effects of drought stress on yield and yield components in safflower genotypes (carthamus tinctorius)

in order to study the effects of drought stress on yield and yield components of safflower genotypes, a split plot based on randomized complete block design with four replications was performed at the research field, islamic azad university, arak, iran during summer of 2009. irrigation treatments included three levels of 100, 75 and 50% crop water requirement and four levels of safflower genotypes included esfahan native, esfahan-14, pi-537598 and il-111. the results showed that drought stress, reduced grain yield and seed oil of safflower. so by decreasing irrigation from 100% crop water requirement to 75 and 50% crop requirement reduced seed yield from 1198 kg ha-1 to 1081 and 936 kg ha-1, respectively. the highest seed yield was observed for esfahan native with 1402 kg ha-1. interaction effects indicated that the maximum seed yield and seed oil were achieved in 100% crop water requirement and esfahan native with 1583 kg ha-1 and 38%, respectively. the highest seed yield and seed oil were obtained for esfahan native under without and with stress. so, it concluded that this genotype of safflower could be produce acceptable amount of seed yield and oil content under water deficiency.