The aim of the study was to determine the effect of various biopreparations on the growth of the apple root system, the number of spores of AMF, the total number of bacteria and microscopic fungi in the rhizosphere soil, and the degree of mycorrhizal association in the roots of two apple tree cultivars. The experiment was established in the spring of 2009 in the Experimental Orchard of the Institute of Horticulture in Dąbrowice. The research objects were one-year-old maidens of the apple cultivars ‘Topaz’ and ‘Ariva’ grafted on M26 rootstock. The trees were treated with the following biopreparations: control, control NPK (standard NPK fertilization), manure, Micosat F + manure, Humus UP, Humus Active + Aktywit PM, BioFeed Amin + manure, BioFeed Quality + manure, Tytanit + manure, Vinassa + manure, Florovit Eko, and Florovit Pro Natura. Treatment of ‘Topaz’ and ‘Ariva’ apple trees with the biopreparations Micosat F, Humus UP, Humus Active + Aktywit PM, BioFeed Amin, Vinassa, Florovit Eko and Florovit Pro Natura produced positive effects on the growth of apple roots and their mycorrhizal frequency, and the size of the populations of microorganisms in the rhizosphere soil.

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