Multivariate analysis for the development of an ideotype of ornamental sunflower (Helianthus annuus L.) in the autumn season
Abstract
The development ideotype ornamental sunflower (Helianthus annuus L.) in autumn has a strategic value because few flowers are available in autumn. This study was conducted to assess the genetic diversity and elite lines that perform better in the autumn season. To fill this gap, 28 multi-headed genotypes that are genetically different were evaluated under semi-controlled conditions of pot culture in a completely randomized design (CRD) with three replications at the Department of Plant Breeding and Genetics, University of Agriculture, Faisalabad, Pakistan. Data were recorded on different parameters such as: Plant height, Stem diameter, Head diameter, Number of heads per plant, Number of leaves and leaf width. Analysis of variance (ANOVA) revealed highly significant variation for all the recoded traits, which substantially shows that there is high genetic variability in the germplasm. Correlation analysis revealed that vegetative traits were strongly and positively correlated with each other, whereas head diameter demonstrated negative correlations with most parameters, which provided evidence of a resource allocation trade-off between vegetative vigor and floral display. Principal component analysis accounted for 58.2 percent of overall variance in the first two components and hierarchical cluster analysis organized the genotypes into two separate phenotypic groups, with Cluster I having homogeneous ideotype-proximate materials and Cluster II having divergent genotypes that could be candidates to provide new combination of traits. The ornamental sunflower ideotype was a medium to small plant height, multiple heads per plant, medium to large diameter of the head, strong stem, and early flowering. Direct selection with genotypes similar to this ideotype is suggested, and divergent members of a cluster are to be utilized as parents in hybridization programs to obtain better ornamental sunflower varieties.