Velvetbean (Mucuna spp.) suppresses speargrass (Imperata cylindrica (L.) Raeuschel) and increases maize yield

Abstract

Abs tract. Speargrass, Imperata cylindrica (L.) Raeuschel, is a serious weed, threatening crop productivity in smallholder farms in West Africa. Since the use of more effective practices such as deep tillage and chemical control is beyond the means of resource-poor farmers who carry out most agricultural activities in this region, low-input alternative technology needs to be developed. F ield studies were conducted during the 1993/1994 and 1995/1996 growing seasons to investigate the influence of three velvetbean accessions and two levels of fertilizer on the control of speargrass during the year of cover crop planting and one year later. The velvetbean accessions in 1993 were: Mucuna cochinchinensis and M. pruriens var. utilis. In 1995, M. pruriens var. IRZ was included in the study. M. cochinchinensis in 1993 and M. pruriens var. IRZ in 1995 had the highest ground cover rating early in the growing seasons whereas M. pruriens var. utilis had the lowest ground cover rating in both years. Inorganic fertilizer at 30 kg ha Ð 1 each of N, P and K increased velvetbean ground cover by 2 ± 22%, with M. cochinchinensis (14 ± 22%) and M. pruriens var. IRZ (5 ± 15%) showing the highest response in 1993 and 1995, respectively. M. pruriens var. utilis showed the least response in both years. After one growing season M. pruriens var. utilis, M. cochinchinensis, and M. pruriens var.IRZ reduced speargrass shoot density by 50, 76, and 68%, and shoot dry matter by 72, 92, and 79%, respectively. Fertilizer reduced speargrass growth in velvetbean plots, while the opposite occurred in plots without velvetbean. Velvetbean residue effectively suppressed speargrass until the beginning of the subsequent cropping season. Maize grown 1 year after velvetbean required 50% less weeding than plots without velvetbean. Maize shade reduced speargrass shoot growth by 30 ± 80% but regrowth of the weed occurred 4 weeks before maize harvest. Maize grain yield was higher in plots previously seeded to velvetbean than in plots without velvetbean. Speargrass shoot density and dry matter were negatively correlated with maize grain yield (r = Ð 0.42 and r = Ð 0.32, respectively, P < 0.01). Although velvetbean may effectively reduce speargrass during the year of establishment and the subsequent cropping phase it has a limited effect on rhizomes and, as such, does not provide a long term control.

Meta-analysis of maize yield response to woody and herbaceous legumes in sub-Saharan Africa

“…The studies included in this analysis reveal that legumes reduce (1) infestation by arable and parasitic weeds (Akobundu et al 2000;Gacheru and Rao 2005;Khan et al 2006;Mureithi et al 2003;Sileshi and Mafongoya 2003;Sileshi et al 2006), (2) damage to maize by soil insects (Sileshi and Mafongoya 2003;Sileshi et al 2005) and (3) plant parasitic nematodes (Arim et al 2006). Rotational fallows of S. sesban have consistently reduced Striga infestation of maize in Kenya (Gacheru and Rao 2005) and Zambia .…”

Herbicidal Activity of Stylosanthes guianensis and its Phytotoxic Components

“…The use of leguminous plants for green manure, intercropping, mulch, cover crops and crop rotation might provide greater efficacies to farmers than other plant species. Akobundu et al. (2000) documented that velvetbean accessions ( Mucuna cochinchinensis , M. pruriens var.…”

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

“…Control of I. cylindrica is difficult, weeding is expensive, labour is scarce and indigenous management methods, such as slashing and burning, are inefficient for its control. As a result, farmers abandon fertile arable land for less infested marginal land (Akobundu et al ., ). Imperata cylindrica infestation suppresses crop growth, delays harvests and, subsequently, reduces yields.…”