International Journal of Science and Research (IJSR) ISSN (Online): 2319-7064 Index Copernicus Value (2013): 6.14 | Impact Factor (2013): 4.438 Volume 4 Issue 1, January 2015 www.ijsr.net Licensed Under Creative Commons Attribution CC BY A Comparative In Vitro Study on Biochemical Alterations in Two Cultivars of Black Gram Exposed to Nickel Stress Smaranika Das 1 , Sagarika Samantaray 2 , Rama Chandra Mohanty 3 , Monalisa Mohanty 4 Chinmay Pradhan 5 1, 2, 3 , 5 Laboratory of Environmental Sciences, Post Graduate Department of Botany, Utkal University, Bhubaneswar-751004, India 4 Department of Botany, Dhenkanal Autonomous College, Dhenkanal-759001, India Abstract: The present hydroponic study compares the tolerance ability of two cultivars (PU31C and Shekhar1C) of black gram [Vigna mungo (L.) Hepper] to Nickel(Ni) treatments. In this context different biochemical parameters were assessed and compared in 14 days treated seedlings under different Ni concentrations. After 14 days exposure to different concentrations of toxic Ni 2+ , the two cultivars of V. mungo i.e. PU31C and Shekhar1C showed significant changes in their phytotoxicity and tolerance index values,, protein and sugar content. Sekhar1C variety seedlings showed more protein and reducing sugar level than PU31C variety, at toxic Ni (100 μM and 200μM) treatments. Whereas total sugar level in PU31C variety of black gram seedlings were significantly more as compared to Sekhar1C variety even at higher treatment dose of Ni. The present in vitro experiment showed hydroponically grown Sekhar1C variety of black gram seedlings under different treatment concentrations of Ni showed better stress tolerance than PU31C variety as evidenced from their tolerance index and phytotoxicity values. Keywords: Nickel, Protein, Phytotoxicity, Sugar, Tolerance index. 1. Introduction Nickel (Ni) occurs abundantly in igneous rocks as a free metal or as a complex with iron. It stands at twenty-second position amongst most abundant elements in the earth crust [1]. Nickel (Ni) is considered to be an essential micronutrient for plants and in small amount is known to improve plant yield and quality [1]. But Ni at high concentrations in the soil environment becomes phytotoxic [2] [3]. Ni 2+ form is stable over a wide range of pH and redox conditions prevailing in the soil. In general, naturally occurring concentration of Ni in soil and surface waters is lower than 100 and 0.005 ppm, respectively but anthropogenic activities further release Ni into the soil through various sources such as smelting, burning of fossil fuel, vehicle emissions, disposal of house hold, municipal and industrial wastes, metal mining, fertilizer application, and organic manures [1]. In plant tissues, the concentrations of Ni may vary from 0.1 to 5.0 ppm (dry wt. basis) with a threshold range of toxicity of 40-246 ppm, depending on plant species [4]. The most common symptoms of nickel toxicity in plants are inhibition of growth, chlorosis, necrosis and wilting [3][5] [6] [7]. Toxicity of this metal has been attributed to its negative effect on photosynthesis, mineral nutrition, sugar transport, water relations and induction of oxidative stress [4]. The impact of Ni toxicity on the biochemistry and physiology of different crop plants depends on the type of plant species, growth stage, cultivation conditions, Ni concentration and exposure time [8] [9] in the soil. It is now crucial to ascertain the role of different variety of crop for their tolerance to Ni stress, which is considered critical for raising a successful agricultural crop. The present in vitro study compares the tolerance ability of two cultivars (Sekhar1C and PU31C) of black gram (Vigna mungo) by assessing various biochemical and physiological changes in response to varying treatment doses of Ni.. 2. Materials and Method 2.1 Plant Material Dry seeds of black gram [Vigna mungo (L.) Hepper] cultivars (PU31C and Shekhar1) were collected from Orissa State Seed Corporation, Bhubaneswar. 2.2 Seedling growth Germinated seeds were hydroponically grown in growth chambers in in vitro conditions. Well aerated hydroponic culture vessels containing half strength Hoagland’s nutrient solution was taken as control and Hoagland’s solution supplemented with different concentrations of Ni (Source: NiCl 2 ) viz. 1μM, 5μM, 10μM, 50μM, 100μM and 200μM for seedling growth. The seedlings were grown under white fluorescent tubes (36 W Philips TLD) with a photon flux density of 52 μ /m2s (PAR) with a 12h photo period inside the growth chamber for 14 days. 2.3 Analysis of Biochemical Parameters 2.3.1 Estimation of tolerance index and phytotoxity values Tolerance indices (TI) and Phytotoxicity (%) in root and shoot were determined by following the formula as given by [10]. TI = (Mean root length of Ni treated seedlings/Mean root length of seedlings grown in control) × 100 Paper ID: SUB151047 2780