Influence of 1-MCP application and concentration on post-harvest peel disorders and incidence of decay in citrus fruit

SummaryThe effect of 1-methylcyclopropene (1-MCP) application and concentration on the incidence of post-harvest peel disorders and decay was evaluated in 'Fallglo' tangerines, 'Hamlin' and 'Valencia' oranges, and white 'Marsh' grapefruit during the 2000-2002 growing seasons. The disorders studied were chilling injury (CI), post-harvest pitting and stem-end rind breakdown (SERB). The major diseases investigated in this study were Diplodia stem-end rot (Diplodia natalensis), anthracnose (Colletotrichum gloeosporioides), and mould (Penicillium digitatum). Our studies confirmed that, in most cases, application of 1-MCP reduced CI and peel pitting in 'Fallglo' tangerine and grapefruit if applied at concentrations between 50-500 µg l–1, while concentrations higher than 1 mg l–1 enhanced the development of decay in 'Fallglo' tangerine and white 'Marsh' grapefruit. In oranges, application of 1-MCP markedly reduced the incidence of SERB and increased the development of decay, if the 1-MCP concentration was high (1–5 mg l–1). In parallel to the above results, fruit weight loss and colour development improved if 1-MCP had a positive effect in reducing the development of peel disorders. Overall, applying 1-MCP at concentrations from 50–500 µg l–1gave the best protection against CI and the development of post-harvest pitting.