Evaluation of yield of safflower (Carthamus tinctorius L.) genotypes under semi-arid conditions

To identify appropriate genotypes for breeding varieties suitable for semi-arid areas, yield components, as well as morphophonological traits of 127 safflower genotypes, were assessed at the Seed and Plant Improvement Institute, Iran. Cluster analysis revealed four distinct groups. The largest group (third cluster) includes 48 genotypes with characteristics such as mostly yellow-coloured flowers, mostly thorny with few thistle genotypes, relatively early-flowering, relatively high number of heads and grains per plant, highest 1000-grain weight with the highest grain yields. In contrast, the smallest group (second cluster) contains 13 genotypes with characteristics such as yellow florets, semi-dwarf, thorny, moderately late-flowering, low number of heads per plant and number of grains per head, low 1000-grain weight, and low grain yield. Principal component analysis results showed that the three components accounted for 29.5, 15.9 and 11.1% of the total variation, respectively. Graphic representation of the biplots based on the first and second principal components showed that the experimental genotypes were classified into four groups. The results also indicated that stem diameter, the number of branches, heads per plant and grains per head had the highest correlation with the first component, and grain yield, flower colour, flowering initiation and plant height had the highest correlation with the second component. These traits can be considered as an appropriate index for the selection of elite safflower genotypes for breeding varieties suited to cultivation in semi-arid conditions.