【摘要】 以中熟籼稻(扬稻6号)和中熟粳稻(扬粳9538)为材料,研究了穗上不同粒位籽粒灌浆过程中粒重、淀粉、可溶性糖和粗蛋白质含量等动态变化,以期通过分析灌浆物质累积动态差异探讨不同粒位间籽粒品质差异形成的生理原因。穗上不同粒位籽粒灌浆物质累积动态存在显著差异,同一穗上早开花籽粒起步灌浆早,初期灌浆速率快;灌浆前、中期籽粒中淀粉和直链淀粉累积速率、累积量与籽粒开花顺序较为一致,即早开花籽粒大于迟开花籽粒,而不同粒位籽粒间的可溶性糖含量变化则与之相反。灌浆在粒位间的差异扬粳9538大于扬稻6号。成熟期籽粒直链淀粉含量则与开花顺序无必然联系。粗蛋白质含量随灌浆进程呈倒"S"型趋势,即灌浆前期下降较快,至最低点后略有回升,前期下降速率迟开花籽粒大于早开花籽粒,但蛋白质含量在整个灌浆阶段则以迟开花籽粒大于早开花籽粒,二次枝梗大于一次枝梗籽粒,穗下部籽粒高于其他部位籽粒。灌浆前、中期同枝梗上较早开花籽粒含水量下降幅度大于迟开花的籽粒,一次枝梗上第1粒尤为明显。以上结果说明,可溶性碳水化合物的供给可能不是弱势粒发育不良的限制因子,弱势粒灌浆充实不良可能与其较低的生理活性有关。更多还原

【Abstract】 The accumulation dynamic of filling matter for spikelets at different positions within a rice panicle was investigated during grain filling to understand the physiological reasons for the variations of grain quality.Two rice cultivars,Yangdao 6(indica) and Yangjing 9538(japonica),were field-grown,and the grain filling character and the contents of starch,soluble sugar,and protein of the spikelets at different positions were studied.There were significant differences in matter accumulation between spikelets at different positions during grain filling.The earlier-flowered spikelets presented dominance over the later-flowered spikelets in initial filling rate and filling intensity.The contents and rates of starch and amylose accumulation in spikelets were consistent with the flowering sequence at the initial and medium filling stages,i.e.,the earlier-flowered spikelets had greater contents and rates of starch and amylose accumulation than later-flowered spikelets,but the soluble sugar content(SSC) exhibited an opposite result.The difference in SSC between the spikelets of Yangjing 9538 was greater than that of Yangdao 6,but the amylase content in spikelets at maturity was not very identical with the flowering sequence of spikelets.The change in crude protein content(CPC) showed an S-shaped curve.The CPC of earlier-flowered spikelets decreased more rapidly than that of those later-flowered ones at the initial filling stage,and CPC in the spikelets on the secondary rachis branch was more than that on the primary rachis branch,but CPC in later-flowered spikelets was higher than that in earlier-flowered spikelets in the whole filling period.Grain water content(GWC) of earlier-flowered spikelets decreased more rapidly than that of later-flowered spikelets in the same branch at the initial and medium filling stages,especially for the first grain among the spikelets on a primary rachis branch.The results suggested that the low biological activity of later-flowered inferior spikelets may be attributed to their poor grain filling rather than carbohydrate supply.更多还原