Seed collection, extraction and germination performance of six multipurpose tree species under tropical conditions

Abstract

The successful propagation of multipurpose tree species is essential for tropical reforestation, agroforestry, and ecological restoration initiatives. This study was conducted to evaluate seed collection, extraction methods, and germination performance of six important tropical tree species: Mimusops elengi, Inga dulcis, Swietenia macrophylla, Acacia mangium, Acacia auriculiformis, and Caesalpinia decapetala. Seeds were collected from mature fruits during the 2024 summer season and subjected to species-specific pre-sowing treatments such as soaking, scarification, and manual cleaning. The experiment followed a Completely Randomized Design (CRD) with three replications per species under controlled nursery conditions. Significant interspecific variation was recorded for all germination parameters. Inga dulcis showed the highest germination percentage (93%), germination energy (85%), germination value (6.8), and seedling vigour index (2790), indicating superior propagation potential. Acacia mangium and Acacia auriculiformis also performed well, showing rapid and uniform germination. In contrast, Swietenia macrophylla failed to germinate, while Caesalpinia decapetala showed very poor germination (1.6%), likely due to dormancy and recalcitrant seed behavior. Statistical analysis revealed significant differences (p<0.05) among treatments for all measured parameters, with CD (5%) values confirming meaningful distinctions. The results are in agreement with prior studies and underscore the need for species-specific seed handling strategies. The study concludes that Inga dulcis, Acacia mangium, and A. auriculiformis are highly suitable for large-scale nursery propagation, while further research is needed to enhance the germination success of S. macrophylla and C. decapetala. These findings offer practical insights for forestry managers, ecologists, and nursery practitioners involved in tropical tree conservation and restoration programs.