study of some physiological traits and yield in spring safflower under water deficit stress

safflower oil seed has high adaptability to different kinds of abiotic stresses such as drought and salinity. the aim of this study was to evaluate the effects of drought stress at different phenological stages on relative water content (rwc), leaf canopy temperature, seed yield and its components in spring types of safflower. the study was carried out in east azarbaijan research center for agriculture and natural resources, (46? and 2? e, 37? and 58? n) during 2007. a factorial experiment including 4 irrigation levels (non- stressed and drought stressed during stem elongation, flowering and seed filling stages) and 2 safflower genotypes (local arak-2811 and local esfahan) based on a complete randomized block design with 3 replications was used. the results indicated that rwc, plant height, capitulum height, capitulum diameter, capitula per plant, seeds per capitulum, 1000 seeds weight and seed and oil yields were significantly decreased and leaf canopy temperature was significantly increased by imposing water deficit during different phenological stages. drought stress at flowering and seed filling stages, led to the highest decrease in seed and oil yields. therefore, it is necessary to provide enough water to get acceptable yield at these stages. between studied genotypes significant differences were detected in rwc, capitula per plant, seeds per capitulum, seed oil percent, seed and oil yields. local esfahan in comparison with local arak-2811 had higher values in stressed and non-stressed conditions. among seed yield with capitula per plant, seeds per capitulum, capitulum diameter, 1000 seeds weight and harvest index, positive and significant correlations were observed. also between rwc and leaf canopy temperature with each other and with seed and oil yields significant correlations were achieved. it seems that rwc and leaf canopy temperature can be used to evaluate water deficit effects on spring types of safflower.