Influence of NPK minerals and biostimulants on the growth, yield, and fruit nutritional value in cv. ‘Sampion’ apple trees growing on different rootstocks

The study was conducted in 2015–2017 to assess the influence of rootstocks on the growth and fruiting of apple trees of cv.‘Šampion’ cultivated on rootstocks M26, P2. M9, and P22 with the following treatments: mineral fertilization (NPK), nano-concentrations of elements (Fe, Co, Al, Mg, Mn, Ni, Ag), natural chicken manure fertiliser, humus, microbial product, plant amino acids, and stillage yeasts. ‘Šampion’ apple trees grew vigorously on rootstocks M26 and P2 when humus and microbiological biostimulants were applied, especially in terms of the shoot diameter and TCSA. The best fruit yield and quality parameters were obtained in apple trees growing on rootstocks M9 and M26 fertilised with microbiological biostimulants and formulations containing plant amino acids. Apples with the highest concentration of nutrients, in particular minerals, were harvested from trees growing on rootstocks M9 and P22 and stimulated with nanoparticle mineral preparations and humus formulations.