INFLUENCE OF MAIN ELEMENTS OF CULTIVATION TECHNOLOGY ON WEED INFESTATION OF CROPS AND SPRING WHEAT YIELD

A distinctive feature of the North-West region is sufficient, and in some years, excessive moisture supply, under which weeds form a significant vegetative mass and cause great harm to cultivated crops, including spring wheat. The aim of the research was to assess the effect of seeding amount, seed size, nitrogen nutrition and herbicide treatment on weed infestation of crops and spring wheat yield in the North-West region of the Russian Federation. According to the research results, it was revealed that introduction of medium (by 0.8-13.6%) and high (by 1.5-14.1%) doses of nitrogen fertilizers leads to significant increase of initial weed infestation of spring wheat, while seeding amount and seed size did not have a significant impact on the number and cover of weeds. Among all the factors studied in the experiment, herbicide treatment had the strongest positive effect on formation of spring wheat crop (by 1.5–4.5 times), but only in the conditions of strong and complex types of weed infestation. Application of average dose of nitrogen led to a significant increase of spring wheat yield throughout the research years (by 19.3-82.8%), whereas effectiveness of high dose directly depended on moisture conditions of initial stage of vegetative period. Seeding amount and especially fractional composition of the seed material had a slight effect on yield and main elements of the structure of spring wheat crop. Interaction of such factors as application of nitrogen fertilizers and herbicide treatment contributed to significant increase of spring wheat yield (by 23.4-183%). The highest grain yield of spring wheat throughout all research years was obtained on seed plots with a seeding amount of 6 million viable seeds/ha, application of a high dose of nitrogen fertilizers and herbicide application (51.1; 29.7 and 40.9 q/ha).