Chickpea and temperature stress: An overview - Legumes Under Environmental Stress: Yield, Improvement and Adaptations - page 85

(b)

(a)

Figure 5.2 Effect of high temperatures on the pollen germination on the stigma. (a) Heat-tolerant: ICC 15614 - pollen germination
on the stigma. (b) Heat-sensitive: ICC 10685 - no pollen germination on the stigma. Reproduced from Devasirvatham et al . (2013).

Figure 5.3 Comparison of seed size under heat stress. Larger seeds (left side) from non-stressed and smaller seeds (right side) from
heat-stressed conditions. Photo courtesy of V. Devasirvatham.

photosynthates to the grain, thus lowering seed weight and
seed number per plant (Wang et al., 2006). Both tempera-
ture stress extremes influenced seed shape and seed coat
colour (Figure 5.3). Generally, temperature stress reduces
cotyledon cell number, cell expansion, grain filling rate and
ultimately seed weight (Munier-Jolain & Ney, 1998).
Temperature stress can influence grain filling by
altering the concentration of hormones, particularly
abscisic acid (ABA) and enzymes, in plant tissue. As dis-
cussed earlier, ABA plays a significant role in both cold
and heat stress tolerance in chickpea (Nayyar et al.,
2005a; Kumar et al., 2012a) and is generally downregu-
lated under stress. Exogenous application of ABA
increased tolerance to cold stress by improving survival
rate through the reproductive stage (Nayyar et al.,
2005a). The exogenous application of ABA decreased
electrolyte leakage and increased pollen viability,

germination, flower retention, pod set, seed size and
grain yield (Kumar et al., 2008). Similarly, Kumar et al.
(2012b) showed that ABA treatment reduced oxidative
injury in chickpea under high temperature. Clearly,
exogenous application of ABA will improve grain filling
under temperature stress and hence grain yield.

5.3 Impacts on nutritional
and processing quality

Environmental stresses during seed development have a
negative effect on the quality of chickpea seeds
(Behboudian et al., 2001). However, comparatively few
studies have dealt with the effect of temperature on seed
development and quality in chickpea. Nayyar et al.
(2005b) reported that under cold stress grain sugar