the effect of irrigation disruption in different reproductive growth stages on yield, yield components and oil content in three spring safflower cultivars

oil has an important role in human food. an experiment was conducted in order to evaluate the response of spring genotypes of safflower to irrigation disruption in reproductive growth different stages, in a spilt plot arrangement based on randomized complete block design with four replications at research farm, faculty of agriculture, university of birjand during 2008. irrigation regimes (full irrigation = whole season irrigation, irrigation until grain filling, irrigation until flowering, and irrigation until heading-bud) and cultivars (mahali isfahan (a local variety), isfahan28 and il111) were arranged in main plots and subplots, respectively. results showed that irrigation until heading-bud stage caused a significant reduction in number of total and fertile head per plant, number of seeds per head, 1000-seed weight, seed yield and oil content and yield. among cultivars, mahali isfahan had the most number of total and fertile head per plant and number of seeds per head and il111 showed just the reverse response. also between yield components, number of total head per plant showed the highest correlation with yield. according to the results, mahali isfahan variety in all of the irrigation disruption regimes produced the highest kernel yield. therefore, due to the nativeness of this cultivar and high adaptation to this arid climatic zone, provide an opportunity for producing higher yields in comparison with other cultivars under water stress.