半干旱雨养区小麦叶片光合生理生态特征及其对环境的响应

分析了黄土高原半干旱雨养农业区田间春小麦叶片光合生理生态特征及其对环境因子的响应。结果表明,天气晴朗时,净光合速率日变化呈典型的双峰曲线,有“午休”现象,上午明显高于下午,且不同生育期峰值出现的迟早不同。蒸腾速率日变化呈不明显的双峰型,其出现最大值的时间晚于净光合速率出现最大值的时间。在生长季节,叶片净光合速率、蒸腾速率和气孔导度均受到多个环境因子的共同影响。不同时期,起主导作用的环境因子不同,且同一个因子对几个生理指标的影响程度和强度都有差异,其中,光合有效辐射是对蒸腾速率影响最强烈的环境因子,湿度对光合作用的影响大于温度。受环境因子制约最为显著的生理指标是叶片的蒸腾速率和气孔导度。

Eco-physiological characteristics of wheat leaf photosynthesis and their responses to environmental factors in semiarid rain-fed region

This paper analyzed the eco-physiological characteristics of spring wheat leaf photosynthesis in the semiarid rain-fed agriculture region of Loess Plateau,and their responses to the environmental factors. The results showed that the net photosynthetic rate (P_n) of spring wheat leaf had a diurnal change of typical two-hump curve,which was obviously higher before noon than after noon,and with a noon break. The appearing time of maximum P_n differed with growth stages. The transpiration rate (T_r) had a diurnal change of weak two-hump curve,and the appearing time of its maximum was later than that of maximum P_n. The P_n,T_r,and stomatal conductance (G_s) were affected by a combination of various environmental factors,with the dominant factor being different at different period,and even,the same factor having different effects on P_n,T_r and G_s. Among the affecting factors,photosynthetically active radiation (PAR) had the most intensive effect on T_r,and a close relation with P_n and T_r in the whole growth period. The effect of relative humidity (RH) on P_n was larger than that of temperature. Among P_n,T_r and G_s,the last two were the eco-physiological indexes most obviously affected by environmental factors.