This article explored the effects of cadmium stress and exogenous salicylic acid on the photosynthesis and physiological characteristics of Viola tricolor L.,providing a basis for rational application of salicylic acid and alleviating cadmium toxicity.Viola tricolor L.was planted under Cd stress(200 mg·kg-1),and spray 0(SA0)and 50(SA1),100(SA2),200(SA3),500(SA4)μmol·L-1 salicylic acid on the leaves,to explore its effects on the growth,photosynthesis,osmoregulation substances and enzymatic protection system of Viola tricolor L.The results showed that 200 mg·kg-1 of Cd can lead to a significant increase in MDA,significantly inhibit the vegetative growth,reproductive growth and photosynthesis of Viola tricolor L.;The application of an appropriate amount of salicylic acid(100-200 μmol·L-1)can reduce the content of MDA and increase the plant length,stem diameter,leaf area,number of leaves and flowers,dry weight,fresh weight and water content of Viola tricolor L.under Cd stress;The net photosynthetic rate(Pn),stomatal conductance(Gs),transpiration rate(Tr)were increased;The application of an appropriate amount of salicylic acid(100-200 μmol·L-1)can also increase the content of proline,soluble protein,soluble sugar and the activity of superoxide dismutase(SOD),catalase(CAT),and peroxidase(POD),but if the concentration reaches 500 μmol·L-1,the effect is not as good as when the concentration is lower,indicating that an appropriate amount of salicylic acid(100-200 μmol·L-1)can significantly alleviate the Cd toxicity of Viola tricolor L.,and 200 μmol·L-1 is the best application concentration based on all indicators.
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