Te role of biofertilizers in improving vegetative growth, yield and fruit quality of apple Walid Fediala Abd El-Gleel Mosa 1,2, *, Lidia Sas Paszt 1 , Mateusz Frąc 1 , Paweł Trzciński 1 , Waldemar Treder 1 , Krzysztof Klamkowski 1 1 Research Institute of Horticulture, Skierniewice, Poland 2 Plant Production Department, Faculty of Agriculture (Saba Basha), Alexandria University, Alexandria, Egypt *Corresponding author: walidbreeder@yahoo.com Abstract Mosa W.F.A.E-G., Sas Paszt L., Frąc M., Trzciński P., Treder W., Klamkowski K. (2018): Te role of biofertilizers in improving vegetative growth, yield and fruit quality of apple. Hort. Sci. (Prague), 45: 173–180. Apple trees which grafted on M.M. 106 stocks were planted at the beginning of spring 2014 in pots at the Research Institute of Horticulture in Skierniewice, Poland. Te used treatments in the experiment were: NPK fertilization and bioproducts: Fertigo (Manure), Micosat, Humus UP, Humus Active + Aktywit PM, BioFeed Quality, BioFeed Amin, Vinassa, Florovit Natura and Florovit Eko. In the spring, these treatments were applied to apple trees alone or enriched with Pantoea sp., Pseudomonas fluorescens, Klebsiella oxytoca and Rhizobium sp. bacterial strains. Growth, yield and fruit quality parameters were evaluated. Te results revealed that photosynthetic rate was greatly improved by the addi- tion of bacteria to Fertigo (Manure), Micosat, Humus UP and Humus Active + Aktywit PM as compared to NPK. Tree trunk thickness was signifcantly enhanced with Vinassa, Florovit Natura and Florovit Eko enriched with bacteria. Te application of bacterial strains increased the efectiveness of Fertigo (Manure), Humus UP, Humus Active + Aktywit PM, Biofeed Amin and Yeast in increasing signifcantly number and weight of fruits as compared to NPK. Keywords: benefcial bacteria; bioproducts; apple; growth tree; productivity Application of native mycorrhizal fungi and ben- efcial strains of bacteria and fungi incorporated in new bioproducts ensures their better adapta- tion and survival in the prevailing environmental conditions, which is an extremely important factor for their long-term efects on plants (Regvar et al. 2003). One of the proposed solutions to environ- mental and human health protection issues is the implementation of natural technologies of plant cultivation and fertilization through the applica- tions of biofertilizers. Products of this kind have a positive infuence on the growth and yielding of crop plants as well as on the soil fauna, including the development of arbuscular mycorrhizal fungi (AMF) (Kuwada et al. 2005). Enriching fertiliz- ers with benefcial strains of bacteria and fungi can increase their efectiveness in crop produc- tion (Chen 2006) by enhancing the physiology of crop plants, stimulating their growth and yielding, as well as by increasing their resistance to envi- ronmental and biotic stresses (Corte et al. 2013). Von-Bennewitz and Hlusek (2006) found that the biofertilization was benefcial in stimulating the growth and fruiting of pome and stone fruits. Moreover, the applications of biofertilizers con- taining benefcial microorganisms instead of syn- thetic chemicals are known to improve fxation of nutrients in the rhizosphere, and produce growth 173 Hort. Sci. (Prague) Vol. 45, 2018 (4): 173–180 htps://doi: 10.17221/101/2017-HORTSCI