Sham I. Change of structure of the weed component of agrophytocoenosis in rotation section of the eastern part of the forest-steppe zone under the influence of agrotechnical and chemical factors

The thesis studies changes of species and quantitative composition of weed seeds in soil, formation of weed groups in stands of farm crops of a rotation section under the influence of a long use of short-term rotations, methods of basic soil cultivation and rates of organic-mineral fertilizers; and also the influence of these factors on productivity and economic-energetic indexes of a rotation section. Efficiency of the action of chemical system of sugar beet protection from weeds was determined. It was established that reduction of weed infestation of farm crops of the rotation section and increase of their productivity were favonted by the alternation of crops of cereal-row crop and field crop rotations with the use of plowing to different depths and differential soil cultivation which included plowing for sugar beet and blade cultivation for other crops of the rotation section and application of 25t manure + N90P120K90. The efficiency of action of the system of chemical protection of sugar beet stands from weeds which included three successive sprayings with herbicides over crop seedlings was determined. The thesis presents calculations of energetic and economic efficiency of sections of rotations.