Population Structure in Natural Stands, Seed Germination and Seedling Growth of Sterculia setigera under Nursery Conditions in Burkina Faso (West Africa)

Abstract

The present study aimed at evaluating S. setigera population structure in natural stands and estimating the effect of pretreatment methods on seeds’ germination capacity and seedling establishment. Dendrometrical measurements were performed on 504 S. setigera trees for population structure assessment. The bell shaped structure obtained indicates that the population of S. setigera is unstable and under threat due to lack of recruitments under threat due to lack of recruitments. An experimental design with four randomized blocks corresponding to four replicates of 25 seeds in each pretreatment (sulphuric acid, boiling water, water at room temperature and the control) was used. Seeds were sown in a medium of clay and dung in the ratio 2:1, in polythene plastic pots measuring 7.5 x 25.5 cm. A total of 400 plastic pots were used in this experiment and kept moist. Forty days after sowing, germination rate was assessed. The results showed that sulphuric acid produced the highest (75%) cumulative germination while boiling water had the lowest (8%). Seeds under control pretreatment gave an impressive germination, which did not differ significantly (p= 0.000) from the results of sulphuric acid. The high rate of germination in the control can be taken as an indicator that S. setigera has the ability to produce seedlings but these seedlings face difficulties of establishment in natural areas. Seedlings growth in term of height were significantly (p=0.016) affected by the type of pretreatment used. Acid pretreatment technique showed the highest seedlings performance. Based on the natural population pattern and the germination traits, we could hypothesize that the lack of S. setigera recruitment is primarily caused by water regime in the soil.