干旱胁迫对黑果枸杞幼苗光合特性的影响

Effect of Drought Stress on Photosynthesis Characteristics of Lycium ruthenicum Seedlings

以当年生黑果枸杞幼苗为试验材料,通过称重控水的方法设置对照（土壤含水量为32.96%～35.35%）、轻度干旱胁迫（土壤含水量为21.18%～22.32%）、中度干旱胁迫（土壤含水量为12.20%～13.82%）和重度干旱胁迫（土壤含水量为7.89%～8.73%）4个水分梯度,研究了干旱胁迫对黑果枸杞叶片光合色素、光合特性、叶绿素荧光特性的影响,以揭示黑果枸杞对干旱胁迫的适应能力和适应机制。结果显示：（1）随着干旱胁迫强度的增加,黑果枸杞幼苗叶片叶绿素含量、类胡萝卜素含量均呈显著下降趋势。（2）黑果枸杞幼苗叶片净光合速率（P_n）、蒸腾速率（T_r）、气孔导度（G_s）在中度和重度干旱胁迫下显著下降;其胞间CO_2浓度（C_i）、水分利用效率（WUE）随干旱胁迫强度的增加而逐渐增加,而气孔限制值（L_s）随干旱胁迫强度的增加而逐渐降低。（3）随着土壤含水量的降低,黑果枸杞幼苗叶片初始荧光（F_0）和非光化学猝灭系数（q_N）逐渐增加,而其最大荧光（F_m）、PSⅡ最大光化学效率（F_v/F_m）、实际光化学效率（Ф_（PSⅡ））和光化学猝灭系数（q_P）均逐渐降低。研究表明,在干旱胁迫条件下,黑果枸杞叶片过多的能量以热的形式被耗散,反应中心开放程度降低,从而避免PSⅡ反应中心受到损伤,表现出一定的耐旱性;黑果枸杞生长所允许的最大土壤水分亏缺为7.89%,维持黑果枸杞具有较高的WUE和P_n的土壤水分阈值为12.20%～13.82%。

To detect the effect of drought on one-year-old Lycium ruthenicum seedlings,we investigated the photosynthetic pigments,photosynthetic characteristics and chlorophyll fluorescence characteristics on four different soil contents：CK（21.18%-22.32% soil moiture）,light stress（12.20%-13.82%）,moderate stress（12.20%-13.82%）and severe stress（7.89%-8.73%）.The results showed that：（1）the chlorophyll content and carotenoid content decreased with the decreasing soil water content.（2）Under the moderate stress,the net photosynthetic rate（P_n）,the transpiration rate（T_r）,stomatal conductance（G_s）decreased significantly.With the decreasing of soil water content,intercellular CO_2concentration（C_i）,the water use efficiency（WUE）increased,whereas stomatal limitation（L_s）performed the inverse trend.（3）With the increasing of the minimal fluorescence（F_0）and nonphotochemical quenching（q_N）value,the maximal fluorescence（F_m）,maximal photochemical efficiency（F_v/F_m）,actual photochemical efficiency（Ф_（PSⅡ））,and photochemical quenching（q_P）decreased.It indicated that the excess energy of the leaves of L.ruthenicumis dissipated by heat,and the open degree of the reaction center is reduced to avoid the damage of the PSⅡreaction center.It suggested that L.ruthenicum keep on vigor above the limitation of 7.89%soil moisture,and the largest WUEand the higher P_narrive on 12.20%-13.82% soil moisture.