不同水分胁迫对紫花苜蓿分枝期光合性能的影响

研究水分胁迫下不同紫花苜蓿品种分枝期光合性能变化和影响因素。结果表明，敖汉苜蓿在不同水分胁迫下分枝期均保持较高的净光合速率，皇后、WL323和Vector苜蓿水分胁迫下的净光合速率较低；WL323的净光合速率随水分胁迫强度的增加而降低，Vector、皇后和敖汉苜蓿分枝期的净光合速率随水分胁迫强度的增加表现先增加后降低的趋势。通过分析水分胁迫紫花苜蓿分枝期叶片气孔导度、蒸腾速率和胞间CO2浓度的变化，认为试验中轻度和中度水分胁迫下光合速率下降的主要因素是气孔因素，重度水分胁迫下光合速率下降的主要因素是非气孔因素。

Change of Photosynthetic Capacity of Alfalfa under Different Water-stress Intensity During Branching

Change and contributing factors of alfalfa p.hotosynthetic capacity were studied under water--stress in the experiment during branching. The results showed that Aohan alfalfa had higher net photosynthetic rate under all water--stress treatment than other alfalfa varieties during branching. Net photosynthetic rate of WL323 alfalfa was decreased with water--stress intensity; however that of Aohan, Vector and Queen alfalfa firstly was increased , then decreased with water--stress intensity. According to transpiration rate, extracells CO2 concentration, stomatic conductance of four alfalfa varieties under water--stress, it was concluded that reduction of photosynthetic rate was primarily resulted from stomatal factors under light and medium water--stress and nonstomatal factors under severe water--stress in the experiment during branching.