appeared after fewer nodes at 60 than at 70'F., irrespective of variety and chuical treatment, and their nubers were also generally reduced at long photoperiod and at high tuperature. Reduction in pistilld’e flower nunbers caused by long photoperiod was nullified by low tenperature on Caserta squash whether treated with the alpha naphthaleneacetic acid or not. when Acorn plants not chemically treated were grown at 60’1'. and flowering occurred, more pistillate flowers preceded the appearance of the first staminate flower than on those plans grown at 70‘1'. _ Morphological studies indicated that maleic ludrazide suppressed cell differentiation in apical neristus and the developent of pollen grains in the androecia of the staminate flower buds which developed on Acorn squash. A theory of auxin versus anti-auxin effects on successive phases of flower sex expression in Acorn squash is suggested as an explana- tion of inhibition of staminate flowers while allowing for simultaneous developent of pistillate flowers. l. 2. 3. h. 5. 6. 7. 8. 9. 10. 82 331mm! Audus, L. J. 1953. Plant Growth Substances. Interscience Publishers, Inc. NJ. pp. 283-316. Bonner, J. and J. Thurlow. 191:9. Inhibition of Plutoperiodic Induction in Xanthiun by Applied Auxin. Bot. Gas. no: 613- Mk' Be Be .1” 3o He wittmre 19h9e Eff.“ 0: cm Gmtl Regulators on Seed Stalk Developent in Lettuce and Celery. Plant fiveiol. 2h: 555-576. Mk, He E. m Xe Re “we 19A2e (butml of mm nth Phytohornones. Sci. 95: 536-537. Currence, T. H. 1932. Nodal. Sequence of Flower Type in Cucunber. Proc. Amer. Soc. Hort. Sci. 29: 1.77-1.79. Currier, H. B. , B. E. Day, and A. 8. Crafts. 1951. Sue Effects of lhleic We on Plants. Bot. Gas. 112: 272-280. Danielson, L. 1.. 191,1... Effect of Daylength on Growth and Re- production of the Gherldn. Plant Physiol. 19: 638-61.8. Darlington, C. D. and J. Heleish. 1951. Action of meic Mra- aide on the Cell. nature 167: 1.07-1.08. Deyson, G. and A. Rollen. 1951. The Anti-mitotic Action of h1eic Hydz‘agide. Conptes Rend. 233: 820-821 (Chu. Abst. 1.6: 1.0- . Edmond, J. B. 1930. Seasonal Variations in Sex Expression of Certain Cucuber Varieties. Proc. Aner. Soc. Sort. Sci. 27: 329-332. Galston, A. W. 191.7. The Effect of 2,3, 5-triiodobensoic Acid on ch-ngwth and Flowering of Soybeans. Amer. Jour. Bot. 31.: 35 3 . mt, We We w He ‘e We lmo Effect of th. Rmtiw Length of Day and Night and Other Factors of the navironsent on Ggwth and Reproduction in Plants. Jour. Agr. Res. 18: 553- 5. 15. 16. 17. 18. 19. 25. . 1923 . Further Studies in Photoperiodism; The Response of the Plant to Relative Length of Day and Night. Jour. Agr. Res. 23: 871-920. Girolami. G. 1952. Anatomical Effects of Maleic Ibdraside on gummy». ijab. (Unpublished dete) thed in Hikkelsen, D. S. a .1.- Agronomy Jour. 1.1.: 533-536. Gregory, F. s. 191.3. The Control of Flowering of Plants. Soc. Exp. Biol. Symposim No. 2 (Growth) pp. 75-103. Gregory, F. G. and O. N. Purvis. 