WEED COMMUNITIES AND THEIR EFFECT ON PRODUCTIVITY OF BREAD SPRING WHEAT IN DRY STEPPE OF WESTERN KAZAKHSTAN

Galina Urakchintseva, Vladimir Kaplin

Abstract: In organic farming the spatial distribution, number and present productivity data of weed communities and their effect on the productivity of spring wheat depending on meteorological conditions, tillage system and sowing were determined. The projective cover and density of weeds were taken into account. Thirty seven types of weed communities were identified by dominant and subdominant species and marked out on the plan. Mapping of weed communities was carried out in the heading stage of wheat. Air-dry above-ground phytomass of weeds was determined. The productivity of wheat was calculated in the identified types of communities. In our experiments the weather conditions of the year had more strong impact on the number and composition of weed communities than tillage system and methods of sowing. The number of communities of weeds increased from conventional to minimum tillage. The number of weed communities decrease from the wet and cool to drier years. Herbaceous perennial weeds (Lactuca tatarica, Euphorbia virgata, Sonchus arvensis, Cirsium setosum) were the most stable component of weed communities. The spring annual weeds with the dominance of Setaria pumila well developed in the years with significant rainfall in March and April. Perennial weeds reduced parameters of spring wheat productivity more than annuals. In communities with a dominance of thistle grain yield was 32-34% lower than in communities with foxtail. Gluten and protein content significantly decreasing in communities of perennial weeds. Understanding spatial pattern of weed communities is necessary for precision weed management, practical application of herbicides.

Keywords: annual weeds; dominant species; perennial weeds; sowing; tillage; yield

Date published: 2017-10-19