The Effect of Salicylic Acid and Methyl Jasmonate on Growth Parameters and Bulb Yield of Field – grown Onion under Drought Stress Conditions

Drought stress is the most important factor which negatively effects the plant growth and crop productivity in arid and semi-arid areas. Therefore, in a field experiment, the effect of Salicylic acid (0, 0.5 and 1mM) and Methyl jasmonate (0, 5 and 10µM) was studied on growth parameters and bulb yield of a Primavera cultivar onion under water stress conditions in 2015. The results showed that drought stress significantly reduced and SA and MJ increased all measured traits. Interactive effects of MJ × drought stress and SA × drought stress was significant on plant fresh weight, chlorophyll a, b and total, and carotenoids concentrations, relative water content, bulb length and diameter and plant height. Interaction of drought stress × methyl jasmonate × salicylic acid on the leaf number, plant dry weight, ionic leakage and the final bulb yield was significant and the highest bulb yield was obtained in non-stress condition treatment and combined 0.5 mM salicylic acid and 10µM methyl jasmonate. The highest bulb yield in drought stress conditions was obtained when plants were exposed to 1mM salicylic acid and 10µM methyl jasmonate treatment.