1938. Studies in Vernalization of Cereals. II. The Vernalization of Excised hture Enbryos, and of Developing Fare. Ann. of Bot. 2: 237-267. Greulach, V. A. and E. Atchison. 1950. Inhibition of Growth and Cell Division in Onion Roots by Maleic Hydrazide. Bull. Torrey Bot. Club 77: 262-267. . 1953- Inhibition of Mitosis in Bean Buds by Maleic Wdraside. Bot. Gas. 111.: 1.78. Hall, w. C. 191.9. Effects of Photoperiod and Nitrogen Supply on Growth and Reproduction in the Gherldn. Plant Wsiol. 21.: 753-769. Hsmner, K. C. and J. Dormer. 1938. Plactoperiodisn in Relation to Nonsense as Factors in Floral Initiation and Development. Bot. Gas. 100: BBS-1.31. Klein, W. H. and A. C. Leopold. 1953. The Effects of Maleic Hydrazide on Flower Initiation. Plant HIysiol. 28: 293-298. flippart, J. H. 1857. An Essay on the Growth, Origin, Diseases, etc. of the Wheat Plant. Ohio State Board Agr. Ann. Report. 12: 562-816. Kraus, E. J. and H. R. Kravbill. 1918. Vegetation and Repro- duction with Special Reference to the Tomato. Oregon Agr. We 3“. 3m. M9: 1"”. Laibach, F. and P. J. Kribben. 191.9. Der Einfluss von Huchsstoff auf die Bildung Hamlicher und Neiflicher Bluten Bei einer lbmsischen Pflanse (m m 1.). Der. Deutsch. Rte We 62: 53-550 . - 71950 a. Der Einfluss von Nuchsstoff auf das Geschlecht der Bluten Bei einer lbnosischen Pflanse. Beitrage Biol. Pflansen 28: 61.-67. 26. 30. 31. 32. 33. 35- 36. 37- 38. 81+ . 1950 b. Der Einfluss von Wuchsstoff Auf die Blutenbildung der Gurke. Naturwissenschaften 37: 111.-115. .- 195", c. Uber die Bedeutung der B-Indolylessigsaure Fur die Blutenbildung. Ber. Deutsch. Bot. Gee. 63: 119-120. ._, 1950 d. Die Bedeutung des Wmhsstoff Fur die Bildung und Geschlechtsbestimung der Bluten. Beitrage Biol. Pflansen 28: 131-11.1.. Leopold, A. C. and W. R. Klein. 1952. Maleic murazide as an Anti-auxin. Physiologia Plantarius 5 : 91-99. Leopold, A. C. and K. V. Thinann. 191.9. The Effect of Amdn on Flower Initiation. Amer. Jour. Bot. 36: 31.2-31.7. McIlrath, w. J. 1953. The Use of Maleic Wdrazide for the Pro- duction of Me Sterility in Grain Sorghum Paper presented Amer. Soc. of Plant Physiologists, Nisan, Wis., Sept. 8, 1953. Nakamura, N. 1951.. Studies on the Artificial Hale-Sterility. I. Hale-sterility of Egg Plant by Chadoal Pouring. The Sci. Reports of the Hyogo Univ. of Agr. 1: 111-111.. Nahmura, N. and M. Terabun. 1951.. Studies on the Artificial Hale-Sterility. 11. Male sterility of Cucumber by Chuical Pouring. The Sci. Reports of the Hyogo Univ. of Agr. 1: Alt-h . Naylor, A. w. 1950. Observations on the Effects of Maleic Hydraside on Flowering of Tobacco, liaise and Cocklebur. Proc. Nat. Acad. Sci. 36: 230-232. Naylor, A. w. and E..A. Davis. 