Effects Of Copper Toxicity On Germination Period Of Rice Seeds And Growth Period Of Seedling And Alleviation Role Of Exogenous Sulfate

Seed germination and hydroponic experiments were conducted to study effectsof excessive copper on the germination period of rice (Oryza sativa L.) seeds andgrowth period of seedling and alleviation role of exogenous sulfate.Results of seed germination experiment indicated that higher concentrations ofCu caused the decreases of radicle and shoot elongation, pigment contents in shoot,germination percentage and contents of ASA and GSH during the seed germinationperiod. As compared to the control, Cu at 10μM significantly also decreased theactivities ofα-amylase, catalase (CAT) and peroxides (POD), increased MDA contentand the relative uptake of Evans blue. In the presence of 10μM Cu, addition of 10mmol/L exogenous sulfate to the medium significantly increased the germinationpercentage, elongation of radicle and shoot, contents of amino acid, chlorophyll andcarotenoid, ASA and GSH and the activities ofα-amylase, CAT and POD, declinedMDA content and the relative uptake of Evans blue.Hydroponic experiment indicated that the lowest sulfur concentration for ricevariety Xiyou 936 to growth in gear was 0.2mM; Plants under 5.01μM copper stressshowed wilt, chlorosis, necrosis in leaves and black in roots, decreased in dry weight,contents of leaf protein and chlorophyll, TT and NPT and the activities of CAT andGR. Increased contents of MDA and H₂O₂ in root and the activities of POD, SOD andAPX in root and leaf. 5.0μM copper stress also significantly increased contents oftotal copper in root and soluble copper in root and leaf, but the content of total copperin leaf depends on the exogenous sulfur concentration. Sulfur at more than 1.0mMcould alleviate the copper toxicity, it appeared that: decreased the inhibition to rootelongation, contents of MDA and H₂O₂ in root, the activity of POD and APX in root, meanwhile, increased the dry weight, the activity of CAT, contents of chlorophyll,amino acid and TT in leaf, the content of protein and NPT in root.