Tomato yield and soil chemical properties influenced by low–molecular–weight organic acids in calcareous soil

Abstract

<p>Calcareous soils have restrictive characteristics that limit and pose a challenge for crop production; in this environment, plants can exude low-molecular-weight organic acids (LMWOAs). This study aimed to verify the influence of exogenously applied LMWOAs in calcareous soils on tomato yield and the chemical characteristics of soil and leachate. <em>Solanum lycopersicum</em> L. seedlings were grown in pots containing calcareous soil in a greenhouse, fertilized by drip irrigation with Steiner nutrient solution in which the treatments 0.1 mM citric acid (CA), 0.1 mM oxalic acid (OA), 0.01 mM salicylic acid (SA) and a control without LMWOAs (T0) were prepared, applied during the whole growth cycle. The experiment was repeated four times, with twenty replicates per treatment, under a completely randomized design. The yield per plant was quantified, while pH and microbial respiration (RMS) were measured in the soil. The pH, electrical conductivity (EC), oxidation-reduction potential (ORP), carbonate (CO<sub>3</sub><sup>2–</sup>), and bicarbonate (HCO<sub>3</sub><sup>–</sup>) contents were quantified in the leachates. SA application reduced the soil pH (8.75). SA and CA improved the fruit yield per plant by 11% and 33%, respectively (p < 0.05). CA induced a 1.7% reduction in leachate pH (p < 0.05) and a 15.9% increase in HCO<sub>3</sub><sup>–</sup> content (p < 0.05). SA decreased EC and CO<sub>3</sub><sup>2–</sup> concentrations by 8.9 and 23.1% (p < 0.05), but increased HCO<sub>3</sub><sup>–</sup> content by 23.1 % (p < 0.05). The use of LMWOAs as a strategy in the management of calcareous soils can promote favorable conditions for tomato yield per plant.</p>