Abstract:

The variation of amylose content(AC)among grains at different positions within a rice panicle was investigated with compact and loose panicle types of japonica rice varieties Zhejing 22 and Zhejing 27 as materials.The differences between the maximum and minimum of grain AC in Zhejing 22 and Zhejing 27 reached 13.53 and 10.30 percent point,respectively.The variation range of AC in compact panicle is larger than that in loose panicle.The AC for each grain in a panicle followed a normal distribution.The correlation coefficients between grain AC and its position in the primary and secondary branches of the panicle in compact and loose panicle types were-0.1167 and-0.3140,respectively,showing that the coefficient of relationship in the loose panicle type was more significant than that in the compact type,and in addition,the coefficient of relationship between AC and grain position in the primary branch was higher than that in the secondary one.The AC of the grains from the top of branch was higher than that of the second grain under the first top one.The distribution of grain AC in a panicle was similar between the loose panicle type and the compact panicle type.It was better to choose the third or forth grains in the panicle branch for AC analysis if whole or half a grain sample should be determined.

Key words: rice quality, panicle morphology, amylose content, distribution, position effect

摘要： 对粳稻密穗型品种浙粳22和散穗型品种浙粳27单株主穗上的单粒稻米，利用碘比色法进行了直链淀粉含量测定。结果表明，浙粳22和浙粳27直链淀粉含量最大值与最小值相差分别达到13.53和10.30个百分点，密穗型比散穗型的变幅大；稻穗内各籽粒在不同直链淀粉含量区间的频数变化趋势呈正态分布；密穗型和散穗型一、二次枝梗籽粒直链淀粉含量与其粒位间的相关系数分别为-0.1167*和-0.3140**，一次枝梗籽粒要高于二次枝梗籽粒，散穗型较密穗型更显著；枝梗顶端籽粒的直链淀粉含量较高，而与此相连的第2粒的直链淀粉含量较低；散穗型与密穗型品种在穗内直链淀粉含量分布上存在相似的规律，如单粒或半粒取样时应以各枝梗上第3、4粒部位的较好。

关键词: 稻米品质, 穗型, 直链淀粉含量, 分布, 位置效应