Effect of different heavy metals (Cd, Cr & Pb) and mycorrhizal treatments on growth, metal uptake and antioxidative capacity in desi and Bt cotton
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Date
2018
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CCSHAU
Abstract
The present investigation was aimed to study the effect of different heavy metals (HM) (Cd, Cr, & Pb) and mycorrhizal inoculations on growth, metal uptake and antioxidative capacity in Desi and Bt cotton. Heavy metal (Cd- 10 ppm, Cr- 10 ppm, & Pb-100 ppm) and mycorrhizal (Glomus hoi) treatments were given in the soil before sowing the seeds in polythene lined cemented pots. The observations were taken at vegetative stage (35 DAS) and flowering stage (65 DAS). Cr treatment was lethal to both genotypes and no plants survived. Cd and Pb treatments adversely affected the membranes as was evident from increased MDA content and electrolyte leakage. Heavy metal stress resulted in a decrease in chlorophyll content, chlorophyll fluorescence and total soluble protein content. Cd and Pb treatments caused oxidative stress resulting in increased production of ROS and H2O2. The activity of antioxidative enzymes SOD, CAT, POX, APX, GR, DHAR, MDHAR and metabolites ascorbate, glutathione and FRSA also increased with HM stress. Bt cotton was more sensitive to HM stress as compared to Desi cotton and Cd was more toxic than Pb. The effect of Cd and Pb was more adverse at flowering stage as compared to vegetative stage. Mycorrhizal inoculations partially ameliorated the toxic effect and resulted in a decrease in MDA content, electrolyte leakage, ROS production, H2O2 content and increase in chlorophyll content, protein content and chlorophyll fluorescence. A further increase in the antioxidative activity was observed with mycorrhizal treatments. Increase in antioxidative activity was more in Desi cotton as compared to Bt cotton. Pb treated plants had more antioxidative activity than Cd.
HM stress resulted in a decline in plant growth, plant height, yield and its attributes. The growth and yield of Bt cotton were more adversely affected by HM. Mycorrhizal inoculation partially alleviated the toxic effect and resulted in an increase in growth and yield. Mycorrhizal inoculations resulted in formation of large sized fungal vesicles in HM treated roots of cotton genotypes and increased the percent colonization. HM treatments also resulted in a significant accumulation of HM in cotton genotypes. HM accumulation was more in roots as compared to shoot. Accumulation was more in Desi cotton as compared to Bt cotton. Mycorrhizal inoculation further increased the phytoremediation potential of cotton genotypes in HM contaminated soil.
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