Effect of seed priming on photosynthetic pigments, seed yield and yield components of safflower (Carthamus tinctorius L.) cultivars under drought stress conditions

Seed priming is an effective method for mitigating water stress effect and improving crop yields. To study the effect of seed priming on photosynthetic pigments, seed yield and yield components of safflower cultivars under water stress conditions a field experiment was conducted as split plot factorial arrangement using randomized complete block design with three replications at Shahrood Agricultural and Natural Resources Research and Education Center, Iran for two years (2015 and 2016). The main plot consisted of irrigation at three levels based on the evaporation from class A evaporation pan including; non water stress (60 mm evaporation), mild water stress (120 mm evaporation) and severe water deficit stress (180 mm evaporation) and subplots consisted of factorial of two factors including; safflower cultivars (Goldasht, Sina and Soffeh) and seed priming (Treated seeds with salicylic acid and non treated seeds). Results showed significant increase in seed yield and its components in priming treatment compared to control both years. Therefore, by applying priming, seed yield and oil yield increased by 8 and 14 percent, respectively. Goldasht cultivar had the highest chlorophyll content under non stress (6.29 mg.g-1FW) and mild stress conditions which resulted in high seed yield and yield components in this cultivar. The highest seed yield (3800 kg.ha-1) was obtained from Goldasht cultivar primed with salicylic acid under non-stressed conditions. However, the highest oil yield (886 kg.ha-1) was obtained from Soffeh cultivar. Results showed that severe stress significantly reduced all measured traits in all cultivars. Under severe stress seed yield (2257 kg.ha-1), oil yield (604 kg.ha-1) and total chlorophyll content (4.72 mg.g-1FW) decreased by 29, 36 and 32 percent, respectively. It can be conluded that application of seed priming with salicylic acid increased seed yield and improved tolerance of safflower cultivars under water stress conditions.