关键词: 紫花苜蓿, 水分胁迫, 叶水势, 蒸腾速率, 气孔导度

Abstract: In order to reveal the stomatal response of Alfalfa under water stress,leaf water potential,transpiration rate(T_r),stomatal conductance(G_s) of alfalfa(Medicago sativa) and their relationship under water stress are studied by adopting pot-cultivation designs.Results show that the leaf water potential,T_r and G_s of alfalfa decreased with water stress increasing.The daily change of the leaf potential,Trand G_s display a bimodal curve pattern with the same mean value.The maximum is obtained under full water supply,followed by light water stress,moderate water stress and severe water stress.The lowest leaf water potential decreases with the decreasing of soil moisture,the peak appearing time of leaf potential and Trunder moderate and severe water stress is earlier than that of full water supply and light water stress.Under moderate and severe water stress,when the water potential was-4.68 MPa,or T_r was 3.27 g·m^-2·h^-1,the stomata begin to close.Under full water supply and light water stress,Tr increases with the decreasing water potential,and Gs increases with the increasing of T_r.The leaf water potential changes not only related with the soil moisture,but also closely related with the leaf development.

Key words: Medicago sativa, Water stress, Leaf water potential, Transpiration rate, Stomatal conductance