Alleviating adverse effects of nickel on growth and ionic composition of wheat (Triticum aestivum L.) with exogenous application of ascorbic acid

Nickel contamination of soils is a widespread problem due to industrialization and urbanization. Plants require a small amount of Ni for their metabolism however its high concentration adversely affects their metabolic functions and growth. It has been reported that ascorbic acid being an antioxidant enhances plant growth and productivity of many plants under stress conditions by scavenging the reactive oxygen species. The purpose of this study was to identify the possible alleviating effect of ascorbic acid on adverse effects of Ni on growth of different varieties of wheat and their ionic composition. For this purpose, wheat plants were grown in hydroponics. The wheat plants were subjected to five treatments having different Ni levels viz. 0, 5, 10, 15 and 20 mg L-1 added to plants and ascorbic acid of 1 mM was applied as a foliar spray to treated plants. The spray was prepared by dissolving ascorbic acid in distilled water along with tween-20 added as a surfactant. In this study the interactive effect of ascorbic acid and nickel on various parameters like root and shoot length, fresh and dry weight of root and shoot, leaf area, no. of leaves per plant, chlorophyll contents, concentration of Ni, Cu, Mn and Zn in shoot and root was observed on three varieties of wheat. The results showed that Ni stress alone reduced the productivity of wheat whereas, ascorbic acid application under nickel stress reduced the uptake of Ni and enhanced the concentrations of Cu, Mn and Zn in shoot and root and also enhanced the fresh and dry biomass of the wheat plants as well as increasing the shoot and root length, leaf area, number of leaves per plant, chlorophyll contents. The application of ascorbic acid has reduced the uptake of excessive nickel ions in treated plants as compared to control plants in which high concentration of nickel was found in roots and shoot, suggesting that ascorbic acid may be used to reduce nickel toxicity on growth and ionic composition of wheat.