Effects of Seed Treatment and Bio-inoculants on Baikiaea plurijuga DC. and Pterocarpus angolensis Harms Seed Germination

Background: This study examined the effect of pre-sowing seed treatments and microbial inoculation on the germination of Pterocarpus angolensis and Baikiaea plurijuga at the Botswana University of Agriculture and Natural Resources. Methods: This tree nursery study employed a 2 × 4 × 2 factorial, randomised experiment to test four pre-sowing treatments: mechanical scarification, soaking in rainwater and warm water (40°C) and untreated seeds- alongside two levels of microbial inoculation: with and without B. ripae. Result: Mechanical scarification slightly improved germination, leading to earlier and more uniform germination in both species, with P. angolensis exhibiting a mean germination time of 10.5 days and a germination velocity coefficient of 9.57. P. angolensis germination decreased from 80.83% to 66.7%, indicating an incompatibility with B. ripae. Conversely, B. plurijuga germination increased from 70.84% to 91.67%. The findings demonstrate that scarification enhances germination in both species and can be used to improve native seedling protocols for the regeneration of dryland forests.