In vitro seed germination for the seedling rescue of Buchanania cochinchinensis (Lour.) M.R. Almeida - a valuable tropical forest tree

Buchanania cochinchinensis (Lour.) M.R. Almeida is a tropical tree from the Anacardiaceae family. Because of the high nutritional value of its seeds and the medicinal properties of various parts, the tree species is socio-economically important. This tree is a rich source of phyto chemicals of great medicinal value in root, bark, leaf, fruit and seeds. This multifunctional tree serves as a vital economic resource for tribal people living in Indian forests by providing food, fuel, fodder, timber, and medicine. However, the tree is at serious risk of extinction due to a lack of natural regeneration capacity and overexploitation of natural habitat. The seeds are the major source of propagation of B. cochinchinensis, but the main constraint is the low germination frequency caused by hard shell and fungal infestation during germination. Traditional plant propagation methods like vegetative propagation are time-consuming and inefficient for this species. A need for alternative seed germination strategies for quality planting material is imperative. Therefore, seed germination was carried out in the current study under ex vitro as well as in vitro condition. The germination of 52% was observed in seeds germinated in the greenhouse with a low seedling conversion rate. Total soluble sugars were estimated from different parts of the B. cochinchinensis seedling; to investigate this low germination rate. The investigation revealed that the root part had the maximum soluble sugar, followed by cotyledons, and the dried kernels had the least. Therefore, in vitro seed germination was attempted with the insight that higher sugars in the early-stage seedlings might be responsible for a low germination rate due to fungal attacks. Murashige and Skoog medium at full and half-strength was used for seed germination, along with different sucrose concentrations- 0%, 1%, 2%, 3%, 4.5% or 6%. Half-strength MS medium fortified with 3% sucrose resulted in highest germination (96.60%) and seedling conversion (60%). Further, during acclimatization, in vitro seedlings survived at a rate of 80%, more than the ex vitro greenhouse-raised seedlings. This study proposed an efficient in vitro seed germination protocol for mass propagation of B. cochinchinensis, where the early-stage susceptible seedlings could be rescued from fungal attack.