Changes in Yield Components of Paddy Rice Due to Short-Term Flooding at the Panicle Developmental Stage and the Ripening Stage

Abstract

We flooded the paddy rice for 1 or 3 days at the late spikelet differentiation stage or the pollen formation stage or 2 days at the early ripening stage or the middle ripening stage, and examined the effects on rice yield components. None of the flooding treatments affected the panicle number. The panicle weight per ear was reduced by 13 to 17% by flooding treatment for 3 days in the late spikelet differentiation stage, and by that for 1or 3 days in the pollen formation stage and in the early ripening stage compared with that of the control. The decrease in one panicle weight due to flooding treatment was mainly due to the decrease in the number of secondary rachis grains caused by the decrease in secondary rachis branches. There was no difference in the one grain weight of the treatment plots in comparison with that of the control. The decrease in yield is mainly due to the decrease in the number of grains due to the abortion or death of the secondary rachis branch.