Abstract
Poor and erratic red blush development in ‘Cripps Pink’ apple causes serious economic losses to growers. The effects of a single pre-harvest spray application of various methyl jasmonate (MJ) emulsions on the development of red blush and fruit quality in ‘Cripps Pink’ apple were investigated at three locations. In the first and second experiments, during 2005, apple trees were sprayed separately with 0.0, 1.0, 5.0, 10.0, or 15.0 mM MJ at Perth Hills (PH) and at Manjimup (MM). In the third and fourth experiments, during 2006, 0.0, 1.25, 2.5, 5.0, or 10.0 mM MJ was sprayed separately at PH and at Donnybrook (DB). In 2005, at PH and MM, fruit treated with 1.0 mM or 5.0 mM MJ exhibited the greatest increases in red blush, in the percentage of export-grade fruit, and in the levels of total anthocyanins, cyaniding 3-galactoside, chlorogenic acid, phloridzin, flavanols, and flavonols. In 2006, at PH, the maximum improvement in red blush, in the percentage of export-grade fruit, and in the accumulation of total anthocyanins and colour parameters (lower CIE L* and h° values, and higher a* and C* values) were achieved with a 1.25 mM MJ spray application. In contrast, at DB, the same results were achieved with 5.0 mM MJ. In both years, fruit quality (i.e., firmness, and the soluble solids concentration: titratable acidity ratio) was not significantly influenced by the application of MJ. In conclusion, a single pre-harvest application of 1.0 – 5.0 mM MJ emulsion improved the development of red blush, the accumulation of total anythocyanins, and the level of flavonoids in fruit skin, without affecting fruit quality at commercial harvest. Orchard location also had a significant influence on the efficacy of the application of MJ on the development of red blush and on the level of flavonoids in ‘Cripps Pink’ apple.