Development of short duration and high yielding indigenous sunflower (Helianthus annuus L.) hybrids

Thirty-eight sunflower hybrids were evaluated for eight agronomic characters under field conditions at the National Agricultural Research Centre (NARC), Islamabad, during the spring 2012. Significance for various characters along with better mean performance for yield indicated the diverse nature of hybrids and selection of better hybrids. In general, genotypic correlations were higher than the corresponding phenotypic correlations that revealed the genetic contribution for the associated response. Days to flower initiation, completion and maturity had positive and highly significant genotypic and phenotypic correlations with plant height. Head diameter had highly significant and genotypic positive association with the plant height. Similarly, oil contents were also significantly and positively associated with the plant height. Hundred seed weight had positive but non-significant association with the head diameter and the seed yield at both levels, which are an indicator of association among the associated traits that by improving head size and seed weight, the seed yield can be increased significantly. Seed yield had negative correlation with oil contents and suggested to break it either through conventional or novel breeding techniques to breed high yielding hybrids with maximum oil contents. The highest indirect positive effect was observed via days to flower initiation, followed by plant height, days to maturity, head diameter and oil contents, hence these characters may be given more emphasis while selecting high yielding sunflower hybrids. Cluster diagram based on Euclidean dissimilarity revealed five clusters at 25% linkage distance; cluster-I consisted of 9 genotypes, cluster-II 7, cluster-III 9 genotypes, cluster-IV 5 and cluster-V had 8 hybrids. Most of the locally developed hybrids fall under cluster-III and cluster V. The scattered diagram and cluster pattern were in coordination and the grouping was mainly attributed toward agronomic performance.