Abstract: Shanyou 4I3, an indica-japonica hybrid rice combination, and its male parent Zhong 413 were selected to investigate the effects of plant growth retardant S-07 on the grain filling of vigorous and weak spikelets, and also to clarify the role of exdogenous and endogenous IAA in grain development. The suppression of vigorous spikelet on weak spikelet during the early grain-filling period can also be realized by the use of exdogenous IAA. Differential change patterns were detected for endogenous IAA content between vigorous and weak spikelets during the grain filling period, where IAA content increased sharply from the beginning of grain-filling and reached its maximum about eight days after flowering for vigorous spikelet, but was rather low during the initial 12 days and increased gradually to the top about 8 days afterwards for weak spikelet. The application of S-07 solution at the booting stage could decrease the IAA content of vigorous spikelet, but increased that of weak spikelet. The vigorous ones had higher transformation efficiency from ³ H-Try to ³ H-IAA and stronger competition for ³ H-IAA from otherparts, which may partially contribute to the different level of endogenous IAA between vigorous and weak spikelets. The results indicated that the application of S-07 solution at the late booting stage had different effects oil spikelet to a certain extent, but as expected, increased the seed weight of weak spikelet by stimulating and accelerating its grain filling.

Key words: indole acetic acid, indica-japonica hybrid rice, uniconazole, vigorous spikelet, weak spikelet

摘要： 以汕优413及其父本品种中413为材料，研究了内外源IAA在籽粒发育过程中的作用及植物生长延缓剂S-07对其强、弱势粒灌浆过程的影响。在灌浆前期，强势粒抑制弱势粒的发育，外源IAA可代替强势粒的这种抑制作用；灌浆过程中强、弱势粒内源IAA的变化动态存在差异，其中强势粒的内源IAA在开花后急剧上升，8 d左右达最高峰；而弱势粒的IAA水平开花后则有一段约12 d的“滞缓期”，在开花后20 d左右才有一高峰出现。强弱势粒对3H-IAA的合成和吸收能力差异可能是导致其内源IAA水平不平衡的原因之一。孕穗末期喷施S-07可部分抑制强势粒的发育而相对促进弱势粒的发育，提高弱势粒千粒重；孕穗末期喷施S-07溶液可降低强势粒但提高弱势粒灌浆前期的内源IAA水平。

关键词: 亚种间杂交稻, 强势粒, 弱势粒, 吲哚乙酸