2022 Fiscal Year Final Research Report

Effect of water management during the rice grain filling period on the nitrogen environment of paddy fields and the rice grain quality

Research Project

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Project/Area Number	19H03071
Research Category	Grant-in-Aid for Scientific Research (B)
Allocation Type	Single-year Grants
Section	一般
Review Section	Basic Section 41030:Rural environmental engineering and planning-related
Research Institution	The University of Tokyo (2021-2022) National Agriculture and Food Research Organization (2019-2020)
Principal Investigator	Nishida Kazuhiro 東京大学, 大学院農学生命科学研究科(農学部), 准教授 (90554494)
Co-Investigator(Kenkyū-buntansha)	塚口直史石川県立大学, 生物資源環境学部, 准教授 (40345492) 吉田修一郎東京大学, 大学院農学生命科学研究科(農学部), 教授 (90355595)
Project Period (FY)	2019-04-01 – 2023-03-31
Keywords	水管理 / 気候変動 / 水田 / 熱環境 / 窒素環境 / 窒素動態 / 水稲 / 米
Outline of Final Research Achievements	To understand the effects of water management during the grain filling stage on rice grain appearance quality, the effects of the water management on the nitrogen environment in a paddy field and the nitrogen contents of rice grain were investigated. The following results were obtained: 1) the effect of water management on the rice grain quality was caused by the changes not only in the thermal environment of the paddy field (temperature of rice) but also in the nitrogen environment (nitrogen contents of rice); 2) the effect of the water management on the nitrogen contents and the quality of rice grain depended significantly on the temperature and nitrogen concentration of irrigation water, and (3) applications of water management that decrease paddy water temperature using low nitrogen concentrations of irrigation water may worsen rice quality due to decrease in nitrogen (protein) content in rice grain.
Free Research Field	農業農村工学
Academic Significance and Societal Importance of the Research Achievements	本研究により，水稲の登熟期の水管理は、水田の熱・窒素環境を共に変化させることで、米の外観品質に影響を与えることが明らかになった。このことは、水管理と肥培管理を組み合わせ対策により水田の熱・窒素環境をうまく制御すれば、従来よりも有効な対策となりうることを示唆する。今後、このような考えに基づく研究や技術開発が行われることで、米の高温障害問題の解決が促進されることが期待される。