盐和干旱胁迫对欧李幼苗光合生理特性的影响

为缓解干旱、半干旱地区水土流失现状，充分发挥欧李（Cerasus humilis）的生态价值，有效进行生态环境修复，设置了两种环境胁迫——盐胁迫（盐胁迫浓度分别为3‰、5‰、8‰，依次记做S1、S2、S3）和干旱胁迫（浇水量分别为田间持水量的30%~35%、40%~45%、50%~55%，依次记做W1、W2、W3），比较叶片的光合气体参数T_r（蒸腾速率）、P_n（净光合速率）、G_s（气孔导度）和C_i（胞间CO₂浓度）的变化；利用P_n-PAR响应曲线比较不同处理下叶片的光响应特征参数L_sp（光饱和点）、L_cp（光补偿点）、R_d（暗呼吸速率）、α（表观量子效率）、P_nmax（最大净光合速率）.结果表明:①欧李幼苗的光合气体参数对盐胁迫的响应较敏感，对干旱胁迫的响应则鲜有显著性差异.②由P_n-PAR响应曲线得出，S1、W2处理下，随着PAR（光合有效辐射）的升高，欧李幼苗出现了光抑制现象；S2、S3、W1、W3处理下则表现出积极的光响应.③盐胁迫下，欧李幼苗的L_cp随盐胁迫的增强而逐渐增大，L_sp最小值882.17 μmol/（m2·s）]出现在S1处理，S2、S3处理下有增加趋势，光能利用效率随盐胁迫的增强而减弱；随着干旱程度的减弱，L_cp先增后减，在W2处理下达到最大值35.79 μmol/（m2·s）]，L_sp最大值1 581.56 μmol/（m2·s）]出现在W1处理，而在W2、W3处理下则减小，说明欧李幼苗对光照环境适应性减弱.研究显示，欧李幼苗对盐和干旱胁迫呈现出完全不同的响应特征，且对盐胁迫的响应更为敏感，研究结果可为欧李在治理水土流失、荒山绿化等生态修复工作中的应用提供依据. 

Effects of Salt and Drought Stresses on Photosynthetic Physiological Characteristics of Cerasus humilis Seedlings

In order to alleviate the current situation of soil erosion in arid and semi-arid areas, give full play to the ecological value of Cerasus humilis and effectively restore the ecological environment, two groups of environmental stresses were set up, namely salt stress (S1, S2, S3, which indicated that the salt stress concentration was 3‰, 5‰, 8‰, respectively) and drought stress (W1, W2, W3, which indicated that the watering capacity was 30%-35%, 40%-45%, 50%-55% of the field capacity, respectively). The changes of photosynthetic gas parameters T_r (transpiration rate), P_n (net photosynthetic rate), G_s (stomatal conductance) and C_i (intercellular CO₂ concentration) were compared. The response curves of P_n-PAR were used to compare light response characteristic parameters of the leaves under different treatments, such as L_sp (light saturation point), L_cp (light compensation point), R_d (dark respiration rate), α (apparent quantum efficiency) and P_nmax (maximum net photosynthetic rate). The results showed that:(1) The photosynthetic gas parameters were sensitive to salt stress, but the response to drought stress was not significant. (2) According to the response curves of P_n-PAR, the photoinhibition appeared at S1 and W2 treatments with the increase of PAR(photosynthetic active radiation), while under S2, S3, W1 and W3 treatments, C. humilis seedlings showed positive light responses. (3)Under salt stress, L_cp increased with the increase of salt stress, the minimum value of L_sp (882.17 μmol/(m2·s)) appeared at S1 treatment, and then increased at S2 and S3 treatments. The light use efficiency decreased as salt stress increased. Under drought stress, L_cp increased first and then decreased with the decrease of drought, reaching the maximum under W2 treatment (35.79 μmol/(m2·s)). The maximum value of L_sp (1581.56 μmol/(m2·s)) appeared at W1 treatment, and then decreased at W2 and W3 treatments, indicating that the adaptability of C. Humilis seedlings to light environment was weakened. The research showed that the response characteristics of C. humilis seedlings to salt and drought stresses were completely different, the response to salt stress was more sensitive. It can provide the basis for applying C. humilis to soil erosion control and barren hill greening.