THE EFFECT OF CARBOHYDRATE AND OF NITROGEN DEFICIENCY UPON GROWTH, FLOWERING, FRUIT SETTING AND DEVELOPMENT OF THE MALE AND FEMALE GAMETOPHYTES OF MUSKMELON, CUCUMIS MELO L.j PEPPER, CAPSICUM FRUTESCENS L. j AND LIMA BEAN, PHASEOLUS LUNATUS L. DISSERTATION Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the Graduate School of The Ohio State University By JAMES CLINKSCALES HOFFMAN, B.S; M.Sc. The Ohio State University 1952 Approved by: Adviser i TABLE OF CONTENTS Page INTRODUCTION ............................................. 1 REVIEW OF LITERATURE..................................... 2 MATERIALS AND METHODS .................................... 13 Cytologic&l procedure ..... ...................... 17 PRESENTATION OF D A T A ..................................... 19 Climatological factors .................................. 19 Relation of cultural treatments to plant vigor ........... 22 Microsporogenesis and megasporogenesis and the male and female gametophyte development as affected by the different cultural treatments ....... ......... 36 Abscission before anthesis ......... 38 Proportion of flowers reaching anthesis and anthers sheddind pollen or microspores ................... 35 Abscission of ovularies and fruit after anthesis as affecting fruit set .............. 56 Relation of fruit harvest to the flowers reaching anthesis .................................. 59 Pollen germination, staining, and abortion ....... 61 Pollination and fertilization as affected by the various cultural treatments ........ ....... 64 Cytological development of the embryo sac....... 83 Stage of development of lima bean ovularies abscising before anthesis........... 83 Stage of embryo sac development on the morning of anthesis ................ 84 Stage of embryo sac development after morning of anthesis until setting of fruit ......... 86 Stage of embryo sac development at period of abscission.................. 93 SP2S758 ii Page Stage of embryo sac development of fruit that set and enlarge.................... .. 98 Fruit set during period of sampling for cytological study . • ......... 102 Refractive indices and per cent soluble solids of peduncle and ovulary sap at time of anthesis......... 104 Fruit and seed development.......................... 106 Muskmelon and pepper seed germination counts .... 107 Counts of lima bean fruit, seed and ovules degenerating ......... ................... Ill DISCUSSION OF THE DATA.................................... 113 Plant vigor ........... 113 Male gametophyte responses ............. 115 Abscission before and after anthesis ............... 115 Relation of treatments to phenotypic viability of the pollen . ........ ....................... 117 Pollination and fertilization ................. 118 Female gametophyte responses ..... ............... 120 Abscission before anthesis ............. 120 Abscission after anthesis as related to fruit set and development ........... 121 Relation of fruit harvest to the flowers reaching anthesis......... 123 Embryo sac development ............. ........ 124 Stage of embryo sac development of lima bean ovularies abscising before anthesis .......... 125 Stage of embryo sac development on the morning of anthesis................ 126 Stage of embryo sac development after morning of anthesis until setting of fruit ........... .... 127 iii Page Stage of embryo sac development at period of abscission .......... ..................... 129 Stage of embryo sac development of fruit that set and enlarge ........... 132 Relation of per cent soluble solids of peduncle and ovulary sap to the setting of fruit ............. 133 Relationship between fruit and seed development .... 134 Muskmelon and pepper seed germination counts ....... 134 Lima bean ovules degenerated at the time of fruit maturity ............. 136 SUMMARY................................................. 137 Male gametophyte responses ..................... 141 Female gametophyte responses.................. 142 LITERATURE CITED.................................... US APPENDIX ..................................... 153 AUTOBIOGRAPHY........................................... 