Phenotypic characterization and genetic analysis for identification of trait-specific germplasm in Sunflower (Helianthus annuus L.)

An experiment conducted at TNAU, Coimbatore, during the rabi season of 2023-2024, evaluated 105 sunflower germplasm lines using ARBD. The ANOVA indicated significant differences among twelve traits, with high genetic variability observed in oil yield per plant, seed yield per plant, and hundred seed weight. Heritability and genetic advance were notably high for plant height, seed yield per plant, and oil yield per plant. Correlation analysis showed that seed yield per plant was positively correlated with plant height, head diameter, hundred seed weight, oil content, and oil yield per plant but negatively with leaf size. Path analysis revealed that oil yield per plant had the most substantial positive direct effect on seed yield, while oil content had the most significant negative direct effect. Plant height, head diameter, and hundred seed weight positively influenced yield indirectly through oil yield per plant but negatively via oil content. Principal Component Analysis (PCA) identified four principal components with Eigen values greater than 1, explaining 62.91 % of the variability. Notably, diverse genotypes included CB-GMU1189, CB-GMU-400, and CB-IB-62. Mahalanobis D2 statistics identified seven clusters, with Cluster 1 containing the most genotypes and Clusters 6 and 7 showing the highest inter-cluster distance, indicating significant genetic diversity. Cluster 5 had the highest mean for several traits. The sunflower germplasm accessions exhibited considerable variability in morphological characteristics such as hypocotyl pigmentation, leaf blistering, leaf serration, petiole pigmentation, stem pigmentation, ray floret shape, stigma pigmentation, seed shape, seed stripes, and seed stripe colour. Therefore, the accessions identified for superior traits include 14 genotypes for very high yield (>35 g/plant), five for high seed oil content (40-43 %), and 22 for high 100-seed weight (>6 g) and can be considered as superior trait-specific accessions in sunflower.