Effect of liming and mineral nutrition on growth of honeybush (Cyclopia spp.) plants

A short-duration pot trial was carried out to determine the effects of liming and of mineral nutrients on Cyclopia spp., a newly commercially significant member of the fynbos flora, which habitually grows in acid, low phosphorus (P) sandy soils. Total dry mass production after four months by C. subternata increased where the soil pH was limed from 4.4 to 5.2 (1M KCl), and also benefited from the addition of 10 mg P kg−1 to the native soil P concentration of 11 mg kg−1. No response was observed to the addition of potassium (K), where the soil contained 25 mg K kg−1. Manganese (Mn) addition did not give a positive response, even though the soil Mn concentration in the unamended soil was low (1.3 mg kg−1). Treatment of the seed with molybdenum, to stimulate Rhizobium, promoted dry mass production in C. subternata, but did not do so consistently in C. maculata. The effects of nitrogen and magnesium on dry mass production in C. subternata and C. maculata were inconsistent.