Abstract
Plant biostimulants are a new emerging category of products especially for organic cultivation that target the promotion of plant growth also throughout the overcome of a stressful situation. The present study aimed to investigate the influence of biostimulants on vegetative growth, production and fruit quality of strawberry, grown in nutrient limitation conditions. The experiment was conducted in greenhouse conditions on strawberry plants cv. Elsanta. Repeated preharvest foliar applications of different biostimulants (humic acids, alfalfa protein hydrolysate, seaweed extract, hydrolysis of microalga and chitosan) were tested. Our results showed that plant growth was positively affected by some treatments. The number of leaves per plant was significantly increased in alfalfa- and chitosan-treated plants (2 leaves/plant more than control ones) at the end of the trial. Plants treated with alfalfa presented 16% higher chlorophyll content in leaves compared to control ones and the accumulated biomass per plant was enhanced in treated plants, though not significantly. Significant higher production levels were found in plants treated with chitosan (+20%). As far as fruit quality, treatments proved to significantly influence fruit weight and fruit firmness. In particular alfalfa treatment increased fruit weight, while chitosan-treated fruits had higher firmness and a tendency to lower soluble solids values compared to the control ones, indicating a possible ripening-delaying effect of this biostimulant product and therefore a probable interesting prolongation of postharvest shelf life of fruits. To conclude, this investigation provides a better understanding of how biostimulant applications might help plant growth in a stressful situation such as nutritional limitation and how these products can promote fruit quality. These biostimulant products may therefore represent a potentially interesting tool, especially within the framework of organic farming, to counteract the effects of limited nutritional support available for the crop.