Journal of Animal and Plant Sciences
J. Anim. Plant Sci. [ISSN 2071 - 7024]
Volume 18(2): 2761 - 2774. Published June, 2013.
Effect
of relative proportion and density on competition between Speargrass
(Imperata cylindrical (L.) Raeuschel) and Maize (Zea mays L.) in a
moist savannah of Southwestern Nigeria
Udensi Ekea Udensi1, 2 and David Chikoye3
1 Department of Crop & Soil Science, University of Port Harcourt, P. M. B 5323, Port Harcourt, Nigeria
2 International Institute of Tropical Agriculture, P. M. B. 5320,
Ibadan, Nigeria Consultant Agronomist, Cassava Project, South&
South Eastern Nigeria Zones
3International Institute of Tropical Agriculture, Director Southern Africa/Crop Production, Zambia
*Corresponding author: emails: ueudensi@yahoo.co.uk or u.udensi@cgiar.org
Key words: Competition, Maize, Speargrass, Relative yield Total
1 SUMMARY
Speargrass (Imperata cylindrica (L.)
Raeusch), is a major problem weed, causing severe yield losses in maize
and other crops in the tropics, due it highly competitive ability over
most crops. . A field study was conducted at International Institute of
Tropical Agriculture (IITA) (7o 30’N, 3o 54’E), Ibadan, Nigeria between
May 2001 and December 2002 to evaluate the competitive relationships
between maize and speargrass grown together in replacement proportion.
The trial was laid out as a randomized complete block design with the
plant densities of 4, 8, 12, 16, 20, 32, 48 and 64 plants of either
sole maize or speargrass per plot and in mixed proportions of
2:2, 4:4, 6:6, 8:8, 10:10, 16:16, 24:24 and 32:32 plants of maize and
speargrass per plot, and replicated three times. Higher maize density
caused speargrass biomass reduction of 41.0 to 55.0%. Interspecific
competition caused maize grain yield reductions of 1.7 to 18.9% when
speargrass densities were between 4 and 16 plants m-2. Maize density
beyond 8 plants m-2 caused grain yield loss of 7.6 to 47.9% plant-1
from intraspecific competition. Planting maize at densities between
50,000 and 80,000 plants/ha can enhance the relative competitive
ability of maize against speargrass.
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