Effects of different nut pretreatments and substrates on germination and seedlings growth of Neocarya macrophylla Sabine in Basse Casamance, Senegal

Neocarya macrophylla Sabine (Gingerbread plum) is a tree species that plays an important role in providing ecosystem services. Despite its importance, the diversity and density of N. macrophylla stands have decreased significantly due to natural and anthropogenic factors. There is a need for better knowledge of N. macrophylla seedling production techniques for successful reforestation. This study aimed to evaluate the effects of pre-treatment and substrates on germination and growth of N. macrophylla seedlings. A completely randomized design with three replications and 12 elementary plots of nine polyethylene bags was installed. The three studied factors were provenances (Enampor and Mlomp), pre-treatments (crushed and non-crushed nuts), and substrates (cow and peanuts manures and control-sand). Nut and kernel size and weight, germination, growth parameters (height, diameter, number of leaves and lateral roots, and length of main root), and dry biomass were measured. The results showed that nut size and weight varied significantly (p<0.0005) among the provenances. Nuts from Enampor were longer (3.41 ± 0.04 cm), wider (2.89 ± 0.03 cm), and heavier (16.15 ± 0.32 g) than those from Mlomp. Pretreatments significantly (p<0.05) influenced germination rate and duration. Crushed nuts had the best rate (43.27 ± 5.19%) and germinated significantly faster (26.23 ± 1.61 days) than non-crushed nuts. Substrate significantly influenced growth parameters and biomass. Peanuts manure promoted a larger growth in height (8.92 ± 0.17 cm), diameter (0.072 ± 0.01 cm), leaf production (10.05 ± 0.18), and biomass (1.80 ± 0.20 g). Leaves (2.03 ± 0.16 g) and roots (2.10 ± 0.16 g) produced more biomass than stems (0.69 ± 0.05 g). The best performance of Neocarya macrophylla seedlings was recorded in peanuts and cow manures.