Classification of confectionary sunflower genotypes based on morphological characters

Abstract

SUMMARYKnowledge of genetic diversity of confectionary sunflower can have a large impact on its use in breeding programmes. However, levels and distribution of genetic variation within the confectionary sunflower gene pool are still not adequately explored. The aim of the present paper was to describe the diversity of 68 confectionary sunflower genotypes: open-pollinated varieties, lines and hybrids. A total of 32 morphological traits were used for characterization. The Shannon & Weaver diversity index (H) was estimated as a measure of morphological diversity. The mean value of the Shannon index was 0·71, which indicates a high morphological diversity. The lowest diversity was found for leaf descriptors, moderately high to high for seed traits, while the highest values were found for disc flowers and ray florets. The highest individual descriptor diversity was found for: head attitude, the angle of leaf lateral nerves and ray floret disposition. The homogeneity analysis (HOMALS) multivariate reduction technique for nominal categorical data proved to be an efficient method for a comprehensive overview of genotype diversity and group homogeneity. Besides diversity, the number of categories and uniformity of genotype distribution determines discriminative power of descriptors. Traits that contributed the most to the distinction of genotypes were identified, enabling differentiation of genotypes with similar phenotypic attributes. The highest discriminative power was observed in traits such as anthocyanin colouration of stigma (DFIA), seed colour of stripes and seed main colour. The genotypes tested formed two distinctive major groups of varieties and hybrids with inbred lines widely dispersed along both axes. A separate grouping was obtained per the most discriminative traits based on HOMALS analysis, while the best separation was obtained using DFIA. Isolated genotypes that may not be representative by yield or seed-specific traits can be useful sources of traits for breeding. Morphological characterization can be used to improve description and classification of confectionary sunflower germplasm when evaluating diversity.