POLYPHENOLIC PATTERN IN APPLE TREE LEAVES IN RELATION TO SCAB RESISTANCE - A PRELIMINARY-STUDY

Polyphenols were analyzed by HPLC in apple tree leaves of different sc ab-resistant and -susceptible cultivars to compare their phenolic cont ents in relation to their resistance to the disease. Quantitative and slight qualitative differences among cultivars were found. Dihydrochal cones (phloridzin and phloretin) and flavonols were the main phenolic compounds determined in all of the cultivars studied. In the younger s tage, it would be possible to differentiate sensitive from resistant a pple varieties on the basis of their flavanols contents and phloridzin /flavanol ratio. Likewise, higher levels of two p-coumaric acid deriva tives were found in cultivars with the polygenic resistance character.