1950. ne1eie Hydrazide es e Plant Growth Inhibitor. Bot. Gas. 112: 112+126. NitSCh, Jo Pa. Bo Bo m2. Jo In mm a Fe We Went. 1952a The Developsent of Sex Expression in Cucurbit Flowers. Amer. Jour. Bot. 39: 32-16. Overbeek, J. van. 1951. Use of Growth Substances in Tropical Agriculture. Plant Growth substances (r. x. Skoog). Univ. Wis. Press pp. 225-2h1.. Rao, 3. N. 1951.. Certain Physiological and Morphological Re- sponses in Potatoes and Onions Induced by kleic l'Iydrazide. Ph.D. Thesis, Michigan State University. 39. 1.0. h5o 1.6. 1+7. 1+9- 85 Retro, s. 1952. Hale Sterile Plants by Chemical Treatment. Nature 170: 38-39. Roberts, R. N. 1951. The Induction of Flowering with a Plant Estraot. Plant Growth Substances (F. K. Skoog). Univ. Wis. Press pp. 31.7-350. Sachs, J. 1865. Wirkung des Lichts Auf die Bluthenbildung Unter Vemittlung der Iaubblatter. Bot. Ztg. 23: 117-121, 125-131, 133-139. Schoene, D. L. and 0. L. Hoffman. 191.9. Maleic Hydraside, A Unique Growth Regulant. Sci. 109: 588-590. Strucloseyer, B. E. 1953. The Effect of Meic Hydrazide on the Anatomical Structure of Croft Easter Lilies. Amer. Jour. Bot. 40: 25-29- Teubner, F. G. and S. H. Wittwer. 1955. Effect of Nam-tolyl- phthalamic Acid on Tomato Formation. Sci. 1%: 71.-7 5. TiedJens, V. A. 1928. Sex Ratios in Cucuber Flowers as Affected by Different Conditions of Soil and Light. Jour. Agr. Res. 36: 73341.6. Ulrich, H. 1939. Photoperiodismus und Bluhlmmone. Ber. Dtsch. mte GOBo 57: we Watson, D. P. 1952. Retardation in Cell Developsent in Leaf and Flower Buds of My. m L. from Foliar Applications of Maleic Hydrazide. Bull. Torrey Bot. Club. 79: 235-2Al. Went, F. W. 191.8. Thermoperiodicity. "Vernalization and Photo- periodism, a Symposiun" (Nurneek A. E. and R. O. Whyte). Chronica Botanica 00., Waltham, Mass. pp. 116-157. Wittwer, S. 8., L. L. Coulter and R. L. Carolus. 191.7. A Chuical Control of Seedstalk Develoment in Celery. Sci. 106: 590. Wittwer, S. H. and I. G. Hillyer. 1951.. Chanical Induction of Male Sterility in Cucurbits. Sci. 120: 893-891.. Wittwer, S. 11., R. Jackson and D. P. Watson. 1951.. Control of Seedstalk Development in Celery by Maleic Wdraside. Amer. Jour. Bot. 1.1: 1.35-1.39. 52. Zimerman, P. W. and A. E. Hitchcock. 191.2. Flowering Habit and Correlation of Organs Modified by Triiodobensoic Acid. Contr. Boyce Thompson Inst. 12: 1.91-1.96. 53. Zukel, J. W. 1955- Literature Smry on Maleic Hydraside. U.S. Rubber Co., Naugatuck, Conn. NHIS No. 60. APPENDH TABLE I Analysis of Variance for Effect of Maleic Hydrazide at Different Con- centrations on the Number of Staminate Flowers Produced by Varieties of Quentin mm. mime Whale. and 9111111131 m (Field Experiment A I T Source D.F. 3.3. 11.3. F Total for Varieties 79 734.9 Replication 1. 1.3.0 12.00 3.22% Variety 15 1.63. 5 30. 90 8.31“ Error A 60 223.1. 3.72 Total for Treatments 799 187 5-9 " " Varieties 79 7311-9 Treatment 9 258- 3 28. 70 31 . 51oM Flower 1 0.9 0.90 Chunical I. 250. 5 62. 62 68. 81ML Flower 1: Chemical 1. 6.9 1.72 1.89 Treatments 1: Varieties 135 359.3 2. 