Abstract

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Title:: Effects of Different Temperature on the Light-response Characteristics of Heracleum moellendorffii Hance Leaf Photosynthesis

Author(s):: ZHANG Fu; YU Xihong; LI Yangdan; HUI Aibin; CHENG Yao; JIANG Xinmei; (Key Laboratory of Biology and Genetic Improvement of Horticultural Crops,Northeast Region,Ministry of Agriculture,Northeast Agricultural University,Harbin,Heilongjiang 150030)

Keywords:: temperature; Heracleum moellendorffii Hance; photosynthesis; light response characteristics

Abstract:: This photosynthetic light-response characteristics of Heracleum moellendorffii Hance leaves at their initial ripening stage at 15 ℃,20 ℃,25 ℃,and 30 ℃ were studied by using LI-6400 photosynthesis determination system．With increasing daily mean temperature，the net photosynthetic rate (Pn),maximum net photosynthetic rate (Pnmax),initial slope (α),and water use efficiency (WUE) decreased after an initial increase,with the maximum of the net photosynthetic rate (Pn) and maximum net photosynthetic rate (Pnmax) at 20 ℃,while the maximum of the initial slope (α) and water use efficiency (WUE) at 25 ℃．The light compensation point (LCP)，the light saturation point (LSP) and dark respiration rate (Rd) had a variation of ‘up-down-up’ with increasing daily mean temperature，but the light saturation point (LSP) decreased slightly at 30 ℃．The transpiration rate(Tr) and stomatal conductance (Gs) increased with increasing daily mean temperature and the maximum of them at 30 ℃，but the miximum of water use efficiency (WUE).It was suggested that the most favorite daily mean temperature for Heracleum moellendorffii Hance photosynthesis was 25 ℃.