The present PhD thesis investigates the dynamics of soil weed seed bank and the impact of cover crops and different intensive tillage systems on the development of weed vegetation. Soil sampling and field experiments were conducted on the experimental field of the Agricultural Institute of Slovenia in Jablje, where a long-term experiment with three tillage systems (conventional [CN], conservation [CS] and no-tillage [NT]) has been ongoing since autumn 2018. The results demonstrated that the density of germinating weed seeds was higher in spring than in autumn, and that weed communities exhibited greater species richness and diversity in spring. The density of weed seeds was found to be consistently lower in the NT system. Our research group was the first in Slovenia to investigate the critical period for weed control (CPWC) in maize. The period during which weed control was required became shorter as the intensity of tillage decreased. Consequently, the period in question was the longest in CN system and the shortest in the NT system. A significant part of the PhD thesis was dedicated to the examination of cover crops. The study included two monoculture cover crops (oilseed radish [Raphanus sativus L.] and berseem clover [Trifolium alexandrinum L.]), as well as a simple mixture of five species and diverse mixture of seven plant species. The oilseed radish exhibited a rapid initial growth, which subsequently declined in the middle of the growing period due to infestation of the common pollen beetle (Brassicogethes aeneus [F.]). After sowing all cover crops exhibited a markedly reduced competitive ability. The oilseed radish demonstrated a consistently high competitive ability throughout the growing period, exhibiting a 30% greater relative weed control ability compared to simple mixture. This was superior to the diverse mixture in several aspects. In the autumn, cover crop growth was terminated by exposure to frost (frost), ploughing, shallow tillage with a disc harrow and rolling with a roller crimper. In the autumn, the optimal results were achieved when growth was disrupted by ploughing. In the subsequent spring, rolling was identified as the most effective termination method that had occurred during the previous autumn. Monoculture cover crops exhibited a greater prevalence of weeds than the mixtures, with the set-aside displaying the highest incidence of weeds throughout the growing season due to the absence of a competing crop.
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