Differences in fruit color development, anthocyanin content, yield and quality of seven 'delicious' apple strains

Seven strains of 'Delicious' apple (Malus domestica Borkh.) 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 t wo 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 tristi mulus colorimeter using the CIE [1976] L*a*b* system providing an objective determination of the three visual attributes of color (lightness, hue angl e and saturation). Anthocyanin content of corresponding skin disks was dete rmined spectrophorometrically. Significant differences were observed betwee n strains in both the chromaticity values and the distribution of anthocyan in on both sides of the fruit, even at the first measurement date. Strains which had a darker red coloration tended to initiate color development earl ier, 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 highe r anthocyanin content, and lower hue angle (empty set 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 conditio ns of the particular year. Whereas in 1993 low temperatures prior to harves t decreased the effects of strain on fruit color, in 1992 and 1994 average temperatures were warm, and there were more differences between strains. Th e temperatures during the current seasons influenced fruit color, and conse quently the season factor and also its interaction with sampling dates were significant. At commercial harvest, a linear regression of anthocyanin con tent of all strains on the hue angle, L* and a*/b* ratio, provided R-2 valu es of 0.79, 0.80 and 0.82, respectively. 'Early Red One' and 'Sharpred' wer e among strains with high cumulative yields. 'Red Chief' (Campspur), 'Elite ' and 'Early Red One' had relatively high firmness at commercial harvest, a nd '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 wi th 'Red Miracle' and 'Topred: