Safflower (Carthamus tinctorius L.) is one of the native plants of our country, which has received attention due to its seed oil quality and tolerance to abiotic stresses in climate change conditions. It is important to know about the diversity or genetic similarity of populations and individuals within them, for the effective use of the genetic resources in breeding programs. The expansion of germplasm resources through crossing between genotypes will greatly help to increase the efficiency of safflower breeding programs. In this study, 64 genotypes including 10 parental genotypes and 45 populations of F2 generation resulting from their crossing and 9 globally selected genotypes as controls were investigated in two irrigation regimes of 90% soil moisture depletion and normal irrigation at 50% moisture discharge. According to this study, high genetic diversity was observed among the genotypes and the effect of genotype on all studied traits and the effect of moisture environment and the interaction effect of genotype with moisture environment on most traits in the F2 generation were significant. Heritability was high for most of the traits including grain yield, which indicates the genetic potential of these traits to be improved genetically. Based on the correlation cofficients results, the trait of plant height with phenological traits and thousand seed weight with grain yield were significant. The results of the mean comparison as well as biplots showed that the presence of G9 parent, which had a high stress tolerance index, in most of the crosses increased the performance stability and increased stress tolerance index of the F2 populations. In addition, parent G74, which had good performance under stress conditions, in combination with G40 and G71, increased the stability index of the mentioned crosses. In general, the results of this research showed that in the studied germplasm, due to exist of high diversity, it is possible to improve most of the traits. In the enzyme study section, the mean comparison of leaf ascorbate peroxidase enzyme in the parents showed that parent G40 had a higher amount of leaf ascorbate peroxidase enzyme concentration, which is related to the amount of catalase enzyme. Genetic analysis by Griffing method showed that in the eva‎luated F2 generations and in both moisture conditions, both additive and non-additive effects were involved in the genetic control of the traits, but for most of them, non-additive effects was more important. Therefore, the production of hybrids and the use of heterosis can be effective in improving these traits. In the genetic study section, the variance of general combining ability (GCA) in normal moisture condition was significant for all the traits, including day to heading, which indicates the importance of additive effects in genetic control of these traits. Under drought stress conditions, GCA were also significant for all traits except for the number of heads per plant, the relative content of leaf water content and the number of branches per plant. The significance of GCA variance indicates the importance of the additive action of the genes in controlling these traits and selection can be useful for improving these traits. Also, the variance of specific combining ability (SCA) in normal moisture condition was significant for all traits, except for head diameter, number of branches per plant and relative leaf water content, but under conditions of moisture stress, the the SCA was significant for days to tillering, head diameter, RWC and 1000-seed weight, which shows that heterosis can be effective for improving these traits.

محمد مهدي مجيدي , قدرت اله سعيدي

مجيد محمدي

محمدرضا سبزعليان دستجردي , سعيد انصاري مهياري