66 2.92 Variety 2: Flower 15 21.7 1.1.5 1.59 Variety 2: Chemical 60 286.9 1..78 5.75” Variety x Flower x Chenical 60 50.7 0.81. Error 3 576 523.1. 0.91 * Significant at 5 per cent level. ** Significant at 1 per cent level. TABLE II Analysis of Variance for Effect of Meic Hydrazide at Different Con- centrations on the Nuber of Pistillate Flowers Produced by Varieties of mm min. saunas. Meals. and W means (Field Experiment A Source D.F. 3.8. 11.8. F Total for Varieties 79 387.8 Replication 1. 32. 3 8. 08 1.. 96** Variety 15 257. 9 17. 19 10. 55“ Error A 60 97.6 1.63 Total for Treatments 799 1652-9 " " Varieties 79 387. 8 Trumant 9 lme 0 11. 11 7 o [A6fl Flower 1 23-5 23- 50 15-77“ Chunical I. 30.3 7.58 5.09“ Flower 1: Chemical 1. 1.6.2 11-55 7-75" Treatments 1 Variety 135 307.0 2.27 l. 52* Variety 1 Flower 15 28.9 1.93 1.30 Variety 1: Chemical 60 206. 3.1.3 2.30“ Variety 1: Flower 1: Chemical 60 72.1 1.20 Error B 576 858.1 1.1.9 ¥ H Significant at 1 per cent level. M e V A Q_L‘_‘ TABLEIII 90 Analysis of Variance for Effect of Maleic Hydrazide and Alpha Naphtha- leneacetic Acid Applied at Different Concentrations on the Huber of Staminate Flowers Produced by Various Varieties of W m and Ms. retina (Field Experiment 13) Source Dope SeSe MeSe F Total for Varieties 11. 5292. 0 Ramation 2 1620 1 810 0 Error A 8 928.8 116.1 Total for Treatments 7!. 11627 . 2 " Varieties 11. 5292. 0 Treatment 1. 631. 5 157. 9 3 . 1.1* "H X N“ X (B 2 Me8 711w“ 1e5h 11H (alone) 2 1.88.7 21.1.3 5.28“ Treatments 3: Variety 16 381.9. 9 21.0. 6 5 . 2011* * Significant at 5 per cent level. ** Significant at 1 per cent level. TABLEIV Analysis of Variance for Effect of Maleic Hydraside and Alpha Naphtha- leneacetic Acid Applied at Different Concentrations on the Nnmber of Pistillate Flowers Produced by Various Varieties of W m and anemia satin». (Field Mari-lent B) j Source D.F. 8.8. 14.8. F Total for Varieties 11. 1063. 55 Replication 2 37.” Variety l. 939- 55 231.- 89 21. 65“ Total for Treatments ' 71. 2781. 55 9 " Varieties 11. 1063. 55 Treatment 1. 236.1.8 59.12 1.590“ Treatments 1: Variety 16 998.85 62.1.3 1.90 Error 8 1.0 1.82.67 12.07 H Significant at 1 per cent level. 91 92 TABLEV Analysis of Variance for Effect of Elsie Hydrazide on the Nnnber of Days for Appearance of First Staminate Flower Produced by Acorn Squash (Field Experiment 0) some De Fe 8 e S e no 8 e F Total 11 1275 g ,1 Replications 2 2 Treatments 3 1275 1.19 156.9M Error 6 16 2.67 " 'fl . -.., ** Significant at l per cent level. TABLEVI Analysis of Variance for Effect of Bileic Hydraside on the Huber of Days for Appearance of First Pistillate Flowers Produced by Acorn Squash (Field Experiment C) Source D.F. 8.8. 11.8. F Total 11 193 Replications 2 6 Treatments 3 155 51. 67 9. 