Photosynthetic characteristics and enzymatic antioxidant capacity of flag leaf and the grain yield in two cultivars ofTriticum aestivum (L.) exposed to warmer growth conditions

Using late sowing practice, the reproductive growth (anthesis and kernel filling) phase of two wheat cultivars, HD1553 and HD2307 was exposed to warmer growth conditions, and the effect on grain yield was examined. The grain weight declined in late-sown plants of both cultivars, but the number of grains per spike decreased drastically in HD1553 plants. In this cultivar exposure to warmer temperature during reproductive phase led to 67 percnt; fewer grains per spike. Examination of photosynthetic and enzymatic antioxidant capacity in flag leaves of late-sown plants revealed a marked reduction in chlorophyll and carotenoid pigmentation in addition to a decline in the activity of H2O2 metabolising enzymes in HD1553 cultivar. The photo-oxidative pigment loss due to warmer growth conditions in late-shown HD1553 plants could lead to a reduction in flag leaf photosynthesis and contribute to poor grain yield.