Browsing by Author "Cronje, P. J. R."
Now showing 1 - 5 of 5
Results Per Page
- ItemEvaluation of Fourier transform-NIR spectroscopy for integrated external and internal quality assessment of Valencia oranges(ACADEMIC PRESS INC ELSEVIER SCIENCE, 525 B ST, STE 1900, SAN DIEGO, USA, CA,92101-4495, 2013) Magwaza, L. S.; Opara, L. U.; Terry, L. A.; Landahl, S.; Cronje, P. J. R.; Nieuwoudt, Helene; Hanssens, A.; Saeys, W.; Nicolai, B. M.
- ItemNIR spectroscopy applications for internal and external quality analysis of citrus fruit - A review(Springer, 2012) Magwaza, L. S.; Opara, U. L.; Nieuwoudt, Helene; Cronje, P. J. R.; Saeys, W.; Nicolai, B. M.
- ItemPostharvest calyx retention of citrus fruit(Acta Horticulturae, 2005-06) Cronje, P. J. R.; Crouch, E. M.; Huysamer, M.Abscission is an active developmental process occurring at the abscission zone of the fruit peduncle. The target cells in the abscission zone, which are involved in the process of separation, are located in the separation layer, which is organized in a few cellular layers. In general, it is accepted that the increase in ethylene production in the fruit is followed by increased sensitivity of these cells to ethylene, which would lead to abscission. The abscission process is divided into two phases with respect to sensitivity to auxin and ethylene. The auxin, 2,4-D (2,4-dichlorophenoxy acetic acid), has been used as a postharvest packhouse treatment to retard calyx abscission (to repress postharvest decay). Commercially the sodium salt 2,4-D (Deccomone®) is applied to the fruit in a dip treatment at 500 ppm. The aim of this experiment was to test three agrochemicals (aminoethoxyvinylglycine (AVG), 1-naphthylacetic acid (NAA) and 1-methylcyclopropene (1-MCP)) that could possibly replace the postharvest application of the auxin 2,4-D. AVG had a fruit firming effect but no significant effect on calyx retention. NAA resulted in a high percentage of abscission, probably due to auxin overdose. The 1-MCP at low concentrations of 100 ppb and 250 ppb resulted in calyx retention but had a desiccating effect on the calyx whereas at a high concentration of 500 ppb there was a significant increase in calyx abscission. There was no loss of internal quality or colour. To conclude, according to what is known about the role of ethylene in abscission, 1-MCP and AVG should have prevented abscission of the calyx. Unfortunately, the results show that this complex plant mechanism is not so readily manipulated and 2,4-D remains the best product to inhibit calyx abscission of citrus fruit.
- ItemPrediction of 'Nules Clementine' mandarin susceptibility to rind breakdown disorder using Vis/NIR spectroscopy(ELSEVIER SCIENCE BV, PO BOX 211, AMSTERDAM, NETHERLANDS, 1000 AE, 2012) Magwaza, L. S.; Opara, U. L.; Terry, L. A.; Landahl, S.; Cronje, P. J. R.; Nieuwoudt, Helene; Mounem Mouazen, A.; Saeys, W.; Nicolai, B. M.
- ItemQuantifying the effects of fruit position in the canopy on physical and biochemical properties and predicting susceptibility to rind breakdown disorder of ?Nules Clementine? mandarin (Citrus reticulate Blanco) using Vis/NIR spectroscopy(ISHS, 2013) Magwaza, L. S.; Opara, L. U.; Cronje, P. J. R.; Nieuwoudt, Helene; Landahl, S.; Terry, L. A.