Cultivation Systems, Vegetable Soil Covers and their Influence on the Phytosocyology of Weeds

Abstract

Phytosociological studies are groups of methods that aim at the identification, composition and distribution of plant species in a community. The objective of this study was to identify and quantify the main weeds found in beans, maize and soybean cultivated in no-tillage and conventional systems. The experimental design was a randomized block one, with four replications. Experiments were conducted during three consecutive years, with summer crop (bean, maize and soybean) treatments, no-tillage system (NTS) composed by the covers, black oat, vetch and forage radish, in addition to their intercrop. In the conventional planting system (CTS), the area was left fallow in the off-season. The shoot dry matter of the covers was evaluated in each crop. The evaluated variables were: frequency, density, abundance, dry matter and the importance value index of the species in the area. Eighteen species of weeds and 12 families were identified, with Asteraceae and Poaceae families showing the highest number of individuals. The shoot dry matter production presented a difference among the covers; the cover black oat alone and intercrop with radish and vetch stood out, with the highest averages in the 3 years of the experiments. Cropping systems and different cover crops within the no-tillage system interfered in the number of encontered species. The emergence of Euphorbia heterophylla was favored, while the emergence of Lolium multiflorum was inhibited. E. heterophylla was the most encountered in the NTS areas, and its germination was negatively influenced by soil mobilization. The intercrop of black oat and vetch provided maximum weed control in soybean.

Optimal plot size for experiments with black oats and the common vetch

“…beneficial aspects of the residue from these species, when intercropped, in relation to soil protection and nitrogen supply, control and a reduction in plant density, have been highlighted (HEINRICHS et al, 2001;FORTE et al, 2018aFORTE et al, , 2018bFORTE et al, , 2018c, and justify the importance of evaluating the FW of these plants. The mean value of the coefficient of variation (CV) for FW in the three trials of each combination was 11.76%, 11.58%, 13.33%, 11.53% and 18.23% for the combinations of 100% BO, 75% BO + 25% VE, 50% BO + 50% VE, 25% BO + 75% VE and 100% VE respectively.…”

“…Greater growth was obtained in maize when grown in succession to vetch as a single cropor intercropped with black oats or turnip (FORTE et al, 2018a). Intercropping these two species gave maximum weed control in a crop of soya (FORTE et al, 2018b). Both single-crop and intercropped black oats and vetch resulted in a lower density of weed species, especially Lolium multiflorum (FORTE et al, 2018c).…”

Densidade de plantas daninhas sob intervenções em três distintas zonas de manejos

“…O uso dos policultivos também gera incremento na produtividade da soja e aumento na biomassa de aveia preta, conforme aponta Pott et al (2019). Forte et al (2018) estudando a resposta da quantidade de massa seca em cobertura reportou relações positivas ao aumento de matéria seca e o controle de plantas daninhas.…”

“…não apresentaram diferenças entre os métodos de manejo adotados durante o outono-inverno. O uso de diferentes manejos de solo influi na presença de espécies daninhas, conforme apontam Forte et al (2018 ) . Para Conyza bonariensis, o efeito das intervenções foi significativo, os resultados encontrados que o uso de escarificação e policultivos são eficientes para o controle da espécie, pois está só desenvolveu alta densidade de plantas no pousio.…”

Rotação De Culturas E Preparo Do Solo Sobre O Banco De Sementes De Plantas Daninhas Em Terras Baixas

“…Visando a associação entre os métodos culturais e químico, a rotação de culturas oferece vantagens em relação ao monocultivo, a rotação de mecanismos de ação de herbicidas, a época de semeadura e o tipo de manejo do solo utilizado (SIMARD; ROUANE; LEROUX, 2011). Isto altera a dinâmica, composição e diversidade da comunidade infestante, onde o crescimento populacional de uma espécie em questão tende a ser favorecido em sistemas de cultivo idênticos e contínuos ao longo das gerações (FORTE et al, 2018).…”