Influences of pre-sowing seed treatments on germination of the cancer bush (Suthertandia frutescens), a reputed medicinal plant in arid environments

Cancer bush (Sutherlandia frutescens L) is a medicinally important perennial legume native to southern Africa. S. frutescens seeds exhibit dormancy like many other legumes. Experiments using physical, mechanical And chemical pre-sowing treatments were conducted to determine the germination response of this species. Among various treatments, soaking the intact seeds for 30 min in concentrated H2SO4 resulted in a high final germination percentage of 97.5% in day 14 of culture. However, seed dormancy was completely broken by mechanical scarification in which 100% germination was obtained in day 2 of culture. The results indicated that S. frutescens seeds possess exogenous dormancy due to the hard seed coat which is the main inhibitor of germination.