Effect of Seed Priming with Salicylic Acid and Jasmonic Acid on Emergence and Early Growth of Pumpkin (Cucurbita pepo L.) Seedlings under Drought Stress Condition

In order to study the effect of seed priming with salicylic acid (SA) and jasmonic acid (JA) on emergence and early growth of pumpkin (Cucurbita pepo L.) seedlings  under drought stress condition, a factorial experiment based on randomized complete block design (RCBD) with four replications was conducted at the greenhouse of Malayer university. Experimental treatments were seed priming with salicylic acid (0, 100 and 200 ppm) and jasmonic acid (0, 50 and 100 ppm) and three levels of drought stress (100, 60 and 30% of field capacity). Based on results, drought stress significantly (P≤0.05) affected the percentage and rate of seedling emergence. In the severe drought stress (30% of field capacity) percentage and rate of seedling emergence were decreased 10% and 54%, respectively. Furthermore, seedling length, seedling dry weight and seedling length vigor index were decreased 11%, 9% and 25%, respectively, whereas at the same condition malondialdehyde and proline content increased 84% and 13%, respectively. Severe drought stress also increased the activity of catalase and proxidase enzymes in pumpkin seedlings up to 39 and 57 percent, respectively. Seed priming with salicylic acid and jasmonic acid significantly (P≤0.05) decreased the negative effect of drought stress on all of the studied traits except seedling emergence percentage. Simultaneous priming with highest level of salicylic acid and jasmonic acid resulted in highest drought tolerance in pumpkin seedlings