The influence of 20% white shade nets on fruit quality of ‘Nadorcott’ mandarin

The external and internal quality of citrus fruit determines consumer acceptance, thereby driving the consumption and demand for fresh fruit. Emphasis is placed on producing a high volume of fruit of good quality, and it is known that light intensity is especially important in influencing sugar content, rind color, and blemish incidence. Extreme environmental conditions are challenging controllable factors. Therefore shade netting is used especially on fruit crops for protection against dramatic climatic events that affect the appearance of the fruit, i.e., excess sunlight, wind, and hail. The study was conducted on 'Nadorcott' mandarin trees planted in 2012 in a commercial orchard in Citrusdal, Western Cape province, South Africa. The aim of this study was to determine the influence of 20% white shade nets on the quality of 'Nadorcott' mandarin fruit. Monthly evaluation of fruit size, rind color, internal quality parameters (°Brix/citric acid ratio) and the incidence of sunburn was performed. The fruit diameter was not influenced by shade net in 2016; however, in 2017 a larger fruit diameter was measured for shade net fruit. Rind color development and internal quality were not influenced negatively by the treatment. Shade net was effective, reducing the incidence of sunburn significantly in both seasons, 2016 and 2017. Moreover, postharvest fruit quality was not negatively affected by the shade net treatments. In summary, our results indicate that shade-netting is a potential preventative technology ensuring unblemished and high quality in 'Nadorcott' mandarins, but further studies are required to evaluate the influence of tree age and microclimatic effect on fruit production and postharvest storage behavior in other citrus cultivars.