Impact of new triazole-based growth regulators on winter ontogenesis of new winter wheat varieties

Triazole-derived compounds are increasingly regarded as promising tools for improving the adaptability and productivity of winter wheat under unstable environmental conditions. Their physiological activity is associated with regulation of growth pr o cesses, enhancement of stress tolerance , and support of metabolic functions linked with overwintering. In t he present study , we evaluated the effects of three new triazole -type compound s, CA-64, CA-79 and CA-67, on winter period performance of five winter wheat varieties Khvylia Dnipra, MIP Roksolana, Vezha, LG Magirus , and LG Litopys. Seeds (1,000 per treatment) were soaked for 24 h in aqueous solutions of the tested compounds at concentrations of 0.01%, 0.02%, and 0.04%; water-treated seeds served as the control. The analysis focused on seed germination, plant survival before and after winter , and soluble sugar content in the tillering node on selected winter dates . The results demonstrated a clear concentration-dependent response. Among the tested agents, CA-79 showed the strongest and most stable stimulating effect, especially at 0.02%, which provided the highest values of germination, survival of plants during winter , and carbohydrate accumulation in the tillering node across most gen o types. CA-64 also produced a positive effect, particularly at 0.02%, while 0.01% was beneficial in several cases and may be regarded as a safer conservative option. By contrast, CA-67 did not provide reliable stimulation, 0.01% was mostly neutral, whereas 0.02% and especially 0.04% reduced sugar reserv es and worsened the survival-related traits. All three compounds were uniformly depressive at a concentration of 0.04%, causing declines in germination, pre-winter plant survival , post-winter survival, and winter carbohydrate status, thus indicating a toxicity threshold. The response was genotype-specific. The U krainian varieties Khvylia Dnipra, MIP Roksolana , and Vezha generally exhibited higher baseline winter-resistance parameters and responded more positively to CA-79 and CA-64, whereas the F rench varieties LG Magirus and LG Litopys had lower baseline sugar levels and greater sensitivity to excessive concentration. In practical terms, CA-79 at 0.02% should be considered the most promising option for enhancing winter tolerance, while CA-64 at 0.02% may serve as an effective alternative. CA-67 cannot be reco m mended as a reliable stimulator under the studied conditions. Further studies should integrate these results with grain yield and grain quality traits to develop variety-specific protocols for the use of novel triazole-based growth regulators in winter wheat.