STUDIES ON THE MORPHOLOGY, PHENOLOGY AND SEED GERMINATION OF PENTACLETHRA MACROPHYLLA BENTH

ABSTRACT

The morphology, phenology and seed germination of the multipurpose African oil bean tree, Pentaclethra macrophylla Benth. belonging to the family Fabaceae were studied. The study area covered  the entire Nsukka zone of Enugu State, Nigeria, and the ten towns randomly selected included: Adani, Amalla Egazi, Ede Oballa, Eha Alumona, Eha Amufu, Ibagwa, Imilike, Nsukka, Ogrute and Orba. Morphological aspects of the study included: the bole type, branching pattern, leaf types, leaf arrangement and crown shape; height of the trees and girth of the bole at breast height; size of the leaves, raches and leaflets; thickness of  the bark, length of some of the buttress  roots and diameter of the roots 20 cm away  from the stem; type of inflorescence and flower, and morphology of pollen. The morphology of the seedling of P. macrophylla was studied and photographed from the onset of seed germination up to 40 days after germination. The phenological aspects of the species studied were period of flowering, fruiting, leaf fall (defoliation) and replacement (refoliation), fruit maturity and ripening. The phenological observations were made every month for three years (2009, 2010 and 2011). There were two flowering periods of the species within a season (May to June and October to February). Fruiting took place between December and the following August. Defoliation of P. macrophylla trees occurred mainly between the months of April and September, with very negligible percentage in the rest of the months. Refoliation was observed from the month of October to March. Fruit maturation and seed dispersal in the locations sampled started in April and ended in November in the three years of sampling. Seed germination was carried out to determine the effects of different types of media on seed germination and seedling growth of P. macrophylla. The media used were Garden soil (which served as control), saw dust (SD), 1:1 mixture of Saw dust and Garden soil (SD+GS), 1:1:1 mixture of Saw dust, Garden soil and Poultry droppings (SD+GS+PD), 1:1 mixture of Garden soil and Poultry droppings (GS+PD), 1:1 mixture of Saw dust and Poultry droppings (SD+PD). The highest percentage germination response was obtained using SD+GS+PD and GS+PD respectively which differed significantly (P<0.05) from SD+PD, SD and SD+GS. The results of the effects of mechanical scarification on the germination of oil bean seeds showed that there was remarkable improvement in the germination rate of the seeds scarified mechanically with sand paper and on rough cement floor at both the micropylar and stylar ends. The seeds scarified at the stylar end on rough cement floor began germinating 11 days after sowing while the control started germinating on the 16th day after sowing with a peak on the 19th day.  The association between tree phenology, temperature and rainfall reinforces the evidence for potential effects of changes in climate on P. macrophylla and probably other species of the Tropical Rainforest.