Yield of Grafted Apple Trees Under Different Water and Nutrient Regimes in Nursery Conditions

This study aims to evaluate the impact of irrigation and fertilisation practices on the productivity of apple trees cultivated in nursery settings. Tree growth and yield in such environments are largely determined by the effective management of water resources and nutrients supplied through fertilisers. Given the growing importance of resource sustainability, diverse management approaches are being employed to optimise the use of water and fertilisers while maintaining desirable yield levels. The study was conducted at a privately operated nursery located in northwestern Romania. A three-factor experimental design (4 × 2 × 4) was employed, comprising five replicates per treatment. Each experimental plot contained four apple trees, planted at a distance of 0.7 x 0.25 m. The main factor was irrigation, the secondary factor was cultivar, and the tertiary factor was fertilisation. MM 106 apple layering, classified within the "Certified" category, served as the main biological material for this research. Grafting material consisted of dormant buds from the Gala and Jonagold cultivars, obtained from a virus-free mother-branch plantation located within the same nursery. Four irrigation treatments were applied: no irrigation, irrigation with 10 mm, 20 mm and 30 mm. Additionally, four NPK fertilisation regimes were tested: (N0 P0 K0 , N8 P8 K8 , N16 P16 K16, N24 P24 K24 ). The application of different doses of NPK resulted in a significant increase in tree production, of 145-187.4%, compared to the non-fertilised variant. Irrigation had a significant effect on the production of grafted trees, with increases of 110.64-158.62%. Fertilisation made the highest contribution to the variability of grafted tree production for the two apple cultivars (57.78%), significantly higher than the effect of irrigation (15.26%) and cultivar (0.75%). Similarly, simple (9.09-11.01%) and double (2.99%) interactions between factors also had significant influences on the production of grafted trees for the apple species.