Rational way to increase the efficiency of rice crop protection systems from weeds

Abstract

The purpose of the research was to assess the reasons for the insufficient effectiveness of the use of known herbicides and to develop ways to reliably control weeds and obtain high yields of sowing rice. Methods. The experiments were field trials. They were carried out in 2018–2020 in crops (rice paddies) of the Rice Institute of the National Academy of Sciences of Ukraine. The counts and analyzes were carried out in accordance with the requirements of the “Methods of testing and the use of pesticides)”, edited by prof. S.A. Triebel, “Soil and Plant Research Methods” and “Research Methods in Beet Growing”. The yield of rice crops was determined by continuous harvesting of registration plots on all repetitions of the variants with a special selection harvester “Sampo 2000”. Results. As a result of analyzes of soil samples from rice paddies, it was found that the largest reserves of live seeds are present in the soil horizon of rice paddies 0–10 cm and amount to 12 987.8 pcs/m2, including 1 381 chicken millet/m2. On plots of option 1 (weed control), the total number of weed seedlings is 426.5 pcs/m2. Of these, sprouts of chicken millet (Echinochloa crus-galli (L.) Pal. Beauv.) – 281.3 pcs/m2, or 65.9% of the total number of weed plants. Soil hebicides, even with the presence of a physical adsorbent, partially showed a phytotoxic effect on seedlings and seedlings of rice plants. Herbicide Frontier Opttma, 72 k. e. at a consumption rate of 1.2 l/ha and the presence of an adsorbent (option 3) reduced the density of rice crops by 35.1%, Dual Gold, 960ES at a rate of 1.4 l/ha and the presence of an adsorbent by 16.9% (option 4). The protective effectiveness of the action of soil herbicides was different. Command, 48 KE at a consumption rate of 0.5 l/ha (option 2) reduced the number of weeds by 46.1%, Front Optima (with adsorbent) – by 77.1%, Dual Gold, 960ES with adsorbent – by 80.3%. Application of herbicide Topshot on germination, 113 OD ppm at a consumption rate of 3.0 l/ha (variants 2, 3, 4) limited the ability of weeds to form their weight in rice crops by 66.8–90.1%. Weed control systems ensured the yield of rice crops at the level: option 1–2.71 t/ha, or 19.5%, option 2 – 10.24 t/ha or 73.6%, option 3 12.1 t/ha or 86.9%, option 4 -12.81 t/ha or 92.0% of the maximum in experiments – 13.92 t/ha (option 5). Conclusions. The research results confirm the presence of significant reserves for improving the systems of protecting rice crops from weeds by selecting and applying physical adsorbents to known herbicides to control the most common and problematic types of weeds in rice paddies.