International Journal of Innovative Horticulture

The peel colour of fruit is one of the most vital quality elements that affects fruit marketability and consumer acceptability. Citrus early varieties and native species generally reach internal maturity with minimum eating quality prior to the onset of colour break, i.e., when the natural colour development is relatively weak and insufficient. Similarly, to avoid any weather inclement or to extend the market, the fruits were harvested early with poor appearance. In such cases, degreening techniques were used to accelerate the colour transition of fruits from green to a desirable colour and to enhance their marketability. Exogenous ethylene degreening has effectively accelerated the external colour development of fruits by triggering ripening-related processes, most notably the breakdown of chlorophyll pigments and the accumulation of carotenoids in citrus peel tissue. The majority of citrus varieties respond favourably to preharvest degreening with ethephon; however, post-harvest degreening is commercially followed in citrus. The major factors affecting degreening processes are the preharvest factors (including fruit maturity stages, tree vigour, climatic effects, and cultural practices) and the post-harvest factors (i.e., atmospheric conditions and packinghouse treatments). The ethylene degreening exposure not only results in desirable appearance and quality improvements to fruit, but it may also have adverse consequences associated with hastened fruit senescence. However, the sensitivity of fruits to calyx senescence varies according to the variety, preharvest situations, and processing characteristics. Therefore, the degreening needs to be carried out in the correct environment for a desirable quality.