Physiological effects and mechanisms of molybdenum on alleviating cadmium toxicity in tobacco
This study used tobacco variety K326 as the test crop.Cadmium-contaminated farmland soil was collected for pot experiments to investigate the alleviating effect of molybdenum application on the physiological characteristics of tobacco seedlings under cadmium stress.Four molybdenum gradients of 0,0.25,0.5,and 1 mg·kg-1 were set up to study the effects of molybdenum on the physiological characteristics of tobacco seedlings under cadmium toxicity,including appearance characterization,enzyme activity,cadmium accumulation,photosynthesis,and antioxidant capacity.The results showed that molybdenum application improved the growth of tobacco seedlings that show signs of stunted growth and leaf chlorosis under cadmium toxicity.It also promoted root growth,with the best effect observed at a concentration of 0.5 mg·kg-1.Compared with the untreated treatment,the application of 0.5 mg·kg-1 of molybdenum promoted the activity of soil enzymes,reduced the cadmium content in tobacco leaves and roots by 17.39%and 40.00%,respectively,and promoted the absorption of molybdenum;0.5 mg·kg-1 of molybdenum could significantly reduce the accumulation of reactive oxygen species and other substances in tobacco leaves,and increase the activity of defense enzymes and the content of stress hormones in tobacco plants.The total antioxidant capacity of 0.25,0.5,and 1 mg·kg-1 of molybdenum treatment was 1.17,1.20,and 1.09 times that of the untreated treatment,respectively.In addition,molybdenum application enhanced the photosynthesis and molybdenum enzyme activity of tobacco under cadmium stress,playing an important regulatory role in the physiological metabolism of tobacco under cadmium stress.This study has shown that applying 0.5 mg·kg-1 of molybdenum has a higher alleviating effect on the physiological characteristics of tobacco seedlings under cadmium stress.
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