Agriculture Reference
In-Depth Information
Chapter 17
Mechanism of Cadmium Toxicity
and Tolerance in Crop Plants
Sarvajeet Singh Gill, Naser Aziz Anjum, Ritu Gill, Mirza Hasanuzzaman,
Pankaj Sharma and Narendra Tuteja
1 Introduction
Environmental pollution by heavy metals is a serious problem worldwide, which
causes considerable loss to agricultural productivity. Over the last few decades,
there is a dramatic, troublesome increase in heavy metal contamination of soil, wa-
ter and air, globally. Heavy metals are ascribed to transition metals with atomic
mass of over 20 and having a specific gravity of above 5 g cm
−3
or more. Every
year, India loses hundreds of millions of rupees from reductions in crop productivity
(Mahajan and Tuteja
2005
). According to Bray et al. (
2000
), the relative decreases
in potential maximum yields associated with abiotic stress factors, vary between
5482 %. Although heavy metals occur naturally in soil as rare elements, burning of
fossil fuels, mining and smelting of metalliferous ores, electroplating, gas exhaust,
energy and fuel production, fertilizer and pesticide application, use of sludge or mu-
nicipal compost, pesticides, fertilizers, and emissions from municipal waste incin-
erators and car exhausts all contribute to their spread in the environment (Alkorta
et al.
2004
; Wei and Zhou
2008
). Major heavy metal pollutants include cadmium
(Cd), chromium (Cr), copper (Cu), lead (Pb), Arsenic (As), mercury (Hg), nickel (Ni),
