Differences in Fruit Color Development, Anthocyanin Content, Yield and Quality of Seven ‘Delicious’ Apple Strains

Abstract

Seven strains of ‘Delicious’ apple ( Malus domesticaBorkh.) were evaluated over a three-year period in the area of Lleida (NE Spain) for fruit color, anthocyanin content, yield and fruit quality. Fruit color was measured at two locations on each fruit blush side and back side at the midpoint between the stem and calix end, with a Minolta Chroma Meter CR-200 portable tristimulus colorimeter using the CIE [1976] L*a*b* system providing an objective determination of the three visual attributes of color (lightness, hue angle and saturation). Anthocyanin content of corresponding skin disks was determined spectrophotometrically. Significant differences were observed between strains in both the chromaticity values and the distribution of anthocyanin on both sides of the fruit, even at the first measurement date. Strains which had a darker red coloration tended to initiate color development earlier. In all strains, rapid color development occurred between the middle of August and the first week of September. High-coloring strains such as ‘Red Miracle,’ ‘Red Chief’ (Campspur) or ‘Early Red One’ had significantly higher anthocyanin content, and lower hue angle (Ø and L* values on both sides of the fruit than low-coloring strains such as Topred’ or ‘Sharpred.’ Fruit color was influenced by the strain and also by the weather conditions of the particular year. Whereas in 1993 low temperatures prior to harvest decreased the effects of strain on fruit color, in 1992 and 1994 average temperatures were warm, and there were more differences between strains. The temperatures during the current seasons influenced fruit color, and consequently the season factor and also its interaction with sampling dates were significant. At commercial harvest, a linear regression of anthocyanin content of all strains on the hue angle, L* and a*/b* ratio, provided R ²values of 0.79, 0.80 and 0.82, respectively. ‘Early Red One’ and ‘Sharpred’ were among strains with high cumulative yields. ‘Red Chief’ (Campspur), ‘Elite’ and ‘Early Red One’ had relatively high firmness at commercial harvest, and ‘Oregon Spur’ (Trumdor) and ‘Topred’ the lowest. ‘Sharpred’ and ‘Topred’ had the highest soluble solids concentrations and ‘Early Red One,’ ‘Elite’ and ‘Red Chief’ the lowest ones. Higher titratable acidity were obtained with ‘Red Miracle’ and ‘Topred.’