Genotype–Trait Interaction Analysis in Camelina Doubled Haploid Lines Using the GGE Biplot Method

Camelina (Camelina sativa), an oilseed crop with high-quality oil, holds significant potential for food and biofuel production. Identifying high-yielding, stable genotypes is key for camelina breeding in dryland conditions. This study used the genotype-trait (GT) biplot method to explore trait relationships in camelina doubled haploid (DH) lines. Fifteen DH lines and Soheil variety were assessed in Gonbad-e Kavous under dryland conditions using a randomized complete block design with three replications in 2022. Traits including days to maturity, plant height, branching height, number of sub-branches, number of pods on the main branch, number of pods on the sub-branch, number of pods per plant, number of seeds per pod, thousand-kernel weight, seed yield, oil content, and oil yield were measured. The GT biplot accounted for 53% of total variance, with the first and second principal components explaining 28.2% and 24.8%, respectively. The GT biplot's polygonal representation identified G1 and G8 as the top genotypes for seed yield, oil yield, plant height and branching height traits. The GT biplot analysis showed positive correlations between seed and oil yields with plant height, branching height, number of pods on the sub-branch, the number of pods per plant, and the number of seeds per pod. Selecting these traits is expected to enhance seed and oil yields, which were positively correlated, whereas the association between seed yield and thousand-kernel weight was weak. The traits closest to the hypothesized ideal were the number of seeds per pod, number of pods per plant, number of pods on the sub-branch, and branching height. G15, G13, G5, and G1 were the most desirable across all evaluated traits, while G10 and G11 were the least favorable. G15 and G13 showed the greatest stability. Trait-based selection plays a crucial role in enhancing seed and oil yields in camelina breeding programs under dryland conditions.