165 iv ACKN0W1EDGMENTS The writer wishes to gratefully acknowledge his appre­ ciation to Dr. Freeman S. Howlett, Head of the Department of Horticulture, The Ohio State University, for his constant counsel and stimulating suggestions given during the course of the re­ search and preparation of this dissertation. The writer is indebted to the Ohio Agricultural Experi­ ment Station for financial support given as a fellowship during part of the investigations and for facilities furnished during the experiments conducted at Wooster. - 1 - THE EFFECT OF CARBOHYDRATE AND OF NITROGEN DEFICIENCY UPON GROWTH, FLOWERING, FRUIT SETTING AND DEVELOPMENT OF THE MALE AND FEMALE GAMETOPHYTES OF MUSKMELON, CUCUMIS MELO L.j PEPPER, CAPSICUM FRUTESCENS L.j AND LIMA BEAN, PHASEOLUS LUNATUS L. INTRODUCTION The abscission of ovularies before and after anthesis, also the developing fruits of muskmelon, pepper and lima bean often causes the grower great concern by reducing yields and final profits. This abscission of ovularies and young fruit generally ©coin’s each season but more severely some years, and with no degree of regularity between varieties. The factors affecting fruit set and development of these economic plants have not been definitely established. There has been much research carried out concerning the factors affecting fruit set and development of the tomato and apple. Cochran (10) has reported his findings on several factors which affect the fruit setting of the pepper. Very little work has been done in studying the factors which affect the fruit setting and development of the muskmelon and lima bean. The objective of the research herein described has been to de­ termine the effects of carbohydrate and nitrogen deficiencies upon microsporogenesis and megasporogenesis and the development of the gametophytes in the muskmelon, pepper and lima bean. Klebs* early re­ search and theory (26-31) suggest that carbohydrate and nitrogen metabolism is very important in the change from the vegetative to the reproductive phase of growth in plants. Since that time other con­ siderations have been shown to be involved, such as the interpretation given to the results of Sachs (47) of hormones being translocated through the plant to the flower primordial regions and that such - 2 - materials necessary for fruit formation were produced in the leaves in the presence of light. REVIEW OF LITERATURE Klebs (26-31) explained the behavior of plants by three general conditions: inheritance, internal relations, and external conditions. He has summarized his work by proposing the principle that plant development is determined by internal relations, which, in turn, may be changed by external conditions. For example, the quan­ tity of available nutrients, especially those of a nitrogenous nature, and light intensity, with their effects upon the synthesis of carbohy­ drates, are the controlling factors in determining the type of plant development. Nightingale (42) concluded in some of his later research­ es on nitrogen nutrition of green plants that the organic nitrogenous and carbohydrate constituents of the ,• nts can scarcely be considered to be the immediate cause of flowering, but intelligent steps may be employed in nitrogen nutrition to decrease or increase vegetative growth and to hasten, delay or entirely eliminate flowering responses under many different conditions of environment. He (43) has used color standards to correlate carbohydrate reserves in relation to nitrogen nutrition in the pineapple, and indicates that this method has supplied a sufficiently precise index of the carbohydrate content. Fischer (16) studying the effects of varying amounts of carbon dioxide upon vege­ tation and reproduction in plants, found that the supply of available carbohydrates are relatively high in relation to the available nitro­ gen, the plants were reproductive, and when the reverse was true the plants were vegetative. Petri (45, 46) found that sterility in olives - 3 - is largely the result of a lack of sufficient nitrogen. While a de­ ficiency of nitrogen may cause a great number of flowers to form, the ovularies fail to grow as fruit with fertilized egg cells. Branches that set fruit contained 2.12 to 2.37 per cent of nitrogen on a dry weight basis, but the unfruitful branches contained from 0.72 to 0.92 per cent nitrogen. He pointed out clearly that the conditions favor­ able for fruitfulness do not always coincide with the best conditions for flower development. Lambeth (34) has shown that heavy side-dressing applications of soluble nitrogenous fertilizers during the blossoming period in­ hibited pod set of the lima bean. The same author showed that the average daily percentage set in snap beans during the first three weeks was as follows: 100 pound nitrogen level, 22.7 per cent, 200 pound nitrogen level, 26.9 per cent, and 19.4 per cent for the 400 pound nitrogen level. Where the 400 pound nitrogen application was used the detrimental effect was very serious for a period of approximately one week following the application. Kraus and Kraybill (32) studied the vegetation and reproduc­ tion of the tomato and demonstrated Klebs’ theory by the control of fruiting. They showed that a plant may be changed by an environment that causes chemical changes within the plant. They recognized four conditions that have a decided effect upon the behavior of the tomato