On-tree ABA application synchronizes fruit ripening and maintains keeping quality of figs (Ficus carica L.)

Abstract

Fresh fig ripening is controlled by abscisic acid (ABA) and ethylene. Uniform fig maturation is stimulated with oil or spray application of ethephon. Fig ripening is asynchronous—a single fruit ripens per shoot at a time—making it a challenge to increase the number of harvested fruit and minimize harvesting costs for growers. Here, we sprayed various concentrations of exogenous ABA on clusters with 3–5 mature fruit of 'Brown Turkey' (summer crop) and 'Autumn Honey' (autumn crop) figs under Israeli climatic conditions to identify suitable ABA concentration and fruit size, and analyze fruit ripening and postharvest qualities. Among the ABA concentrations tested in 2 consecutive years, application of 2.27 mM ABA to 'Brown Turkey' figs with pinkish ostioles that were 35–40 mm in diameter, and 2.84 mM ABA to 'Autumn Honey' figs that were 37–41 mm diameter, in clusters of 3–5 fruit per branch, resulted in uniform early onset of ripening followed by significantly increased fruit size and weight, and lower firmness compared to controls. During storage of ABA-treated 50% ripened fig fruit, weight, diameter, firmness, acidity and soluble solid contents were not significantly different from their respective controls for either cultivar. Thus, normalized concentrations of exogenous ABA could be sprayed on clusters of fruit of the selected size to increase the yield of fresh figs up to fivefold, reducing harvesting costs and accommodating market demand with no adverse effect during commercial storage.