Evaluation of foliar biostimulants and micronutrient complexes for improving tomato growth, yield, and fruit quality in Southeastern Kazakhstan

Tomato (Lycopersicon esculentum L.) is a vital horticultural crop in Kazakhstan, especially in the southern and southeastern regions, where yields often fall short of their biological potential. This study evaluated the effects of selected foliar-applied biostimulants and micronutrient formulations on vegetative growth, yield, fruit quality, and economic performance of tomato under the agroecological conditions of Southeastern Kazakhstan. The experimental design included seven treatments: six commercial products—Fitolaza, Nano Sulfur, Scudo, Calcium Humate, CompleMet-Tomato, and BioSok Energy—applied individually or in combination, alongside a non-treated control. All treatments improved vegetative parameters such as plant height, stem diameter, leaf number, and total biomass. The T3 treatment (Fitolaza + Nano Sulfur) consistently delivered superior performance across all growth stages and achieved the highest fruit yield (26.10 t/ha), representing a 31.49% increase over the control. T7 (CompleMet-Tomato) and T5 (Calcium Humate) also demonstrated notable yield improvements. Biochemical analyses revealed that these treatments enhanced dry matter, total sugar, and vitamin C content in fruits, while keeping nitrate levels below the permissible threshold. Economic evaluation identified T3 as the most profitable treatment (USD 1,932.99/ha), followed by T7 and T5, with profitability rates exceeding 140%. These results highlight the potential of foliar biostimulant strategies to enhance both productivity and profitability in tomato cultivation, offering a viable path toward more sustainable and resource-efficient horticultural practices.