Comparison of the effects of mechanical scarification and gibberellic acid treatments on seed germination in Pterocarpus angolensis

Abstract

Pterocarpus angolensis is a savanna tree species growing mostly in the miombo and undifferentiated woodlands found in the southern and central parts of Africa. Exploitation for its medicinal and commercial uses has led to a diminishing of wild populations. Artificial propagation, domestication and exploitation in a sustainable manner depend on detailed knowledge on germination of the seeds. The effects of eight potential dormancy-breaking treatments, compared with no treatment, on promoting the germination of P. angolensis seeds were examined. Five seed provenances were used, namely Mufulira and Chati from Zambia, and Gokwe, Matopos and Mtao from Zimbabwe. Seeds were treated by nicking to remove a small piece of seed coat near to the radical, soaking in cold water or an aqueous solution of gibberellic acid (GA₃ at 10, 50, 100 or 1 000ppm; GA4/7 at 10 or 1 000ppm). Treatments with gibberellic acids, regardless of the concentration, had little effect on germination rates when compared with the control seeds. With nicking, high and rapid rates of germination occurred for all provenances within approximately 5d of sowing the seeds, suggesting that nicking alone could improve seed germination.

Southern Hemisphere Forestry Journal 2007, 69(1): 63–70