Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 18, 2005
Publication Date: N/A
Interpretive Summary: Apple peel color is considered one of the most important commercial grading criteria for most cultivars. Elevated consumer preference can result from enhanced coloration of apples. Because of this, various cultural practices have been developed to enhance coloration. More recently, methyl jasmonate (MJ) treatment has been shown to vastly enhance red coloration in whole 'Fuji' apple fruit under laboratory conditions. The present field study indicates that MJ applications made to apple fruit during growth does improve coloration although with some detrimental effects with copious application. By limiting application rates and optimizing spray timing, MJ may provide a viable means to increase red coloration and therefore value of some apple cultivars.
Technical Abstract: Repeated pre-harvest applications of methyl jasmonate (MJ) to 'Fuji' apple [Malus sylvestris var. domestica (Borkh.) Mansf.] fruit were evaluated for impacts on peel color, growth, fruit finish, and maturation. MJ treatments at 2 week intervals began 48 days after full bloom (early season) or 119 DAFB (late season) and fruit were harvested 172 DAFB. Color readings were made weekly, growth evaluations at mid-season and after harvest, and finish and maturity evaluations immediately following harvest. While MJ treatment stimulated significant increases in peel red color, the treatments failed to override environmental effects possibly related to temperature. Following early season treatment, MJ treatment adversely affected diameter and length/diameter ratio. In late season treatment, MJ treatments elevated bitter pit and splitting incidence; however, fruit size remained unaffected. MJ advanced climacteric respiration but impeded softening and starch hydrolysis following late season treatment. Similar effects on softening and starch hydrolysis wee observed in early treated fruit. Results suggest timely application of MJ may provide useful coloration enhancement with minimal negative effects on fruit quality. Chemical name used: methyl 3-oxo-2-(2-pentenyl)cyclopentane-1-acetate (methyl jasmonate).