334 Int. J. Postharvest Technology and Innovation, Vol. 2, No. 4, 2012 Copyright © 2012 Inderscience Enterprises Ltd. Some initial changes in ‘Hass’ avocado (Persea Americana Mill.) physiology due to ethephon Robert J. Blakey*, Samson Z. Tesfay, Nhlanhla Mathaba, Isa Bertling and John P. Bower Department of Horticultural Science, University of KwaZulu-Natal, Private Bag X01, Scottsville, 3209, South Africa E-mail: robblakey@gmail.com E-mail: szeray@gmail.com E-mail: mathaban@gmail.com E-mail: bertlingi@ukzn.ac.za E-mail: josan@telus.net *Corresponding author Abstract: Ethylene is used commercially to hasten ripening of avocados, but the presence of ethylene in the storage atmosphere can increase the risk of physiological disorders. To investigate the short term effect of ethylene on avocado physiology, fruit were dipped in a low concentration ethephon solution. The ethephon treatment significantly increased the ethylene production rate of avocados after 6 h, compared to untreated fruit. After 6 h, the respiration rate of treated fruit increased significantly during the investigation while that of the untreated fruit did not show a significant increase from the initial measurement. Lipid peroxidation increased after dipping, reaching a peak after 4 h, and then declined to a level similar to untreated fruit. Mannoheptulose declined significantly during the 6 h investigation in both the untreated and treated fruit. It is concluded that avocado fruit can undergo significant physiological changes, and quality loss, in a short amount of time, which is exacerbated by exposure to ethylene. Keywords: avocado; ethylene; mannoheptulose; lipid peroxidation; postharvest management; fruit quality. Reference to this paper should be made as follows: Blakey, R.J., Tesfay, S.Z., Mathaba, N., Bertling, I. and Bower, J.P. (2012) ‘Some initial changes in ‘Hass’ avocado (Persea Americana Mill.) physiology due to Ethephon’, Int. J. Postharvest Technology and Innovation, Vol. 2, No. 4, pp.334–344. Biographical notes: Robert J. Blakey recently completed his PhDAgric on avocado postharvest physiology at the University of KwaZulu-Natal (UKZN), Pietermaritzburg, South Africa. He is currently working on the non-destructive determination of avocado quality using near-infrared spectroscopy. His work has been presented locally and internationally at various conferences. Samson Z. Tesfay is a Postdoctoral Researcher in the School of Agricultural Sciences and Agribusiness at the UKZN. His research is focused on the anti-oxidants and sugars in subtropical and temperate fruit. He also lectures on plant physiology at the same institution. He is passionate about plant anti-oxidants.