69* Error 6 32 5-33 * Significant at 5 per cent level. TABLE VII 93 Analysis of Variance for Effect of Maleic Hydraside on Node Number Pre- ceding the First Staminate Flower Produced by Acorn Squash (Field Ex- periment C) W Source D.F. SeSe MeSo F Tom 11 162600 25 Replications 2 6. 50 Treat-tents 3 1597.58 532.53 158.49” Error 6 20. 17 3 .36 H Significant at 1 per cent level. TABLE VIII Analysis of Variance for Effect of Maleic ludraside on Node Nnnber Pre- ceding the First Pistillate Flower Produced by Acorn Squash (Field Ex- periment C ) Source D.F. . 5.3. 14.3. 1" Total 11 122. 92 Replications 2 l. 17 Treatments 3 71.. 92 21.. 97 3 . 20 Error 6 h6o83 7.&) 91. TABLE IX Analysis of Variance for Effect of Maleic Hydraaide on the Number of Pistillate Flowers Produced by Acorn Squash (Field Experiment 0) __v_ Source D.F. 8.3. 14.8. F Total 11 817 Replications 2 26 Treatments 3 668 222.7 10.86“ Error 6 123 20- 5 ** Significant at l per cent level. TABLEX Analysis of Variance for Effect of Maleic Hydrazide on the Nnmber of Staminats Flowers Pinoduced by Acorn Squash (Field Experiment 0) some De F o S e S e H. S o F Total 11 3331.. 0 Replications 2 87.2 Treatments 3 31.86.2 1162.1 22. 1.H Error 6 Bus 5 510 9 ** Significant at 1 per cent level. 95 TABLE II Analysis of Variance for Effect of Meic 1hrdrazide on the Number of Pistillate Flowers Preceding the First Staminate Flower Produced by Acorn Squash (Field Experiment 0) ‘f Source D.F. 3.3. 11.8. - F Total 11 272. 539 Replications 2 1.. 880 Treatments 3 21.6. 501 82.167 23.21.“- Error 6 21. 208 3. 535 ** Significant at 1 per cent level. TABLE XII Analysis of Variance for Nnmnber of Staminate Flowers Produced by Acorn and Caserta Squash When Subjected to Various Photoperiods, Night Tempera- tures and Chemical Growth Regulators (October 21, 1955 to February 25, 1956) Source of Variation D.F. S.S. H.S. F Total for Photoperiods 5 1081. 5 Temperature 1 1051..0 1051.. 0 133 . 1.211% Photoperiods 2 11.7 5.85 Taperature x Hnotoperiod 2 15.8 7.9 Total for Varieties 11 15 51..3 " " Photoperiod 5 1081.5 Variety 1 1.1.0.0 1.1.0. 0 676. 92“ Variety x Temperature 1 10. 7 10.7 16.1.6 Variety x Photoperiod 2 20.8 10.1. 16.00 Variety x Photoperiod x Temperature 2 1.3 0.65 Total for Treatments 359 3369.6 " " Varieties 11 1551.. 3 Treatments 5 192. 7 38. 51. 11..22** Chunicals 2 181.. 2 92. l 33 . 98“ Flowers 1 6. 9 6. 9 2. 55 Chemical x Flower 2 1.6 0.8 Treatments x Tanperature ‘ 5 201..5 1.0.9 15.09" Chemical x Taperature 2 . 203.6 101.8 37.56" Flower 1: Temperature 1 0.1 Flower x Chanical 1: Temperature 2 0.8 Treatments 1: Photoperiod 10 70.2 7.02 2. 59" Treatments 1: Variety 5 88.6 17.72 6. 51." Variety x Chmical 2 78.5 39.25 11.4.8“ Variety x Flower 1 6. 5 6. 5 2.1.0 Variety x Chanical x Flower 2 3.6 1.8 Treatments x Tuperature x Photoperiod 10 88.3 8.83 3.26" " x 9 x Variety 5 311.9 62.38 23.02" " x Variety x Photoperiod 10 50.2 5.02 1.85 Error 298 ”809 2071 “- Significant at 1 per cent level. 