IMPROVEMENT OF QUALITY IN SOUTH AFRICAN POME FRUIT THROUGH FRUIT MINERAL ANALYSIS

Mineral analysis are conducted on the apple cultivars Golden Delicious, Top Red, Granny Smith, Royal Gala and Bracburn as well as the pear cultivars Packham's Triumph, Beurre Bose, Beurre Hardy, William's Bon Chretien, Comice and Forelle. Mineral analysis samples are collected at 60 days after full bloom and a second sampling from the same trees takes place two weeks before the projected start of harvest. Results of the mineral analysis are fed into a data base which then provides an important source of useful information. A comparison between years and between areas within years, gives and early warning of low calcium levels due to unfavourable conditions early in the season. This information is relayed back to the producers via weekly maturity indexing meetings and bulletins. Producers can then establish the number of calcium sprays which must be applied. The mineral analysis results two weeks before harvest are used to determine the storage potential for the fruit. This takes into consideration the potential of postharvest disorder development, such as bitter pit, senescent breakdown, internal browing, low temperature breakdown, superficial scald and water core. Orchards on individual farms cn be ranked according to fruit mineral status. This enables selection of fruit with the best mineral composition for longer storage periods.