Chin J Plan Ecolo ›› 2011, Vol. 35 ›› Issue (3): 322-329.doi: 10.3724/SP.J.1258.2011.00322
• Research Articles •
XIA Jiang-Bao1, ZHANG Guang-Can2*, SUN Jing-Kuan1, LIU Xia2
Aims Our objective was to investigate the threshold effects of photosynthetically active radiation (PAR) and soil mass water content (Wm) on photosynthetic and physiological parameters of Prunus sibirica, and understand the adaptability of P. sibirica to light and soil moisture conditions. We determined optimal Wm and PAR for P. sibirica to maintain higher net photosynthetic rate (Pn) and water use efficiency (WUE). Methods Using CIRAS-2 portable photosynthesis system, we measured Pn, transpiration rate (Tr), WUE and other photosynthetic and physiological parameters of three-year-old P. sibirica under different soil moisture conditions. Important findings Pn, Tr and WUE of P. sibirica had the critical response to soil moisture content and PAR. With increases in Wm (6.5%–18.6%), the light compensation point decreased and light saturation point, apparent quantum yield and maximum Pn increased. When Wm was about 18.6%, the low and high light use efficiency of P. sibirica was maximal. The index of Pn, Tr obviously increased with increasing Wm (9.2% to 18.6%), but Pn, Tr decreased when Wm was too high or low. When PAR ranged from 800 to 1 200 μmol·m–2·s–1, Pn and WUE were higher and the light saturation points of Pn and WUE were from 983 to 1 365 μmol·m–2·s–1. These indicated that P. sibirica possessed higher adaptability to light conditions. Based on photosynthetic and physiological parameters, the soil water availability and productivity of P. sibirica were classified and evaluated. For P. sibirica woodland, < 9.2% or >22.3% were low productivity and middle WUE, 20.5%–22.3% was middle productivity and low WUE, 9.2%–12.9% of Wm was middle productivity and middle WUE and 12.9%–20.5% of Wm was high productivity and high WUE. The optimum high productivity and high WUE of Wm were about 18.6%, and the corresponding optimum PAR was about 1 365 μmol·m–2·s–1.
XIA Jiang-Bao, ZHANG Guang-Can, SUN Jing-Kuan, LIU Xia. Threshold effects of photosynthetic and physiological parameters in Prunus sibirica to soil moisture and light intensity[J].Chin J Plan Ecolo, 2011, 35(3): 322-329.
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