The investigation was conducted to evaluate the effect of drought stress on role of proline, hydrogen peroxide and total antioxidant activity (TAA) of two wheat varieties viz. WH 1105 (Drought sensitive) and WH 1025 (Drought sensitive) after anthesis. Drought was given by only pre sown irrigation. Analysis of data revealed that drought stress results an increase in proline and hydrogen peroxide (H2O2) contents in leaves and developing grains of both wheat varieties after anthesis, however more increase in imino amino acid proline was observed in WH 1025 which is ascribed to improved drought tolerance through osmotic adjustment of cellular contents. Drought sensitive wheat variety WH 1105 had accumulated higher hydrogen peroxide (H2O2) than WH 1025. Stress tolerance to plants is determined by the pool size of antioxidants and protective plant pigments particularly carotenoids. This study also revealed that the total antioxidant activity (TAA) was increased in leaves and developing grains of both wheat varieties with higher and significant increase in WH 1025 than WH 1105.

Climate change imposes many environmental stresses out of which drought stress is a major concern that significantly restricts crop production in arid and semi-arid regions. The negative impact on grain quality caused by drought stress is responsible for reduced grain yield and quality. Many previous studies aimed to understand the tolerance level of wheat varieties, but studies on grain quality traits assessment were less. Therefore, the aim of the present investigation was to study some grain quality traits and to determine how drought stress affected these parameters. Experiments with two wheat varieties viz. WH 1105 and WH 1025 were conducted in microplots with RBD design in open fields. Grains were selected after harvest of the crop and were used to evaluate sedimentation value, β carotene, crude fibre, total sugars and starch. Sedimentation values (ml) were increased more in WH 1025 (6.9 per cent) than WH 1105 (3.8 per cent). Beta carotene content (µg g-1 DW), crude fibre (%), total sugar (%) and starch (%) contents were decreased in both wheat varieties and more decrease was observed in WH 1105 than WH 1025 under drought condition than irrigated condition. The study revealed that quality traits of WH 1105 were much affected than WH 1025 under drought stress.

Drought stress induced physiological changes such as chlorophyll fluorescence, canopy temperature and total leaf protein were studied in the present investigation in two wheat varieties viz. WH 1105 and WH 1025. Chlorophyll fluorescence is excellent tool to study stress induced changes in PSII. The Fv / Fm value denotes the injury to PS II due to influence of stress factors. Chlorophyll fluorescence decreased under drought stress in leaves of both varieties from 7 th to 28 th DAA. Canopy temperature indicates crop water status. Canopy temperature of 31.98 o C was recorded at 28 th DAA in WH 1105 and the value is lower in WH 1025. Total soluble protein content was decreased under drought stress in leaf samples. Total soluble protein levels in leaves do not clearly indicate senescence symptoms driven by severe drought at grain filling period.

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Two wheat (Triticum aestivum L.) varieties viz. WH 1105 and WH 1025 are subjected to drought stress. The non enzymatic antioxidant defense system which contains antioxidant metabolites such as ascorbic acid, glutathione and carotenoids contents were studied in drought sensitive and drought resistant varieties days after anthesis (DAA) in leaf and grain samples. As part of protective mechanism against drought, wheat plants produced more of ascorbic acid and glutathione with a concomitant decrease in carotenoid content. The increase in ascorbic acid and glutathione were more in WH 1025 than WH 1105. Carotenoids protect plants by minimizing ROS formation by quenching oxygen. The reduction in carotenoid content was observed in both wheat varieties days after anthesis (DAA) in leaf and grain samples but more reduction was observed in WH 1105 which is a drought sensitive variety of wheat. These antioxidant metabolites played a key role in protecting wheat plants against reactive oxygen species (ROS) mediated oxidative damage and their redox buffering capacity generates stress tolerance in drought tolerant wheat variety WH 1025.