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Ecological plasticity and stability in productivity of seven varieties of winter soft wheat were studied in 2020-2021. As a result of the study it was found that on average for 2 years the most productive varieties were Grom, Surava and Biryuza with yields of 60.5, 48.5 and 46.5 dt/ha, respectively. Moisture and protein content in all the varieties studied were within the optimum limits. The environment index showed that growing conditions were worse in 2021 (Ij = -12.8) than in 2020 (Ij = 12.9). The varieties Grom, Biryuza and Krastal were the most plastic (bi - 1.3; 1.53; 1.41, respectively). These varieties should be cultivated according to intensive technology. The yields of these varieties on improved growing conditions are high. The value of the linear regression coefficient for the variety Povolzhskaya Niva is practically zero (bi = 0.01). This variety does not respond to changes in growing conditions. In varieties Skipetr, Doneko and Surava the linear regression coefficient approached 1. These varieties respond to improved growing conditions. The calculation of the ecological plasticity index showed that the varieties Grom, Surava and Biryuza are also ecologically plastic. The Povolzhskaya Niva and Doneco varieties were found to be the most stable. Their standard deviation (σd2) was 0.004. In the other varieties it was between 0.01 and 0.8. The most unstable variety was Krastal. The standard deviation (σd2) was 1.1.

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The aim of the research is to substantiate the scheme of plant protection of winter wheat against perennial and annual weeds, including monocotyledonous weed species. This scheme provides high grain yield and quality standardized seeds output. To achieve this goal the production experiment was conducted. The experiment was repeated three times, the location of the plots was systematic. The predecessor was peas. The main weeds of winter wheat were representatives of the classes: Asteraceae (field sowthistle, Canada thistle, chamomile odorless), ranging from 15% to 24%, Cabbage – Brassicaceae Burnett (field pennycress) – 7-14%, Goosefoot family – Chenopodiaceae (pigweed white) – 1-6%, Vonkova – Convolvulaceae (convolvulus arvensis) – 10-8% and Poaceae (PPE foxtail, millet, chicken, wild oat common) – from 24 to 42%. The species composition of the weed is suppressed almost completely when using the tank mixture of graminicide together with the broad-spectrum herbicide (Lastik Top 0.5 l/ga + Balerina 0.4 l/ga). In average, per years of research the biological efficiency of this variant was 96%. The plants of winter wheat under treatment of crops with protection means against weeds receive stress, which is manifested in a sharp decrease of chlorophyll concentration in the leaves. The inhibition of plants is manifested regardless of the application of graminicide, herbicide or tank mixtures. Under favorable weather conditions for plant growth and development the chlorophyll concentration in leaves restores after 8 days of applying plant protection means up to normal. The highest yield of winter wheat, maximum yield of quality standardized seeds and the propagation coefficient factor of varieties is formed when using a tank mix Lastik Top (0.5 l/ga) + Balerina (0.4 l/ga), regardless of variety and year of growing. The use of graminicide Lastik Top (0.5 l/ga) in tank mix with herbicide Balerina (0.4 l/ga) suppresses the development of monocotyledonous species of weeds of the same Botanical group that includes winter wheat. The second component tank mix herbicide Balerina suppresses the entire spectrum of dicotyledonous weeds. This results in the improvement of conditions for the growth and development of plants, providing higher grain yield, quality standardized seeds output and the rate of reproduction of varieties.