BIOMETRIC PARAMETERS AND WEED INFESTATION OF SUNFLOWER DEPENDING ON THE APPLICATION RATES OF WORKING SOLUTION OF POSTEMERGENCE HERBICIDES
Abstract
Purpose. To scientifically substantiate the selection of optimal application rates of post-emergence herbicides in sunflower crops under the Express technology and to determine the rational rate of working solution aimed at increasing weed control efficiency, improving biometric parameters, and crop productivity. Methods. The experimental study was conducted in 2023–2025 at the fields of LLC “Agrofirma im. Horkoho”, Novomoskovsk district, Dnipropetrovsk region. The research methodology was based on the use of modern methods, including field, gravimetric, laboratory-analytical, and statistical approaches. All methods complied with current methodological requirements and standards accepted for agronomic field experiments. Results. Studies conducted in 2023–2025 showed that the application rates of working solution of post-emergence herbicides significantly affect the duration of vegetation, plant growth, and weed control efficiency in sunflower crops. The use of herbicides increased the vegetation period by 12–19 days compared to the control, with a maximum of 118–119 days at a water rate of 200 L/ha. The highest plant height (185 cm) was obtained under split application of herbicides with a working solution volume of 200 L/ha, whereas reducing it to 50–100 L/ha led to a decrease in growth parameters. The technical efficiency of herbicides in 2023–2024 was high (95–97%) and decreased with a reduction in the working solution rate. In 2025, under high temperatures and moisture deficit, herbicide efficiency significantly decreased to 32–66%, accompanied by signs of herbicide stress in sunflower plants. It was established that the optimal approach is the use of herbicides at a working solution rate of 200 L/ha with split application, ensuring maximum weed control efficiency and favorable crop growth conditions. Conclusions. It was found that the application of post-emergence herbicides Express and Express Gold at a working solution rate of 200 L/ha ensures an extension of the sunflower vegetation period by 12–19 days compared to the control. A positive effect of herbicide protection on plant growth was observed, with plant height increasing by 0.6–6.9%, reaching a maximum under split application of Express (25+25 g/ha) at 200 L/ha. Reducing the working solution volume to 100–50 L/ha decreased herbicide efficiency and growth parameters. The highest level of weed control (95–97%) was achieved under split herbicide application combined with 200 L/ha, while reducing the working solution volume led to a decrease in technical efficiency by 10–20%. The optimal technological element is the use of herbicides in split doses with a working solution volume of 200 L/ha, ensuring maximum protection efficiency and favorable sunflower development.
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