Levantamento de plantas daninhas em área rotacionada com as culturas da soja, milho e arroz irrigado no cerrado de Roraima

Abstract

Levantamento de plantas daninhas em área rotacionada com as culturas da soja, milho e arroz irrigado no cerrado de Roraima). As famílias com maior ocorrência foram as Amaranthaceae, Euphorbiaceae e Poaceae. Dentre as espécies, 82,60% pertencem à classe botânica das dicotiledôneas. Palavras-chave -Composição Florística. Matocompetição. Plantas invasoras.Abstract -This study had as its objective to identify and to quantify the levels of population density of the weeds species in crops rotated with soybean, rice, and corn in the savannah of The State of Roraima. Through the inventory square method, the identifi cation and count of the species was realized, with 30 sampling of 1m² in an area of 120 ha. Although some weeds have also been observed in other surveys in Brazil, some species were in insignifi cant levels of population in this survey, but were not considered as relevant, because the damage caused by weeds were infl uenced by both the density and the survivability of each species. The knowledge of the diversity and number of weeds in the crop is the fi rst step towards the realization of effective control. Therefore, it avoids unnecessary spending with inappropriate products and decreases the risks of environmental pollution arising from the misuse and abuse of herbicides. Twenty three species were identifi ed from 15 botanical families. The species with larger populations were Lindernia crustacea (288.667 plants ha ), and Physalis angulata (125.000 plantas ha -1 ). Families with higher prevalence were the Amaranthaceae, Euphorbiaceae and Poaceae. Within the species, 82.60% belong to the botanical class of dicots.

Weed Incidence After Soybean Harvest in No-Till and Conventional Tillage Croprotation Systems in Roraima’s Cerrado

“…Other studies conducted in Roraima's cerrado have confirmed the species number predominance of the Fabaceae family (Cruz et al, 2009;Flores and Rodrigues, 2010;Albuquerque et al, 2013Albuquerque et al, , 2014.…”

“…However, it is extremely important that 3 weed surveys are conducted over cultivations, in order to have greater representativeness of the invading species (Cruz et al, 2009). …”

“…In the agronomic point of view, knowing species diversity is essential to understand the dynamics of weeds and agricultural crops. In spite of this importance, few works were published about surveying weeds in this state (Cruz et al, 2009;Albuquerque et al, 2013Albuquerque et al, , 2014Oliveira et al, 2015).…”

Weed Phytosociological and Floristic Survey in Agricultural Areas of Southwestern Goiás Region

“…These families were also representative in the soybeans rotated with maize and rice in Brazilian state Roraima (Cruz et al, 2009). These latter authors state that Asteraceae and Poaceae are the two main families of existing weeds in the cerrado, being present in different grain production systems, sugarcane, floodplain fields exploitation and pastures.…”

“…The highest population densities and the most harmful species in agricultural areas must be observed, from conducting floristic and phytosociological studies (Pitelli, 2000;Cruz et al, 2009).…”