To determine the effects of high temperature, droug ht, combined high temperature and drought, and re-watering on protective enzymes and lipid peroxidation of Phyllostachys edulis seedlings, an experiment was set up with treatments: 1) optimal temperature (day 28 ℃/night 22 ℃) and normal hydration (75% of field water-holding capacity) as a control group, 2) optimal temperature and drought (35% of field water-holding capacity), 3) high temperature (day 40 ℃ /night 22 ℃) and normal hydration, and 4) combined stress fol-lowed by re-watering to determine the effects on antioxidase, hydrogen peroide (H2O2), and malondialdehyde (MDA). Samples were respectively collected on Day 7 after the start of treatment, and at 9:00 am on Day 0, 1, 3 after re-watering, sample weight of each group is 1.0 g. Results showed that 1 ) With high temperature SOD activity increased the most (P<0.01), and with drought POD activity was greatest (P<0.05);after drought the H2O2 level was significantly higher (P<0.01) than other conditions. After combined stress, POD and APX ac-tivities increased the most (P<0.01), and the level of MDA was higher than other treatments (P<0.05). 2) On Day 1 after re-watering, H2O2 increased (P<0.05) leading to an increase of POD and CAT activity (P <0.05) with APX activity decreasing then increasing (P<0.05). On Day 3 after re-watering, levels of MDA and H2O2 returned to levels of the control group, but with the combined-stress treatment, SOD, POD, and CAT ac-tivities continuously decreased(P<0.05) and APX activity and H2O2 levels decreased and then increased (P<0.05) with MDA levels continuing to rise (P<0.05). On Day 3 after re-watering MDA and H2O2 were at high levels and significantly higher than those of drought conditions (P<0.05). Thus, the protective mechanism for Ph. edulis seedlings with high temperature was CAT, with drought was POD, and with combined-stress condi-tions were APX and POD, with SOD playing an important role in anti lipid peroxidation for all three stresses.%为探讨高温、 干旱、 高温+干旱复合胁迫及复水对毛竹Phyllostachys edulis实生苗保护酶、 脂质过氧化的影响,以毛竹实生苗为材料,研究了适温(昼/夜温度为28℃/22℃)正常供水(田间持水量的75%,对照),适温下干旱胁迫(田间持水量的35%),高温(昼/夜温度为40℃/22℃)正常供水,高温下干旱胁迫以及干旱胁迫后复水等4个处理对毛竹实生苗叶片中抗氧化酶、 过氧化氢(H2O2)和丙二醛(MDA)的影响.结果表明:①在3种胁迫处理下,超氧化物岐化酶(SOD),过氧化物酶(POD),过氧化氢酶(CAT)活性均显著上升(P<0.05),抗坏血酸过氧化物酶(APX)活性在干旱胁迫、 高温干旱复合胁迫下显著上升.其中高温处理毛竹叶片SOD和CAT活性上升幅度最大;干旱处理POD活性上升幅度最大,其次为CAT,同时过氧化氢显著高于其他各处理,达278.7 nmol·g-1;高温干旱复合胁迫下POD和APX活性上升幅度最大,MDA显著高于其他各处理.②复水后,干旱处理下过氧化氢在复水后第1天上升,引起POD和CAT活性上升,APX活性先降后升,复水后第3天毛竹叶片MDA,过氧化氢均恢复至对照水平;高温干旱复合胁迫下SOD,POD和CAT活性持续下降,APX先下降又有回升,同时MDA持续上升,过氧化氢先下降后又升高,在复水后第3天均处于较高水平,且与干旱胁迫相比差异显著(P<0.05).毛竹实生苗在不同胁迫下有不同的保护机制,CAT和POD分别是毛竹适应高温和干旱的主要抗氧化酶,APX和POD对复合胁迫较为敏感,SOD则在3种胁迫下均对抗膜脂过氧化起到重要作用;在一定的干旱胁迫后复水,保护酶协同作用,表现出较强的恢复能力,而高温加剧了干旱对竹苗的伤害,在高温干旱复合胁迫后复水竹苗并未得到恢复.
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