The present study demonstrates the effect of polyethylene glycol-6000 (PEG) induced water-deficit stress on growth, physiological and biochemical responses in six wheat (Triticum aestivum L.) cultivars viz. C 306, C 273, PBW 175 (drought tolerant), PBW 534, PBW 343 and PBW 550 (drought susceptibile) at seedling stage for six days. Stress caused short stature in shoot and elongated roots in all cultivars. Significant reduction in chlorophyll content and increase in membrane injury index and lipid peroxide content were observed in all the cultivars. Water stress accentuated sucrose synthase/phosphate synthase activities while sucrolytic enzymes namely; acid, neutral and sucrose synthase (cleavage) got repressed. Higher build up of sucrose and lower activity of amylase in root and shoot further decreased reducing sugar (glucose, fructose) content in stressed seedlings. Though the sugar supply (sucrose) under stress was not a limiting factor for germination but the poorer ‘metabolic conversion efficiency’ via sucrolytic enzymes in root and shoot resulted in their favoured utilization in amino acid, proline and glycine betaine. It may therefore be concluded that certain traits namely: membrane stability parameters, sugars, enzymes and osmolytes might help the cultivars to tolerate water deficit conditions.
Key words: Carbohydrates, chlorophyll, sucrose metabolism, membrane stability parameters, proline, protein, starch, Triticum aestivum, water-deficit.