Effects of single and combined stresses of Mn and Cd on the physiological and biochemical characteristics of Morus alba

The purpose of this study was to explore the stress resistance of Morus alba to the remediation and treatment of single and complex heavy metal soil pollution, to provide a theoretical basis and practical references for the application of Morus alba in the restoration and ecological treatment of heavy metal polluted land.

In this study, 16 heavy metal pollution gradients were set up in the soil culture test to study the effects of single and combined stresses of Mn and Cd on chlorophyll, MDA, POD, SOD and other common physiological and biochemical indices of plants.

The results showed that during the process of heavy metal stress, the degree of influence on chlorophyll, MDA, POD, SOD and other physiological characteristics of Morus alba was in the order of Mn and Cd combined stress > single Cd stress > single Mn stress. The chlorophyll content of Morus alba decreased gradually with the increase of stress gradient. The MDA content of mulberry increased with the increase of stress gradient. The POD activity and SOD activity increased under the treatments of the first to the third gradients and decreased under the treatment of the fourth gradients. When the Mn stress level was greater than 25 mg/L and Cd stress level was greater than 200 mg/L, the POD and SOD activities of mulberry were inhibited to varying degrees, and the range of activity changes was more obvious under combined stress, which has greater damage effects on Morus alba.

The changes in the chlorophyll, MDA, POD, SOD and other physiological indexes of Morus alba under single and combined Mn and Cd stresses have the greatest effect on plants, followed by single Cd stress, and single Mn stress has the least effect. The changing amplitude of chlorophyll and MDA is opposite, while the changing amplitude of POD and SOD is similar.