Foliar Applied Silicon Improves Water Relations, Stay Green and Enzymatic Antioxidants Activity in Late Sown Wheat

A field study was conducted to evaluate performance of late sown wheat to overcome the adversities of heat stress by the foliar applied silicon (Si) at Agronomic Farm, University of Agriculture, Faisalabad, Pakistan during two consecutive years. The study was consisted of three different sowing dates at optimum (10th November), late (10th December), very late (10th January) and an optimized dose of Si (100 mg L −1 ) was sprayed at different growth stages (control, tillering, booting and heading). Temperature was increased in late and very late sown condition at all growth stages when compared to the normal sowing. Results indicated that wheat sown under late and very late sown conditions significantly reduced the relative water content (RWC), turgor potential, osmotic potential, water potential and chlorophyll contents of flag leaves. While Si applied at heading stage offsets the adverse impact of high temperature by raising RWC water potential, osmotic potential, turgor potential and photosynthetic pigments of flag leaves. Similarly, Si alleviated the adversities of high temperature on late sown wheat by inhibiting the oxidative membrane damage due to high antioxidant enzymes activity i.e. catalase (CAT) and superoxide dismutase (SOD) which ultimately enhanced the yield of wheat under both normal and late sown conditions. Results indicate that foliar application of Si alleviates the detrimental effect of heat stress on late sown wheat by improving the antioxidants systems. From the results, it is suggested that foliar applied Si at heading stage may ameliorate the negative impacts of high temperature in late sown wheat.