ANALYSIS OF THE STRUCTURE OF THE SPRING WHEAT CROP IN VARIOUS WEATHER CONDITIONS IN THE TYUMEN REGION

Abstract

Abstract. During the growing seasons of 2014-2016, 22 varieties of spring soft wheat were evaluated according to economically valuable characteristics. The purpose of the work was to determine the features of the formation of the yield of the studied varieties based on the analysis of the variability of the main elements of its structure in the conditions of the taiga agro-climatic zone of Tyumen region. Varieties belonging to two groups of ripeness (medium-early and medium-ripe) were evaluated on plots with an accounting area of 1 m2, the repetition of the experiment was 4-fold. The soil is loamy in terms of granulometric composition, the humus content is 4.5 %, pH=7.1. The limiting factor of the wheat harvest in the first year of the study was insufficient heat supply (the average daily air temperature is 1.4 0C lower than the average long-term value) against the background of a lack of precipitation (62 % relative to the norm), which caused the formation of a puny grain. In the second year, heavy precipitation (155 % of the norm for the growing season) and having a stormy character in July led to the lodging of plants and an increase in the contamination of grain with fungal diseases. In the third year, the high air temperature (3.2 0C higher than long-term indicators) caused a reduction in the duration of the tillering phase and a decrease in the number of productive shoots. The signs - the number of shoots, the weight of grain from the ear, the weight of 1000 grains and the length of the stem (the coefficients of variation (CV) were – 20...22 %) were subject to a significant degree of variation during the study period, the number of grains in the ear and the length of the ear (CV – 2...3 %) practically did not change. We observed the compensation of some elements of the crop structure by others. Thus, the insufficient number of stems was compensated by an increase in the share of productive stems, a low number of productive shoots – by a higher productivity of the ear, a relatively low water content of the ear – by an increase in the mass of 1000 grains. As a result, the yield level varied slightly over the years of the study (CV-7 %)