灌浆期不同光强对水稻不同粒位籽粒品质的影响

Effect of light intensity on grain quality of rice at different spike positionsduring grain-filling stage

  • 摘要: 为探讨灌浆期光照强度对水稻籽粒品质的影响及在不同品种类型和粒间差异, 揭示弱光下水稻籽粒充实不良和米质变劣的生理机制, 本文以代表性的超级稻品种"扬两优6号"和"武运粳23"为材料, 以穗中部不同粒位籽粒为研究对象, 以自然光强为对照, 设置3种弱光处理(光强分别为对照的71%、55%和40%), 研究了灌浆期不同光照强度对稻米品质的影响。结果表明: 1)灌浆期光照强度对稻米品质影响较大, 光强减弱稻米品质变劣, 光照对米质形成的影响因光照强度大小、品种类型和籽粒着生位置不同而存在差异, 同枝梗上迟开花籽粒稳定性较差, 早开花籽粒稳定性较好。2)随光照强度降低, 整精米率和直链淀粉含量降低, 垩白度增加, 不同光强下一次枝梗籽粒变化幅度大于二次枝梗籽粒; 光强越弱, 崩解值越低, 消减值和粗蛋白含量越高, 稻米蒸煮食味品质变差。3)生产上应因品种类型合理安排播期, 通过栽培措施改善稻株受光条件, 减轻光照不足对稻米品质形成的影响。

     

    Abstract: Light intensity is an important ecological factor that greatly influences rice grain formation and quality. This study discussed the effects of light intensity on rice quality at grain-filling stage and the differences in variety types and spikelets at different panicle positions. To do this, two pot-grown super rice cultivars, "Yangliangyou 6" (indica) and "Wuyunjing 23" (japonica), were subjected to three light intensity treatments (71%, 55% and 40% of normal light intensity respectively) at post-anthesis grain-filling stage, with normal outdoor growth as the control. The study aimed to throw more light on the physiological mechanisms of rice grain formation to lay the theoretical basis for improved rice quality. The results suggested that light intensity during grain-filling greatly influenced rice quality. Compared with the control, rice grain quality under the three treatments worsened with the weakening of light intensity. Grain quality response to light intensity varied with light intensity degrees, variety genotypes and grain positions on rice panicles. While grain quality on spikelets with late flower formation was poorly stability, that on spikelets with early flower formation was relatively stable. Milled rice and rice amylose content decreased and chalkiness increased with the weakening of light intensity. Amplitude change in grains on primary tillers was relatively larger than in grain on secondary tillers. Also the weaker the light intensity, the lower was the breakdown value, the higher were the setback value and crud protein content, and the worse were the rice cooking and eating qualities. Reasonable sowing times based on variety type and scientific cultivation practices for improved light conditions and rice growth likely mitigated any negative impacts of low light intensity on rice quality.

     

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