Abstract: Caryopsis development was investigated with four rice varieties as materials which differed remarkably in grain weight. The number of endosperm cells was calculated by the technique that the endosperm cell suspension was filtered with a microspore filtering membrane. The structure of pericarp and endosperm cells was observed with a light microscope and an electron microscope. For the largegrain varieties, the caryopsis development was slower, the number and dry weight of endosperm cells, weight of each endosperm cell were more than those in the smallgrain ones. With the same grain weight, the caryopsis development and starch accumulation in indica rice were faster than those in japonica rice. In the largegrain varieties, the starch accumulation and cell growth yield in ovary wall cells were more than those in the smallgrain ones. Also the pericarp and the dorsal vascular bundles in the ovary maintained a longer functional period. The outer layer endosperm cells transformed into aleurone layer cells 7 days after flowering in the small grain varieties, but 10 days after flowering in the largegrain ones. The larger space formed by both the inner and outer glumes and longer active period of the caryopsis in the largegrain resulted in the notable expansion of the caryopsis.

Key words: rice, caryopsis, endosperm, amyloid, aleurone layer, development

摘要： 以粒重差异较大的4个水稻品种为供试材料，采用树脂切片、酶解胚乳细胞和显微观察等方法，比较研究了品种间在颖果生长、胚乳细胞增殖、果皮和胚乳结构等方面的差异，探讨了影响颖果生长的因素。 大粒品种颖果发育时间较小粒品种长，其胚乳细胞数、胚乳干质量及单个胚乳细胞平均干质量均高于小粒品种。在粒重相近的情况下，籼稻颖果发育和淀粉积累快于粳稻。与小粒品种相比，大粒品种子房壁细胞中淀粉粒多，子房壁细胞生长的持续时间长，果皮及背部维管束衰亡迟。 小粒品种胚乳外层细胞在花后7 d已转化成糊粉层细胞，大粒品种胚乳外层细胞要在花后10 d才转化成糊粉层细胞。 大粒品种的库容大和生理活性期长是其颖果能显著增大的生理原因。

关键词: 水稻, 颖果, 胚乳, 淀粉体, 糊粉层