Influence of soil ameliorants and microflora on induction of antioxidant enzymes and growth promotion of Jatropha curcas L. under saline condition

Abstract

This study investigated the influence of inoculation with plant growth promoting rhizobacterium, Enterobacter clocae (MSA), Pseudomonas pseudoalcaligenes (MSC) and Bacillus sp., with a mycorrhizal fungus, Glomus intraradices, on seed germination parameters, vegetative growth, mineral nutrient uptake in leaves of Jatropha curcas L., soil nutrient management, antioxidant enzyme activities, phosphatase activity, solute accumulation under 2% salinity stress. Inoculation with plant growth promoting rhizobacteria (PGPR) increases the number of roots, root length, fresh weight of root and dry weight of root, number of leaves, and chlorophyll content. Addition of mycorrhizal inoculation was the next most effective in growth promotion of Jatropha. Inoculation of vermicompost increases shoot width as compared to other treatments. Soil analysis showed increase in C, N, and P in plants inoculated with PGPR strain. Further plant analysis showed that PGPR could increase uptake of N, P, K and Na. However, mycorrhizal fungus was observed to increase sulphur uptake while, vermicompost increase uptake of iron and copper. Treatment with vermicompost and PGPR showed an increase in acid and alkaline phosphatase. Salt stress increased proline concentration, particularly in plants inoculated with PGPR. Increased salinity stress raised significantly the antioxidant enzyme activities, including those of ascorbate peroxidase and catalase of Jatropha leaves. The PGPR strain induced a higher increase in these antioxidant enzymes in response to salinity. Inoculation with selected PGPR could serve as a useful tool for alleviating salinity stress in Jatropha.