盐胁迫对葡萄种间杂交砧木F_1株系光合特性的影响

Effect of salt stress on photosynthetic characteristics in grape rootstock of interspecific F_1 hybrids

以目前生产上耐盐性较强的葡萄(Vitis sp.)砧木‘1103P’为参照品种,对‘左山一’בSO_4’杂交砧木F1代的6个株系(A15、A17、A34、A35、A38和A48)和‘左山一’ב101-1’杂交F_1代2个株系(B24和B26)的一年生盆栽扦插苗进行100 mmol·L^(-1)NaCl胁迫处理,胁迫20 d后根据表观症状进行盐害分级,并挑选F_1代杂交株系中耐盐性较强的A34、耐盐性中等的A38和耐盐性较弱的B26测定NaCl处理下葡萄叶片叶绿素含量、光合气体交换参数、叶绿素荧光参数等指标,探讨葡萄种间杂交砧木F1代株系的盐响应机制。结果表明,100 mmol·L^(-1) NaCl胁迫下,各株系的净光合速率和气孔导度均降低,而胞间CO_2浓度表现出升高趋势,说明光合作用的下降是由非气孔限制引起的。与‘1103P’相比,盐胁迫20 d后耐盐性较强的A34叶绿素含量、光系统II(PSII)最大光化学效率、光合性能指数以及实际光化学效率等降幅较小,PSI和PSII之间激发能分配平衡偏离系数变化较小,说明葡萄种间杂交F1代中耐盐性较强的株系在盐胁迫下能够维持较高的叶绿素含量,降低PSII激发压,从而维持光系统之间激发能的平衡,缓解叶片PSII光抑制程度。

One-year potted cuttings of 6 grape（Vitis sp.） hybrids（A15, A17, A34, A35, A38 and A48） of ‘Zuoshan 1＇ × ‘SO_4＇ and 2 grape hybrids（B24 and B26） of ‘Zuoshan 1＇× ‘101-1＇ were irrigated with 100 mmol·L^（-1） NaCl. NaCl tolerance of these plants were classified according to their phenotype after 20 days of NaCl treatment. A34, A38 and B26 with high, moderate and low salt tolerances, respectively, were selected to study salt tolerance mechanism. The chlorophyll content, photosynthetic gas exchange and chlorophyll fluorescence parameters were determined under salt treatment. The results show that net photosynthetic rates and stomatal conductances in different strains decreased under 100 mmol·L^（-1） NaCl, while intercellular CO_2 concentrations increased, indicating that the decrease of net photosynthetic rate resulted from non-stomatal limitation. Compared to ‘1103 P＇, chlorophyll content, net photosynthetic rate, photosynthetic performance indexes and actual photochemical efficiency in A34 strain slightly decreased, and the coefficient deviation on excitation energy between two photosystems changed to a small extent. It is suggested that PSII photoinhibition occurs in different strains under salt stress. Strains with high salt tolerance could remain high pigment contents, decrease PSII excitation pressure, keep balance excitation energy, and thereby alleviate PSII photoinhibition under salt stress in grape leaves.