Banco de sementes e fitossociologia de plantas daninhas em função de sistemas de cultivos de culturas de inverno e de verão

Abstract

The northern region of Rio Grande do Sul State stands out for its agricultural activity, cultivating species for winter and summer. Use of different cultivation models has attracted lot of producers, this is because some methods used are causing major problems in controlling weeds, pests and diseases. These soil or vegetation management methods can change the phytosociology and seed bank present in the soil. This becomes a problem regarding the control of weed species present in the crops, since they adapt according to the form of production adopted by the producer. Therefore, the objective of this work was to determine the effect of different management systems of the vegetation present in the crop such as notillage, conventional and soil fallow, on the phytosociological characteristics and on the weed seed bank for four crop years. Thus, field experiments were conducted between 2017 and 2021, in a randomized block experimental design, using soil cover in the winter period and annual summer crops, in the no-tillage, conventional and fallow system, under the management desiccation and mowing. The phytosociology, the weed seed bank in the soil and the yield components related to summer crops were evaluated. Eighteen weed species were identified, distributed in 11 families, with Asteraceae and Poaceae representing most of the species found. Among the two that appeared the most, the Asteraceae family had the highest number of species. Regarding the vegetation control method, when existing weeds resistant to glyphosate, the herbicide may not be efficient in desiccation and when the species has an extensive root system, perennial habit and underground reserves, the use of mechanized mowing is not recommended. The intercropping of cover crops is more efficient than the use of just one species, paying attention to the phenological stage for the desiccation of the green cover. The best system for weed control was no-tillage system in association with desiccation management with glyphosate. The conventional and fallow planting system, associated with mowing management, presented the highest incidence of weeds. As for the seed bank, the notillage system was more efficient in controlling weed germination associated with the desiccation with glyphosate.