Bridging the knowledge gap: new insights published on optimal honeybush harvesting 

by Brigitte du Preez, 18 February 2021


Until recently, little was known about optimum harvesting practices of honeybush plantations that would ensure a quality product. High quality honeybush plants should have leaves that produce an herbal tea with a good aroma and taste, as well as extracts with high bioactivity such as antioxidant properties.

In her PhD study on the impact of harvest season on the quality of honeybush tea, Ms Gugu Mabizela, who studied at ARC Infruitec–Nietvoorbij, identified Summer as the optimum season to harvest Cyclopia subternata plantations. She based her results on the analyses of several genotypes, originally selected for cultivation and breeding trials within the ARC honeybush genetic improvement programme. Genotypes refer to the genetic make-up of the honeybush plant which is different for each plant, unless it was cloned. This programme aims to identify the best selections (genotypes) for cultivation of plants with superior quality.

Important selection criteria for genotypes include yield, growth characteristics and the sensory quality of the tea, as well as the concentration of phenolic compounds, i.e., those compounds associated with certain health-promoting properties. Therefore, Mabizela analysed the sensory characteristics of the tea infusions produced from the processed plant material of different genotypes in terms of aroma, flavour, taste and mouthfeel, as well as the phenolic content in the green (unprocessed) leaves. The plant material was harvested at the four different seasons in a year. Results indicated that the harvest season and genotype affected these two aspects.

New insights into the optimum harvest time have laid a foundation for screening of more genotypes during summer to expand the genetic pool of C. subternata plantations and to determine the effect of cultivation practices on quality. It is important for any cultivated crop to have a broad genetic breeding pool to enable plant breeders to breed for desirable characteristics and adaptability of the crop e.g. climate change. This will support efforts in achieving sustainable cultivation of honeybush as an emerging crop.

Ms Mabizela completed her PhD degree in Horticulture from Tshwane University of Technology under the umbrella of the DSI/ARC honeybush project. Her graduation is scheduled for June 2021. One of the scientific outputs of her doctoral study, titled "Effect of genotype and harvest season on quality characteristics of Cyclopia subternata: Phenolic content and sensory profile", was recently published in the South African Journal of Botany.

"By investigating the effect of the harvest season, climate and drought stress on the sensory profile and phenolic content, we can assist growers in improving their cultivation practices," she says.