Effects Of Biochar On Growth And Physio-biochemis Try Of Pumpkin Seedlings Under Cadmium Stress

With the development of industrial economy,heavy metal pollution becomes more and more serious.Cadmium pollution is very serious and threatens biosecurity,huma n health and the ecological environment.In this study,the effects of cadmium ions on the growth and physio-biochemistry of pumpkin seedlings were studied,and then diff erent proportions of biochar were used to alleviate the harm of cadmium pollution to pumpkin seedlings.These provide theoretical support and reference for cadmium remed iation.The main results are as follows:With the increase of cadmium ion concentration,the cadmium accumulation in pu mpkin seedling tissues showed a rising trend.The cadmium accumulation was the hig hest in root and the lowest in cotyledon.Meanwhile,the root fresh weight,root lengt h,hypocotyl length,SOD activity and CAT activity in cotyledon of pumpkin seedlings showed a downward trend.The cotyledon fresh weight,root SOD activity,root POD activity and root CAT activity showed a rising trend.High concentration of cadmium stress had great effect on root metabolites of pumpkin seedlings.37 metabolites promo ted root growth and 5 metabolites inhibited root growth.There were 5 metabolites ha d a great influence on root growth.Butyric acid,glucopyranoside and butanediamine p romoted root growth.Phenylamine and phthalic acid inhibited root growth.Cadmium s tress influenced aminoacyl-tRNA biosynthesis,glyoxylate and dicarboxylate metabolism,alanine,aspartate and glutamate metabolism,glycine,serine and threonine metabolism,sulfur metabolism,butanoate metabolism,amino sugar and nucleotide sugar metabolis m,propanoate metabolism,glutathione metabolism,galactose metabolism,cyanoamino a cid metabolism and indole alkaloid biosynthesis in root.24 metabolites promoted hypo cotyl growth and 6 metabolites inhibited hypocotyl growth.Cadmium stress also affect ed the metabolites in cotyledon of pumpkin seedlings.22 metabolites promoted cotyled on growth and 32 metabolites inhibited cotyledon growth.With the increase of biochar content,the cadmium accumulation in pumpkin seedl ing tissues showed a decreasing trend.The cadmium accumulation in root and hypocot yl decreased significantly.The cadmium accumulation in pumpkin seedling tissues was in the order of root,hypocotyl and cotyledon from high to low.The root fresh weigh t,hypocotyl fresh weight,cotyledon fresh weight,root length,hypocotyl length and hy pocotyl thickness of pumpkin seedlings showed a rising trend.The root SOD activity,hypocotyl and cotyl POD activity,and root and hypocotyl MDA contentes showed a d ownward trend.The effect of high content biochar affected root metabolites.Thirty me tabolites promoted root growth.Twelve metabolites inhibited root growth.