Impact of Optimized Potassium-Magnesium Fertilizer on Reactive Oxygen Metabolism and Hormone Levels in Later Growth Stage of Tobacco
In order to investigate the optimal potassium-magnesium ratio for improving tobacco leaf quality,a field randomized block experiment was conducted.The study set a control group with conventional farmer fertilization(T1,N∶P2O5∶K2O=1∶0.68∶3,with K2O application rate of 315 kg/hm2),as well as treatments with optimized potassium fertilizer(T2,N∶P2O5∶K2O=1∶0.68∶2,with K2O application rate of 210 kg/hm2),optimized potassium fertilizer+MgO at 19.5 kg/hm2(T3),and optimized potassium fertilizer+MgO at 39.0 kg/hm2(T4).The effects of these treatments on the growth,reactive oxygen metabolism,and hormone levels in the later growth stage of tobacco were investigated.The results showed that,compared to the control group,T3 treatment exhibited the best growth performance in terms of leaf development.The potassium-magnesium ratio was reduced by reducing the amount of potash fertilizer application and increasing the amount of magnesium fertilizer application,and increasing magnesium fertilizer application significantly increased the biomass during the bunching and final harvesting stages.It also significantly increased the content of soluble proteins in the plant tissues,as well as the activities of enzymes such as SOD,CAT,and POD.The enzyme activities of SOD and CAT were highest in the T3 treatment.Lowering the potassium-magnesium ratio significantly reduced the levels of hydrogen peroxide,LOX enzyme activity,and hormones such as IAA,ABA,and IAAO in the tobacco leaves,with the lowest ABA hormone level observed in the T3 treatment.On the other hand,it increased the levels of GA3 and CTK hormones.In conclusion,applying a potassium-magnesium ratio of N:P2O5:K2O=1:0.68:2 and supplementing with 19.5 kg/hm2 of magnesium fertilizer during the later growth stage of tobacco resulted in improved growth and enhanced characteristics for tobacco curing.
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