Brachiaria decumbens supresses the initial growth of Coffea arabica

Brachiaria decumbens is becoming one the most common weeds growing in young coffee orchards because, besides its fast growth and difficulty of control, new coffee orchards are usually established in pasture areas. In order to verify the effect of B. decumbens plant density on the early growth of coffee (Coffea arabica L. cv. Catuaí Amarelo), a competition experiment was conducted under semi-controlled humidity conditions. Soil collected in a Typic Haplustox was placed in 70 L asbestos cement boxes and one coffee seedling was planted in each box. The B. decumbens seedlings were transplanted to the boxes at the 2-4 leaf stage. Treatments consisted of 0, 4, 8, 12, 16, 20, 24, 36, 48, and 60 weeds m-2. The experimental period started 120 days after transplanting and the experimental design was organized as completely randomized blocks, with four replicates. All coffee plant parameters evaluated were negatively affected by the interference. The most sensitive characteristics were leaf area (41.8% reduction with 8 plants m-2, reaching 68.7% at a density of 60 plants m-2). Therefore, at a density of 8 plants m-2 the reduction in leaf dry biomass was 41.4% compared with the check. At the density of 60 plants m-2 it was 72.8%. B. decumbens, at a density of 8 or more plants m-2, suppressed coffee plants during a growth period of 120 days. Brachiaria decumbens vem se tornando uma das plantas daninhas mais freqüentes na infestação de cafezais em formação, pois além de sua elevada agressividade e dificuldade de controle, está ocorrendo expansão das áreas cafeeiras para locais anteriormente ocupados por pastagens. Objetivou-se neste trabalho avaliar os efeitos desta planta daninha, em densidades crescentes, sobre o desenvolvimento inicial de mudas de café (Coffea arabica L. cv. Catuaí Amarelo). O experimento foi conduzido em condições semi-controladas, sem limitação de água. Uma muda de café foi transplantada em caixa de amianto com capacidade para 70 L, preenchida com terra coletada da camada arável de um Latossolo Vermelho. Os tratamentos constaram de diferentes densidades de transplante de capim-braquiária, a saber: 0, 4, 8, 12, 16, 20, 24, 36, 48 e 60 plantas m-2. O ensaio foi conduzido por um período experimental de 120 dias após o plantio (DAP). Todas as características analisadas foram afetadas negativamente pela interferência da planta daninha, mas as que se mostraram mais sensíveis a essa interferência foram à área foliar e a biomassa seca das folhas. Houve red