Currently, the main direction in the production of feed, along with an increase in volumes, – quality improvement. Moreover, the most important aspect of this problem – feed protein.

The structure of the morphological parts of the maize plant is given and the influence of weather conditions, genotype, plant standing density, sowing and harvesting dates on the proportion of cobs, stems, leaves and wrappers in the harvest of green and dry mass is shown. It is established that under the influence of these factors, the share of cob, as the most valuable part of the plant, in the dry matter yield varies in a wide range – from 22,2 to 55,8 %.

Three-year studies on three hybrids (FAO 210, 230 and 250) showed the effect of weather conditions, plant density, sowing and harvesting dates on the dry matter content of leaves, stems, wrappers, cobs and maize plants. The most effective factors for changing the dry matter content in the cobs are the density of standing plants and the period of harvesting maize for silage, in leaves and wrappers – the harvesting period and weather conditions of the year, in the stems – the genotype. The density of standing plants (70– 130 thousand plants per 1 ha) and the sowing period with a difference of 2 weeks, in contrast to the harvesting period, have a slight effect on the dry matter content in maize plants.

The article presents the results of the analysis of the morphometric parameters of tarwi lupine (Lupinus mutabilis Sweet) various samples seedlings. The degree of correlation between seed productivity of plants and five indicators characterizing the degree of seedling development – sprout length, pod-cotyledon length, root length, number of lateral roots and average length of lateral root were determined. A direct correlation between the indices of yield and the length of sprout, the average length of lateral root, and the number of lateral roots of seedlings was found. The revealed pattern can be recommended for the effective selection of the most productive plants at the initial stages of creating new varieties of tarwi lupine.

Studies on sandy loam soil have established that the inclusion of winter rye as an intermediate crop during the cultivation of alfalfa allows not only to reduce the weed infestation in the first year of its life, but also in the variant with preliminary shallow soil treatment to bring the protein harvest to 14,3 c/ha, the exchange energy – to 87,2 GJ/ha, which is 2,4 and 2,9 times more, respectively, than in the variant of the basic spring uncovered sowing. At the same time, alfalfa sown after harvesting rye shows 35 % greater productivity in protein and 29 % – in exchange energy.

Aerodynamic separation is an additional method of preparing seeds of Sudanese grass, contributing to an increase in their sowing qualities. When using calibrated seeds, the field germination of Sudanese grass increases by 6–10 %. The use of Hydrohumate, 0,5 l/t and Ecosil, 100 ml/t for pre-sowing treatment of growth regulators helps to increase the field germination of Sudanese grass by 3–10 %, depending on the size of seeds and conditions in the pre-emergence period.

In the article the data about the dynamics of the number of sucking pests from the families Aphididae and Thripidae in the sorghum crops are presented. In the species composition of insects Rhopalosiphum padi L., Aphis solanella Theob., R. maidis Fitch., Limothrips denticornis Hal. were dominated. It was found that the beginning of sorghum colonization by aphids took place in the phase of 6–7 leaves, the peak of their abundance (60,5–96,5 ind./stalk) was noted in the phase of waxy ripeness. Thrips colonized sorghum plants in the 8–9 leaf phase. In the phase of panicle ejection – flowering of sugar sorghum, their plant population reached a maximum – 40,0 %, broom – 28,0 %, grain – 9,0 %. R. padi L., Sitobion avenae F. and L. denticornis Hal. were dominated among the sucking pests of the sorghum–sudangrass hybrid, with a population of 2,0–8,0 % and 64,0 %, respectively in the panicle ejection phase.

The biological effectiveness of the fungicide Priam, EC (0,6 l/ha) when applied twice ("pink bud", "end of flowering") against apple scab was 36,1–93,7 %, and against scab on fruits – 16,0–95,3 %. The use of the fungicide Priam, EC at a rate of 0,6 l/ha made it possible to significantly increase the apple-tree yield by 20,4–20,9 с/ha.

The research was carried out on spring cereal crops (wheat, triticale, barley, oat) in 2018–2021. Biodiversity of Fusarium fungi causing root rot varied depending on growing season and region of the republic. On wheat F. equiseti dominated, on western and central regions F. oxysporum was also isolated. On barley roots on eastern part of Belarus F. equiseti, F. oxysporum, F. solani were isolated, whereas on central part F. equiseti, F. oxysporum, F. culmorum dominated. At the same time on western part F. oxysporum, F. solani, F. equiseti prevailed. On triticale from eastern region F. solani, F. oxysporum, F. equiseti dominated whereas at the center and on the west F. equiseti prevailed. On oats from west and central part of the country F. equiseti dominated, and from the east F. avenaceum prevailed.

The article presents the results of studying the biological and economic efficiency of two- and three-component tank mixtures of herbicides against annual and some perennial dicotyledonous weeds in flax crops, including preparations with the active substance MCPA-acid, sulfonylurea derivatives, clopyralid with reduced consumption rates. The most effective two-component mixtures of herbicides have been established, which provide flax protection in terms of the number of weeds up to 96 % and their weight up to 98 %, an increase in the yield of flax products almost 2 times, and obtaining trusts number 1,50 with the required weediness.

Development of neoplasms (inturmescences / edema; oedema) on leaves or fruits is a specific physiological disorder observed in certain crops developing in greenhouse conditions. It can be mistaken for infectious disease or insect damage. The article presents the results of studies showing that against the background of increased air humidity and when potato plants are treated with salicylic acid or methyl jasmonate, there is an active formation of inturmescences that damage the leaves and is accompanied by a decrease in photosynthetic and enzymatic activity and an increase in proline content by more than 3 times. The application of epibrassinolide favors reducing the negative effect of the resulting swelling at high humidity, causing an increase in peroxidase activity and a moderate increase in proline content.