Strategies to resources optimization in tomato, combination of soil water monitoring and biostimulation

Spain is one of the most important tomato producers of the European Union, but the elevated water requirements of this crop together with the water scarcity that the country undergoes, lead farmers to look for new alternatives to optimize the use of the water and nutrients used for its growth. For this reason, the aim of this study was to evaluate the effect of a combined treatment of biostimulation and irrigation reduction on the yield parameters, irrigation water productivity (WPi), productivity of the macronutrients nitrogen (N), phosphorous (P) and potassium (K) and soil enzymatic activity in two commercial greenhouses of tomato (Solanum lycopersicum L.). The treatments evaluated were: i) FARMER: irrigated by farmer criteria, and ii) BIO: Biostimulated with seaweed extracts and microorganisms, and irrigated by monitoring the soil water content during the whole crop cycle through the use of real-time probes. The biostimulation program consisted of Ascophyllum nodosum extract applied by foliar and drip irrigation in both trials. In addition, the application of a third biostimulant composed by Bacillus paralicheniformis was added in trial 2. In both trials, the water savings in the BIO treatment with respect to their FARMER were 842 m³ ha^-1 and 117 m³ ha^-1, for trial 1 and 2, respectively. BIO treatment increased the number of fruits and the yield of tomato, therefore, an increase in the WPi and the productivity factor of N-P-K was observed. In addition, the enzymatic activities of the soil, β-glucosidase, phosphatase and urease showed a trend to improve in the BIO treatments in comparison to FARMER, making the nutrients more available for the plants. In conclusion, the application of biostimulants combined with irrigation reduction has been proved to be a strategy that allows reducing the water irrigation and fertilizers applied to tomato, improving its yield and soil enzymatic activities. This combination increases the economical and environmentally sustainable of tomato under greenhouse.

This work is a result of the AGROALNEXT programme and was supported by MCIN with funding from European Union NextGenerationEU (PRTR-C17.I1) and by Fundación Séneca with funding from Comunidad Autónoma Región de Murcia (CARM). Funding has also been received from the FMC Agricultural Sciences chair of the UPCT, an agreement between FMC Agricultural Solutions and UPCT.