Application of biostimulants obtained from brewing industry waste in greenhouse tomato ( Solanum lycopersicum Mill. cv. Mina) crop

Biostimulants produced through enzymatic hydrolysis are agronomic tools of considerable interest, as they provide an alternative to the use of inorganic fertilisers. In this work, the effect of two biostimulants obtained from brewing industry by-products in greenhouse tomato (Solanum lycopersicum Mill. cv. Mina) crop is studied. In addition to the subtilisin used to carry out the protein hydrolysis, one of the biostimulants incorporated an enzymatic cocktail to degrade the β-glucans present in the by-products and transform them into free glucose. Both biostimulants were applied four times throughout the crop growth period via foliar and root applications at doses of 2.5 and 5 g L−1. During this period, plant height, fruit number, and the content of nutrients and photosynthetic pigments in leaves were measured. On the other hand, β-carotene and lycopene contents, equatorial diameter and mean fresh and dry weight were determined in the fruit. Finally, dehydrogenase activity was determined in the substrate. The results showed higher values when a biostimulant without β-glucans at the higher dose was applied via root application, due to greater root development and higher microbial activity in the substrate.