Studies On The Reproductive Biology Of Shibataea Chinensis And Arundinaria Simonii F. Albostriatus

The sexual reproduction process of two bamboos, Shibataea chinensis which was abortive and Arundinaria simonii f. albostriatus which had low seed-setting rate, was investigated for the first time and the reason why Shibataea chinensis was abortive and Arundinaria simonii f. albostriatus had low seed-setting rate was analyzed. The results are as follows:The flowering phenology of Shibataea chinensis was different from that of Arundinaria simonii f. albostriatus. The flower buds differentiated in October of last year and bloomed in March of next year for Shibataea chinensis. The whole process lasted for about 6 months.While the flower buds differentiated in March and bloomed in April for Arundinaria simonii f. albostriatus. The inflorescence structure of Shibataea chinensis is indeterminate type, but it is determinate one for Arundinaria simonii f. albostriatus. The breeding system of Arundinaria simonii f. albostriatus is mainly outcrossing, but partly may be self-compatible. Artificial pollination can improve the seed setting. The seeds could be harvested more or less every year. However, Shibataea chinensis never bore any seeds. The pollen germination rate of Arundinaria simonii f. albostriatus was obviously higher than the one of Shibataea chinensis.Using TEM, SEM, fluorescence staining and traditional paraffin section, the process of megasporogenesis and microsporogenesis and the development of female and male gametophyte of the two bamboo species were studied. The anther wall consisted of four layers.They were epidermis, endothecium, middle layer and tapetum. The development of anther wall belonged to the monocotyledonous type. The tapetum was of typical glandular type. The cytokinensis was successive and the microspore tetrads are bilaterally. Mature pollen grains were 2-cell or 3-cell with one germinal aperture. The simple ovary consisted of two carpels. Single ovule with parietal placenta was anatropous, double integument and tenuinucellatae. The megasporocyte underwent meiotic division to form four megaspores arranged in a line, and the micropylar megaspore was the functional one. The formation of the embryo was of polygonum type. The fertilization of Arundinaria simonii f. albostriatus occurred in15-20h after pollination. The zygote had a dormant for 5 days. The development type of embryo is graminad and the development type of endosperm is nuclear.The reasons why Shibataea chinensis is abortive lies in the low pollen germination rate , abortive pollen and poor pollination. While the low seed-setting rate of Arundinaria simonii f. albostriatus is due to the poor pollination effectiveness and inhibited pollen tube growth .