结实期低土水势对水稻强弱势粒灌浆特性及主要米质性状的影响

Effects of Low Soil Water Potential on the Grain-filling Characters and the Main Quality Properties of Superior and Inferior Grains in Rice during Filling Period

以扬稻6号和武育粳3号为供试材料,研究了结实期-40kPa低土壤水势对水稻强、弱势粒灌浆特征和主要米质性状的影响,并分析了强弱势粒灌浆特征与稻米垩白之间的关系。结果表明:结实期低土水势对强弱势粒米质主要性状、米粉RVA谱、籽粒灌浆特征和物质的积累有着显著的影响,而且强弱势粒间存在明显的差异。低土水势下,强势粒的起始灌浆势R0增加,而弱势粒R0减小;强弱势粒达到最大灌浆速率的时间Tmax提前,活跃生长期缩短。水分胁迫下弱势粒中蔗糖、可溶性糖含量明显偏高,而淀粉积累明显缓慢。这表明低土水势下强势粒灌浆过快,弱势粒又易丧失对灌浆基质的转化能力,这种籽粒灌浆进程的异常和灌浆物质的分配变化,易形成垩白。低土水势下,强弱势粒米粒的整精米率降低,粗蛋白含量显著增加,米粉的RVA谱特征值发生明显的变化,米饭的食味变差,导致米质变劣。

With Yangdao6 and Wuyujing9 as materials, effects of low soil water potential （SWP, -40kPa） on the main characters of superior and inferior grains quality and the properties of grain filling during filling period were examined. The main results showed that low SWP had significant effects on the grain quality, RVA profile, grain-filling character and the accumulation of starch, and the difference in the superior and inferior grains was found. The initial growth power Ro of superior grains was enhanced subjected to low SWP, while which of inferior grains were reduced. The tine when the growth rate is maximum Tmax for superior and inferior grains and the vigorous filling period D were shorted. The contents of sucrose and soluble sugar in inferior grains under low SWP were significantly higher than those under well water, and the accumulation of starch in inferior grains under low SWP was very slow. The results suggested that grain filling of superior grains subjected low SWP were too rapid, and the inferior grains subjected low SWP were apt to lose the assimilating ability on the filling substances. The abnormity of grain filling and the alternation of filling substances contributed to the formation of chalkiness. Head milled rice under low SWP was decreased, and the content of protein was increased. The characteristics of RVA profile for superior and inferior grains under low SWP differed obviously from those under well water. And so the eating quality was affected by low SWP. In a word, the rice quality was poor subjected low SWP.