Impact of High Nitrogen Doses and Living Mulch on Growth, Yield and Fruit Quality of Young Apple Trees (cv. ‘Sampion’)

The experiment aimed to evaluate the effectiveness of using high doses of nitrogen (N) and delaying the sowing of living mulch in the apple tree (Malus domestica Borkh.) orchard as factors stimulating tree growth and influencing fruit quality. Blue fescue (Festuca ovina L.), as a cover crop, was sown in the tree rows in the second and fourth year after tree planting. It was compared to herbicide fallow control treatment. In each floor management, four N doses (50, 80, 110, and 140 kg ha−1) were used every year. The study indicated the dominance of living mulch, especially sowing in the second year after tree planting as a factor influencing the reduction in growth and yield but improving the red blush surface on the fruit skin. The growth of trees was also strongly influenced by biotic and abiotic stress factors, which did not allow for a clear assessment of N fertilization. With objectively low cropping levels and poor growth of all trees tested in the experiment, their N needs were satisfied by a dose of 50 kg ha−1. The application of the highest dose of 140 kg N ha−1 had a significant and negative impact on the red color of the fruit skin.