Phytotoxicity of Arsenite on Early Seedling Growth of Mung Bean: A Threat to Potential Pulse Cultivation

Arpita Swarnakar

doi:10.13189/azb.2020.080206

Abstract

Arsenic toxicity has gained at present an alarming global importance. Pulse crop is very sensitive to arsenic contaminated groundwater. In order to determine the phytotoxicity, effects of Sodium arsenite (NaAsO2) on seed germination and early development of Mung bean (Vigna radiata (L.) Wilczek cv. B-105) seedlings were investigated. Sodium arsenite had a toxic effect and posed a stress over germination parameters and early growth of mungbean seedlings. Considerable reduction in seed germination percentage and seedling vigour index was recorded due to arsenite. Sodium arsenite inhibited growth at very small concentrations such as 0.5µM. With the increase in concentration of sodium arsenite (0.5µM, 1µM, 2µM), significant decrease in seedling length i.e., shoot length and root length was observed. Arsenite was found to be more toxic for root growth than for shoot growth. Decrease in primary leaf area was also observed with increase in concentration of sodium arsenite. Number of stomata decreased and hence, reduction in stomatal density and stomatal index was also observed. Fresh weight and dry weight also reduced appreciably in the arsenite stressed seedlings. Treatment with 2µM concentration proved to be the most sensitive concentration for arsenite application by giving least values for seedling length and seedling vigour index.

Highlights

Arsenic a ubiquitous, carcinogenic trace metalloid [1], is found in virtually all environmental media [2]
Arsenic is known to have many toxic effects on living organism and is ranked first, in the priority list of hazardous substances compiled by the US Environmental Protection Agency (USEPA) ATSDR [3]
After 5 days, arsenite induced damaging effects were observed and shoot length and root length of growing mung bean seedlings were measured in all the sets

Summary

Introduction

Carcinogenic trace metalloid [1], is found in virtually all environmental media [2]. Arsenic is known to have many toxic effects on living organism and is ranked first, in the priority list of hazardous substances compiled by the US Environmental Protection Agency (USEPA) ATSDR [3]. Arsenic exists in the environment in various organic and inorganic forms (species) [4]. The most important inorganic species are arsenate (As V) and arsenite (As III). Its toxicity to plants depends on its valence state. Due to greater cellular uptake, As III is much more soluble, mobile and toxic than As V [5]

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Discussion

Conclusion