Rice (Oryza sativa L.) is one of the world’s most important food crops and is a staple food in Japan. In recent years, decreased yield and deterioration of appearance quality and palatability due to abnormally high temperatures during the ripening period have become serious problems for rice farmers in Japan. To clarify the optimal water management in large-scale fields under high temperatures at the ripening period, effective water management 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.
Dr. Matsue Yuji Graduated from Tottori University graduate school master’s course in 1978, Ph.D. in Agriculture, Tottori University, March, 1993. Business Careers: General director of the Fukuoka Agriculture Research Center, Kyushu University (Professor) and Global Innovation Center, Kyushu University, The president of Japanese Society for Rice Quality and Palatability. Specialized field: Rice Agronomy and Breeding, Palatability and physicochemical properties of rice, Genetic analysis on palatability and physicochemical properties of rice. Publications: Rice palatability science from the viewpoint of crop production. Yokendo, Tokyo, Matsue Yuji ed. 2018. Appearance quality and palatability of rice -Latest research and improvement techniques-. Yokendo, Tokyo. Awards: Tianjin International Science and Technology Cooperation Award, 2010, Japan Prize of Agricultural Science, 2012.