RESPONSE OF PEA GRAIN YIELD TO THE USE OF INOCULANTS AND SEED DRESSINGS AFTER DIFFERENT PRECEDING CROPS IN THE STEPPE ZONE OF UKRAINE

Abstract

Against the backdrop of increasing climatic variability and phytosanitary risks in the Steppe zone of Ukraine, there is a need to optimize pea seed pre-sowing treatment by combining inoculants and seed-applied fungicides in accordance with the previous crop. The aim of the study was to assess the yield response of field pea (cv. Madonna) to combinations of inoculants and fungicidal seed dressings under different previous crops in the Steppe zone of Ukraine and to identify technological solutions that ensure yield stability in years with contrasting moisture supply. Field experiments were conducted in 2023–2025 on a common, low-humus, medium-loam Chernozem. A two-factor field design was used: factor A – previous crop (winter wheat; sunflower); factor B – seed treatment (untreated control; fungicidal dressings Vibrance RFC, Redigo, Spherico, Avido; inoculant systems Rizolain + Rizosave and Atuva + Premax; and their “inoculant + fungicide” combinations). The data indicate that inoculation is the key prerequisite for increasing and reproducing yield; adding a fungicidal seed dressing to the inoculant performs a stabilizing function by reducing the likelihood of losses from seed– and soil-borne infections. After winter wheat, the highest yields were formed by inoculant + fungicide combinations: in particular, Rizolain + Rizosave + Vibrance RFC produced 4.47 t·ha⁻¹ vs 3.77 t·ha⁻¹ in the control in 2023, 2.44 vs 2.16 t·ha⁻¹ in 2024, and 1.78 vs 1.67 t·ha⁻¹ in 2025 (+0.11 t·ha⁻¹). Three-year mean yields after winter wheat were 2.90 t·ha⁻¹ for this combination vs 2.53 t·ha⁻¹ in the control; inoculation with Rizolain + Rizosave alone yielded 2.82 t·ha⁻¹, whereas the fungicidal dressing Vibrance RFC alone gave 2.68 t·ha⁻¹. After sunflower, the relative advantage of biological schemes increased: Rizolain + Rizosave + Vibrance RFC achieved 4.20 t·ha⁻¹ vs 3.47 t·ha⁻¹ (2023), 2.26 vs 1.94 t·ha⁻¹ (2024), and 1.58 vs 1.42 t·ha⁻¹ (2025). The three-year averages for 2023–2025 confirmed the dominance of the previous crop as a systemic factor: winter wheat consistently provided higher yield levels than sunflower across all pea seed-treatment variants. The practical significance lies in enabling flexible choices: under typical risks and sufficient resources, the integrated inoculant + fungicide scheme is advisable as the baseline; under budgetary or organizational constraints, inoculation alone provides an almost equivalent level and is the priority minimum requirement, especially after sunflower. The novelty of the study is a three-year comparison of inoculant-fungicide combinations simultaneously under two contrasting previous crops in real Steppe conditions, including an extremely dry year, which made it possible to quantify the crucial role of inoculation and to delineate the conditions under which combining it with fungicidal seed treatment is justified for pea.