外源H2O2对低温胁迫下大红柑生长及叶片生理指标的影响

以陕西汉中地区栽培的柑橘品种大红柑秋梢为试材，采用Hoagland营养液培养方法，研究了外源过氧化氢（H2O2）对低温（4 ℃）胁迫下大红柑叶片生长状况及生理指标的影响，筛选缓解柑橘低温伤害的最佳H2O2处理浓度，并探讨外源H2O2处理对柑橘耐寒能力的影响机制。结果显示，随低温胁迫时间的延长，大红柑叶片卷曲和叶片细胞膜伤害程度逐渐加重。0.1和1.0 mmol·L-1 H2O2处理均能缓解低温胁迫引起的大红柑叶片卷曲和萎蔫，但1.0 mmol·L-1 H2O2比0.1 mmol·L-1 H2O2缓解低温胁迫对大红柑的伤害效果更为显著。1.0 mmol·L-1 H2O2显著降低叶片中相对电导率（REC）和丙二醛（MDA）含量的升高，减轻叶片细胞中超氧阴离子（O.-2）和内源H2O2含量的积累，提高超氧化物歧化酶（SOD）和过氧化氢酶（CAT）的活性，从而降低低温对柑橘叶片细胞膜的伤害。较高浓度的外源H2O2不仅未起到缓解作用，反而产生了一定的毒害作用。

Effects of exogenous hydrogen peroxide on growth and physiological index of Citrus reticulata Blanco cv. Dahonggan leaves under low temperature stress

 Fall shoot of citrus （Citrus reticulata Blanco cv. Dahonggan） planted in Hanzhong City， Shaanxi Province， were cultured in Hoagland hydroponic solution and were used as experimental materials. The effects of different concentrations of H2O2 treatments on growth and physiological indexes of Dahonggan leaves under low temperature stress （4 ℃） were studied， in order to select the optimum concentration of H2O2 and to investigate the role of exogenous H2O2 in alleviating chilling injury of citrus to cold. It was shown that the degree of curl and cell membrane damage of Dahonggan leaf gradually increased with the extension of low temperature stress time. Both 0.1 and 1.0 mmol·L-1 H2O2 could ease leaves curling and wilting in Dahonggan caused by low temperature stress; however， the effect of 1.0 mmol·L-1 H2O2 was more significant than the concentration of 0.1 mmol·L-1 on alleviating damage of Dahonggan leaves caused by chilling stress. 1.0 mmol·L-1 H2O2 could obviously reduce the damage of cell membrane by lowering the increase of REC and MDA， reducing the accumulation of O.-2 and H2O2 and improving the activities of SOD and CAT in Dahonggan leaves under low temperature. Relatively high concentrations of exogenous H2O2 could not show alleviating effects; on the contrary， it produced some toxic effects.