Graphic analysis of relationships between traits and selection of superior hybrids in sunflower

The sunflower is one of the most important oilseed plants in the world that its oil has nutritional and high economic value. Therefore, the selection of high yielding genotypes is especially important in this plant. In this regard, 11 new hybrids along with four cultivars Golsa, Ghasem, Shams and Farrokh were evaluated in a randomized complete block design with four replications in agriculture research station of Dezful during 2018-2020. In this study, the methods of genotype × trait (GT) and genotype by yield × trait biplot (GYT) were used to identify interrelationships between different traits and selection of the best sunflower genotypes. Based on polygon view of GT biplot, the genotype No. 1 had good characteristics regarding seed yield and traits related to yield. The vector view of GT biplot showed high correlation between seed yield with stem diameter, plant height, head diameter and seed number per head. Based on average tester coordinate (ATC) view of GYT biplot, the genotypes No. 1 and 6 in terms of all positive yield-trait combinations were recognized as the best genotypes and genotypes No. 12, and 7 as the weakest genotypes. According to the results, a significant positive correlation was observed between stem diameter, head diameter, plant height and early maturity in combination with seed yield. Therefore, it seems that traits of stem diameter, head diameter, plant height and early maturity could be used as a suitable selection criterions for increasing seed yield in sunflower.