tailieunhanh - báo cáo khoa học: " Responses of photosynthetic capacity to soil moisture gradient in perennial rhizome grass and perennial bunchgrass"

Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành y học dành cho các bạn tham khảo đề tài: Responses of photosynthetic capacity to soil moisture gradient in perennial rhizome grass and perennial bunchgrass | Xu and Zhou BMC Plant Biology 2011 11 21 http 1471-2229 11 21 BMC Plant Biology RESEARCH ARTICLE Open Access Responses of photosynthetic capacity to soil moisture gradient in perennial rhizome grass and perennial bunchgrass Zhenzhu Xu 1 Guangsheng Zhou1 2 Abstract Background Changing water condition represents a dramatic impact on global terrestrial ecosystem productivity mainly by limiting plant functions including growth and photosynthesis particularly in arid and semiarid areas. However responses of the potential photosynthetic capacity to soil water status in a wide range of soil moisture levels and determination of their thresholds are poorly understood. This study examined the response patterns of plant photosynthetic capacity and their thresholds to a soil moisture gradient in a perennial rhizome grass Leymus chinensis and a perennial bunchgrass Stipa grandis both dominant in the Eurasian Steppe. Results Severe water deficit produced negative effects on light-saturated net CO2 assimilation rate Asat stomatal conductance gs mesophyll conductance gm maximum carboxylation velocity Vc max and maximal efficiency of PSII photochemistry Fv Fm . Photosynthetic activity was enhanced under moderate soil moisture with reductions under both severe water deficit and excessive water conditions which may represent the response patterns of plant growth and photosynthetic capacity to the soil water gradient. Our results also showed that S. grandis had lower productivity and photosynthetic potentials under moderate water status although it demonstrated generally similar relationship patterns between photosynthetic potentials and water status relative to L. chinensis. Conclusions The experiments tested and confirmed the hypothesis that responsive threshold points appear when plants are exposed to a broad water status range with different responses between the two key species. It is suggested that vegetation structure and function may be shifted when a .

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