Leaf dynamics: leaf mean residence time and photosynthetic efficiency

2015 Fiscal Year Final Research Report

• Project/Area Number: 25440230
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Ecology/Environment
• Research Institution: Tohoku University
• Principal Investigator: Hirose Tadaki 東北大学, 生命科学研究科, 名誉教授 (90092311)
• Co-Investigator(Kenkyū-buntansha): HIKOSAKA Kouki 東北大学, 大学院生命科学研究科, 教授 (10272006)
• Co-Investigator(Renkei-kenkyūsha): OIKAWA Shimpei 茨城大学, 大学院理工学研究科, 助教 (90400308)
• Project Period (FY): 2013-04-01 – 2016-03-31
• Keywords: 生理生態 / 葉群動態 / 平均滞留時間 / 光合成生産効率

Outline of Final Research Achievements

We studied leaf dynamics with respect to mean residence time and photosynthetic efficiency using cockleburs and rice. Cockleburs were grown at two densities and the effects on leaf dynamics of light gradient within a canopy and of nitrogen sink strength were studied. Light gradient was stronger in a dense stand due to mutual shading, while nitrogen sink strength was stronger in an open stand due to higher branching and reproductive activities. Nitrogen use efficiency (NUE) in rice plants was analyzed at leaf, shoot, and whole-plant level, with factorization into nitrogen productivity (NP) and mean residence time (MRT). No significant difference was found in MRT and harvest index between rice and wild annuals. The high NUE in rice was ascribed solely to its high NP. Because of high opportunity costs of reducing NP, MRT may not be increased further in rice. By contrast, high NUE in perennials was due to high MRT. Their NP was as low as wild annuals'.

Free Research Field

植物生態学