96 TABLE XIII 97 Analysis of Variance for Number of Pistillate Flowers Produced by Acorn and Caserta Squash When Subjected to Various Photoperiods, Night Tempera- tures and Chemical Growth Regulators (October 21, 1955 to February 25, 1956) Source of Variation D.F. 8.8. 14.8. F Total for Photoperiods 5 150.856 Tennperature 1 101.. 51.1. 101.. 51.1. 6. 02 Photoperiods 2 ll. 572 5. 79 Temperature x Phot0period 2 31..71.0 17.37 Total for Varieties 11 205.189 " " Photoperiod 5 150.856 Variety x Temperature 1 8.711 8.711 7-h1 Variety x Photoperiod 2 10.339 5.1695 2.32 Variety x Photoperiod x Tanperature 2 7.505 3.75 1.38 Total for Treatments 359 1253.389 9 1‘ Varieties 11 205.189 Treatments 5 155-289 31-058 117.33“ (Rnennicals 2 117.1.22 58.711 32. 7611* Flowers 1 19. 600 19. 600 10. 91.“- Chanical 2: Flower 2 18.267 9.131. 5.097” Treatments x Temperature 5 111.. 556 22.911 12. 78“ Chemical 2: Temperature 2 110.556 55.28 30. 85“- Flower x Temperature 1 2.178 2.178 1.22 Flower 3: Chemical 3: Temperature 2 1.8% .911 Treatments x Photoperiod 10 31.028 3.1.03 1.89K' Treatments x Variety 5 95.188 19.038 10.62** Variety 2: Chemical 2 90.822 1.5.1.11 25.3.1.4“1 Variety x Flower 1 .2775 .2775 Variety x Chanical x Flower 2 1..088 2.01.1. 1.11. Treatments x Temperature x Phot0period 10 10.860 1.086 x Tanperature x Variety 5 87.523 17.505 9.77“ " x Variety x Photoperiod 10 16.795 1.6795 Error 298 533 . 961 1. 792 * Significant at 5 per cent level. ** Significant at 1 per cent level. TABLEXIV 98 Analysis of Variance for Node Number Preceding the First Staminate Flower Produced by Acorn and Caserta Squash When Subjected to Various Photoperiods, Night Temperatures and Chemical Growth Regulators (October 21, 1955 to February 25, 1956) Source of Variation D.F. 3.3. 14.3. F Total for Photoperiods 5 1.91..l6 Tanperature l 1.85.35 1.85.35 170. 3*“ Photoperiods 2 3.11 1. 56 Temperature x Photoperiod 2 5.70 2.85 Total for Varieties 11 687.83 " " Photoperiod 5 1.91..16 Variety l 179. 22 179. 22 75. 91.* Variety x Temperature 1 .03 .03 Variety x Photoperiod 2 9.70 1..85 2.06 Variety x Photoperiod 1: Temperature 2 1..72 2.36 Total for Treatments 359 1607.16 " " Varieties 11 687.83 Treatments 5 366. 36 73. 27 91. 36“ Chanicals 2 361..09 182.01. 226.78“ Flowers 1 1.12 1.12 1.1.0 Chemical x Flower 2 1.15 .58 Treatments x Temperature 5 1.65 .33 Chemical x Temperature 2 0.29 Flower x Tanperature 1 0.00 Flower x Chemical x Temperature 2 1.36 .68 Treatments x Photoperiod 10 31..79 3.1.8 1.. 31.M Treatments x Variety 5 85.38 17.08 21.30" Variety x Chanical 2 84.02 1.2.01 52.38"M Variety x Flower 1 .89 .89 1.11 Variety x Chemical x Flower 2 .h7 ~21. Treatments x Temperature x Photoperiod 10 36.00 3.60 1..1.9W " x " x Variety 5 13.81. 21.. 77 30.88" " x Variety x Photoperiod 10 32.20 3.220 1..01** Error 298 2390].]. 