RESEARCH ARTICLE Nickel accumulation and its effect on growth, physiological and biochemical parameters in millets and oats Vibha Gupta 1 & Pradeep Kumar Jatav 1 & Raini Verma 1 & Shanker Lal Kothari 2 & Sumita Kachhwaha 1 Received: 14 December 2016 /Accepted: 26 June 2017 # Springer-Verlag GmbH Germany 2017 Abstract With the boom in industrialization, there is an in- crease in the level of heavy metals in the soil which drastically affect the growth and development of plants. Nickel is an essential micronutrient for plant growth and development, but elevated level of Ni causes stunted growth, chlorosis, nu- trient imbalance, and alterations in the defense mechanism of plants in terms of accumulation of osmolytes or change in enzyme activities like guiacol peroxidase (POD), catalase (CAT), and superoxide dismutase (SOD). Ni-induced toxic response was studied in seedlings of finger millet, pearl millet, and oats in terms of seedling growth, lipid peroxidation, total chlorophyll, proline content, and enzymatic activities. On the basis of germination and growth parameters of the seedling, finger millet was found to be the most tolerant. Nickel accu- mulation was markedly lower in the shoots as compared to the roots, which was the highest in finger millet and the lowest in shoots of oats. Plants treated with a high concentration of Ni showed significant reduction in chlorophyll and increase in proline content. Considerable difference in level of malondialdehyde (MDA) content and activity of antioxidative enzymes indicates generation of redox imbalance in plants due to Ni-induced stress. Elevated activities of POD and SOD were observed with high concentrations of Ni while CAT activity was found to be reduced. It was observed that finger millet has higher capability to maintain homeostasis by keeping the balance between accumulation and ROS scavenging system than pearl millet and oats. The data pro- vide insight into the physiological and biochemical changes in plants adapted to survive in Ni-rich environment. This study will help in selecting the more suitable crop species to be grown on Ni-rich soils. Keywords Nickel accumulation . Oxidative stress . Millets . Oats . Seedling growth . Phytoremediation Introduction Heavy metals are naturally present in the soil, but their con- centration has increased to toxic levels in several places due to industrialization, increased use of fertilizers and pesticides in agriculture, extensive mining, smelting of metals, burning of fossil fuels, production of batteries and other metal products in industries, sewage sludge, and municipal waste. As a result, the natural biogeochemical cycles have been disturbed (Raskin et al. 1994; Shen et al. 2002). Natural resources such as air, water, and soil have been polluted. The accumulation of heavy metals (HMs) is a problem for ecological, nutritional, and environmental balance (Nagajyoti et al. 2010). Heavy metal contamination of soil may pose risks and hazards to humans and the ecosystem through the food chain, drinking of contaminated groundwater, reduction in food quality (safe- ty and marketability) via phytotoxicity, and reduction in land usability for agricultural production causing food insecurity (McLaughlin et al. 2000a, b; Ling et al. 2007). Heavy metals are non-biodegradable, persistent inorganic constituents hav- ing cytotoxic, genotoxic, and mutagenic effects on humans, animals, and plants (Flora et al. 2008). Plants need metals for their growth and development; these metals are categorized into essential (Fe, Cu, Zn, Mn, Mg, Mo, Se, Cr, Co, and Ni) and non-essential elements (Cd, Sb, Pb, Ag, As, and Hg) Responsible editor: Elena Maestri * Sumita Kachhwaha kachhwahasumita@rediffmail.com 1 Department of Botany, University of Rajasthan, Jaipur 302004, India 2 Amity Institute of Biotechnology, Amity University Rajasthan, Jaipur 302006, India Environ Sci Pollut Res DOI 10.1007/s11356-017-0057-4