2018 Fiscal Year Final Research Report

Analysis of maturing of crops in relation to plant water

Research Project

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Project/Area Number	16H04867
Research Category	Grant-in-Aid for Scientific Research (B)
Allocation Type	Single-year Grants
Section	一般
Research Field	Crop production science
Research Institution	Kyushu University
Principal Investigator	Iwaya-Inoue Mari 九州大学, 農学研究院, 学術特任教員 (2016年度教授) (60091394)
Co-Investigator(Kenkyū-buntansha)	湯淺高志宮崎大学, 農学部, 教授 (40312269) 石橋勇志九州大学, 農学研究院, 准教授 (50611571) 鄭紹輝佐賀大学, 農学部, 教授 (90253517)
Project Period (FY)	2016-04-01 – 2019-03-31
Keywords	乾燥ストレス / ダイズ / ササゲ / 子実 / 一斉登熟 / 貯蔵物質
Outline of Final Research Achievements	Unlike other annual legume crops such as cowpea, soybean leaves drop, and stems lose their green color with seed maturation. A soybean-specific phenomenon called green stem syndrome (GSS) prevents soybean stems and leaves from drying down properly, albeit the mature seeds lose water. GSS lowers both grain yield and grain quality and interferes with machine harvesting. Our results suggested that cytokinin and autophagy were involved in GSS of soybean. In addition, drought stress caused decrease in seed dry weight due to decrease in contents of protein and lipids while increase in soluble sugar content in seeds. On the other hand, drought stress in cowpea did not affect germination rate, indicating that seed viability and its quality were maintained. Consequently, cowpea yield under drought stress was maintained, despite a decrease in photosynthetic rate, by translocation of photoassimilates from leaves via temporary sink and source organs, especially from flower stalks to the seeds.
Free Research Field	作物生理学
Academic Significance and Societal Importance of the Research Achievements	ダイズは他のマメ科作物と異なり一斉登熟性をもつが、「青立ち」株では機械収穫の際に茎葉の水分により汚粒を発生し、古くから農業上の大きな問題となってきた。本研究では、一斉登熟性をもたないササゲと比較し、摘莢や乾燥ストレスを与え、シンクソースバランスを崩すことにより「青立ち」のメカニズムを解明し、栽培技術の向上を目指した。根や葉の植物ホルモンに着目した結果、ダイズでは、サイトカイニンの制御が青立ち抑制に有効であることを明らかにした。一方、ササゲでは、乾燥ストレスによりＡＢＡ合成が促進され、葉の脱水に伴い、糖は花柄へ移動し、さらに花柄から子実への転流促進により、登熟が正常に起ることを示した。