00m * Significant at 5 per cent level. ** Significant at 1 per cent level. TABLE XV 99 Analysis of Variance for Node Nunber Preceding the First Pistillate Flower Produced by Acorn and Caserta Squash When Subjected to Various Photoperiods, Night Temperatures and Chemical Growth Regulators (October 21, 1955 to February 25, 1956) Source of Variation D.F. 8.8. 11.8. F Total for Photoperiods 5 91.. 39 Temperature 1 13.61 13.61 Photoperiods 2 38.31. 19.17 Temperature x Photoperiod 2 1.2.1.1. 21.3 Total for Varieties 1.1. 283. 66 fl " Photoperiod 5 94-39 Variety 1 59.21 59.21 12.62 Variety x Tanperature l 33.61 33.61 7.17 Variety x Photoperiod 2 87.07 1.3. 51. 9.28 Variety x Photoperiod x Temperature 2 9.38 1.. 69 Total for Treatments 359 1295.99 " " Varieties 11 283.66 Treatments 5 170. 86 31..17 73.09” Chanicals 2 165.71 82.86 55.99** Flowers 1 1.88 1.88 Chanical x Flower 2 3.27 1.61. Treatments x Temperature 5 11.1..85 28.97 19. 5711* Chemical x Tenperature 2 135.51. 67.77 1.5.79** Flower x Temperature 1 0.10 0.10 Flower x Chemical x Tupsrature 2 9.21 1..60 3.11* Treatments x Photoperiod 10 11..O9 1.1.1 Treatments x Variety 5 72.85 11.. 57 9.81.496 Variety x Chemical 2 71.20 35.60 21.05“ Variety x Flower l 0028 0028 Variety x Chemical x Flower 2 1.37 0.68 Treatments x Temperature x Photoperiod 10 10.1.0 1.01. I. x 3' x Variety 5 1060657 21029 111.03% " x Variety x Photoperiod 10 51.37 5.11. 3.1.7“ Error 298 Mal-M. LAB * Significant at 5 per cent level. ** Sigiificant at 1 per cent level. TABLEIVI Analysis of Variance for Nmnber of Days for Appearance of First Staminate Flowers Produced by Leon: and Caserta Squash When Subjected to Various Photoperiods, Night Tanperatures and Chanical Growth Regu- lators (October 21, 1955 to February 25, 1956) Source of Variation D.F. 3.8. 11.8. F Total for Photoperiods 5 957.1.5 Temperature 1 91.1..11. 91.1..11. 320.05“ Photoperiods 2 7.1.1 3.70 1.25 Tanperature x Photoperiod 2 5. 90 2. 95 Total for Varieties 11 1135. 57 fl " Photoperiod 5 957-h5 Variety 1 156.03 156.03 162. 53** Variety x Temperature 1 19.13 19.13 19.13“ Variety x Photoperiod 2 1.01. . 52 Variety x Photoperiod x Temperature 2 1.92 .96 Total for Treatments 359 2164.20 " " Varieties 11 1135-57 Treatments 5 513.02 102.60 11.9.78" Chanicals 2 511.78 255.89 373.56” Flowers 1 1.01 1.01 1.1.7 Chm-1m x Flower 2 ea .11 Treatments x Temperature 5 125.51. 25.11 36.66“ Chemical x Temperature 2 121..20 62.10 90.66" Flower x Tanperature l .1.6 .1.6 Flower x Chemical x Temperature 2 .88 .1.1. Treatments x Photoperiod 10 21..12 2.1.1 3.5?“ Treatments x Variety 5 1.8.25 9.65 11.09“ Variety x Chmical 2 1.6.31 23.16 33.81" Variety x Flower 1 .99 .99 1.1.1. Variety x Chanical x Flower 2 .95 .1.8 Treatments x Tauperatm x Photoperiod 10 27.97 2. 797 1..08“ " x " x Variety 5 61..62 12.92 18.86" " x Variety x Photoperiod 10 21.03 2.10 3.06“ Error 298 204.08 .685 ** Significant at 1 per cent level. 