Effectiveness of a Plant-Derived Protein Hydrolysate to Improve Crop Performances under Different Growing Conditions

The aim of the current work was to determine whether the use of a commercial plant-derived protein hydrolysate ('Trainer') could improve the growth and nitrogen uptake of maize and lettuce grown in a floating system using full strength and reduced nutrient solution concentrations (100 and 10%, respectively) (Experiment 2). In Experiment 1, 'Trainer' was applied to the maize roots at the following concentrations 0, 0.25, 0.50 and 2.5 ml L-1, whereas in Experiment 2, two concentrations (0, and 2.5 ml L-1) of 'Trainer' were used as foliar spray. Increasing 'Trainer' concentration from 0 to 2.5 ml L-1 significantly increased the plant height, shoot dry biomass, SPAD index and leaf nitrogen of maize, whereas an opposite trend was observed for the root-to-shoot ratio. In Experiment 2, at reduced solution concentration (10% of standard solution), weekly foliar applications of 'Trainer' at 2.5 ml L-1 increased the fresh weight biomass, SPAD index and leaf nitrogen in lettuce by 50, 11 and 11%, respectively. Thus the application of biostimulants could be considered as a good production strategy for obtaining high growth and yields of valuable crops with lower impact on the environment.