Agriculture Reference
In-Depth Information
ABSTRACT
Environmental stress is the primary cause of crop losses worldwide, re-
ducing average yields for most major crops by more than 50%. High
temperatures and limited soil moisture are the major causes of low yields
of vegetables. Elevated temperature can disrupt the normal growth and
development of plants, which ultimately affects crop productivity. Under
heat stress seed germination, seedling and vegetative growth, flowering
and fruit set, and fruit ripening are adversely affected. The plants respond
to the heat stress by altering different morphological, anatomical, physi-
ological and biochemical mechanisms. High temperature stress can be
avoided by crop management practices,
viz
., selection of proper sowing
methods, choice of proper sowing date, cultivars, irrigation methods,etc.
,
as well as by developing improved cultivars resistant to heat stress. The
most recent trend in control of heat stress is by use of molecular tools.
10.1 INTRODUCTION
Stress is any factor of environment that interferes with the complete ex-
pression of the genotypic potential of the plant (Singh, 2000).Environ-
mental stress is the primary cause of crop losses worldwide, reducing av-
erage yields for most major crops by more than 50% (Boyer, 1982; Bray
et al., 2000). The response of plants to environmental stresses depends
on the plant developmental stage and the length and severity of the stress
(Bray, 2002). Plants may respond similarly to avoid one or more stresses
through morphological or biochemical mechanisms (Capiati et al.
,
2006).
Environmental interactions may make the stress response of plants more
complex or influence the degree of impact of climate change. One of the
most detrimental stresses among the ever-changing components of the en-
vironment is the constantly rising ambient temperature. The prediction of
IPCC (2007) that global air temperature is to rise by 0.2 °C per decade,
eventually leading to rise in temperatures up to 1.8-4.0°C higher than the
current level by 2100 is a threat to the biosphere, as heat stress has known
effects on the life processes of organisms, acting directly or through the
modification of surrounding environmental components. Plants being ses-
sile organisms, cannot move to more favorable environments as a result
of which plant growth and developmental processes are substantially af-
