外源茉莉酸甲酯对花铃期棉花耐高温能力的影响

Effects of exogenous methyl jasmonate on cotton tolerance to heat stress during flowering and boll-setting stage

【目的】探讨外源茉莉酸甲酯(methyl jasmonate,MeJA)对花铃期棉花耐高温能力的影响。【方法】以自育品系ZS08为试验材料,在人工高温胁迫(昼温38.0℃/夜温30.0℃,持续3 d)和自然高温胁迫(昼平均气温35.2~37.5℃,夜平均气温26.4~27.2℃,持续10 d)下,比较200μmol·L^(-1)、400μmol·L^(-1)和600μmol·L^(-1)MeJA和清水(对照)喷施处理后的花铃期棉花的花粉活力、光合效率相关指标、抗氧化酶活性、丙二醛(malondialdehyde,MDA)含量、产量和纤维品质。【结果】在人工高温胁迫下棉株花粉活力降低。与对照相比,3种浓度的MeJA处理的花粉活力受高温胁迫影响的程度均减弱;高温胁迫2~3 d,400μmol·L^(-1)、600μmol·L^(-1)MeJA处理的主茎倒四叶的净光合速率(net photosynthetic rate,Pn)、蒸腾速率(transpiration rate,Tr)和气孔导度(stomatal conductivity,Gs)较对照均有不同程度提高,增幅分别为1.6%~3.7%、7.2%~15.7%和44.4%~53.4%。高温胁迫下2~3 d,400μmol·L^(-1)、600μmol·L^(-1)MeJA处理的主茎倒二叶超氧化物歧化酶(superoxide dismutase,SOD)活性和过氧化物酶(peroxidase,POD)活性比对照分别提高3.1%~7.2%和5.7%~20.0%,同时MDA含量较对照降低10.9%~17.9%。在自然高温胁迫下,不同浓度的MeJA处理下棉花成铃率、铃重较对照有不同程度的提高,皮棉产量较对照显著提高9.0%~18.3%。【结论】在花铃期遭遇高温胁迫,施用MeJA可以增加高温胁迫下叶片的Pn、SOD活性和POD活性,降低叶片受伤害程度,提高花粉活力,从而增强棉花的耐高温性能,减轻高温胁迫对成铃率和铃重造成的影响,减少产量损失。

[Objective]This study aims to explore the effects of exogenous methyl jasmonate(MeJA)on cotton tolerance to the heat stress.[Method]The self-bred line ZS08 was used as the test material.Distilled water(CK)and MeJA with different concentrations(200μmol·L^(-1),400μmol·L^(-1)and 600μmol·L^(-1))were used on plants at the flowering and boll-setting stage.And after the artificial heat stress of 38.0℃/30.0℃(day/night)for three days or under natural heat stress of 35.2-37.5℃/26.4-27.2℃(day/night)for ten days,the pollen viability,photosynthetic characteristics,antioxidant enzyme activity,malondialdehyde(MDA)content,yield and fiber quality of each treatment were measured.[Result]The pollen viability was reduced under the artificial heat stress.The MeJA treatment of three concentrations all had alleviated the inhibition of heat stress on pollen viability compared with the water control.The net photosynthetic rate(Pn),transpiration rate(Tr)and stomatal conductance(Gs)of the fourth leaf from top of the main stem in the 400μmol·L^(-1)and 600μmol·L^(-1)MeJA treated plants were increased in various degree than those of the control under 2-3 days heat stress by 1.6%-3.7%,7.2%-15.7%,and 44.4%-53.4%,respectively.The activity of superoxide dismutase(SOD)and peroxidase(POD)of the second leaf from top on the main stem in 400μmol·L^(-1)and 600μmol·L^(-1)MeJA treatment were increased by 3.1%-7.2%and 5.7%-20.0%than those of the control under 2-3 days heat stress.While the content of MDA was reduced by 10.9%-17.9%.Under the natural heat stress,plants which were treated by different concentrations of MeJA had improved boll-setting rate and boll weight in varying degree,and had significantly improved lint yield by 9.0%-18.3%compared with the control.[Conclusion]When encountering heat stress during the flowering and boll-setting stage,the application of MeJA can increase Pn and the activities of SOD and POD,reduce the degree of leaf damage,and improve pollen viability,thereby enhance the heat tolerance of cotton,and reduce the impact of heat stress on boll-setting rate,boll weight,and yield loss.