Demand-Driven Technologies for Sustainable Maize ... - IITA

175Table 3. Effects of previous crops on plant population, Striga infestationand incidence, crop damage severity, and grain yield of maizein two villages in northern Nigeria, 2003.CroppingsystemsMaize plantsha -1 at12 WASStriga no.ha -1 at12 WASNo of maizeplants infestedha -1 at 12 WASCropdamageseverity*Grain yield(kg ha -1 )Sole maize 23,022b** 489a 273a 4.5a 1167cSoybean followed23,296a 291ab 173ab 3.8ab 1569bcby 2 yrof maizeCowpea followed23,216a 293ab 178ab 4.1a 1398cby 2 yr ofmaizeTwo yr of soybean23,263a 111b 98b 3.3b 2185afollowedby maizeTwo yr of cowpea23,076b 121b 86b 3.7ab 1939abfollowed bymaizeMaize-cowpeaintercrop22,611c 94b 73b 4.1a 1400cWAS = weeks after sowing.* = Crop damage severity using a scale of 1 - 9, where 1 = healthy plants and9 = completely dead plants.**Means followed by the same letter(s) within a column are not signifi cantly different at0.05 level of probability (DMRT).Effects of two-year rotations and intercropping on Striga andmaize in 2003As in 2001 and 2002, the plant population at harvest was lower than therecommended for all treatments in 2003 (Table 3). However, there wasimprovement in plant population from 2001 to 2003. Maize grown aftertwo years of soybean and one year of soybean or cowpea followed bytwo years of maize produced signifi cantly higher plant populations thanintercropped maize, continuously cropped maize or maize grown after twoyears of cowpea. Maize grown after two years of cowpea and continuouslycropped maize had higher plant populations than intercropped maize.The number of emerged Striga was signifi cantly higher in continuouslycropped maize than in maize grown after two years of soybean orcowpea and intercropped maize. Striga incidence was reduced by 73%in intercropped maize, 64% in maize after two years of soybean, and68% in maize after two years of cowpea than in the farmers’ practice ofcontinuous sole cropping of maize for three years. The Striga incidencewas reduced by 64% in maize after two years of soybean and by 80% aftertwo years of cowpea than in maize after one year of soybean and cowpea,respectively. Crop damage severity was higher in continuously croppedand intercropped maize and one year rotation with cowpea than in maizegrown after two years of soybean. Maize grain yield was 85% higherafter two years of rotation with soybean, 66% higher after two years