Influence of benzyladenine (BA) based agrochemical on mineral nutrition and productivity of apple tree (Malus domestica Borkh.)

The field experiment was established in 2017. During three consecutive seasons, we evaluated the influence of benzyladenine (BA) (applied in concentration 20 g L^‑1) on productivity and mineral nutrition of apple trees (cultivar ‘Zhigulevskoye’ grafted on rootstock B-396). The foliar applications were done when fruits had the following diameters: 6-8 and 10-12 mm. We did not apply additional fertilizers on the experimental plot, but performed an annual soil analysis to confirm the mineral composition. The application of BA reduced the fruit set considerably. The impact on the content of nutrients in leaves and fruits was contradictory in different years of research. Leaf nitrogen decreased by treatment in a 6-8 mm stage, but at the same time, the content of this nutrient increased in fruits during the whole research period. The amount of phosphorus in leaves and fruits did not have significant changes. The potassium content in both treatments increased in leaves and fruits; the amount of calcium increased in leaves and fruits when treated in a 6-8 mm stage. In general, most changes in the mineral status of plants occurred in the 6-8 mm stage treatment. The BA stabilized the productivity of apple trees, especially in off-year (2019) after on-year, with a high yield (2018).