Effect of carbon dioxide concentration, pH, and electrical conductivity on tomato yield in hydroponics of the Chechen Republic

Abstract

Introduction. To increase tomato productivity in hydroponic cultivation, precise regulation of carbon dioxide (CO₂), acidity (pH), and electrical conductivity (EC) is essential. However, their combined effects in combination with different substrates under the conditions of the Chechen Republic remain insufficiently studied.
Aim. To evaluate the effect of CO₂ concentration, pH, and EC of the nutrient solution on the yield and agrobiological parameters of Merlis F₁ and Santiana F₁ tomato hybrids grown hydroponically on GRODAN and BIOGROW substrates.
Materials and Methods. The research was conducted in the greenhouse complex of YugAgroHolding LLC (Grozny). Four CO₂ levels were studied: 400 ppm (control), 850, 1200, and 1500 ppm. The experiment controlled pH in the range of 5.0–6.5 and EC of 1.5–4.5 mS/cm under supplemental lighting of 18,000 lx and a photoperiod of 16 h.
Results. It was found that increasing CO₂ to 850–1500 ppm, maintaining pH at 5.5–6.5, and EC at 3.2–3.6 mS/cm contribute to increased yield of both hybrids. The BIOGROW substrate provided higher performance compared to GRODAN.
Conclusion. The highest tomato productivity is achieved by combining elevated CO₂ concentration, optimal pH and EC values, and the use of the organic substrate BIOGROW. The obtained results can be used to improve greenhouse tomato production technologies.

To cite: Isaeva P.M., Akhmedova P.M. Effect of carbon dioxide concentration, pH, and electrical conductivity on tomato yield in hydroponics of the Chechen Republic. Agrarian Bulletin of the North Caucasus. 2026;16(2):57-68. (In Russ.) https://doi.org/10.31279/2949-4796-2026-16-2-57-68 EDN NROLAX