The correlation between fruit mineral nutrient content and apple fruit cv. Red Delicious peel pigmentation

Incomplete apple fruit skin pigmentation could be one of the main causes of decreasing marketability in red cultivars. In this study, the correlation between total anthocyanin and fruit skin color parameters with mineral nutrient content and ratios in 20 commercial apple orchards growing cv. red delicious was investigated. At each orchard, fruits were harvested at commercial maturity stage and categorized into three groups with 20 fruits, according to dark red, medium and light red color. Fruit peel colors parameters such as hue (°h), lightness (L*), chroma (C), green-red (a*), blue-yellow (b*) and total anthocyanin, and nitrogen, phosphorous, potassium, calcium and magnesium contents and mineral nutrient ratios were measured. Results showed that there were a negative correlation between anthocyanin with L*, h°, b* and C* and a positive correlation with a*. Furthermore, a negative significant correlation was found between fruit nitrogen content with anthocyanin and a* and a positive significant correlation with L* and h°. A negative correlation was observed between fruit calcium content with L* and magnesium content with anthocyanin. Furthermore, a positive significant correlation was found between N⯰ with L*, h° and b*, but a negative correlation between Mg/Ca with total anthocyanin and a* and a positive significant correlation with L*, h° and b* value. There was a negative significant correlation between N/Ca with anthocyanin and a* and a positive correlation was observed with L*, h° and b* value. Overall, results showed besides climate condition, optimum tree fertilization especially nitrogen and calcium can be important on apple fruit cv. Red Delicious pigmentation.