Forming of the spring rape agrophytocenosis under an influence of the cultivation technology in the southern forest-steppeof Western Siberia

This article presents the data of field trials on the medium deep heavy loamy low humus ordinary black earth (chernozem) under the conditions of the southern forest-steppe of Western Siberia in 2013-2015. In these experiments seeds of the spring rape of the Highlight grade of the Bayer CropScience firm were used. In the seed- bed period the experimental land was treated with a herbicide of continuous action (Glifos - 2 l/ha). The rape seeds were also treated with the Modesto insecticide. The sowings were sprayed with the tank mixture of the Galera-334 Furore (0.325 l/ha) plus Ultra (0.625 l/ha) herbicides and with the Biskaya insecticide. If necessary, sowings were additionally treated with insecticides and the Basta desiccant. In the period before the harvest the number of weeds was reduced by 65.0-71.5 % due to the use of herbicides. Against the background of fertilizers (N40P26) this figure decreased to 52.1-58.5 %. The mass of weeds decreased, respectively, by 87.1-87.4 % and 80.4-86.5 %. The above-ground mass of the rape by use of fertilizers increased by 47 %, but by use of herbi- cides against the unfertilized background by 54.5 % and by the use of herbicides against the fertilized back- ground - by two times. At complex protection of rape plants their mass was more by 2.2-2.8 times. The propor- tion of all weeds in the agrophytocenosis of the spring rape against the unfertilized background was 28.8 %, and including the bluegrass - 23.5 %. With the introduction of nitric-phosphoric fertilizers, due to a more powerful development of cultural plants, the proportion of weeds decreased by 1.7 times. The use of herbicides provided a weak degree of clogging, when the proportion of weeds was 3.8 %. This index was even less when using the integrated plant protection, especially against the background of fertilizer - 2.3 % or 92.0 % less than the control figures.