Enhancing Yield, Physiological, and Quality Traits of Strawberry Cultivated Under Organic Management by Applying Different Non-Microbial Biostimulants

Organic farming is an environmentally friendly management practice that excludes the use of synthetic inputs, but at the same time is associated with lower yields than conventional production. In an attempt to compensate for yield reduction, resulting from foregoing the use of synthetic fertilizers, we hypothesized that the use of biostimulant products could provide much-desired food security. In light of this, a greenhouse experiment was conducted to compare and evaluate the effects of the foliar application of three different non-microbial biostimulants (a seaweed extract, a plant protein hydrolysate, and a plant extract) on the yield, mineral profile, and physiological response of strawberry (<i>Fragaria</i> × <i>ananassa</i> Duch.) grown in an organic farming context. Regardless of the type of biostimulant, treated plants showed significant improvement in photosynthetic performance. Specifically, the application of plant-derived protein hydrolysate increased ACO₂ by 34.5% compared with control. Despite this, only the application of plant-derived protein hydrolysate significantly increased fruit yield per unit area (+13.5%). The improved performance of plants treated with plant-derived protein hydrolysate was associated with an overall improvement in mineral profile (compared to control +49.4 and 33.0% in NO₃^- and Mg²⁺ concentration, respectively). In contrast, application of the seaweed biostimulant increased (+17.4%) fruit antioxidant activity (DPPH) compared with control plants. These results underscore how the diverse origins of non-microbial biostimulants are responsible for specific responses in crops that can be exploited by organic growers to increase productivity.