Chapter 6 - Effect of High-Temperature Stress on the Metabolism of Plant Growth Regulators

Abstract

An ever-expanding world population and globally changing climatic conditions have put considerable pressure on the worldwide agricultural community to produce more food, feed, and bioenergy crops. As a result, marginal land areas will need to be used to meet the increasing requirements of future generations, however these marginal areas commonly impose abiotic stresses on crops. Endogenous plant growth regulators play an important role in regulating plant responses to abiotic stress by sensitizing growth and developmental processes. While the physiological and molecular mechanisms linked to the role of abscisic acid and cytokinins in stress tolerance are well explained, there is growing interest to elucidate the associations of auxins, ethylene, gibberellins, and brassinosteroids, in stress tolerance mechanism and also on a possible crosstalk mechanism among different growth regulators during stress tolerance acquisition. Researches have also provided some leads in exploiting the potential of growth regulators in enhancing resistance to abiotic stresses of crops. Plant growth regulators are biochemical and chemical compounds that stimulate plant growth and productivity when applied, even in small quantities at appropriate plant growth stages. These are being extensively used in agriculture to enhance the productivity of agricultural crops. A better understanding of the mechanisms involved in plant tolerance to heat stress is of vital significance. Manipulation of phytohormones through breeding or exogenous application of various phytohormones at optimal doses may help to manage heat stress and thereby sustain crop production in the face of climate change. It is worth mentioning that activation of hormone-responsive genes in a specific tissue is crucial for the induction of stress tolerance and thus targeted manipulation of the plant hormone pool offers better efficacy for modulating the response of plants to heat stress. The use of growth regulators has become an important component of agrotechnical procedures for most cultivated plants, and especially for fruit plants. So far in fruit crops, excessive fruit drop can be controlled by the exogenous application of plant growth regulators. Auxin and gibberellins are widely used to control fruit drop and to improve the quality of fruit.