关键词: 亚种间杂交稻, 强势粒, 弱势粒, 吲哚乙酸

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