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Multivariate procedures were used to evaluate the effect of different pre-harvest calcium treatments on the changes of respiratory rate and ethylene production in apples both at harvest and after extended cold storage. The study was carried out over two years on 'Golden Smoothee' apple trees from Lleida (Spain). Trees were sprayed with a calcium chloride based formulation (STOPIT) at a concentration of 1% (v/v). The first (6 applications) and second (12 applications) treatments began 60 days after full bloom (DAFB) and were repeated at intervals of 15 and 7 days respectively. After harvesting, the fruit was stored for 4 and 6 months under controlled ultra-low oxygen atmosphere conditions (CA-ULO). Each time fruit was withdrawn from storage, carbon dioxide and ethylene production were measured for 14 days at 20 • C. Independently of the calcium treatments, respiration rates fell from harvesting until 6 months of storage, while ethylene production was greater on withdrawal from storage than at harvest. Respiratory rate and ethylene production correlated negatively with calcium content. However, calcium apparently had a greater effect on the respiratory capacity (CO 2 ) of fruit than on ethylene production.

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Chemometric techniques were used to analyse the effects of two preharvest calcium strategies applied to increase the calcium content and improve the quality of Golden Smoothee apples after prolonged storage in controlled atmosphere, ultralow-oxygen (CA-ULO; 1% O 2 , 2% CO 2 ) conditions. In a two-year study the strategies applied by sprays were started 10 and 60 days after full bloom (DAFB) with 10 and six calcium sprays respectively at 15 day intervals throughout the growing season. The most effective results for increasing the calcium content of the apples were attained when the calcium was applied from 60 DAFB with six sprays. Although the chamber effect and mainly the length of storage differentiate the fruits much more than the calcium spray strategies, the evaluation of the results suggests that calcium and ®rmness remain correlated for up to 4 months of cold storage under CA-ULO conditions. The effect of calcium decreases with storage time. Titratable acidity and bitter pit incidence correlated negatively with calcium content in year 2. Comparison of the results obtained in the two years indicates that the relationship between calcium and the quality attributes depends not only on the calcium content per se, but also on other factors such as the nutritional status.

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