100 TABLE XVII Analysis of Variance for Number of Days for Appearance of First Pistillate Flowers Produced by Acorn and Caserta Squash When Subjected to Various Photoperiods, Night Temperatures and Chenical Growth Regu- lators (October 21, 1955 to February 25, 1956) Source of Variation D.F. 8.8. 11.8. F Total for Photoperiods 5 672.1.2 Tmperature 1 508.85 508.85 9.25 Photoperiods 2 53. 57 26. 78 Tmperature x Photoperiod 2 110.00 55.0) Total for Varieties 11 839.96 " " motoperiod 5 - 672.1.2 Variety 1 31.85 31..85 Variety x Tmnperature 1 11.. 39 11.. 39 8.18 Variety x Photoperiod 2 109.77 51+.88 3.38 Variety x Photoperiod x Tuperature 2 8. 53 1..26 12.88 Total for Treatments 359 2021.29 " " Varieties 11 839. 96 Treatments 5 Mal-02 33-20 59.19“ Chemicals 2 1.31..1.1 217.20 11.5.77“ Flowers 1 3.60 3.60 2.1.2 Chaim x flower 2 3e01 lo” 1.01 Treatments x Temperature 5 110.15 22.03 11.78" Chmical x Tenperature 2 101. 53 50.76 31..O7** Flower x Tenperature l .17 .17 Flower x Chuical x Tenperature 2 8.1.5 1..22 2.83 Treatments x Photoperiod 10 18.90 1.89 1.27 Treatments x Variety 5 1.9.35 9.87 6.62“ Variety x Chunical 2 1.2. 73 21.36 1.1..31." Variety x Flower 1 1.11 1.11 Variety x Chuical x Flower 2 5.51 2.76 1.85 Treatments x Temperature x Photoperiod 10 8.1.0 .81. " x " x Variety 5 21.88 1..38 2. 91.* " x Variety x Photoperiod 10 86.1.3 8.61. 5.&** Error 298 1.1.5.20 1.1.9 * Significant at 5 per cent level. H Significant at 1 per cent level. 101 TABLE XVIII 102 Analysis of Variance for Number of Pistillate Flowers Preceding the First Staminate Flower Produced by Acorn and Caserta Squash Subjected to Various Photoperiods, Night Temperatures and Chemical Growth Regulators (October 21, 1955 to February 25. 1956) _a Source of Variation D.F. 3.8. 14.8. F Total for Photoperiods 5 32.787 Temperature 1 30.991 30. 991 1.6.2611- PhotOperiods 2 .1.5 5 .228 Temperature x Photoperiod 2 1.31.1 . 670 Total for Varieties 11 1.3. 506 " " Photoperiod 5 32.787 Variety 1 9.1.51. 9.1.51. 18.83* Variety x Temperature 1 .156 Variety x Photoperiod 2 .105 Variety x Photoperiod x Tanperature 2 1.001. . 502 Total for Treatments 359 178.101 " " Varieties 11 1.3 . 506 Treatments 5 36.703 7.31. 29.1.8** Chanicals 2 33-7h5 16.87 67.75" Flowers 1 2. 503 2.503 10.05“- Chemical x Flower 2 .1.55 .228 Treatments x Temperature 5 2. 521. .505 2.03 Chemical x Tanperature 2 1.81.6 .923 3.71* Flower x Tunperature 1 Flower x Chemical 1: Temperature 2 Treatments x Photoperiod 10 1..076 .1.08 1.61. Treatments x Variety 5 7.61.1. 1. 529 6.11.“ Variety x Chemical 2 5.901. 2.952 11. 86” Variety x Flower 1 .016 .016 Variety x Chunical x Flower 2 1.721. .862 3.1.6* Treatments x Temperature x Photoperiod 10 1..11.7 .1.15 1.60 " x " 1: Variety 5 3.095 .619 2.1.8* " x Variety x Photoperiod 10 2. 231 . 223 Error 298 71..175 .21.9 * Significant at 5 per cent level. ** Significant at 1 per cent level. no Date Due “In 9 2 . 0 n. m P. ) I 111111111 HEW 30 W.” Ml U" 293 0 IIHIUIHIHHII