Drought stress related biochemical changes in antioxidant metabolism and quality attributes in wheat (Triticum aestivum L.)
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Date
2016
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Publisher
CCSHAU
Abstract
The present investigation was conducted to study the effect of drought stress on antioxidant
and proline metabolism in leaves and developing grains of two wheat varieties viz. WH 1105 and WH
1025. Drought stress was imposed by giving pre-sowing irrigation only and samples were taken at
seven days interval from 7th to 28th days after anthesis. The results showed that during grain
development, activities of antioxidant enzymes viz. superoxide dismutase, catalase, peroxidase,
ascorbate peroxidase and glutathione reductase increased more in WH 1025 under drought stress than
WH 1105. Antioxidant metabolites such as ascorbate, glutathione, proline and hydrogen peroxide
content increased under drought stress in leaves and developing grains while the carotenoid content
decreased. The enhancement of antioxidant metabolites was also reflected in concomitant enhancement
of total antioxidant activity. Isozyme pattern of superoxide dismutase, catalase, peroxidase and
ascorbate peroxidase altered under drought stress with enhanced intensities in leaves and developing
grains from 7th to 28th days after anthesis. Alteration in proline level under stress was due to changes in
the activities of enzymes involved in proline metabolism. Proline synthesizing enzymes such as Δ1
pyrroline-5-carboxylate synthetase and Δ1 pyrroline-5-carboxylate reductase were also increased under
drought stress; however proline degrading enzyme, proline oxidase activity decreased. Physiological
parameters related to flag leaf membrane injury like lipoxygenase, malondialdehyde increased while
leaf membrane stability, leaf lipids and total soluble protein content decreased under drought stress.
Physiological parameters such as relative water content, osmotic potential, chlorophyll content and
chlorophyll fluorescence gradually decreased under drought stress while canopy temperature increased.
Quality parameters like grain appearance, hectolitre weight, grain hardness, crude fibre, total sugars
and starch content decreased under drought stress, but sedimentation value, crude protein and gluten
content increased. Phenological parameters like days to heading, days to anthesis, days to maturity and
grain filling duration declined under drought stress. Yield attributes such as grain number per spike,
grain weight per spike, test weight and grain yield per square meter decreased under the influence of
drought stress. The reduction in physiological, biochemical, yield and grain quality traits was found to
be more pronounced in WH 1105 in comparison to WH 1025. Drought susceptible index found to be
less in WH 1025 than WH 1105.
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Keywords
Drought stress in wheat, Developing grains, Antioxidant enzymes and metabolites, Antioxidant isozymes, Proline metabolizing enzymes, Physiological parameters quality, Phenological parameters and yield attributes