College of Agriculture, Engineering
and Science (CAES)

Best Poster Award for Avocado PhD Research

Mr Sakhile Mathe, a PhD candidate in Horticultural Sciences, received the Young Minds Award for best poster at the 30th International Horticultural Congress (IHC) organised by the International Society for Horticultural Sciences (ISHS) in Istanbul, Turkey.

Mathe, whose trip was funded by the Post-Harvest Innovation Programme, presented his poster on girdling as a tool to unravel the “Hass” avocado skin colour problems. Poor skin colour change of South African “Hass” avocados is an issue that impacts export of the fruit to other countries. The concern is that the fruit does not effectively change colour from emerald green to purple to black to indicate ripeness which affects consumers’ decisions to buy the product and compromises market competitiveness.

Mathe felt the IHC had been an informative event where he was especially interested in avocado research and horticultural management studies presented. He previously presented his research at the 2016 and 2017 Combined Congresses and at another ISHS event.

Mathe has worked on this research with the Agricultural Research Council (ARC) where he is part of their Professional Development Programme (PDP). The ARC Tropical and Subtropical Crops (TSC) was commissioned by the South African Avocado Growers’ Association (SAAGA) to investigate both pre- and postharvest factors causing this conundrum.

Mathe’s study involves an investigation of several pre and postharvest factors which could explain poor ‘Hass’ avocado skin colour development during ripening. The study recommended girdling trees for earlier maturation to resolve the problem of the skin colour not changing when the fruit got ripe, especially with early harvest fruit.

Mathe, who completed his undergraduate and Honours degrees in Agricultural Management, was inspired to pursue his Master’s and PhD studies in Horticultural Sciences by Professor Isa Bertling and Dr Renate Oberholster.

Dr Samson Tesfay of UKZN and Dr Nhlanhla Mathaba of the Perishable Product Export Control Board (PPECB) are supervising his doctoral research.

Mathe’s Masters research comprised a comparative study of the antioxidant potential of some leafy vegetables with emphasis on African leafy vegetables such as amaranthus and exotic vegetables. He believes indigenous vegetables have potential to alleviate problems of malnutrition and hunger, and extraction of antioxidants could have applications in medicinal development.

Mathe hopes to go into a research career, potentially including molecular level work on this problem facing the avocado industry.

He thanked his supervisors, friends and staff at the ARC, in particular Mr Justice Mlimi and Mr Jan Ntandane, for their support. He also thanked Ms Bridgette Machipyane from the University of Limpopo, the UKZN Horticultural Sciences team as well as his family.

Words and photograph: Christine Cuénod