Browsing by Author "Cronje, Rudolph John"
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- ItemEffect of fruit canopy position, harvest maturity and storage duration on post-harvest mealiness development of ‘Forelle’ pears (Pyrus communis L.)(Stellenbosch : Stellenbosch University, 2019-12) Cronje, Rudolph John; Crouch, E. M.; Steyn, Wiehann J.; Stellenbosch University. Faculty of Agrisciences. Dept. of Horticulture.ENGLISH ABSTRACT: Preliminary studies indicated a link between fruit canopy position and higher total soluble solids (TSS), respectively, and mealiness development during ripening of ‘Forelle’ pear. In this study this link is further explored to establish whether different parts of the canopy result in differences in maturity and ripening rates which affect mealiness incidence after ripening post-harvest. This study also investigates whether mealiness incidence is related to the micro-climactic differences within the canopy. Mealy textured pears were in general bigger sized fruit associated with higher TSS, lower titratable acid (TA), a redder blush colour, yellower background colour, and lower firmness after a period of ripening. Mealy fruit were also associated with a lower juice area and juice mass that were measured using a confined compression method. Mealiness incidence was the highest for red blushed outer canopy ‘Forelle’ pears associated with the highest exposure to sunlight, coupled with the highest fruit surface temperatures and vapour pressure deficit. The shading of outer canopy pears reduced mealiness incidence significantly, compared to that of sun-exposed outer canopy pears, which could be an indication that direct exposure to full sunlight coupled with high fruit temperatures for most part of the day could be one of the determining factors in ‘Forelle’ mealiness development. However, not all outer canopy fruit developed a mealy texture and therefore another unidentified tree factor might also play a role. The ripening rate developed earlier for outer canopy pears (earlier loss of firmness and an earlier transition to a more yellow ground colour) compared to intermediate and shaded inner canopy pears for both seasons, irrespective of harvest maturity. This is an indication that outer canopy fruit are in a more advanced stage of maturity than the other fruit positions. Fruit harvested at post-commercial maturity seems to be more susceptible to mealiness development. Highest mealiness incidence was observed after 8 weeks of cold storage at - 0.5 °C with 4, 7 and 11 days of ripening at 20 °C (8w RA + 4, 7 and 11d SL), while mealiness decreased with prolonged cold storage. Mealiness does however, not seem to be directly linked to ethylene production rate.