Evaluation of red sanders (Pterocarpus santalinus L.f.) germplasm for conservation and breeding

Pterocarpus santalinus L.f., an endangered species endemic to India’s Eastern Ghats, faces threats from illegal trade due to high demand and limited legal supply. Field genebanks are essential for conserving genetic diversity and supporting sustainable use. This study evaluated a 12-year-old P. santalinus germplasm collection of 500 accessions, grown ex situ, for growth and heartwood traits. The survival rate was 80%, with notable variation in tree height (5.5–11.8m), girth at breast height (GBH, 26–78cm), clear bole height (0–6.2m), and heartwood core length (0–6.6cm), indicating substantial genetic diversity. Early heartwood formation (< 12 years) occurred in 18.50% of accessions, earlier than the typical 15 years. Superior accessions included S5R1-19 (6.6cm heartwood) and S7R1-4 (5.5cm), while S1R1-13, S5R4-20, and S1R3-18 exhibited desirable deep red heartwood. Accessions from Petbasheerabad showed high survival and heartwood yield, suggesting their value as elite seed sources. GBH positively correlated with heartwood length (r = 0.443), supporting its use as a selection trait. Principal component analysis and clustering grouped accessions into three clusters: Cluster 1 showed superior timber traits (high clear bole, low percentage of forking), whereas Cluster 3 displayed less desirable traits. These findings aid in identifying elite accessions and developing conservation and breeding strategies. Integration of molecular tools such as genome-wide association studies and transcriptomics is recommended to accelerate genetic improvement.