纯化腐植酸对NO_3^-胁迫下黄瓜种子萌发及生理生化特性的影响

Effects of Purified Humic Acid on Cucumber Germination and Physiological and Biochemical Characteristics Under NO_3^- Stress

以‘新泰密刺’和‘津优1号’黄瓜种子为试材,采用培养皿发芽方式,研究了添加纯化腐植酸PHA(添加浓度0、25、50、100、150mg·L^(-1))对NO_3^-胁迫下(75mmol·L^(-1))黄瓜种子萌发及幼芽抗氧化物酶活性的影响。结果表明:NO_3^-胁迫使黄瓜种子发芽率、主根长、侧根长、侧根数、下胚轴长度和粗度以及幼芽鲜质量明显减少;添加PHA处理使2个黄瓜品种的上述项目值都明显增加,表明部分缓解了NO_3^-胁迫。黄瓜种子发芽过程中,由于NO_3^-胁迫,幼芽的电解质渗漏率显著增加、子叶中α-淀粉酶活力下降、胚根脱氢酶活力增加;胚根和胚轴中丙二醛(MDA)及可溶性蛋白质含量、超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)活性均增加。添加PHA后,幼芽的电解质渗漏率显著减小,随PHA浓度的增加,减小的差值变小;子叶中α-淀粉酶活性和胚根脱氢酶活性增加,添加PHA浓度高时呈下降趋势;胚根和胚轴中MDA含量减少,添加PHA浓度高时又有增加趋势;可溶性蛋白质含量增加,添加PHA浓度高时显示下降趋势;SOD、POD、CAT活性均呈下降趋势。黄瓜种子发芽受到NO_3^-胁迫时,都因PHA的添加而表现出不同程度对NO_3^-胁迫的正向缓解,使幼芽趋于正常。黄瓜种子发芽在NO_3^-胁迫添加PHA后的生理生化指标的变化也表现出品种和器官不同的感受性差异。该试验表明,以PHA添加100mg·L^(-1)处理对胁迫NO_3^-下黄瓜种子效果较佳。

In order to explore the effects of PHA on cucumber seed germination and physiological and biochemical characteristics under NO3-（75mmol·L-1）stress,‘Xintai Mici＇and‘Jinyou No.1＇cucumber seeds were used as experimental cultivars,treated with different PHA concentration（0,25,50,100,150mg·L-1）.The results showed that seed germination,radicle length,lateral root length,lateral root number,hypocotyl length and diameter,and seedling fresh weight were decreased under NO3-stress.The above indices of adding PHA treatments were increased obviously and showed that PHA could partly alleviate NO3-stress.The seedling electrolyte leakage rate and seed cotyledonα-amylase activity were decreased but radicle dehydrogenase activity was increased under nitrate stress.MDA and soluble protein content,SOD,POD,CAT activity were increased.After adding PHA,the seedling electrolyte leakage rate was significantly reduced,but with the increasing concentration of PHA the decreases difference became smaller.Cotyledonα-amylase activity and radicle dehydrogenase activity were increased and showed downward trend when added high PHA concentration.Radicle and hypocotyl MDA content decreased when treated with PHA but increased with high PHA concentration.Soluble protein content were increased but decreased with high PHA concentration.SOD,POD,CAT activity showed a downward trend treated with PHA compared with NO3-stress.Cucumber seed under NO3-stress was alleviated by adding PHA so that cucumber seedling growth became normal.The physiological and biochemical indices during cucumber seeds germination under NO3-stress and PHA treatments showed difference in different varieties and different organs.100mg·L-1 PHA treatment showed the best effects.