Abstract Salinity stress is one of the most important abiotic stresses that plays a very important role in reducing plant yield. In order to investigate the effect of salinity stress on morphological and agronomic traits, this study was performed on 49 recombinant genotypes resulting from crosses among three species (Carthamus tinctorius L) (first study) as well as 100 genotypes of a world wide collection of safflower (second study). Experiments was carried out in the research farm of the Faculty of Agriculture of Isfahan University of Technology, located in Lavark, Najafabad, in 2020-21 crop year. Genotypes were eva‎luated under salinity stress and non-salinity stresses as a complety randomized block design. The results of the first study showed that there is a high genetic variation among the recombinant lines in terms of tolerate salinity stress, agronomic and morphological traits. The highest value of broad sense heritability in non-salinity stress conditions was related to 100-seed weight (71.42%) and then plant height (66.93%). Heritability in salinity stress environment was highest for oil content with 75.22% and plant height with 60.63%. Salinity stress reduced head weight per plant, 100-seed weight, grain yield per plant and plant height. The highest percentage of reduction related to grain yield per plant was 54.53% and the lowest percentage of reduction was related to height trait with 5.9% decrease. Stress tolerance index showed positive correlation with traits such as 100-seed weight, day to maturity, day up to 50% flowering and seed oil percentage. Stability index also has a significant correlation with oil percentage. In salinity stress environment, head diameter had a high and significant correlation with traits such as head weight, 100-grain weight and grain yield per plant. The results of the second study showed that there was a very high diversity in the studied germplasm in terms of all traits and tolerance to salinity stress. Existence of high yielding and stress tolerant foreign cultivars showed that exotic germplasm are useful as gene pool for improving yield, drought tolerance and some undesirable characteristics of domestic cultivars (such as late maturity and height). Based on the results G96 cultivar from Kermanshah, was the best in terms of YSI performance stability index (the least changes from normal to stress environment). On the other hand, G52 cultivar from the United States can be introduced as the most tolerant to salinity stress in terms of STI index (highest performance in both environments). G90 cultivars from Kerman and G96 from Kermanshah in both stress and non-stress environments had the highest percentage of seed oil. Since safflower and its close relatives are diffused in a wide geographical range from east to west of the world and especially Iran and in some of these areas due to the special climatic conditions there is a possibility of development of special accession, the results of this study can useful for breeding of traits in the future.

محمد مهدي مجيدي، قدرت اله سعيدي

فرشيد نور بخش، حسين اهتمام