Evaluación del rendimiento y otros atributos agronómicos en el germoplasma comercial de girasol argentino (1986-2006)

Sunflower breeding in Argentina resulted in a constant genetic progress for yield in all growing regions of this species. In this study, we applied linear mixed models and multivariate analyses to an historical series of 17 years of trials belonging to the territorial trial net (RET), conducted at the Pergamino Research Station of INTA. The aim was to contribute to the knowledge of the variability observed for phenotypical traits in sunflower hybrids released during the period 1986-2006. Cluster analysis applied to the hybrid × attribute matrix allowed grouping the 64 hybrids tested for at least 3 years into 5 groups differing in the average year of release of the component hybrids. Principal component analysis showed positive association between oil yield and its immediate determinants grain yield and oil concentration, lack of association between both determinants and positive association between time to flowering and height; both traits being negatively associated with oil concentration, positively associated with grain yield and showing lack of association with oil yield. Two groups of hybrids of different genetic origin converged through years of plant breeding into a new type of high grain and oil yield and intermediate maturity and height. Modern hybrids do not longer show the variability for agronomic traits that the old hybrids used to present.