Pre-harvest spray application of methyl jasmonate plays an important role in fruit ripening, fruit quality and bioactive compounds of Japanese plums

The effects of pre-harvest methyl jasmonate (MeJA) treatment on ethylene production, respiration rate, bioactive compounds and physico-chemical parameters of plum fruits (Prunus salicina Lindell cvs. ‘Black Beauty’ and ‘Black Amber’) were investigated in this study. Whole trees were sprayed once with an aqueous solution containing MeJA (0 and 2240 mg L−1) two weeks before the anticipated commercial harvest for each cultivar separately. Compared to control treatment, MeJA-treated trees had higher yields. However, fruit mass and geometric mean diameters of MeJA-treated fruits were lower than the fruits of control. Ethylene production and respiration rate were significantly increased with MeJA. MeJA-treated fruits significantly maintained higher flesh firmness, except for initial harvest date. MeJA treatment significantly decreased L* and hue angle of plum fruits. Soluble solids content significantly increased with MeJA treatment and but MeJA treatment reduced titratable acidity. MeJA-treated fruits exhibited higher levels of total antioxidant activity and total phenolics. In all harvest dates, MeJA treatment resulted in significant increases in chlorogenic acid, caffeic acid, rutin, naringenin and kaempferol of ‘Black Beauty’ and chlorogenic acid, caffeic acid, p-coumaric acid, ferulic acid, quercetin and kaempferol of ‘Black Amber’ plums.