The progress of grain filling and changes in endogenous IAA,ABA,GA1 and GA3 contents in the superior and inferior spikelets of a heavy panicle hybrid rice (Oryza sativa L.) Peiai 64s/E32 were studied.The overall contents of different hormones in developing grains were IAA﹥GA1+GA3﹥ABA.IAA and ABA contents were higher in superior spikelets while GA1+GA3 level was higher in inferior spikelets.Positive correlations have been found between the hormone contents and grain weight increase rates with the highest correlations between IAA content per unit fresh weight (ng/g FW) and fresh weight increase rate (r=0.8218* *) and between the average IAA content per grain (ng/grain) and dry weight increase rate (r=0.8485* *).The results suggest that a relatively high level of IAA may be required to initiate and maintain grain filling.ABA may have the functions of positively regulating assimilate accumulation and accelerating seed maturation.GA1+GA3 may play a special role in maintaining the viability of inferior spikelets during their delayed grain filling.%研究了重穗型杂交水稻培矮 64s/E32的灌浆过程和强、弱势颖花中内源IAA、ABA 和GA1+GA3 水平的动态状况.籽粒发育过程中不同内源激素水平高低依次为:IAA﹥GA1+GA3﹥ABA.IAA 和ABA水平在强势颖花中较高而GA1+GA3水平在弱势颖花中较高.3种激素水平的变化与谷粒增重速率之间均存在正相关,两个最高的相关系数值分别存在于单位鲜重样本的IAA含量(ng/g FW)与籽粒鲜重的增重速率之间(r=0.8218* *) 和单个籽粒 IAA含量(ng/grain)与籽粒干重的增重速率之间(r=0.8485* *).推测启动和维持籽粒灌浆过程可能需要较高的IAA水平;ABA可能具有促进籽粒中同化物的累积和种子成熟的作用;GA1+GA3可能具有保持弱势颖花活性的特殊作用.
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