Clarification of physiological mechanism and hull yellowing related to ripening of rice

Research Project

Project/Area Number	20K06008
Research Category	Grant-in-Aid for Scientific Research (C)
Allocation Type	Multi-year Fund
Section	一般
Review Section	Basic Section 39020:Crop production science-related
Research Institution	National Agriculture and Food Research Organization
Principal Investigator	Arai Yumiko 国立研究開発法人農業・食品産業技術総合研究機構, 作物研究部門, 上級研究員 (50547726)
Co-Investigator(Kenkyū-buntansha)	岡村昌樹国立研究開発法人農業・食品産業技術総合研究機構, 中日本農業研究センター, 主任研究員 (00757908)
Project Period (FY)	2020-04-01 – 2023-03-31
Project Status	Completed (Fiscal Year 2022)
Budget Amount *help	¥4,290,000 (Direct Cost: ¥3,300,000、Indirect Cost: ¥990,000) Fiscal Year 2022: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000) Fiscal Year 2021: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000) Fiscal Year 2020: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000)
Keywords	水稲 / 登熟 / 黄化籾率 / HSV色空間 / 収穫適期 / 登熟期間 / イネ / 黄化
Outline of Research at the Start	本研究課題では、水稲の収穫適期の判断基準に重要な籾の「黄化程度」と、登熟に伴う乾物動態」と「水分動態」の関係性を圃場群落レベルで明らかにする。さらに一穂籾数や単位面積当たりの総籾数、籾以外の部位の生理形質や栽培環境を考慮に入れることで、登熟の生理的メカニズムを解明する。
Outline of Final Research Achievements	We developed a method to objectively measure the grain yellowing rate, which is one of the indicators of the optimum harvest timing, through image analysis. The objective of this study was to elucidate the factors that contribute to the cultivar differences in the duration of grain filling based on the grain yellowing rate. Compared to measurements by visual observation, the root mean square error was 8.1% for the training data and 11.2% for the test data, indicating high accuracy in estimation. Regression of the grain yellowing rate against the cumulative temperature after heading using logistic curves resulted in a good fit with determination coefficients above 0.99 for both the "Yamadawara" and "Emidawara". It was quantitatively revealed that the grain yellowing rate in "Emidawara" reaches its maximum value earlier than “Yamadawara”, suggesting initiation of maturity, as determined by grain yellowing, is earlier in “Emidawara.”
Academic Significance and Societal Importance of the Research Achievements	出穂から収穫適期までの長さ、すなわち登熟期間は水稲の生産性を決める重要な形質の一つである。しかし収穫適期の客観的な判断が困難であるため，登熟期間の品種間差をもたらす要因については不明な点が多い。そこで本研究では収穫適期の指標のひとつである黄化籾率を画像解析により客観的に測定する方法を開発した。本研究で開発した客観的な黄化籾率測定方法により、登熟期間に関する基礎的研究が進み、品種や栽培環境から登熟期間を予測できるようになると期待する。