EFFECT OF SILICON PRIMING ON SEEDLING GROWTH, ROOT XYLEME ANATOMY AND ION ACCUMULATION OF BARLEY (Hordeum vulgare L.) TO ALLEVIATE DROUGHT STRESS

The detrimental drought effects could be listed as the loss in dry weight and silicon is known to enhance crop tolerance to drought by increasing seedling growth and hydraulic conductivity. To investigate the effects of silicon priming (0, 1 and 2 mM as sodium silicate), on seedling growth and root anatomy of three barley cultivars (Khatam, Rihane, and Nimrooz) a laboratory experiment was conducted under drought stress induced by 3.6 mM polyethylene glycol (PEG). Under 3.6 mM PEG, the highest root length was observed in Nimrooz barley cultivar (7.86 mm) at 2 mM silicon. In Nimrooz, seedling dry weight increased from 0.19 mg plant-1 in control to 0.27 mg plant-1 at 2 mM silicon (29.6% increase). At 2 mM silicon, Nimrooz with highest root surface area had the highest hydraulic conductivity (6.29×10 -9 m s-1 MPa-1) while in Rihane and Khatam was low as 5.38 and 5.19×10-9 m s-1 MPa-1 under 3.6 mM PEG, respectively. In Nimrooz, positive relationship was observed between application of 2 mM silicon and increasing the mean diameter of peripheral metaxylem vessels under drought. In all barely cultivars, drought stress affected the diameter of the vessels more than the number of the vessels. Also, under 3.6 mM PEG, K+ and Ca2+content increased from 0 mM silicon to 2 mM. Overall, silicon priming at 2 mM, especially in Nimrooz appears to be a promising and cost-effective procedure to alleviate the drought stress.