稻米营养品质性状的间接选择和遗传改良

INDIRECT SELECTION AND GENETIC IMPROVEMENT FOR NUTRIENT QUALITY TRAITS IN INDICA RICE

利用9个籼型不育系与5个籼型恢复系按不完全双列杂交方式配制杂交组合，采用胚乳遗传模型分析籼稻碾磨和外观品质与营养品质性状间的多种遗传相关．结果表明，籼稻稻米营养品质与其它一些品质性状间存在着较强的胚乳直接加性相关、胚乳直接显性相关、细胞质相关、母体加性相关和母体显性相关．糙米重与赖氨酸指数等以正向加性相关和细胞质相关为主的成对性状，具有较好的间接选择效果．除了糙米宽与营养品质成对性状外，糙米长厚比与蛋白质含量等以负向加性相关为主、细胞质相关不明显或为负值的成对性状，将不易取得良好的同步改良效果．多数细胞质相关具有正向的较大相关系数，表明控制不同稻米品质性状表达的细胞质效应之间的相关是不可忽视的．糙米宽与蛋白质含量等以显性相关为主的成对性状则可以在杂交稻育种中加以应用．

Genetic correlations analysis between nutrient traits of rice and other quality traits was conducted for the experiment of incomplete diallel crosses with nine cytoplasmic male sterile lines and five restorer lines in Indica rice,by using the genetic model for quantitative traits of seeds of cereal crops.The results showed that there exisled significant genetic correlations including endosperm direct additive correlation(rA),endosperm direct dominance correlation (rD),cytoplasmic correlation(rC),maternal additive correlation(rAm),and maternal dominance correlation (rDm) for most of the pairwise traits.Indirect selection were expected for the pairwise traits which had significant positive rA,rAm and rc,such as brown rice weight and lysine index.Except for the pairwise traits of brown rice width and nutrient quality traits,the simultaneous improvement were not available for the pairwise traits which the additive correlations were negative and cytoplasmic correlation was also negative or not signif cant,such as protein content and ratio of length to width.Since most of the cytoplasmic effects for the pairwise traits were significantly positive and had larger correlation coefficients,it was important for the cytoplasmic correlation which controlled the relationship of different quality traits of rice in genetic correlation.The pairwise traits which had significant dominance correlations,such as protein content and brown rice width,could be effectively applied in hybrid rice breeding.