Application of protein hydrolysate-based biostimulant as new approach to improve performance of bedding plants.

Bedding plants are an important component of the public green spaces and private gardens. However, they are not always properly watered and suffer from drought, salinity and pollution especially in peri-urban and urban areas. Any sustainable improvement in agricultural practices to increase the performance of ornamentals under non-optimal conditions would be of great interest. A promising and effective strategy would be the use of plant biostimulants. Protein hydrolysates (PHs) are an important group of plant biostimulants The aim of this study was to assess the effects of four concentrations of plant-derived protein hydrolysate “Trainer” (0, 1, 3 or 5 mL L-1) on growth, ornamental quality, leaf gas exchanges and mineral composition of three bedding plants: Begonia tuberhybrida, Pelargonium peltatum and Viola cornuta. In the present study the enhancement in growth and ornamental quality recorded in PH-treated bedding plants were species dependent. Our data indicated that the 1 mL L-1 concentration tested enhanced several growth and quality parameters (plant height, canopy volume,leaf area and number of flowers plant-1) in Pelargonium peltatum, whereas an opposite trend was observed for Viola cornuta. Significant differences among treatments were observed for net photosynthesis, stomatal conductance and transpiration. The better crop performance observed in Pelargonium peltatum and Begonia tuberhybrida treated with PH containing amino acids and small peptides could be attributed to an increase in total N and nitrate contents.