Abstract: Differences in cooking and nutritional quality characteristics among the grains at different positions within a rice panicle were studied.The characteristics investigated included the distribution of gel consistence(GC),amylose content(AC) and crude protein content(CPC) for different grains in a panicle under different nitrogen levels(0,120,and 240 kg/hm²),by using two rice cultivars,Yangdao 6(indica) and Wuyujing 3(japonica) as tested materials.The grains on the primary and secondary branches at the basal part of a panicle had smaller GC and greater AC than those at the upper or middle part of a panicle.The first of earlier-flowered grains on a secondary branch exhibited the greatest GC,whereas the second of later-flowered grains on a primary branch showed the greatest AC.For Yangdao 6,the CPC in the grains on a primary branch at the middle part of a panicle was lower,contrary to that at the upper or basal part of a panicle.For Wuyujing 3,there was no significant difference in CPC of the grains on the primary and secondary branches among the upper,middle and basal parts of a panicle.GC in the grains was increased,whereas AC was reduced from no nitrogen application(0) to low amount of nitrogen application(120 kg/hm²),and the result was reversed from nitrogen at 120 kg/hm² level to medium amount of nitrogen application(240 kg/hm²).CPC in grains was increased with the increase of the amount of nitrogen application.

Key words: rice, grain position, cooking quality, nutritional quality, nitrogen fertilizer

摘要： 以中熟籼稻扬稻6号和中熟粳稻武育粳3号为材料，研究了不同施肥水平下稻米蒸煮及营养品质在穗上不同粒位籽粒间的差异及其分布特点。 总体而言，穗下部一、二次枝梗籽粒的胶稠度较低，直链淀粉含量较高；穗中、上部一、二次枝梗的胶稠度较高，直链淀粉含量较低。在同一个枝梗上，二次枝梗上早开花的第1粒的胶稠度最高，穗子中、上部一次枝梗迟开花的第2粒的直链淀粉含量较高。扬稻6号穗中部一次枝梗籽粒的粗蛋白含量较低，穗上、下部枝梗上籽粒的粗蛋白含量较高；而武育粳3号一次枝梗和二次枝梗籽粒的粗蛋白含量在穗上、中、下三部位间无明显差异。从不施氮到少量施氮（120 kg/hm2），稻米的胶稠度和粗蛋白含量增加，直链淀粉含量降低。但从少量施氮（120 kg/hm2）到中等施氮（240 kg/hm2），稻米的胶稠度降低，直链淀粉和粗蛋白含量有不同程度增加。

关键词: 水稻, 粒位, 蒸煮品质, 营养品质, 氮肥