【摘要】 测定了不同土壤湿度下2年生紫藤叶片光合速率(Pn)、蒸腾速率(Tr)及水分利用效率(WUE)等生理参数的光响应过程,探讨了紫藤正常生长发育所需的土壤水分和光照条件.结果表明:紫藤叶片的Pn、Tr及WUE对土壤湿度和光照强度的变化具有明显的阈值响应.维持紫藤正常生长(同时具有较高Pn和WUE)的土壤湿度范围为:体积含水量(Wv)15.3%～26.5%、相对含水量(Wr)46.4%～80.3%,最佳土壤湿度约为Wv23.3%、Wr70.6%.紫藤叶片对光照环境的适应性较强,在光合有效辐射强度(PAR)为600～1600μmol.m-2.s-1时,Pn和WUE具有较高水平,饱和光强在PAR为800～1000μmol.m-2.s-1.紫藤叶片光合作用非气孔限制的发生与土壤湿度与光照强度密切相关,Wv为18.4%～26.5%、Wr为55.8%～80.3%时,光合作用主要受气孔限制,光照强度的影响较小;超出此范围后,其受光照强度的影响较大,出现由气孔限制转变为非气孔限制的PAR临界值.紫藤正常生长允许的最低土壤湿度约为Wv11.9%、Wr36.1%,允许最高PAR约为1000μmol.m-2.s-1,是紫藤叶片光合机构受到破坏的临界点.更多还原

【Abstract】 With two years old Wisteria sinensis as test material,this paper measured the light response of its leaves net photosynthetic rate(P_n),transpiration rate(T_r)and water use efficiency(WUE)under different soil moisture conditions,aimed to ascertain the optimal soil moisture and light conditions of W.sinensis growth.The results showed that the P_n,T_r and WUE had evident threshold responses to the variations of soil moisture and light intensity.To maintain the normal growth and higher levels P_n and WUE of W.sinensis,soil volumetric moisture content(W_v)and relative moisture content(W_r)should be within the range of 15.3%-26.5% and 46.4%-80.3%,and the optimal W_v and W_r were 23.3% and 70.6%,respectively.W.sinensis leaves had stronger adaptability to light conditions.When the photosynthetic active radiation(PAR)was 600-1 600 μmol·m-2·s-1,the P_n and WUE were at higher level,and the light saturation points of P_n and WUE were all at about 800-1 000 μmol·m-2·s-1.The appearance of non-stomatal limit was significantly correlated with soil moisture and light intensity.When W_v ranged from 18.4% to 26.5%,the decline of P_n was mainly caused by stomatal limit rather than PAR.Out of this range,P_n was obviously affected by PAR,and the critical turning point of PAR was observed with the change from stomatal limit to non-stomatal limit.The minimal values of W_v and W_r for the normal growth of W.sinensis were 11.9% and 36.1%,respectively,and the maximal PAR was 1 000 μmol·m-2·s-1,the critical point of detriment in leaf photosynthetic organ.更多还原