2018 ASHS Annual Conference

Chinese chestnut (Castanea mollissima Blume) has noteworthy ecological, economic, and cultural importance in China. However, a high proportion of empty cupules is mainly responsible for low yield in chestnut. To elucidate the causes of the empty cupules, we investigated pollen germination and pollen tube growth into pistils, and ovule development after self-pollination (SP) and cross-pollination (CP). Controlled pollinations were carried out with chestnut trees cultivated on the qianxi county of Heibei province. Ten pistils for each treatment were sampled at different intervals (0, 3, 6, 9, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 27, 30 days) after pollination for observation of pollen tube growth into pistils and ovule development by microscopy. The results showed that there were no significant differences in pollen tube behavior following SP and CP during the first 18 days of growth, regardless of different pollen tube speed in the style. We found that most self-pollen tubes were hampered in the ovule after 23 days. Double fertilization was significantly higher following CP vs. SP. We observed that a lot of embryo sac atrophy, or gradually disintegrated embryo sac, and ovule abortion 30 days after SP. Most selfing ovules could not develop normally, indicating that there was an obstacle before fertilization in SP. These results indicated that a high frequency of ovule abortion contributed to the high proportion of empty cupules in chestnut.