Evaluation of the World Collection of Safflower, Carthamus tinctorius L. IV. Yield and Yield Components and Their Relationships1

A study of a collection of 903 varieties of safflower (Carthamus tinctorius L.) for the mean yield per plant and the three major yield components, number of heads per plant, number of seeds per head, and seed weight, revealed marked differences in the potential of lines from different origins. Because of the mutual compensation of the yield components, the differences in yield were not as marked as they were for the components. The collection contains an abundance of genetic variability which is available for breeding higher‐yielding safflower varieties. There were regional differences in the components due to human and/or natural selection. A multiple stepwise regression analysis showed that the most important yield component was the number of heads per plant. The number of seeds per head was of little importance, except for lines from Iran. Seed weight had no effect on yield per plant, except for a minor influence in the Iranian lines. The number of heads per plant had negative but negligible correlations with oil content. Yield per plant was not correlated with season length or oil content. Since the findings were obtained under spaced nursery conditions, they are not necessarily applicable directly to dense field stands.