Safflower genetic diversity based on agronomic characteristics in Mato Grosso state, Brazil, for a crop improvement program
Safflower, Carthamus tinctorius (Asteraceae), is an oilseed plant with good adaptability to warm and dry climatic conditions. It is used for biodiesel production, human food, animal feed, and in the pharmaceutical industry. Recently, the crop has been highlighted, mainly for its oil quality and for biofuel production. We compared 124 safflower genotypes, which are a part of the State University of Mato Grosso germplasm collection, based on their agronomic characteristics, to provide the initial guidelines for a breeding program. Evaluations were carried out during the crop cycle and parameters were defined according to the descriptions recommended by International Board for Plant Genetic Resources and by the Ministry of Agriculture, Livestock and Supply. Multivariate analysis was used to assess the divergence among genotypes, by using Average Euclidean Distance, which ranged from 0.07 to 0.57, showing considerable genetic diversity among safflower genotypes for the agronomic characteristics that were evaluated (flowering, plant cycle, number of branches per plant, plant height, number of chapters per plant, number of seeds per chapter, chapter diameter, stem diameter, weight of 100 seeds, seed size and plant yield. Tocher and Unweighted Pair Group Method with Arithmetic Mean (UPGMA) clustering methods were partially consistent in ordering similar genotypes. The agronomic characteristics: plant yield, number of chapters per plant and plant height provided the greatest contribution to genetic divergence among the genotypes. According to the groupings established with each methodology and depending on the variation structures within each group, several genotypes stood out in terms of agronomic performance and may be indicated for future crosses aiming to obtain improved safflower cultivars for Brazil.