Chemometric analyses of 'Golden Smoothee' apples treated with two preharvest calcium spray strategies in the growing season

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% CO2) 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 fi om 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 firmness 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. (C) 2001 Society of Chemical Industry.