紫花苜蓿分枝期光合蒸腾特性及其与相关因子的关系

目的]研究不同紫花苜蓿品种的分枝期光舍蒸腾日变化及其与相关生理生态因子的关系，为其开发利用和新品种选育提供依据。方法]在自然条件下，测定4个紫花苜蓿品种（阿尔冈金、WL323高品质、WL414、大富豪）分枝期的Pn、Tr及相关的生理因子（Tl、Gs、Ci）和生态因子（PAR、Ca、Ta）的日变化，计算瞬时水分利用率（WUE）和光能利用率（LUE），并进行相关性分析。结果]4个苜蓿品种的PAR、Ta、Pn、Tr的日变化均呈先上升后下降的单峰曲线；水分利用率的大小依次为WL323高品质〉阿尔冈金〉WL414〉大富豪；4个紫花苜蓿品种的LUE差异不显著。相关分析结果表明，Pn主要受PAR、Gs、Ci的影响；Tr主要受PAR和Ta的影响。结论]WL323高品质为高光合、高水分利用率和低蒸腾的苜蓿品种，适应干旱的能力强；PAR、Ta、Gs、Tl是4个紫花苜蓿品种Tr的主要决定因子，Ca和Ci是其主要的限制因子；Gs是4个紫花苜蓿品种Pn的主要决定因子，Ci是其主要限制因子。

Photosynthesis and Transpiration Characters of Alfalfa (Medicago sativa) and Their Relationship with Relevant Factors during Branching Stage

Objective] The paper presents the diurnal changes of photosynthesis and transpiration of different alfalfa varieties and their relationship with the associated physiological and ecological factors during branching stage,so as to provide a basis for the development,utilization,and breeding of alfalfa.Method] Under natural conditions,the diurnal changes of net photosynthetic rate(Pn),transpiration rate(Tr),the relevant physiological factors including leaf temperature(Tl),stomatal conductance(Gs) and internal CO2 concentration(Ci),as well as the relevant physiological factors including photosynthetic available radiation(PAR),CO2 concentration in field(Ca) and air temperature(Ta) were measured in four alfalfa varieties(Algonguin,WL323 HQ,WL414,and Millionaire).The water use efficiency(WUE) and light use efficiency(LUE)were calculated,and the correlation among them was also analyzed.Result] The Pn,Tr,PAR and Ta of the four varieties appeared to vary in a single-peak curve;the sequence of WUE was WL323 HQ>Algonguin>WL414>Millionaire;there was no significant difference in LUE among the four alfalfa varieties;coefficient analysis showed that Pn was mainly affected by PAR,Gs,and Ci,while Tr by PAR and Ta.Conclusion] WL-323 HQ is the variety with high Pn,high WUE and low Tr,and has strong adaptability to drought.In four alfalfa varieties,PAR,Ta,Gs,and Tl are the primary determining factors while Ca and Ci the limiting factors of Tr;Gs is the primary determining factor while Ci the limiting factor of Pn.