Competition between weeds and irrigated wheat in the Nigerian Sahel zone

During the 1983–84 and 1984–85 cold, dry harmattan seasons two wheat‐weed competition experiments were conducted at the Baga experimental station of the Lake Chad Research Institute, Maiduguri, Nigeria. The objectives were to investigate the effects of different weed competition durations with wheat, variety Indus 66, on the crop growth and yield, and determine the critical period of weed competition. The results showed that full impact of weed competition occurs early in the growing season, and wheat tolerated two/four weeks of early weed competition with minimal yield reduction. Weedy wheat yield decreased as weed competition period lengthened from two to eight weeks, primarily because wheat plants under competitive stress produced less numbers of tillers and panicles, shorter panicles and fewer grains per panicle. Unweeded wheat crop suffered a yield loss of about 60% from severe competition with weeds that were predominantly made up of Cenchrus biflorus, Dactyloctenium aegyptium and Sorghum aethiopicum.