Evaluation of Water Stress in Spring Safflower (Carthamus tinctorius L.) Cultivars using Tolerance Indices in Hamadan Region

Drought as one of the most important environmental stresses causes serious threats in amount and efficiency of crop productions. To evaluate drought resistance by using drought tolerance indices in safflower varieties, a research was conducted at the Research Farm of BuAli Sina University. Experiment was planed as split-plot on the basis of randomized complete block design with three replications. Irrigation treatment as the main factor was including three levels, such as without stress (control), cut off irrigation at 50% of flowering stage to maturity (flowering stress) and cut off irrigation from the onset of seeding stage to maturity (seeding stress). Six cultivars of safflower including PI, local Ajabshir, Mec11, Faraman, local Zarghan6 and Sina were compared in three levels of irrigation treatment. The results of correlation analysis between drought tolerance indices and grain yield indicated that MP, GMP, STI, SNPI and HARM in flowering stress, and GMP, MP, STI and HARM were suitable to select high yield cultivars in seeding stage. Sina were identified as the most tolerant cultivars, while local Zarghan6 and local Ajabshir were sensitive cultivars under two stress conditions. The above findings were also confirmed by the results from biplot and three- dimensional graph of MP, STI and GMP.