Effects of Cadmium Stress on Growth Physiology and Cadmium Subcellular Distribution in Different Varieties of Chinese Cabbage
To elucidate how cadmium(Cd)stress affects the growth physiology and how Cd distributes at the subcellular level in differ-ent varieties of Chinese cabbage,pot experiments with different soil Cd concentrations were conducted to study the differences in growth,physiology and Cd subcellular distribution in three varieties of commenly grown cabbage in Guizhou.The results showed that under Cd stress,the King of Chunxin Hotpot grew in a better state and an overall pattern of promotion at low concentrations and inhibi-tion at high concentrations(except for the performance of aboveground dry weight on Chibai 2).The chlorophyll content(SPAD)of Chinese cabbage showed an overall trend of increase and then decrease.The maximum value of chlorophyll was found in the King of Chunxin Hotpot.The Cd concentrations in all parts of Chibai 2 correlated significantly and negatively with the chlorophyll concentra-tions.The concentration of phytochelatins(PCs)generally showed a trend of increase-decrease-increase.The concentrations of Cd and soluble Cd in the aboveground parts of the King of Chunxin Hotpot correlated significantly and negatively with PCs.The Cd concentra-tions in all parts of the three investigated varieties of Chinese cabbage increased significantly with the increase of exogenous Cd(P＜0.05),showing generally higher concentrations in the aboveground parts than the roots.There were significant differences in BCF,TF among different varieties of Chinese cabbage.showing an order of Qingcui＞Chibai 2＞King of Chunxin Hotpot.There was a signifi-cant negative correlation between shoot fresh weight and available Cd content in three varieties of Chinese cabbage.The subcellular dis-tribution of Cd in Chinese cabbage leaves treated with different Cd concentrations was generally cell wall＞soluble＞organelle fraction.With the increased Cd concentrations in the treatments,the Cd proportion decreased in the cell wall fraction but increased in the solu-ble fraction,which even exceeded that in the cell wall fraction.In summary,among the three varieties of Chinese cabbage investigated in this study,King of Chunxin Hotpot has a high Cd tolerance and is suitable for planting in areas with elevated Cd background concen-trations.
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