水分胁迫对白三叶光合特性的影响

以品种“海发”为试材,研究了水分胁迫对白三叶（Trifolium repens）叶片光合作用和叶绿素荧光参数的影响。结果表明,土壤相对含水量为75%和50%时,白三叶的光合参数日变化呈双峰趋势,叶绿素荧光参数受到的影响不大,说明白三叶在这两种水分条件下能够正常生长;土壤相对含水量为25%时,PSⅡ反应中心遭到破坏,原初光能转化效率（Fv/Fm）、PSⅡ电子传递量子产量（ΦPSⅡ）和光化学猝灭系数降低;净光合速率、蒸腾速率下降明显,日变化曲线表现为单峰特征,气孔导度显著降低,而胞间CO2浓度升高,非气孔限制成为Pn下降的主要原因;说明白三叶在重度干旱（HD）条件下,生理机能遭到破坏,不能正常生长。

Effect of Water Stress on Photosynthesis of Trifolium Repens

Daily dynamics of photosynthesis and chlorophyll fluorescence parameters in Trifolium repens cv. Haifa leaves under water stress were studied. The results were that the curves of diurnal variation of Pn, Tr and Gs of Trifolium repens leaves showed two peaks when the relative soil moisture content was 75% or 50%, but they showed one peak when the relative soil moisture content was 25% in the meantime, the chlorophyll fluorescence parameters such as conversion efficiency of primary light energy （Fv/Fm） of PS Ⅱ, the photochemical quenching coefficient（ q p）and the quantum yield of PS II electron transport（ФPS Ⅱ ）decreased respectively. Nonstomatal limitation was the main reason responsible for Pn declination.