Influence of seeding rates and herbicide application methods on weed infestation and oil radish seed yield

Abstract

The article presents the results of the research carried out to determine the influence of seeding rates and herbicides application methods on the weed infestation and the seed yield of a new variety of oilseed radish in the conditions of the forest-steppe of the Central Federal District of Russia. The study was carried out during the period from 2019 to 2021 at the Lipetsk Rapeseed Research Institute. The scheme of a two-factor field experiment included the options where in certain conditions (factor A) – with or without herbicide application (in the phase of 5-7 true leaves), the seeding rates of germinating seeds (factor B) were studied - 0.5, 1.0; 1.5; 2.0; 2.5 million pieces/ha. The soil in the experimental plots was leached medium-thick heavy loamy chernozem. During the years of the experiment, the applications of herbicides significantly reduced the number of weeds in the agrocoenosis, and the decrease in the seeding rate caused the opposite effect. During the flowering phase, oilseed radish weed infestation, at the studied seeding rates in the conditions with no chemical plant protection products applied, decreased by 47-57%, and in the conditions when chemical plant protection products had been applied – the index decreased by 74-84%. At the same time, the differences in the number of weed plants between the studied seeding rates decreased. By the end of the growing season, the phytosanitary state of this crop generally improved, and this was most noticeable with the variants that included herbicide application. It has been determined that an increase in the seeding rate within the studied limits reduced the crop yield, and the chemical protection of the plants from weeds, on the contrary, significantly increased it. Consequently, the largest seed yield of a new variety of oilseed radish Alpha was provided by the cultivation technology, where a seeding rate was 0.5 million units/ha and herbicides were applied.