REGULATORY MECHANISM OF DEVELOPMENT IN RICE PLANT

1.茎发育研究以两个深水水稻品种为材料，研究了茎发育的阶段变化。深水、干旱等环境因子对Pahse变化影响不大。赤霉素或内源赤霉素生物合成抑制剂的应用对此有很大的影响。2.分蘖发育。第一个试验是深水处理，将水深提高到一定程度，以抑制分蘖芽的生长。另一种是抽穗后斩穗处理，以促进休眠芽的生长。结果表明，在低源/库条件下，穗部下部小穗位置的籽粒在早期发育过程中生长缓慢，当分蘖花蕾最终形成芽时，将出现生长转折点。玉米素的应用促进了籽粒的早期生长，增加了最终粒重。这些效应类似于提高源/库比的处理，表明细胞分裂素可能参与调节籽粒的自然发育。

1.Stem developmentThe phase change of stem development was studied using two deepwater rice cultivars. The pahse change was little affected by environmental factors such as deep water or drought. This was greatly affected by application of gibberellin or an inhibitor of biosynthesis of endogenous gibberellin.2.Tiller developmentWe carried out two experiments concerning the turning point of the growth phase of the tillers of rice plants. The first experiment was the deep water treatments by raising the water depth in to some grades in order to inhibit the growth of the tiller buds. Another one was the decapitation treatments by cutting off the panicles after the heading stage in order to stimulate the growth of resting buds. We concluded that there would be a turning point of the growth phase when the tiller bud reached its final shape as a bud.3.Grain developmentThe grains on the lower spikelet positions within the panicle grow slowly during its early development period under the low source/sink conditions. Application of zeatin enhanced the early growth of these grains and increased final grain weight. These effects resembles the effects of treatments increasing the source/sink ratio and indicate the possibility of the involvement of cytokinin in regulating the natural grain development.