a SciTechnol journal Research Article Saumya and Yogesh Kumar, J Plant Physiol Pathol 2013, 1:3 http://dx.doi.org/10.4172/2329-955X.1000107 Journal of Plant Physiology & Pathology All articles published in Journal of Plant Physiology & Pathology are the property of SciTechnol, and is protected by copyright laws. Copyright © 2013, SciTechnol, All Rights Reserved. International Publisher of Science, Technology and Medicine Arsenic Phytotoxicity in Black Gram (Vigna mungo L. Var. PU19) and its Possible Amelioration by Phosphate Application Saumya Srivastava 1 * and Yogesh Kumar Sharma 1 Abstract To study the toxic effect of arsenic on black gram (Vigna mungo var. PU19) a pot experiment was conducted. Arsenic reduced the germination percentage and root and shoot length of black gram. Higher dose of arsenic (100 µM sodium arsenate) signifcantly reduced the level of photosynthetic pigments. Increased oxidative stress was observed as evident from enhanced level of lipid peroxidation and electrolyte leakage percentage. However, decreased catalase activity indicated its failure as antioxidant enzyme against arsenic exposure. Treatment of phosphate together with arsenic induced growth and metabolism in black gram as compared to arsenic treatment alone. Keywords Arsenic; Vigna mungo; Pigment; Lipid peroxidation; Catalase; Phosphate Introduction Arsenic, a group A carcinogen [1] is most commonly found in oxidized states i.e arsenite and arsenate. Geologic and anthropogenic activities like smelting operation, fossil fuel combustion [2] together with use of arsenic based agrochemicals, fertilizer and disposal of municipal & industrial wastes accounts for its widespread contamination [3]. However, arsenic laden groundwater and soil are considered major sources of contamination in the food and water supplies. Also, irrigation of soils with arsenic laden water signifcantly elevates the arsenic levels in the soil [4], rendering it unft for most crop production, and severely afects the growth and development of plants, and causes toxicity resulting in various physiological and biochemical disorders [5]. Arsenic induced toxicity has been reported in many plant species in the past [4,6-12]. Arsenic is quite similar to phosphate as both are placed in same group, Va in the periodic table, have similar electron confguration, chemical properties and compete for the same uptake carriers in the root plasmalemma [13,14]. Tis also suggests its possible role in ameliorating arsenic toxicity. We selected black gram as its sensitivity/tolerance towards arsenic *Corresponding author: Saumya Srivastava, Department of Botany, University of Lucknow, Lucknow-226007, Uttar Pradesh, India; E-mail: sonata906@gmail.com Received: February 25, 2013 Accepted: June 27, 2013 Published: July 01, 2013 toxicity is poorly understood. Black gram is an important pulse crop in India and a rich source of protein. It is also grown for forage and hay [15], and crop residues are an important feed for livestock. In the present study, we investigated arsenic-induced toxicity in black gram (Vigna mungo var. PU19) by studying the morphological and physiological changes. Also, application of phosphate together with arsenic was tested to determine the alterations it caused in various growth and metabolic functions. Methodology Black gram (Vigna mungo var. PU19) seeds procured from the Durga Egro Seeds Farm, Daliganj, Lucknow, Uttar Pradesh were surface sterilized and presoaked in a petri-dish for 4 hours containing sodium arsenate (Na 2 HASO 4 .7H 2 O) solution of following concentrations as 0 µM(control), 50 µM and 100 µM with or without 40 ppm dipotassium hydrogen phosphate (K 2 HPO 4 ) solution. Seeds were then sowed in earthen pots having alluvial soil and compost (in ratio 3:1). 500 ml of arsenic solution of above concentration was given weekly in each pot kept in wire house. Plants were analyzed for all parameters afer 45 days of sowing (except germination percentage which was analyzed afer 7 days of sowing). Germination percentage was calculated in each pot using formula- Germination % = Number of germinated seeds X 100 Total number of seeds Te root and shoot lengths of black gram plants (both treated and control) were measured afer washing and rinsing plants with tap and deionised distilled water respectively. Levels of photosynthetic pigments (total chlorophyll, chlorophyll a and chlorophyll b) were measured in black gram leaves according to Arnon [16]. 100 mg leaves were crushed in 10 ml 80% chilled acetone. Te extracts were centrifuged at 2000 g for 10 minutes. Absorbance of supernatant was estimated spectrophotometrically at 645 nm and 663 nm using a spectrophotometer (Toshniwal TSUV 75). Pigment contents were expressed in terms of mg/g fresh weight of tissue. Carotenoid contents were estimated according to the method of Duxbury and Yentsch [17]. Electrolyte leakage percentage (ELP) was estimated according to Sullivan & Ross [18]. Catalase activity was measured according to the Euler, H. von & Josephson, K. method [19]. Catalase activity was measured in terms of µM H 2 O 2 degraded/g fresh weight of tissue. Peroxidase activity was estimated according to Luck, 1963 [20]. Lipid peroxidation was evaluated to access the membrane damage in black gram plants. For this, TBA (Tiobarbituric acid) test was used to measure MDA (malondialdehyde) level which is an end product of lipid peroxidation [21]. Te experiment was conducted in a completely randomized design (CRD) with 3 replications. Te data were analyzed by One Way ANOVA using sofware program Sigmastats 3.5. It was followed by comparison of mean values using Holm Sidak method at p ≤ 0.05. Results and Discussion Germination percentage decreased with increasing arsenic