Abstract: By using hybrid rice Xieyou 9308, Xieyou 9312, Ⅱyou 162 and their restorer lines as plant materials, and 3H glucose, PCIB, TIBA as chemical materials, the process of grain filling and effects of IAA, TIBA, PCIB on sugar content in superior and inferior spikelets were studied. The overall contents of IAA and grain weight increment rate in superior spikelets were higher than those in inferior spikelets. The sugar contents (fructose, glucose, sucrose) in inferior spikelets were not higher than those in superior spikelets until 7 days after pollination, and higher than those in superior ones after that time. Physiological activity differences between superior and inferior spikelets were more significant in hybrid rice combinations than those in their restorer lines. IAA inhibitors decreased IAA contents in both superior and inferior spikelets and reduced 3H glucose radiaton activity. By treated with high concentration exogenous IAA on young panicle before heading, the seed setting rate difference between superior and inferior spikelets was significantly decreased, and the total seed setting rate was increased.

Key words: apical grain superiority, superior spikelets, inferior spikelets, grain filling, indole acetic acid, soluble sugar

摘要： 以超级杂交稻协优9308和杂交稻协优9312、Ⅱ优162及其相应恢复系为材料，对灌浆初期籽粒中内源IAA、糖分的变化，以及IAA抑制剂对IAA以及3H标记葡萄糖吸收分配和籽粒灌浆的影响进行了研究。结果表明在籽粒灌浆初期强势粒的IAA含量以及增重的速度始终高于弱势粒。在开花受精7 d以前，强势粒中果糖、葡萄糖及蔗糖的含量高于弱势粒，之后相反。强、弱势粒间存在的这种灌浆势差异，杂交组合大于其相应的恢复系。IAA合成及运输抑制剂明显降低3H葡萄糖在籽粒中的分配。外源IAA对幼穗的处理，缩小了强、弱势粒间结实率的差异，使整穗的结实率也有所提高。

关键词: 粒间顶端优势, 强势粒, 弱势粒, 籽粒灌浆, 吲哚乙酸, 可溶性糖, 杂交水稻