Microbial biostimulants affect the development of pathogenic microorganisms and the quality of fresh strawberries (Fragaria ananassa Duch.)

Abstract

Strawberries, as non-climacteric fruits, undergo unfavourable changes after harvest such as cell damage, softening and a loss in fruit quality. One of the methods of maintaining high-quality fruit is using ecological preparations defined as biostimulants, which also eliminate the usage of pesticides and support a sustainable agriculture approach. The effectiveness of microbial preparations used as biostimulants was studied in our experiment. The use of preparations containing Bacillus subtilis and Paenibacillus polymyxa strains and bioactive substances (K4, K5 and K6) delayed the ripening processes of the Honeoye and Rumba strawberry, which resulted in a brighter colour of the skin as compared to the control (K1 I, K1 II). After applying the biopreparations, the taste was improved and the nutritional value of the strawberries increased. An average of a 14 % increase in the soluble solid content (SSC) content was observed for Honeoye strawberries treated with K4 and K6 and also the Vibrant variety treated with K6, compared to the control samples (K1 I, K1 II). The antioxidant capacity, which was determined in terms of the DPPH level in the three cultivars of the strawberries (Honeoye, Rumba and Vibrant) treated with the tested preparations, was similar and ranged between 83 and 90 %. The greatest differences in the content of antioxidants were found for anthocyanins, whose content increased by an average of 27 % in the Vibrant (K5, K6) and Rumba (K3, K5, K6) strawberries. Together, these results show that the selected preparations improve the quality of strawberries of the Honeoye, Vibrant and Rumba varieties.