Effects of Different Protective Agents on Reactive Oxygen System and Endogenous Hormones in Sunburned Flue-Cured Tobacco Leaves
In order to explore the preventive effects of different protective agents on sunburn injury of flue-cured tobacco leaves,this experiment was conducted using sunburn simulation method through treating with strong light(2 000 μmol·m-2·s-1)after spraying clean water,0.1％potassium fulvate(T1),56 mg·L-1 sodium hydrosulfide(T2),75 mg·L-1water droplet breaker(T3)and 0.2％commercial sunscreen(T4)on tobacco leaves,respectively.The field test was carried out to research their effects on leaf temperature,reac-tive oxygen content,antioxidase activity,related hormone content and economic characters of cured tobacco.The results showed that compared with spraying clean water before treating with strong light(CK2),spraying potassium fulvate significantly reduced leaf temperature by 2.36 ℃.Spraying protective agents on leaves signif-icantly increased the activities of SOD,CAT and POD as a whole,among which,SOD activity increased by 17.68％～48.54％in T1～T4 treatments,CAT activity increased by 48.29％～81.39％in T2～T4 treatments and POD activity increased by 4.50％～22.18％in T1～T4 treatments.Spraying protective agents on leaves sig-nificantly reduced ABA and JA contents,and the decrease rates were 34.29％～71.43％and 9.15％～60.31％,respectively.Compared with spraying clean water,spraying protective agents on leaves could reduce the burn rate and burn index of tobacco plants by 33.40％～60.00％and 11.38％～66.47％,and increase the yield,output value,average price,proportion of superior tobacco and proportion of upper and middle tobacco after cured by 2.33％～6.91％,0.42％～1.36％,3.08％～8.38％,0.47％～5.06％and 1.85％～4.39％,respective-ly.To sum up,the protective agents used in this experiment could improve the resistance of tobacco leaves to strong light by regulating the activities of antioxidant enzymes and the contents of ABA and JA,and spraying 75 mg·L-1 water droplet breaker had the best protective effect.This study could provide theoretical basis for the control of tobacco sunburn injury,and provide technical support for the application of sunburn protection agent in production.
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