The effect of green cover within rows on the qualitative and quantitative fruit parameters of full-cropping apple trees

Increased tendency towards organic fruit production advances alternative methods in orchard floor management. The effect of differences of sowing year of the living mulch Festuca ovina L. within tree rows on selected quantitative and quality parameters of apple fruit was evaluated on the trees budded on three different rootstocks. Long-term observations of full cropping trees in the period from 2013 to 2016 revealed no significant differences in cropping efficiency coefficient among the analysed treatments. Sowing of blue fescue in the 2nd year after orchard establishment resulted in approximately 30% decreased mean annual yield compared to herbicide treatment. Crop loss was less pronounced in treatments in which blue fescue was sown several years since the trees planting. No significant differences in selected fruit quality parameters (soluble solids, starch index, colour parameters L* and h degrees) were detected among different treatments and rootstocks in growing season 2016. Analysed compounds were determined in fruits with the use of HPLC system. Total sugars and organic acids were not differed among treatments. Five phenolic groups were analysed in apple peel and pulp. No significant differences of secondary metabolites content were measured in apple pulp between living mulch treatments and herbicide fallow. The results are expected as plants usually react to stress with the production of phenolics in outer tissues. Consequently, higher levels of some phenolic groups were detected in apple in treatments, which included blue fescue sowing in the 4th or 5th year after tree planting on semi-dwarf P 60 and M.26 rootstocks-the combinations which also the best mitigated the negative influences of living mulch on the yielding level.