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以‘津研四号’黄瓜为试材,分别用0、2.5、5、7.5、10、12.5、15、17.5、20 mmol·L~(-1)浓度的对羟基苯甲酸(PHBA)溶液对黄瓜种子处理72 h,选出胁迫作用较明显的10 mmol·L~(-1)浓度;再分别用0、1、10、25、50、75、100μmol·L~(-1)的褪黑素(MT)溶液对10 mmol·L~(-1)PHBA下的黄瓜种子预处理24 h,72 h后观察MT的缓解效果.结果表明:缓解PHBA胁迫效果最明显的MT浓度为75μmol·L~(-1).随着PHBA浓度的升高,黄瓜种子胚根伸长的抑制作用明显增加;用10、25、50、75、100μmol·L~(-1)的MT预处理PHBA胁迫下的黄瓜种子均能不同程度缓解PHBA胁迫对胚根的抑制作用,其中以75μmol·L~(-1)的MT缓解效果最好.用MT预处理黄瓜种子可显著提高PHBA胁迫下黄瓜种子中淀粉酶活性及胚根中超氧化物歧化酶、过氧化物酶、过氧化氢酶和抗坏血酸过氧化物酶活性,并降低胚根中O_2~-·的产生速率及H_2O_2和丙二醛含量.外源MT能够通过降低氧化胁迫和促进淀粉的分解转化来降低PHBA对黄瓜发芽的影响.
Taking ’Jinyan No.4’ cucumber as test material, the cells were treated with 0, 2.5, 5, 7.5, 10, 12.5, 15, 17.5 and 20 mmol·L -1 of p-hydroxybenzoic acid Cucumber seeds were treated for 72 h, and the stress concentration of 10 mmol·L -1 was selected. The cucumber seeds were treated with 0, 1, 10, 25, 50, 75, 100 μmol·L -1 melatonin (MT) was used to pretreat cucumber seeds under 10 mmol·L -1 PHBA for 24 h and 72 h, respectively. The results showed that the most effective concentration of MT to alleviate the PHBA stress was 75 μmol·L ~ (-1) .With the increase of PHBA concentration, the inhibition of cucumber seedling root elongation was significantly increased. Under the condition of PHBA stress pretreated with 10,25,50,75,100μmol·L -1 MT Cucumber seeds could alleviate the inhibitory effect of PHBA stress on the radicle at different degrees, of which 75 μmol·L -1 MT showed the best mitigation effect.The pretreatment of cucumber seeds with MT significantly increased the starch content in cucumber seeds under PHBA stress The activity of SOD and the activity of superoxide dismutase, peroxidase, catalase and ascorbate peroxidase in the radicle and the decrease of the production rate of O 2 - - and the content of H 2 O 2 and malondialdehyde in the radicle. MT can pass Reduce the oxidative stress and promote starch decomposition and transformation to reduce the PHBA cucumber germination.