In July 2022, the European Union (EU) imposed strict phytosanitary measures on fruit imports from South Africa. Phytosanitary refers to the control, prevention and treatment of plant diseases, pests and invasive species. The new measures required South African farmers to apply extreme cold treatment to all Europe-bound oranges and to keep the fruit at 2 °C or lower for 25 days to ensure they were free from the False Coddling Moth (FCM). This necessitated a quick study by horticulturist Dr Sabelo Shezi to assess the impact of these measures on the South African citrus industry, as oranges (the most exported fruit) are sensitive to low temperatures.

His research project, funded by the National Research Foundation (NRF) Thuthuka Post-PhD Grant, is entitled "Metabolomics and antioxidant content of oranges in response to chilling injury" and focuses on the dominant varieties, navel and Valencia oranges.

Shezi, a senior lecturer in the Department of Environmental Sciences at Unisa’s College of Agriculture and Environmental Sciences, is a renowned member of the International Society of Horticultural Scientists (ISHS). His research focuses on maturity indexing, plant physiology, photosynthetic efficiency, photo-protection, fruit physiology and biochemistry.

Through his scholarly work, Shezi seeks to develop methods for harvesting fresh produce and preserving it until it reaches consumers. "This is necessary to maximise the shelf life and hence the marketing period of the fresh produce, while also sustaining nutritional quality," he says.

The NRF Y-rated researcher is serving as co-investigator on another project, this one funded by the South African Avocado Growers’ Association (SAAGA), with collaborators from the University of KwaZulu-Natal and Cranfield University, England. This research project investigates the maturity indexing for Lamb Hass avocados and re-evaluates the effectiveness of the maturity indices currently used for the Hass cultivar.

Engaged scholar with impact

On his path to establishing himself as a proven and engaged scholar, Shezi’s research directly benefits fruit growers by offering alternative methods to maintain fruit quality and extend shelf life. "For instance, one of my projects resulted in an improved postharvest handling protocol for tomatoes that was shared with ZZ2 (a farming enterprise and fresh produce company) and smallholder farmers in Limpopo," he says.

His current project on oranges will assist the Citrus Growers’ Association (CGA) by producing data on the response of major export orange cultivars to storage at 2 °C. This will provide insight into the feasibility of adopting the EU phytosanitary requirements. Part of this work was presented at the IV International Symposium on Beverage Crops, held at Skukuza, Mpumalanga, from 15 to 20 March 2026.

The project's findings on the optimal harvesting stage for the Lamb Hass cultivar across different provinces in South Africa will be communicated to SAAGA.

The quality of Shezi’s research outputs, as reflected in his profiles on Scopus, ResearchGate, Semantic Scholar and Google Scholar, where he has an H-index of 7, an i10 index of 6 and a total of 297 citations since 2019, indicates the broad impact he has on industry and society.

* By Mpho Moloele, PR and Communications, Department of Research, Innovation and Commercialisation