Abstract: Under the field conditions, six japonica cultivars with erect panicle and four japonica cultivars with curved panicle were applied to compare the difference in the amylose content (AC) of rice grains and its position distribution in a panicle. Results indicated that the panicle type had a considerable influence on the AC variation of rice grains within a panicle. The cultivars with erect panicle generally had higher variation coefficient, larger dispersing degree and wider variation range of AC than the cultivars with curved panicle, despite it was not significantly related to the AC of cultivar; The AC variation of rice grains within a panicle was closely related to the position of rice grains on the rachis branches, the grains with the relatively low AC often appeared at the bottom or in the middle of the panicle while the grains with the relatively high AC was generally at the top of the panicle. However, more grains with low AC, distributed in the middle of the panicle, could be observed in the cultivars with erect panicle than in the cultivars with curved panicle.

Key words: rice, panicle type, amylose content, position effects

摘要： 以6个直穗型和4个弯穗型粳稻品种为材料，对两者在相同栽培条件下的穗内粒间直链淀粉含量变异及其频数分布、粒位特征进行了比较分析。结果表明：水稻穗型虽然与品种间的直链淀粉含量高低无直接关系，但对其穗内不同籽粒间的直链淀粉含量差异存在着较大的影响；直穗型粳稻品种单一稻穗内直链淀粉含量的粒间差异明显大于弯穗型品种，其直链淀粉含量的粒间变异系数与离散程度均高于后者；同一稻穗内不同籽粒间的直链淀粉含量变化与其相应的粒位有关，两种穗型粳稻品种均表现为穗顶部籽粒的直链淀粉含量相对较高、穗基部籽粒的直链淀粉含量相对较低这一基本趋势。但与弯穗型粳稻品种相比，直穗型粳稻品种大量低直链淀粉含量籽粒产生的部位是在其稻穗的中部，而不仅仅局限在稻穗基部的3个枝梗上。

关键词: 水稻, 穗型, 直链淀粉含量, 粒位效应