外源ABA和GA对水稻不同粒位籽粒主要米质性状的影响

以中熟籼稻扬稻6号和中熟粳稻扬粳9538为材料，灌浆初期通过喷施低浓度的ABA (75.7 μmol L^-1)和GA (57.7 μmol L^-1)处理，研究其对水稻穗部不同粒位籽粒品质的影响。结果表明，灌浆初期喷施低浓度的外源ABA和GA对米质影响较大，影响程度因激素种类和籽粒着生部位不同而异。ABA增加千粒重和整精米率，降低垩白度；其影响对同枝梗上开花较迟的籽粒大于对其他粒位籽粒，对同部位二次枝梗籽粒大于对一次枝梗籽粒。外源GA处理则显著或极显著降低千粒重、整精米率、胶稠度、粗蛋白含量，增加垩白度、直链淀粉含量；同一枝梗不同粒位籽粒间，对较早开花籽粒千粒重和整精米率的影响大于对较迟开花籽粒，对垩白度、直链淀粉含量和蛋白质的影响则与ABA相反。

Effects of Exogenous ABA and GA on the Main Quality Characteristics of Grains at Different Positions of Panicle in Rice

Plant hormones play important roles in plant growth and development and yield formation. ABA and GA are two important kinds of hormones controlling rice grain development and filling, but the mechanism of regulating grain quality by them is not understood completely. In order to study and document the influence of ABA and GA on grain quality, the solutions with low concentrations of exogenous ABA (75.7 μmol L^-1) and GA(57.7 μmol L^-1) were sprayed at earlier filling stage. The results indicated that the effects of exogenous hormones at early filling stage on rice quality were great, and varied with exogenous hormone varieties and different grain positions. The exogenous ABA increased the 1000-grain weight (KGW) and head milled rice rate (HMRR), and reduced chalkiness degree (CD); the effect of ABA on grain quality varied with the positions of branch and grain in a rice panicle, which was greater on the later-flowered spikelets than on the earlier-flowered spikelets in the same branch, and on second branch than on primary branch. With spraying exogenous GA, KGW, and HMRR, gel consistence and crude protein content (CPC) were decreased significantly, while CD and amylase content were increased. The effect of spraying GA on KGW and HMRR of the earlier-flowered spikelets was greater than that of the later-flowered spikelets, but it was reversed on CD, AC, and CPC compared with spraying ABA.