A Study On The Fertility Of Papaya (Carica Papaya L.)

The materials for the study were flowers and fruits of female, hermaphrodite and male plants of three different kinds of Carica papaya L.. The study of pollen fertility of different types, the effect of fertility on the fruitage performance, and the observation of the genesis and development of megaspore , female gametophyte and embryo by paraffin method were conducted in the research. The main results were as follows:1.Pollen fertility: The pollen viability of male plant with green stalk was comparatively stable, whereas that of male flower of hermaphrodite plant with purple stalk varied with seasons.2.Genesis and development of megaspore and female gametophyte: Carica papaya L. has anatropous ovule with long funiculus, which attached to parietal placenta. The development of megaspore was belonged to Polygonum type, whereas that of female gametophyte was the variation of Polygonum type. Antipodal cells degenerated before fertilization. The mature embryo sac was one with five nucleus, i.e., egg apparatus and two-nucleus central cell. The maturation of embryo sac of hermaphrodite plants occurred before blossom, while that of male plant was comparatively slowly.3.Embryo development :Quick endosperm division followed double fertilization, most hybrids could initiate only after a long dormant period .The division of both endosperm and zygotic embryo led to the development of dicotcotyledonous endosperm-carrying seed with aril . Embryo development si Carica papaya L. was belonged to Onagrad type. Hundreds of seeds were harvested in six hybridization combinationsrespectively ,and embryo abortion could occur at any stage of embryo development .Substantial postzygotic disruptions were observed ,including cavitation of nucellar cells, lack of normal endosperm development and abortion of hybrid embryos,4.Fruitage performance: All of the three kinds of female plants had the capability of autonomic parthenocarpy. Pollination increased the fruit weight and volume of female plants, and the fruitage performance of hermaphrodite plant with purple stalk was superior to that of hermaphrodite plant with green stalk. Hermaphrodite flowers and fruits could be seen on the male plant in certain circumstances.