A Novel Protein Hydrolysate-Based Biostimulant Improves Tomato Performances under Drought Stress

Abiotic stresses adversely affect crop production causing yield reductions in important
crops, including tomato (Solanum lycopersicum L.). Among the different abiotic stresses, drought is
considered to be the most critical one, since limited water availability negatively impacts plant growth
and development, especially in arid and semi-arid areas. The aim of this study was to understand
how biostimulants may interact with critical physiological response mechanisms in tomato under
limited water availability and to define strategies to improve tomato performances under drought
stress. We investigated the physiological responses of the tomato genotype ‘E42’ grown in open
fields under optimal conditions (100% irrigation) and limited water availability (50% irrigation)
treated or not with a novel protein hydrolysate-based biostimulant (CycoFlow, Agriges, BN, Italy).
Plants treated with the protein hydrolysate showed a better water status and pollen viability, which
also resulted in higher yield under drought stress compared to untreated plants. The treatment
with the biostimulant had also an effect on antioxidant contents and activity in leaves and fruits
depending on the level of irrigation provided. Altogether, these results indicate that the application
of protein hydrolysates on tomato improved plant performances under limited water availability
and in different experimental fields.