Identification of ‘Calanda’-Type Peach Genotypes Tolerant to Monilinia laxa (Aderh. & Ruhland) Honey

One of the diseases that has the greatest negative effect on peach production is brown rot, produced by the fungus, Monilinia spp. The way to diminish this disease is the selection of genotypes with a high tolerance to Monilinia spp. while maintaining fruit quality. In this study, the tolerance to Monilinia laxa and agronomic and biochemical characteristics of forty-two hybrids derived from the ‘Andross’ × ‘Calante’ cross were studied under controlled conditions during two consecutive years, and compared with their parents. The assessment of tolerance to brown rot was estimated on inoculated fruit with M. laxa, recording the incidence of brown rot and colonization, lesion diameter and extent of colonization, to establish the severity of incidence and colonization. At harvest, physicochemical traits and antioxidant compounds (vitamin C, total phenolics, flavonoids and relative antioxidant capacity) were determined. We have found inverse relationships between fruit firmness, pH, titratable acidity and antioxidant contents with the disease symptoms in fruit. Our results confirm that the accumulation of antioxidants tends to reduce the lesion and colonization in inoculated fruit. Principal component analysis allowed the selection of two genotypes, AC-24 and AC-93, of ‘Calanda’-type peaches with a known standard quality, high antioxidant content and minimal susceptibility to brown rot.