Before or after Planting? Mycorrhizal and Bacterial Biostimulants and Extracts in Intense Strawberry (Fragaria x ananassa Duch.) Production

The aim of this research was to evaluate the effect of a combination of several mycorrhizal and bacterial biostimulants, applied before and after planting, on the 'Clery' strawberry's performance. Vegetative and reproductive parameters (the number of crowns per plant, root/canopy weight and dimensions, the number of fruits per plant, individual fruit weight, and fruit yield per plant) were monitored on nine harvest dates. Additionally, external and internal fruit quality (firmness, color, soluble solids content, and primary and secondary metabolites) was determined. The application of product combinations resulted in significantly improved vegetative growth, fruit dimensions, and fruit weight. Consequently, more than 30% higher yields were determined for the treated plants. A minor decrease in vitamin C (approx. 6%), total individual sugars (approx. 10%), organic acids (approx. 9%), and total phenolics (approx. 7%) was detected in the treated plants, but the differences were not uniform during the harvest. The accumulation of anthocyanins was least affected by product application, and the fruit exhibited comparable color characteristics, which is important for the consumers. The use of biostimulants in intense strawberry production is justified as the products improve the vegetative development of strawberry plants, which produce significantly more marketable fruit.