Response of rice quality and yield to drought-flood abrupt alternation during grain filling period
To investigate the effect of drought-flood abrupt alternation on rice quality and yield during the grain filling period,Xiangzaoxian 6 was selected as the research object.Based on barrel planting test,a four-factor three-level orthogonal test was designed,four factors were drought level(65％±5％,50％±5％and 35％±5％field holding),drought time(5,7 and 9 d),flooding level(50％,75％and 100％inundation plant height),flooding time(5,7 and 9 d),a total of 9 drought-flood abrupt alter-nation treatments,and control treatment(CK)were adopted.The changing pattern of each rice quality index and yield under drought-flood abrupt alternation during the grain filling was investigated,and a comprehensive evaluation of yield and quality by TOPSIS analysis based on the principal component analysis was made.The results show that drought-flood abrupt alternation during the grain filling period will lead to shorter and narrower rice grains,significantly higher transparency and yellow grain rate,and higher chalkiness and chalky grain rate by 13.42％-69.16％and 6.14％-48.72％,respectively,compared with CK.The straight-chain starch content increases by 12.39％to 34.46％compared to CK under drought-flood abrupt alternation during the grain filling period,while the decrease in gum con-sistency ranges from 25.26％to 36.84％.Except for the alkali extinction value,rice quality under drought-flood abrupt alternation during the grain filling period is affected by both drought and flooding,and the level of flooding is the main influencing factor for most quality indicators.Compared with the control group,drought-flood abrupt alternation during the grain filling period results in 67.32％to 98.71％yield reduction in rice,and most quality indicators are negatively correlated with yield,with the strongest negative correlation between aspect ratio and yield(r=-0.78***)and positive correlation between gum consistency and yield(r=0.68***).The optimum treatments for the comprehensive qua-lity of rice yield and quality under drought-flood abrupt alternation during the grain filling period are light drought-light flood abrupt alternation,and the treatments with the worst comprehensive quality are heavy drought-heavy flood abrupt alternation.The results of the study can provide a theoretical basis for the improvement of rice quality in response to drought-flood abrupt alternation and the development of mitigation strategies.
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