Water Management for Improvement of Rice Yield, Appearance Quality and Palatability with High Temperature During Ripening Period

To clarify the optimal water management in large-scale fields under high temperatures at the ripening period, effective water managements during this period for improvement of yield, appearance quality and palatability were investigated. Compared with intermittent irrigation and flooded irrigation, the soil temperature with saturated irrigation remained low throughout the day, and the decrease rate of the bleeding rate of hills was the lowest. These results suggested that the saturated irrigation maintained root activity. For the three irrigation types, the number of spikelets per m2 and 1000-grain weight were similar, however, saturated irrigation resulted in significantly higher rice yield due to improvement in the percentage of ripened grains. The saturated irrigation produced a high percentage of perfect rice grains and thicker brown rice grain, furthermore, the palatability of cooked rice was excellent because protein content and hardness/adhesion ratio were both low. Thus, under high-temperature ripening conditions, soil temperature was lowered and root activity was maintained when applying saturated irrigation after heading time. The results indicated that saturated irrigation is an effective countermeasure against high-temperature ripening damage.