Studies On Pollination Biology Of Chinese Jujube

Chinese jujube (Ziziphus jujuba Mill.) is one of the characteristic and economic trees in China. It is necessary for Chinese jujube to develop new cultivars with combined quality traits by cross breeding. However, pollination biology which was the foundation in cross was not profound in Chinese jujube.The stigma receptivity and pollen viability of Chinese jujube had been studied using excellent cultivar at germplasm garden of Chinese jujube of Baoding Lvlong Group and Germplasm Nursery of Chinese jujube of Cangxian. Pollen germination rate was evaluated by in vitro culture and stigma receptivity by benzidine-H₂O₂ method.The germination of pollen on the stigma and the growth of pollen tube in Chinese jujube were observed under fluorescent microscope after manual pollination. The main results were as follows:1. Stigma receptivityThe stigma receptivity changed significantly in different cultivars. Cultivars with high stigma receptivity were 'Kongfusucuizao','Huizao','Huluchanghongzao'.The stigma receptivity of different variety changed during flower season. The stigmareceptivity of 'Dongzao' and 'Yueguangzao' showed the higher value at the beginning ofthe flowering season(June 4) and the highest value at the peak of the floweringseason( June 23).JMS3 showed the highest value at the beginning of the flowering season(May 29). It rised at the beginning of the flower season and then declined approximately.The best period of stigma receptivity was mainly three days after dehiscence. The stigma receptivity of 'Dongzao' was higher than 'Yueguangzao' and JMS3. There was no significant difference of stigma receptivity between 'Yueguangzao' and JMS3.2. Pollen germination rateThere was significant difference of germination rate of pollen sampled from cultivars at different spot and time . However, the germination rate of pollen was more than 10% only in 'Yueguangzao', 'Junzao', 'Xiangzao' and 'Duanguochanghongzao' of 32 cultivars or types of Chinese jujube. 3. Pollen germination and pollen tube growth after pollinationThe rate of pollen germination and growth of pollen tube changed significantly after pollination in a cross. Mass pollen germinated and pollen tube reached the base of style 72 hours later.There was significantly difference of pollen germination rate and pollen tube growth among cross combinations. Because of relative higher pollen germination rate and more vigorous growth of pollen tube, the combinations of 'Dongzao'×'Dayewuhe', 'Dongzao'×' Wuhexiaozao',and'Dongzao'×'Pingguozao',JMS3×'Wuhexiaozao',JMS3×' Ji nmangguo',JMS3×'laishuilingzao'and JMS3×'Lajiaozao'were efficient combination for cross breeding of Chinese jujube.