Genotype × year interaction of pod and seed mass and stability of Pongamia pinnata families in a semi-arid region

Abstract

Sixteen pongamia families were evaluated in a field experiment for eight consecutive years in dryland conditions to identify stable, high-yielding families. The trial was conducted in a randomized complete block design with three replications. Each family, consisting of nine trees per replication, was planted at a spacing of 3 m × 3 m. Yield stability was analyzed using (1) Eberhart and Russel’s regression coefficient (βi) and deviation from regression ($$S_{\text{d}}^{2}$$), (2) Wrike’s ecovalence ($$W_{i}$$); (3) Shukla stability variance ($$\sigma_{i}^{2}$$); and (4) Piepho and Lotito’s stability index ($$L_{i}$$). Families were also analyzed for adaptability and stability using AMMI and GGE biplots graphical methods. The study revealed significant variances due to family and family × year interaction for pod and seed yield. Families performed differently and ranked differently across years. The performance of families was influenced by both genetic factor and environmental conditions in different years. Among families tested, TNMP20, Acc14, TNMP14 and Acc30 were high yielders for pods, and Acc14, Acc30, TNMP6, RAK19 and TNMP14 were high for seed yield. According to the Eberhart and Russell model, Acc30, TNMP14 and TNMP3 were stable across years. In the graphical view of family × year interaction based on AMMI methods, TNMP3, TNMP4 and TNMP14 had greater stability with moderate seed yield, and Acc14 and Acc30 had moderate stability with high seed yield. On the other hand, GGE biplots revealed Acc14, Acc30 and TNMP14 as high yielders with moderate stability. AMMI and GGE biplots were able to capture nonlinear parts of the family × year interaction that were not be captured by the Eberhart and Russel model while also identifying stable families. Based on different methodologies, Acc14, Acc30 and TNMP14 were identified as high yielding and stable families for promoting pongamia cultivation as a biofuel crop for semi-arid regions.