结实期低温对杂交水稻胚乳结构的影响

以两系和三系杂交稻组合两优培九、103S/郑粳2号、丰优香占和汕优63为材料，分别于花后0~10 d、11~20 d和21~30 d 3个时期设18℃的低温处理，以常温（24～27℃）为对照，用扫描电镜观察了胚乳结构形成过程。结果表明，灌浆期不同时段的低温处理，对籽粒的粒型、垩白面积、胚乳结构三者的影响趋势基本一致，使籽粒外形异常，垩白面积提高；复粒和单粒淀粉体的体积变小且彼此差异变大，排列变疏松；复粒淀粉体变少，单粒淀粉体变多。低温处理愈早，对胚乳结构的影响愈大。灌浆前期进行低温处理、以后在正常温度下灌浆成熟的籽粒，其强势粒的粒型、垩白面积、胚乳结构均无明显改变，但弱势粒的变化较大。

Effects of Low Temperature during Grain Filling on the Structure of Endosperm in Hybrid Rice

The structure of endosperm is closely related with the grain quality of rice and is believed to be mediated by environmental conditions. The objectives of this study were to investigate the structure of rice endosperm and the grain quality by a scanning electron microscope. Using four hybrid rice combinations, Liangyoupeijiu, 103S/Zhengjing 2, Fengyouxiangzhan and Shanyou 63, grown in pot and treated with low temperature at 18℃ during 0–10 days(T₁), 11–20 days(T₂), and 21–30 days(T₃) after flowering respectively，and the control temperature 24–27℃. The results showed that the grain was abnormal in exterior shape, the area of chalkiness increased, and the size of the amyloplast, either complex or single, decreased, the difference in the size between complex and single amyloplast increased, their arrangements loosened, and resulted in more complex and fewer single amyloplast by the low temperature treatments. The earlier the low temperature treatment was, the more serious the effect was on the endosperm structure. If plants were subjected to low temperature at early grain filling stage and then grown under a normal temperature at late stages, effects of the low temperature on the grain shape, structure of endosperm and the chalkiness area for inferior grains were serious, whereas those for superior grains were not obvious. The results suggest that the structure of endosperm is deteriorated by low temperature during the grain filling period, leading to poor grain quality of rice.