Foliar Applications of Protein Hydrolysate, Plant and Seaweed Extracts Increase Yield but Differentially Modulate Fruit Quality of Greenhouse Tomato

The current research aimed 1) at evaluating the effects of three biostimulants (legume-derived protein hydrolysate, PH; plant and seaweed extract, PE and SWE) on yield performance and nutritional quality, mineral profiling, antioxidant activities, lycopene, total phenols and ascorbic acid of greenhouse tomato (Solanum lycopersicum L.) under soil culture and 2) to assess the economic profitability of biostimulant applications. Plants were sprayed four times during the growing cycle with a solution containing 1, 3, and 3 mL·L−1 of PE, SWE, and PH, respectively. Foliar applications of biostimulants improved the early and total marketable yield of fresh tomato. The increase of total yield by PE, SWE, and PH was 11.7%, 6.6% and 7.0%, respectively, in comparison with untreated plants. Legume-derived PH increased lycopene, total soluble solids, and K and Mg contents, thereby increasing the nutritional value of the fruits. The applications of SWE, and to a lesser degree PH, enhanced the Ca concentration in the fruit tissue. Our findings indicated that the three tested biostimulants, although they increased the total production cost, improved the nutrient status and yield performance of the crop to a level resulting in net economic benefits