Phytosociology of We Ed Communit Y in Culture of Cowpea ( Vigna Unguiculata L. Walp ) and Controlling Possibilities With P Re - Emergent Herbicides

Abstract

This study has aimed to diagnose and compare the predominant weed species in cowpea crop in the Amazon region and to evaluate the effectiveness of herbicides applied in pre-emergence. The weed sampling was obtained before planting, the cowpea cultivar was BRS Aracê, by collecting all the plants present within a 0.25 m² hollow frame, randomly thrown 40 times in experimental area to calculate the phytosociological indices. The herbicide efficiency experiment was conducted in a randomized block design with four replications, in time subdivided plot model. Treatments were applied one day after crop planting, their doses (g/ha ai) were: metribuzin (360), sulfentrazone (600), S-metolachlor (1200), pendimethalin (750), oxadiazon (1000), alachlor (2400), metribuzin + pendimethalin (360 + 750), metribuzin + alachlor (360 + 2400), manual weeding and weedy check. The evaluations of weed control were done at 21, 28 and 35 DAP. The most important weed in phytosociology was Tridax procumbens. Cultivation of the crop with weeds caused a reduction of more than 66% in crop productivity. The application of the metribuzin herbicide prevented the emergence of all cowpea seedlings while oxadiazon satisfactorily controlled the weeds without affecting the crop yield.

Effect of the use of pre- and post-emergence herbicides on nodulation and production of cowpea (Vigna unguiculata L.) in the Amazonian savannah

“…The results for grain yield showed that all treatments were satisfactory when compared to the coexistence of the crop with the weeds that significantly reduced productivity. Similar results were obtained by Gonzaga et al (2018), who observed a 67% reduction productivity in cowpea yield with weeds present. According to Lamego et al (2011), the low yield in some treatments can be explained by the phytotoxicity exhibited by the crop, which reduces growth and causes the death of some plants, affecting productivity.…”

“…One of the main problems faced by producers in the northern parts of Brazil is weed interference (Costa et al, 2017). Since sowing is carried out using wider spacing, crops show slow initial growth, allowing weeds to compete directly with cowpea for space, water, light and nutrients (Lamego et al, 2011;Linhares et al, 2014), and consequently, reduce the crop yield by more than 66% (Gonzaga et al, 2018).…”

“…use of herbicides) has proven to be the most practical, effective and economical way to control accessible or inaccessible plants or harmful weeds (Yadav et al, 2017). There are no registered herbicides for cowpea in Brazil, which prevents recommendations; however, 27 and 55 herbicides are registered for crops belonging to the same botanical family (Fabaceae) such as the common bean (Phaseolus vulgaris L.) and soybean (Glycine max L.), respectively (Gonzaga et al, 2018).…”

Periods of weed interference in cowpea crop in the semi-arid of Minas Gerais, Brazil

“…The reduction in grain yield due to weed interference throughout the cowpea cycle is quite variable in several studies, with values of 64% (Yadav et al, 2018), 66% (Gonzaga et al, 2018), 68% (Adigun et al, 2014) and up to 90% (Freitas et al, 2009). For phaseolus species, this same trend in reducing yield happens (Frenda et al, 2013;Esmaeilzadeh & Aminpanah, 2015;Odero & Wright, 2018).…”

Ocorrência de plantas espontâneas da vegetação natural na savana amazônica, Brasil

“…Alguns trabalhos de pesquisa realizados em área de savana do estado de Roraima com o intuito de levantar o banco florístico da mesma, no entanto, os trabalhos realizados para levantamento dos parâmetros fitossociológicos se restringem às áreas já cultivadas (CRUZ et al, 2009;ALBUQUERQUE et al, 2013;ALBUQUERQUE et al, 2014;EVANGELISTA et al, 2015;ALBUQUERQUE et al, 2017a;ALBUQUERQUE et al, 2017b;GONZAGA et al, 2018;CRUZ et al, 2018). Porém existem poucos trabalhos que contemplam o levantamento fitossociológico das espécies vegetais da savana de Roraima ainda não incorporada ao sistema produtivo (MIRANDA; ABSY, 1997; MIRANDA; ABSY, 2000; FLORES; RODRIGUES, 2010).…”