Additive Gene Action and Cross-Specific Heterosis Shape Yield Traits in Pigeonpea: Evidence from NC-III Design

Understanding the relative contribution of additive and non-additive gene effects is essential for designing efficient breeding strategies in pigeonpea ( Cajanus cajan (L.) Millsp.). The present study employed a North Carolina Design III (NC-III) in biparental populations derived from three crosses (PADT-16 × Pusa 992, PADT-16 × UPAS 120, and PADT-16 × PAU 881) to simultaneously dissect genetic variance components, heritability, and heterotic responses for ten agronomic traits. Significant variability among progenies indicated effective recombination and generation of exploitable genetic diversity. Additive variance predominated for most traits, particularly number of pods per plant and plant height, suggesting high potential for selection-based improvement, whereas dominance effects were appreciable for seed yield and pod length in specific crosses, indicating the importance of non-additive gene action. Moderate to high narrow-sense heritability coupled with substantial genetic advance further supported the effectiveness of early-generation selection for key traits. Heterosis analysis revealed cross-specific advantages, with PADT-16 × Pusa 992 exhibiting superior performance for yield-related traits, while PADT-16 × PAU 881 was advantageous for earliness and seed attributes. By integrating variance components, heritability, variability, and heterotic responses, this study proposes a trait-specific and cross-specific breeding framework that aligns genetic architecture with optimized selection strategies. The findings provide practical insights for improving yield and adaptability in pigeonpea and demonstrate the utility of NC-III-derived biparental populations for decision-oriented breeding.