The field experiment (2009–2012) was conducted to assess the influence of different biofertilizers (AMF liquid/granular inocula, humic and seaweed extracts) on the growth and yielding of ‘Topaz’/M.26 apple planted on SARD soils in Poland. During conversion to organic orchard trees’ growth, fruit yield, their quality indices as well as nutritional status of leaf and fruit was ascertained. Fruit polyphenol content and their free radical scavenging activity were assessed. Moreover, the mycorrhizal root parameters (mycorrhizal and arbuscules frequency) were also presented. The most vigorous trees were inoculated with liquid inocula MicoPlant M and MicoPlant S. The plants treated with MicoPlant S gave the highest total yield (12.12 kg/tree) and revealed the best productivity (> 1 kg cm^-2) as well as the average fruit weight. The liquid suspended inocula were more effective than granular one in terms of mycorrhizal root colonisation. Investigated biofertilizers increased P, K and Cu content of leaf. Organic soil extract (HumiPlant) decreased P and K content of fruit, while seaweed extracts (AlgaminoPlant) increased Ca amount of fruit. These treatments had the lowest K:Ca ratio. Used biofertilizers influenced apples polyphenol content as well as their antioxidant status.

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