外源H_2O_2对低温胁迫下大红柑生长及叶片生理指标的影响

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

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(H_2O_2)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H_2O_2处理浓度,并探讨外源H_2O_2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-1H_2O__2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-1H_2O_2比0.1 mmol·L-1H_2O_2缓解低温胁迫对大红柑的伤害效果更为显著。1.0 mmol·L-1H_2O_2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H_2O_2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H_2O_2不仅未起到缓解作用,反而产生了一定的毒害作用。

Fall shoot of citrus （Citrus reticulata Blanco cv.Dahonggan） planted in Hanzhong City, Shaanxi Prov-ince , were cultured in Hoagland hydroponic solution and were used as experimental materials .The effects of different concentrations of H 2 O2 treatments on growth and physiological indexes of Dahonggan leaves under low temperature stress （4℃） were studied, in order to select the optimum concentration of H 2 O2 and to investigate the role of exoge-nous H2 O2 in alleviating chilling injury of citrus to cold .It was shown that the degree of curl and cell membrane dam-age of Dahonggan leaf gradually increased with the extension of low temperature stress time .Both 0.1 and 1.0 mmol· L^-1 H2 O2 could ease leaves curling and wilting in Dahonggan caused by low temperature stress ;however , the effect of 1.0 mmol· L^-1 H2 O2 was more significant than the concentration of 0.1 mmol· L^-1 on alleviating damage of Da-honggan leaves caused by chilling stress .1.0 mmol· L^-1 H2 O2 could obviously reduce the damage of cell membrane by lowering the increase of REC and MDA , reducing the accumulation of O2^- 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 .