The study focuses on the response of apple primary and secondary metabolism and some important quality parameters to three living mulch treatments, classical herbicide fallow, and black polypropylene strip application in two apple cultivars. Primary and secondary metabolites were analyzed after 10 years of ground cover experiments. Soluble solids, firmness, and color measurements indicate differences among orchard floor management treatments. Significantly, lower levels of individual sugars have been measured in fruit of different living mulch treatments compared with fruit harvested from trees subjected to the herbicide strip treatment. Total sugar content was higher in fruit of the herbicide strip treatment in both cultivars analyzed. Significantly higher levels of total organic acids were only detected in 'Pinova' fruit of the Festuca ovina L. treatment. Long-term response of both cultivars to living mulch treatments indicated that apples increase the accumulation of almost all analyzed individual phenolic compounds.
Keywords: Malus domestica Borkh.; black polypropylene strip; living mulch; organic acids; phenolics; sugars.