Obstacles and ways of forming effective protection of rice crops from weeds

Abstract

Goal. Assessment of the current level of soil contamination in rice checks with weed seeds and determination of the reasons for insufficient efficiency of herbicide application to ensure high yields of rice sown in the south of our country. Research methodology: Field small-site experiments were conducted in crops (rice checks) of the Institute of Rice of NAAS of Ukraine (Antonivka village, Skadovsk district, Kherson region). The size of the sown experimental plot is 66 m2, the accounting area is 50 m2. The experiments were repeated 4 times. Placement of plots is regular in two tiers. Accounting and analysis were performed in accordance with the specifics of the requirements «Methods of testing and application of pesticides» edited by Professor S.O. Tribel, and Methods of research in beet growing. The level of yield of rice crops was determined by continuous harvesting of accounting plots on all repetitions of variants by a special selection combine «Sampo-2000» with the subsequent conversion into t/ha. Results. Washing of soil samples from rice checks and analysis of washed seeds and organs of vegetative reproduction revealed that the largest stocks of live seeds are present in the horizon 0—10 cm, and average 1310.0 pieces/ m2 of rooster millet. The total stock of seeds of different types of weeds that retained the ability to germinate in the soil was 12987.8 pieces/ m2. The number of weed seedlings in weed control crops (option 1) averaged 894.8 pcs/m2. In crops of option 2 after application of soil herbicide Kommand 48, KE (Clomazon, 480 g/l) with a concentration of working solution — 0.25%, at the rate of consumption of 0.5 l/ha before germination, the number of weed germs decreased to 550.5 pcs/ha or by 38.5%. Spraying of crops of rice of sowing in the period of formation — 3 leaves with a norm of expenses of working liquid of 200 l/hectare, herbicide Topshot, 113 OD of m.d. normal sow 3.0 l/ha with a concentration of working solution — 1.5%, further reduced the number of weeds in crops. The overall decrease in the number of weed plants in rice crops averaged 90.2%. Seedlings of acute plague died by 91.0%, rooster millet by 97.1%, bitter gourd by 96.3%. At the same time, the seedlings of Korsakov’s monochoria died out by 79.4% of the compact reed tuber by 77.1%, and the spreading plague by 76.2%. In crops of sown rice, 59.5 pcs/ m2 of weed plants of different species still remained to grow. Surviving plants were formed in rice crops on average 1452 g/m2 weight or 39.5% of its maximum volume in the experiments (option 1). The main part of the mass of weed plants was monocotyledonous species — 73.9%. The yield of rice crops was 5.12 t/ha or 44.8% of the maximum in the experiments (option 3). Conclusions: Systems of measures to protect rice crops should be aimed primarily at reliable and systematic control of seedlings and seedlings of the most numerous and problematic weed species: members of the botanical families Osokov and Tonkonogov.