Rooting dynamics of ‘kustee’ honeybush (Cyclopia genistoides) as affected by seasonality and the manipulation of stock plant characteristics

Abstract

Honeybush (Cyclopia spp.), a legume endemic to the Fynbos biome of South Africa, has gained popularity as a herbal tea, particularly for its unique honey-like flavour, low tannin content and high antioxidant status. However, extensive wild-harvesting practices are a concern as this continued practice is placing pressure on natural stands. To ensure a sustainable supply of high-quality tea, a switch to clonal cultivation is required. In this study, the rooting potential of cuttings from four clonal types of Cyclopia genistoides was evaluated, following rejuvenation of stock plants over various regrowth periods, with cutting material collected over different seasons and phenological phases. The highest rooting success of >90 % was achieved following either six- or nine months of regrowth in winter and spring. Cutting dry weight positively correlated with rooting percentages in summer and autumn rooted cuttings. Extended periods of regrowth highlighted clonal differences in rooting success whilst no clonal differences occurred in shorter regrowth periods of less than a year. Cuttings (clones ‘GK3’ and ‘GK5’) made following regrowth of more than 12 months differed significantly, with ‘GK3’ rooting percentages that were lower in comparison to ‘GK5’ cutting material, when harvested in winter (30 %; 82 %) and the following autumn (37 %; 100 %), but were comparable when harvested in the preceding summer, autumn and spring. Stock plant phenology of C. genistoides at harvesting influenced rooting as low rooting percentages consistently coincided when the harvesting of cutting material coincided with the flowering period. The use of terminal cuttings collected from the current season's growth during a vegetative phase, following a six- or nine-month regrowth period, is recommended for C. genistoides stock plants to achieve acceptable to high rooting success in cutting material.