祝光苹果胚珠发育与生理落果的关系

在祝光苹果的生理落果期中,观察到两个明显的落果高峰。第一个落果高峰出现在盛花后第二周。此期正常果的胚株内,胚已发育至线形胚阶段;胚乳处游离核时期;珠被、珠心细胞和胚乳游离核周围均有淀粉粒分布。而此期落果中,多数胚珠的珠心和内球被退化,没有胚和胚乳的发育;仅存的外珠被中也未见淀粉粒。第二个落果高峰出现在盛花后第五周。此期正常果的胚珠内,胚处于心形期至鱼雷期;胚乳已细胞化:胚囊和珠心组织中淀粉粒消失;珠被中淀粉粒增多。而此期落果的胚珠内,胚处心形期;胚乳出现退化迹象;珠被中淀粉粒较少;承珠盘细胞内出现棕褐色沉积物。

The Relation Between Development of the Ovule and Physiological Premature Drop in Apple

During the physiological premature drop of apple American Summer Pearmain two obvious premature drop peaks were observed. The first drop peak appeared in the second week alter full blossom. During this stage filamentous embryos in normal fruit were formed, development of endosperm was at free nuclear stage, there was distribution of starch grains in integumental and nucellar cell and around the endosperm free nucleus. In premature drop nucellusof most ovule and inner integument were degenerated, there were no development of embryo and endosperm, starch grains were not found in outer integument.Second drop peak appeared in the fifth week after full blossom. During this stage development of embryo in normal fruit was from heart stage to torpedo stage, endosperm was developed into cells, starch grains disappeared in embryo sac and nucellus but increased in integument. In the ovule of premature drop development of embryo was at. heart stage, sign of degeneration appeared in endosperm, there were few starch grains in integument, brown deposits appeared in hypostase cells.