磨盘柿杂交种种皮异常突起形成分析

磨盘柿是优良的育种资源,然而与日本甜柿杂交,正常种子仅有8%左右,大部分种子败育。败育种子中80%以上由异常突起引起。异常突起于授粉后40 d左右在种孔处产生,以后不断膨大,导致种孔附近的种皮腐烂、破裂,胚乳退化外漏,最终种胚死亡、种子败育。本实验旨在研究异常突起形成的原因,揭示磨盘柿杂种败育的机制,以期提高磨盘柿种质资源的利用效率。为此,从形态学、组织学上对突起种子的形成进行了研究。结果显示:1)突起产生在相邻子房室的孔隙内,一般在受粉后40 d发生,并在突起处种皮腐烂变黑;2)授粉后45 d,带突起的种子在突起处的胚乳细胞个体大、细胞壁薄且破裂,细胞核退化;3)在授粉后132 d,带有异常突起的种子发育速度快,胚乳分裂旺盛,种子饱满;种胚分化速度快,且分化时期比正常胚提前5 d以上。研究认为种子发育速度比子房室的生长过快。在胚乳和果肉的双重挤压下,种皮在2个子房室间的孔隙中突出,产生了异常突起。

Cause of abnormal protuberant hybrids coat of ''Mopanshi'' persimmon

Mopanshi was crossed as a female parent with Ze njimaru and Taishu,the Japanese nonastringent cultivar,and the resulting hybrids were studied.Only a few seeds(about 8%) were normal,but more than 90%,were abnormal.More than 80% of abnormal seeds were induced by protuberance around the hilum.Histological and morphological observations for improving germination rate and use of the germplasm resource,showed that: 1) Protuberance occurred at the aperture between two neighboring locules 40 d after pollination,frequently with black spot production.2)The protuberant endosperm cells were characterized by large degenerate nucleus and thin,usually collapsed cell wall,45 d after pollination.3) Comparatively, the protuberant seed grows faster,inside which,the endosperm for seed plumpness and an embryo that develops 5 d faster than normal seed exhibits vigorous differentiation and growth,132 d after pollination.Our primary conclusion is that the protuberance was produced in an aperture between two neighboring locules following pressure between fast growing seeds and limited space between locules.