Genotype and Plant Biostimulant Treatments Influence Tuber Size and Quality of Potato Grown in the Pedoclimatic Conditions in Northern Apennines in Italy

In marginal mountain areas, farm management presents challenges, particularly the sustainable improvement of yield and quality. To ensure this agronomic result, it is crucial to select appropriate varieties and apply sustainable agricultural practices, such as the use of plant biostimulants. To address these challenges a two-year field study was conducted using three potato varieties (Désirée, Kennebec and Spunta) in the Tuscan-Emilian Apennines. These varieties were treated with two plant biostimulants: one based on hydrolyzed proteins from animal epithelial tissue (Fitostim®) and another based on seaweed extracts (FitostimAlga®). Agronomic and biochemical traits were used to evaluate the development of plants, yield and tubers quality. Significant interactions among factors were found, resulting in higher or lower efficiency of the plant biostimulant treatment depending on weather conditions and potato genotype. Furthermore, results demonstrated that plant biostimulant treatments increased the leaf chlorophyll content (+ 11.5%), the number of leaves per plant (+ 13.3%) and the height of potato plants (+ 6.5%), while no effects were observed on yield. The Désirée variety achieved the highest yield (0.54 kg plant-1), whereas Kennebec was shown as the best variety to use for production of French fries due to a lower tuber quantity of reducing sugars, which were reduced also by plant biostimulants treatment (-18%). Moreover, Spunta tubers had the highest content of polyphenols, and the best value was achieved by Spunta variety treated with Fitostim® alga in the second year. Our finding have proven that plant biostimulant treatments can increase the quality of potato tuber without compromising yield.