Genetic Diversity and Correlation Analysis in Sunflower (Helianthus annuus L.) Genotypes

The experimental trial was conducted at the Oilseeds Research Institute, Agriculture Research Center (ARC), Tando Jam, during the Rabi season of 2023. Analysis of variance revealed significant differences (p < 0.01) for all traits studied, indicating substantial variation among the sunflower genotypes. The genotype SMH-1900-E demonstrated the highest germination percentage (87.66%), while SMH-1900-A had the shortest time to first flowering (62.66 days) and maturity (99.33 days). SAHRA-SUN-66 showed the largest head diameter (15.33 cm), and ACSUN-F1 recorded the highest 1000-grain weight (44.00 g). The highest seed yield plant-1 was observed in ORISUN-701 (761.3 g), while FH-829 had the highest seed yield per hectare (568.7 kg ha-1). Correlation analysis revealed significant positive relationships between days to first flowering and germination (r = 0.22*), plant height (r = 0.31*), head diameter (r = 0.35**), and 1000-seed weight (r = 0.33**). Plant height had a significant positive correlation with 1000-seed weight (r = 0.24*) and seed yield plant-1 (r = 0.53**). Head diameter was positively correlated with the number of seeds per head (r = 0.24*), seed yield plant-1 (r = 0.21*), and seed yield per hectare (r = 0.22*). Additionally, plant population showed a significant positive correlation with seed yield plant-1 (r = 0.29*). A dendrogram based on Jaccard’s similarity coefficients, generated by UPGMA cluster analysis, classified the genotypes into two main clusters. Cluster 1 included nine genotypes, while Cluster 2 comprised eleven genotypes, indicating distinct relationships between the groups. Principal Component Analysis (PCA) identified that plant height, germination rate, number of seeds per head, and seed yield (kg ha-1) were the main factors contributing to genotype variation. The highest variability was explained by PC-VI and PC-VII, accounting for 98.3% and 97.1% of the total variation, respectively.