不同BR施用方式诱导黄瓜幼苗对Ca(NO_3)_2胁迫抗性的研究

为探讨外源油菜素内酯(brassinosteroid,BR)诱导黄瓜幼苗对Ca(NO3)2胁迫抗性的效果,研究了3种外源BR施用方法(0.01mg·L-1 BR浸种、0.1mg·L-1 BR喷叶及其二者结合施用)对Ca(NO3)2胁迫(60mmol·L-1)下黄瓜幼苗生长、生理活动以及光合作用的影响。结果表明:(1)3种外源BR方法处理后,Ca(NO3)2胁迫下的黄瓜幼苗株高、茎粗、展开叶片数、叶面积、干重含水量均显著提高,同时其叶片游离脯氨酸和可溶性糖含量上升,过氧化物酶活性提高,而其丙二醛(MDA)含量趋于无Ca(NO3)2胁迫对照的水平;(2)外源BR处理还提高了Ca(NO3)2胁迫下黄瓜幼苗的净光合速率、蒸腾速率和气孔导度,却抑制了Ca(NO3)2胁迫下胞间CO2浓度的升高。研究认为,适宜浓度的外源BR浸种和喷叶处理均可有效增强黄瓜幼苗渗透调节能力,降低细胞膜质过氧化伤害程度,提高抗氧化酶活性和光合效率,从而表现出对Ca(NO3)2胁迫的抗性,并以操作简便、用量极低的0.01mg·L-1 BR浸种方法效果最佳。

Inducing Effects of Exogenous BR Application with Different Methods on Ca(NO3)2 Stress Resistance of Cucumber Seedlings

To explore the role of exogenous BR on the induced resistance of cucumber seedlings to Ca(NO₃)₂ stress,we determined the effects of different treatments of exogenous BR (0.01 mg·L^-1 BR soaking seeds,0.1 mg·L^-1 BR spraying leaves and combination of both) on growth,physiological indexes,and photosynthetic characteristics of cucumber seedlings under 60 mmol·L^-1 Ca(NO₃)₂ stress in this paper.The result indicated that:(1)the exogenous BR significantly increased the height,stem diameter,number of expand leaves,leaf area,contents of proline and soluble sugar of cucumber seedlings and decreased the content of MDA,activity of POD increased,promoted the photosynthesis rate,transpiration rate and stomatal conductance of cucumber seedlings and inhibited the increase of intercellular CO₂ concentration.(2)BR soaking seeds and spraying leaves with suitable concentration of exogenous BR could effectively enhance the cucumber seedlings osmotic adjustment capacity,reduce membrane peroxidation damage,improve antioxidant enzyme activity and photosynthetic efficiency,thus showing Ca(NO₃)₂ stress resistance,and the treatment of 0.01 mg·L^-1 BR soaking seeds showed the best results.