Foliar Applied Silicon Improves Water Relations, Chlorophyll Contents and Antioxidants in Late Wheat Planting.

In rice-wheat and cotton-wheat cropping systems, late planting of wheat is a major concern and cause significant reduction in yield due to sudden rise in temperature at reproductive phase of the wheat crop. High temperature stress induces changes in water relations, decrease photosynthesis and cell membrane thermostability. Silicon (Si), being a beneficial nutrient provides significant benefits to plants at growth and developmental stages and may mitigate the adversities of heat stress. A field study was conducted at Agronomic Research Area University of Agriculture; Faisalabad Pakistan to assess the performance of late sown wheat by the foliar applied Si. Experiment was comprised of three sowing dates; 10^th Nov (normal), 10^th Dec (late), 10^th Jan (very late), two wheat varieties (Sehar-2006 and Faisalabad -2008) and optimized dose of Si (100 mg L^-1) sprayed at different growth stages (control, tillering, booting and heading). Results indicated that 100 mg L^-1 foliar applied Si at heading stage offset the negative impact of high temperature and induced heat tolerance in late sown wheat. Silicon application improved relative water contents (RWC), water potential, osmotic potential, turgor potential and chlorophyll contents in wheat flag leaf. Results further demonstrated that Silicon application alleviates the adversities of high temperature by preventing the oxidative membrane damage due to enhanced activity of superoxide dismutase (SOD) and Catalase (CAT). Overall results of this field study demonstrated that foliar application of Silicon (100 mg L^-1) at heading stage enhanced the water relations, chlorophyll contents and antioxidants in wheat flag leaf which ameliorated the adverse effects of high temperature in late sown wheat.

Key words: Silicon, high temperature, antioxidants, water relations, late sown wheat