【作者】 周述波；

【导师】 肖浪涛；

【作者基本信息】 湖南农业大学 ， 植物学， 2005， 硕士

【摘要】 穗上芽是指作物在收获前遇到连续高温高湿天气,籽粒穗上发芽的现象。在杂交水稻制种生产上,穗上芽的发生成为制约制种产量和品质的主要因素之一。本研究以穗上发芽难易程度不同的两水稻品种为试验材料,对种子发芽和穗上芽发生过程中相关的生理生化变化进行了研究;于齐穗后7d用外源GA₃和ABA喷施水稻,研究了外源植物生长物质对穗上芽发生、内源激素及其它相关生理生化变化,相关农艺性状指标变化的影响情况,结论如下: 发芽势高的水稻品种种子易穗上发芽。穗上芽发生难易除种子自身遗传因子的影响之外,还与水稻种子自身内源激素GA₃和ABA含量密切相关,尤其与GA₃/ABA比值有关,易穗上发芽品种GA₃/ABA比值相对较高。研究表明,易穗上发芽水稻品种在穗萌到穗芽过程中α-淀粉酶活性、可溶性糖含量、可溶性蛋白和种子中含水量比不易穗上发芽的品种均相对较高。 外源植物生长物质能在一定程度上影响穗上芽的发生,经外源GA₃处理后能明显提高不易穗上发芽种子金23B的穗芽率。穗芽率升高可能是由于外源GA₃作用改变了内源GA₃水平,引起种子内一系列生理生化变化,如提高了GA₃/ABA比值、α-淀粉酶活性和可溶性糖含量,淀粉类物质降解加速,从而使田间种子不经休眠直接在穗上发芽。经外源ABA处理后易穗上发芽种子V20B的穗芽率明显降低,内源ABA含量提高,相关生理生化特征发生变化,从而促进种子休眠,抑制穗上芽发生。 外源GA₃处理在一定程度上增加穗长,但对籽粒充实度、千粒重有一定的负面影响。此外,外源GA₃处理还可使种子休眠降低,在短期内种子的发芽势提高,为异地制种加快种子繁殖缩短时间,但种子活力降低,不利于种子长期贮藏。外源ABA处理,可以促进种子的休眠,并在一定程度上提高籽粒充实度,增加千粒重,但解除种子休眠需一定时间,V20B为60d,金23B大约为90d。更多还原

【Abstract】 Preharvest sprouting is seed germination in the spike suffering successive high-temperature-damp climate before harvest. During seed production in hybrid rice, preharvest sprouting is one of the main restricting factors for yield and quality. Seed germination, preharvest sprouting and their related physiological and biochemical characteristic were studied by using two rice varities as the experimental materials with different preharvest sprouting abilities. Effect of exogenous plant growth substance on the preharvest sprouting formation, endogenous phytohormones and related physiological and biochemical characteristic and agronomic properties were studied by spraying the exogenous GA3 and ABA on rice on the seventh day after tasseling, the results are as follows:Rice variety with high germinating potential is easier for preharvest sprouting. Besides the genetic factors, the contents of endogenous phytohormones GA3 and ABA is closely related with the preharvest sprouting ability, especially the ratio of GA3/ABA, then easier preharvest sprouting rice variety has higher ratio of GA3/ABA. The results showed that the rice with easier preharvest sprouting has higher a-amylases activity, soluble sugar contents, soluble protein contents and water content than one with the uneasy preharvest sprouting rice from preharvest germination to sprouting.The treatment with exogenous plant growth substances on rice can affect preharvest sprouting formation in a certain degree. The treatment with exogenous GA3 on Jin 23B which has uneasy preharvest sprouting can remarkably improve the ratio of preharvest sprouting. Maybe this is the result that the exogenous GA3 led to the change of endogenous GA3 and many other physiological and biochemical characters,caused increases in the ratio of GA3/ABA, a-amylases activity, soluble sugar content,speeded up the starch decompose and decreased seed dormancy,eventually the preharvest sprouting took place without dormancy.Exogenous ABA treatment on V20B, an easy preharvest sprouting ,remarkably decreased its ratio of preharvest sprouting, increased endogenous ABA content and changed a serious of related physiological and biochemical indexes, therefore, promoted seed dormancy and inhibited preharvest更多还原