Trait interrelationships and composite bio-yield potential index-based selection of Pongamia pinnata (L.) Pierre genotypes for biofuel feedstock improvement

Pongamia pinnata (L.) Pierre is a promising non-edible, leguminous tree-borne oilseed species with strong potential as a feedstock for biofuel and sustainable aviation fuel (SAF). This study evaluated 20 P. pinnata genotypes from different parts of Tamil Nadu to quantify variability in pod, seed and shell traits and to identify superior genotypes. Substantial variation was observed with pod length, pod breadth, seed length and 100 seed weight (130.5–205.4 g). Shell percentage showed wide variation (36.2–57.8 %) and was negatively correlated with 100-seed weight (r = -0.48), whereas seed traits exhibited strong positive correlations with seed weight (r = 0.62–0.78), indicating their collective influence on kernel biomass. Principal component analysis (PCA) explained 72.4 % of the total variation in the first 3 components and, together with heatmap clustering, grouped trees into distinct performance categories. To integrate key bioresource traits, a composite bio-yield potential index (BPI) was formulated from standardized pod yield, 100 seed weight and shell percentage and it ranged from 0.60– 0.84. Five genotypes viz., PP14, PP11, PP19, PP10 and PP2 were identified as elite, combining heavier seeds with lower shell proportions (36–49 %), traits favourable for improved oil recovery. Overall, integrating trait interrelationships with multivariate and composite index approaches proved effective for identifying high-yielding P. pinnata trees. The selected elite genotypes provide a strong foundation for genetic improvement, seed orchard development and the establishment of suitable feedstock resources to support India’s expanding biofuel and SAF sectors.