IMPACT OF SUN EXPOSURE ON HARVEST QUALITY OF 'HASS' AVOCADO FRUIT

SUMMARY Harvest quality of fruit exposed to the sun on the tree (sun fruit) was compared with that of completely shaded fruit (shade fruit). A range of attributes was examined on the exposed and unexposed sides of the sun fruit, and compared to shade fruit. Temperatures of 35 to 40°C were observed in the flesh of sun fruit, even in spring. At harvest, and during ripening, significant differences were found between the two fruit types, and between sides of the sun fruit. Sun fruit were found to have higher dry matter, and higher levels of potassium, calcium and magnesium. Sun fruit took longer to ripen than shade fruit, and the exposed side of sun fruit was firmer than the unexposed side. The exposed side of sun fruit was lighter in colour with a higher chroma and lower hue angle (more yellow) than the unexposed side of sun fruit and shade fruit. Sun fruit had higher oil content than shade fruit, with relatively little difference between exposed and shaded sides of sun fruit. The fatty acid composition of the total oil was determined. Sun exposure increased the proportion of the saturated fatty acid palmitic acid, and decreased the proportion of monounsaturated fatty acid oleic acid (which is the major fatty acid in avocado oil). Thus, sun exposure of ‘Hass’ avocados has a range of significant effects on fruit quality at harvest, and when ripe.