Особливості видового складу бур’янів у посівах ячменю ярого в умовах північно-східної України

Abstract

Протягом трьох років в умовах польових дослідів і під час основного обстеження полів у господарствах встановлено видовий склад бур’янів у посівах ячменю ярого. Серед 105 виявлених бур'янів і 11 засмічувачів виділено найбільш поширені види, вказані серед них особливо шкодочинні.

На протяжении трех лет в условиях полевых опытов и при основном обследовании полей в хозяйствах определен видовой состав сорняков в посевах ячменя ярового. Среди 105 видов обнаруженных сорняков и 11 засорителей выделены наиболее распространенные виды, среди них отмечены особо вредоносны.

The efficiency of weeds control, especially through chemical methods, varies depending on whether the weeds-species composition in plantings is taken into account. As far as barley-sown fields are concerned, this issue has not been sufficiently studied in the context of the north-eastern Ukraine. In this connection, over the years of 2013 to 2015, some qualitative weight estimates of weeds in spring-planted barley were made in the course of a research into cases where no herbicides had been applied. This research work was performed on the research fields of the Kharkiv National Agrarian University named after V. V. Dokuchayev and the Plant Growing Research Institute named after V. Ya. Yuryev. In as little as three years, 14 research years were covered. The second part of the research laid in the general monitoring over fields that were under working conditions and belonged to four farms in the territory of Kharkiv region. In essence, 85 fields and land lots were investigated. In this case, the weeds-species composition was identified through an ocular estimate method. Species that accounted for over 10 % in the total mass of weeds were counted as dominant ones, species accounted for 3 to 10 % as subdominant ones, and species accounted for below 3 % as accompanying ones. While categorizing separate species by the ranks of main weeds, use was made of a generalized index of dominance that was held forth by us. Where a certain species was a dominant one on some fields, this index was calculated through multiplying the percentage of these fields by the coefficient of 3, where it was subdominant on some fields the index was calculated through multiplying the percentage of these fields by the coefficient of 2, and where it was an accompanying species on some fields, the index was calculated through multiplying the percentage of these fields by 1. Then the three indicators were summarized to give a relevant index. By correlating the research findings obtained in field experiments and in the herbological monitoring over farm crops, the following species were identified as being the top ten on the ranked list of main weeds on the barley-sown fields in the order of their dominance: Cirsium arvense, Setari glauca, Chenopodium album, Echinocloa grusgalli, Fallopia convolvulus, Stachus annua, Amaranthus retroflexus, Ambrosia artemisifolia, Convolvulus arvensis, Sonchus arvensis. As a whole, the investigations in the barley-sown fields revealed 105 species of weeds and 11 contaminating pests (fruit droppage of cultivated plants). The most damage to barley, among contaminating pests, was done by sunflower. The second and third places among contaminating pests were taken, respectively, by buckwheat and millet. The role of individual species and groups of weeds in the segetal association, in terms of phytocenosis, was identified as being not so much quantity related as mass-related. According to the materials of field investigations, the bilobed underage weeds numbered 391.0 pc/sq.m and had a raw mass of 212,5 g/sq.m prior to crop harvesting, with the corresponding figures for the other weeds being as follows: 208.0 pc/sq.m and 108.3 g/sq.m for millet-like grass weeds, 19.8 pc/sq.m and 205.6 g/sq.m for root-shooting weeds, and 13.8 pc/sq.m and 66.4 g/sq.m for contaminating pests. The most competitive, and thus the most detrimental to barley plantings, are root-shooting species of weeds. Among the bilobed underage weeds, the heaviest harm is done by Amrosia artemisifolia i Xanthium strumarium. The millet-like grass weeds, notwithstanding their considerable quantity, are less harmful to barley plantings than the above mentioned weeds. The reason for this is that these, being late spring weeds, give rise to sprouts well after barley does and, hence, compare poorly with barley in terms of competition. Only at the end of June, when barley begins to get ripe and casts smaller shadows over the ground surface, the multigrain weeds are intensively gaining their mass. So, at the beginning of the barley growing season, this group of weeds accounted for 5 % in building-up the total mass of the segetal component in the plantings, and, prior to harvesting, its share went to 8 %.