早籼稻品种遗传改良进程中株型的演变特征

 以不同年代育成的28个代表性早籼稻品种为材料，在同一生态条件下种植，系统研究了叶型、茎型、穗型若干株型性状的演变特征。结果表明，早籼稻品种改良进程中，上部3片功能叶均变短、变厚、变直、变挺；各节间变短、变粗，节间密度变大，尤以基部节间和穗下节间最为显著，而单位鞘重变化不显著；每穗粒数、二次枝梗数、着粒密度均变大。据此认为，早籼稻叶型改良应在保持现有叶片曲率的前提下增加叶长；茎型改良应增加基部节间的粗度和穗下节间的长度；穗型改良应增加每穗粒数和枝梗数。

Evolution Characteristics of Plant Type During Genetic Improvement in Early Season indica Rice

Twenty eight early season indica rice cultivars released from 1934 to 2006 and widely planted ever in south China were selected and classified into four rice genotypes, i.e. tall cultivar, dwarf cultivar, dwarf and resistant cultivar, good quality and super rice cultivar. Some evolutional characteristics of leaf, stem and panicle types were systemically investigated under conventional cultivation conditions in 2008. During the evolution, the top 3 leaves became straighter, erecter, shorter, and thicker. Every internode became shorter and thicker especially the basal internode and internode below panicle, the density of internode became larger, while the weight of leaf sheath had no change. Grain number per panicle, secondary branch number, grain density per panicle were significantly improved. The results indicate that more attention should be paid on increasing leaf length but keeping the present leaf curvature for leaf type, on increasing the thickness of basal internode and the length of the internode below panicle for stem type, and on increasing grains per panicle and branch number for panicle type in early season indica rice breeding.