Foliage Applied Silicon Alleviates the Combined Effects of Salinity and Drought Stress on Wheat Seedlings

摘要

Salinity and drought are the most important abiotic stresses limiting the agricultural productivity worldwide. A greenhouse experiment was conducted to evaluate the potential of silicon (Si) in alleviating the adversities of salinity and drought stressed in wheat seedlings. Experimental treatments included control (no salinity and drought nor Si sprayed), only salinity (50 mM NaCl), only drought (40% water holding capacity), only Si (50 mM), salinity + drought (50 mM NaCl + 40% water holding capacity), salinity + Si (50 mM NaCl + 50 mM Si), drought + Si (40% water holding capacity + 50 mM Si), salinity + drought + Si (50 mM NaCl + 40% water holding capacity + 50 mM Si). Wheat seedlings exposed to salinity and drought stresses produced negative effect on morphological, physiological and biochemical attributes. Morphological attributes (shoot and root dry weight, length and biomass of seedlings); water relations, photosynthetic pigments and gas exchange parameters of wheat seedlings were adversely affected uponexposure to salinity and drought separately or in combination; however the combined effect was more negative. However, foliage applied Si significantly improved the morphology, water relations, photosynthetic pigments and gas exchange parameters of wheat seedlings under salinity and drought stress individually or in combined. Moreover, Si spray improved the activities of enzymatic antioxidants i.e. catalase, superoxide dismutase and peroxidase under salinity, drought and salinity + drought stresses. In conclusion, foliage applied Si may be a potential strategy to improve the salt and drought tolerance in wheat owing to significant rise in enzymatic antioxidants, photosynthetic pigments, photosynthesis rate, stomatal conductance and leaf turgor pressure.