1, 2, 4-triazole derivatives, including tebuconazole, have been reported to show positive physiological effects in cereals apart from fungicidal activity and to increase plants’ tolerance against temperature stress. This study investigates the mechanisms of increasing frost resistance of etiolated winter wheat (Triticum aestivum L., “Irkutskaya” variety) seedlings by tebuconazole-based seed dresser “Bunker” (1.5 μL g⁻¹ of seeds) and tebuconazole (30 μg g⁻¹ of seeds). To identify ABA-dependent and ABA-independent pathways of frost resistance, we used fluridone (FLD, 5 mg L⁻¹), an inhibitor of endogenous abscisic acid (ABA) synthesis. FLD effectively inhibited the accumulation of carotenoids in the shoots and prevented the formation of carotenoids caused by the “Bunker” and tebuconazole. In non-hardened seedlings, FLD stimulated coleoptile and first leaf growth, but did not suppress the growth inhibitory effects of “Bunker” and tebuconazole. In shoots of hardened seedlings, FLD reduced the retarding effect of tebuconazole. Regardless of seedling age, temperature, and the protectant treatment, FLD had no effect on the sugar content in the shoots. FLD did not essentially influence frost resistance induced by “Bunker” and tebuconazole in cold-hardened seedlings. Fluridone increased H₂O₂ content and guaiacol peroxidase activity under control conditions (both with tebuconazole and without tebuconazole) and during cold hardening (in seedlings from seeds treated with tebuconazole). ABA levels in cold-hardened seedlings treated with FLD alone, tebuconazole alone, or a combination of the two were two to three times lower than in untreated hardened seedlings. Changes in indole-3-acetic and salicylic acids in response to FLD and tebuconazole treatment indicate complex interactions with signaling cellular systems. Our results suggest that tebuconazole activates ABA-independent pathways more strongly than ABA-dependent pathways in enhancing frost resistance. The potential mechanisms of tebuconazole action in plant cells are discussed.

Strobilurin and triazole class fungicides are actively used in agriculture as part of dressers to protect plants from fungal disease. In addition, they have various physiological effects on plants, including increased resistance to adverse environmental factors. The combined effect of these fungicides under water stress is understudied. The present work aims to examine the individual and combined effects of tebuconazole and azoxystrobin on the growth characteristics of wheat and its resistance to water stress. The study used winter wheat (Triticum aestivum L. ) plants grown from seeds treated with tebuconazole (2 mg/50 g seeds) and azoxystrobin (4 mg/50 g seeds) suspensions separately or together. In order to create water stress, five-day seedlings were transferred to 20% polyethylene glycol solution (PEG 6000), with stability assessed at seven and nine days. Tebuconazole was found to have a retardant effect on shoots and stimulate root growth. Azoxystrobin inhibited shoot growth and particularly root growth. When used together, tebuconazole partially reduced azoxystrobin-induced root inhibition. Azoxystrobin increased the negative effect of water stress, while tebuconazole effectively protected the root system of seedlings, partially reducing the effect of azoxystrobin. The stimulation of root growth with tebuconazolewas concluded to play an important role in providing resistance of winter wheat to water stress and to have the potential for use in agriculture.