Competition between Imperata cylindrica and maize in the forest savannah transition zone of Nigeria

Abstract

Imperata cylindrica is a noxious weed that infests annual and perennial crops in most tropical regions. High crop densities may offer opportunities to reduce I. cylindrica competition in small-scale farming systems. The competitive ability of maize relative to I. cylindrica was evaluated in an addition series experiment in the forest savannah transition zone in 2006 and 2007 at Ibadan, Nigeria. Maize and I. cylindrica were planted in eight monoculture densities (4, 8, 12, 16, 20, 32, 48 and 64 plants m À2 ) and in a 1:1 mixture at eight total densities (2:2, 4:4, 6:6, 8:8, 10:10, 16:16, 24:24 and 32:32 maize: I. cylindrica plants m À2 ) as in monoculture. Non-linear regression models were used to relate crop and weed shoot biomass to their densities and total grain yield to maize density. In maize, intraspecific competition was more than interspecific competition; in I. cylindrica, interspecific competition was higher than intraspecific. As expected, total grain yield was lower in the mixture than in maize monoculture at all total densities. Average maize grain yield in maize monoculture differed from that in mixtures by 0.77 t ha À1 in 2006 and 0.57 t ha À1 in 2007. Niche differentiation indices were <1 in 2006 and >1 in 2007, indicating that both species competed for similar resources in 2006, but not in 2007. The greater competitive ability of maize over I. cylindrica may be associated with rapid growth and canopy development observed in the field.

Effect of Mulching with Vegetative Residues on Soil Water Erosion and Water Balance in an Oxisol Cropped by Cassava in East Cameroon

“…Because of the high net primary production in the forest–savanna transition zone in east Cameroon, a large amount of biomass of savanna vegetation is available around the fallow croplands. Imperata cylindrica (L.) is one of the most dominant, competitive and difficult weeds to control in the forest/savanna transition zone in West Africa (Chikoye et al, ; Chikoye et al, ). There is no use for the residues of I. cylindrica , and it does not cost farmers for its application as mulch except for the labour cost.…”

Índices fitossociológicos da comunidade infestante presente em sistema agroflorestal na Amazônia Tocantina, no inverno e verão amazônico

“…Dentre os fatores que comprometem a produtividade e qualidade da produção agrícola, tem-se a interferência das plantas daninhas que estão presentes na comunidade infestante (Soares et al 2010), onde no ambiente de campo estabelecem relações de concorrência com a cultura de interesse econômica pelos recursos disponíveis, sendo os mais passiveis dessa competição, os nutrientes, luz, água e espaço, ocorrendo prejuízo mútuo ao crescimento das plantas (Chikoye et al, 2014). Pode-se destacar ainda a liberação de substâncias alelopáticas no ambiente e hospedar pragas e doenças (Freitas et al, 2006).…”