CRITICAL PERIOD OF WEED INTERFERENCE IN MAIZE/RICE MIXTURE
USMAN, A., ELEMO, K. A., LAGOKE, S. T. O., ADIGUN, J. A., MISARI, S. M.
Abstract
Afield experiment was conducted during the 1994 and
1995 "wet season at the research farm of the Institute for Agricultural
Research, Samaru (1 l°]lfN,07°E 680m) in the northern Guinea savannah
ecological zone of Nigeria with the objective of determining the critical period
of weed control in maize/rice mixture. The treatments consisted of ten period
of weed interference laid out in a randomized block design with three replications.
Significantly taller plants of maize and rice were obtained from weed free plots
than from the unseeded plots. Weed free for just the initial 3 weeks after sowing
(WAS) did not alleviate the grain yield. Also weed infestation for the initial
3 WAS only did not adversely affect the grain yields of maize and rice. Weed
infestation for 9 WAS and above and the weed removal for just 3 WAS cause severe
reductions in total yields of both crops. However, uncontrolled weed growth
throughout the crop life cycle resulted in 83.03 and 93.85% reduction in average
grain yield of maize and rice respectively. The critical period of weed control
of maize/rice mixture was ascertained to be between 6-9 WAS.
Key words:
critical period, weed interference, maize, rice