Research On The Physiological Responses And Cadmium Accumulation Differences Of Different Koelreuteria Paniculata Cultivars To Cadmium Stress

Soil contamination by heavy metal is threatening food security and human health.Because of a higher heavy metal-accumulation capacity,better growth,more biomass and a stronger applicability,Panicled goldenrain tree(Koelreuteria paniculata)has been considered as the most promising woody species to repair the contaminated-soils in the mines wasteland.However,the differences and physiological mechanism of Cd-accumulation among cultivars are scarcely reported.Using pot experiment,the effects of cadmium stress on the plant height,chlorophyll content,superoxide dismutase(SOD)activity,peroxidase(POD)activity,catalase(POD)activity,,soluble protein content and free proline content were measured.The accumulation levels of cadmium in leaves and roots of shoots were determined.The aim of this study was to compare the cadmium tolerance of the three Koelreuteria paniculata Cultivars and to screen out the cultivars with strong cadmium tolerance,and make theoretical guidance for the selection of dominant species of cadmium soil.(1)With the increase of cadmium concentration in the soil,the increment of plant height of three kinds of Koelreuteria paniculata decreased gradually.In addition to cadmium concentration of 50mg ·kg-1 treatment,the other treatment of plant height is significant different compared with CK.(2)With the increase of cadmium concentration in the soil,The chlorophyll content of three cultivars of showed the trend of increasing first and then decreasing,and the chlorophyll content of the three cultivars was as follows:Koelreuteria Bipinnata>Koelreuteria Integrifolia>Koelreuteria paniculata.The chlorophyll content of each treatment was significantly different from CK,but the difference of chlorophyll content among different cultivars was not significant.When the concentration of cadmium was 400 mg · kg-1,the chlorophyll content of the three cultivars was lower than that of the control.(3)Under different Cd stress,the activities of SOD,POD and CAT in leaves and roots of three species of Koelreuteria paniculata showed a tendency to increase first and then decrease with the increase of cadmium concentration.The activity of leaves enzyme was higher than that of roots,and SOD,POD,CAT activity in leaves and roots reach the peak at different concentrations of cadmium stress.The difference between the enzyme activity and CK was significant or extremely significant.(4)Under different cadmium stress,the content of soluble protein in leaves and roots of three cultivars of Koelreuteria paniculata leaves increased first and then decreased with the increase of cadmium concentration,and the soluble protein content in leaves was higher than that in roots.The content of free proline in leaves increased gradually with the increase of cadmium concentration,while the content of proline in root decreased at the concentration of cadmium at 400mg ·kg-1.(5)Under different cadmium stress,the cadmium accumulation of the roots of was higher than that of the leaves,and the difference of cadmium content between the treatments and the cultivars was significant.The results showed that the the physiological mechanism of cadmium accumulation in Koelreuteria paniculata is the root absorb cadmium in the soil,transfer cadmium into leaves.The activity of antioxidant enzymes and the content of soluble protein and free proline increased can enhance the resistance to cadmium stress.Compared with two other Koelreuteria Paniculata cultivars,Koelreuteria Bipinnata cadmium resistance is stronger,so Koelreuteria Bipinnata can be used as repair tree to soil cadmium pollution.