Why does leaf hydraulic conductance decline under drought stress?

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K15554
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 40010:Forest science-related
• Research Institution: Japan International Research Center for Agricultural Sciences (2021-2022); Forest Research and Management Organization (2020)
• Principal Investigator: Kawai Kiyosada 国立研究開発法人国際農林水産業研究センター, 林業領域, 任期付研究員 (50846334)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: 亜熱帯気候 / 海洋島 / 気候変動 / 固有種 / 植物解剖学

Outline of Final Research Achievements

On the Chichi-jima, which experiences strong dry stress during the summer season, we investigated the diurnal variation of leaf hydraulic conductance and examined the factors that contribute to the differences in patterns among six tree species with diverse leaf physiological and morphological characteristics. The diurnal patterns of leaf hydraulic conductance varied greatly among tree species, with some species showing an increase in the morning followed by a decrease in the afternoon, some peaking in the afternoon, and others exhibiting little variation. The maximum hydraulic conductance throughout the day showed a positive correlation with the percentage loss of conductance, indicating a trade-off between maximum water transport capacity and its maintenance ability. The percentage loss of conductance was also positively related to the capacity of osmotic adjustments in leaf, suggesting that the maintenance of cell turgor is crucial for sustaining water transport in leaves.

Free Research Field

樹木生理生態学

Academic Significance and Societal Importance of the Research Achievements

葉の通水性は、植物個体全体の水輸送を律速する要因であり、物質生産や環境適応にも影響する。葉の通水性は乾燥ストレスや光強度などの環境要因に応答して変化することが知られているが、樹種による応答の違いやそのメカニズムについては、特に野外においてよくわかっていない。本課題では、野外の樹木における葉通水性の環境応答には大きな種間差があり、その応答性は、葉の特性と密接に関係していることを見出した。これらの結果は、変動環境における樹木ならびに森林の生理機能の応答予測に貢献する。