Effect Of Phosphorus-copper Interaction On Copper Accumulation And Physiological And Biochemical Changes Of Chrysanthemum Coronarium

Copper is one kind of essential micronutrients for plants’ growth,but the effective content of copper in the soil for the growth of plant is very limited.Once copper in the soil exceeds a critical value,it will be toxic to plants.This study mainly focused on the copper contamination,and firstly investigated the present situation of Cu pollution in some greenhouse soils in suburban vegetable land of Changchun City.Then,the Chrysanthemum Coronarium was chosen as the experimental plant to study the physiological and biochemical characteristics,especially the changes of root exudates of Chrysanthemum Coronarium under Cu stress via hydroponic experiment.Furthermore,Pot experiment was conducted to study the change and mechanism of Chrysanthemum Coronarium’s tolerance for copper at the joint action of phosphorus and copper.These results would provide experimental basis and theoretical supporting for solving the problem of heavy metal pollution in black soil.The main conclusions are summarized as follows:1.The situation of copper pollution in soil and seasonal vegetables in some greenhouses was analyzed and evaluated by using the single pollution index method.The results showed that Cu in some soil samples exceeded the standard,but Cu contents in vegetables were not higher than the standard.2.The physiological and biochemical characteristics of Chrysanthemum Coronarium under Cu stress were studied by hydroponics.The results showed that with the increase of Cu concentration in nutrient solution,the content of Cu accumulated by the plant increased,the content of chlorophyll in leaves decreased,and the content of malondialdehyde and leakage rate of electrolytes in roots increased.However,the contents of non-peptidyl sulfhydryl and root uronic acid in the shoots presented no change.Compared to control,both the total amount of the seven amino acids and the total amount of the six low-molecular-weight organic acids secreted by Chrysanthemum Coronarium roots with different Cu treatments were higher,and both present the same tendency,i.e.they both increased first and then decreased with treated Cu concentration increasing.3.Pot experiments were conducted to study the accumulation and transformation characteristics of Cu by Chrysanthemum Coronarium under the Cu-P cooperative effect.The results showed that the Cu contents increased with the increase of spiked Cu contents.The spiked P further enhanced the uptake of Cu in root,but inhibited the transporting of Cu from roots to shoots.The P spiked in soils led to the changes of the species distribution of Cu and the contents of low-molecular-weight acids in the soil.In a word,with the increase of Cu contents in both nutrient solution and soil,the Cu accumulated in Chrysanthemum Coronarium increased and indicated that Chrysanthemum Coronarium had some tolerance to copper.The cooperative effect of P and Cu can enhance the uptake of Cu by Chrysanthemum Coronarium,but limited the migrating of Cu from roots to the aboveground.