水稻不同粒位籽粒米质对花后不同时段温度胁迫的响应

为探讨花后高温胁迫对水稻籽粒米质的影响，以中熟籼稻扬稻6号和中熟粳稻扬粳9538为材料，研究了灌浆前期(花后0~10 d)和灌浆中期(花后10~20 d)的高温(35℃)对米质的影响，并进一步探讨了不同粒位间的差异。结果表明，与常温CK (25~27℃)相比，灌浆结实期高温处理对稻米品质影响较大，总体上前期(0~10 d)大于中期(10~20 d)，且因供试品种和粒间位置而异。灌浆前、中期高温处理，降低了精米率、整精米率、直链淀粉含量，增加了垩白粒率、垩白度和粗蛋白含量；其中，温度对二次枝梗与同枝梗上较迟开花籽粒的碾米品质的影响大于一次枝梗与较早开花的籽粒；前期高温显著增加了一次枝梗和各枝梗上开花较早籽粒的垩白粒率和垩白度；前期高温显著降低了直链淀粉含量，对一次枝梗籽粒的影响大于二次枝梗。不同供试品种对花后不同温度处理的敏感性不同，影响程度亦受花后温度胁迫时段的不同而异。生产上通过合理安排播期、平衡施肥和合理灌溉可以减轻结实期高温胁迫对籽粒品质的影响。

Effect of Temperature at Different Durations after Anthesis on Rice Quality and Variations between Positions on a Panicle

The aim of this study was to investigate the effect of high temperaturesimposed at early and mid grain filling stages on the quality of grains at different positions on a panicle, and to seek cultivation techniques to improve rice quality. Two rice cultivars, Yangdao 6 (indica) and Yangjing 9538 (japonica), were pot-grown and subjected to high (35℃) temperatures during the initial (0–10 d) and mid (10–20 d) grain filling stages after anthesis. Compared with atmospheric temperature (25–27℃, CK), the high temperature treatments significantly affected grain quality. Generally, the influence of the temperature treatment at the initial filling stage was more than that at the mid filling stage, however, the grain quality varied with cultivars and grains positions. High temperatures imposed at early and mid grain filling stages reduced brown rice rate (BRR), head rice rate (HRR), head milled rice rate (HMRR), but increased crude protein content (CPC), and the grains on primary branches were affected more than those on secondary branches, and later-flowered grains were affected more than early-flowered grains. High temperature imposed at the early grain filling stage significantly increased chalkiness degree (CD) and chalky grain percentage (CGP) of early-flowered grains at the same branch; high temperature treatments imposed at the early grain filling stage decreased amylose content (AC), and grains on primary branches were affected more than those on secondary branches.Sensitive of grain quality to temperature varied with cultivars and treatment times after anthesis. The influence of temperature on rice quality was more at the early grain filling than at the mid filling stage. Some cultural practices, such as balanced fertilization, arrangement of sowing date, and precise irrigation, would alleviate the influence of high temperature on rice quality.