Environmental Engineering Reference
In-Depth Information
Chapter 5
Physio-Anatomical Responses of Plants
to Heavy Metals
Riffat Batool, Mansoor Hameed, Muhammad Ashraf, Muhammad Sajid
Aqeel Ahmad and Sana Fatima
Abstract
Environmental pollution caused by heavy metals is a global issue, which
seriously affects growth and development of agricultural crops, as well as the native
flora. It is known that metal toxicity can significantly alter soil physico-chemical
properties of the soil, mainly organic matter, pH and cation exchange capacity. The
devastating impact of heavy metals may be related to retarded growth and devel-
opment, ionic imbalance, metal toxicity, reduced photosynthetic rate, degradation
of chloroplast and photosynthetic pigments, and more importantly disturbed plant
water relation. Heavy metal in the soil can also induce alterations in anatomical
parameters. Among anatomical changes, disintegration and reduced size of paren-
chymatous tissue, reduced size of xylem vessels, degraded and smaller mesophyll
tissue, and as a whole reduced root and stem diameter and leaf growth. Moreover,
there is a spatial accumulation of heavy metals in different organs, more commonly
in dermal, parenchymatous and phloem tissues. However, tolerance to heavy met-
als varies among different species, and even within populations of a same species.
Overall this chapter describes how far heavy metal toxicity can promote the devel-
opment of specific structural and functional modifications in plants exposed to
metal-enriched environment and how these features could help plants to thrive well
under such harsh conditions.
Keywords
Accumulation
·
Metal toxicity
·
Plant anatomy
·
Photosynthesis
·
Tolerance
