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Several maize (Zea mays L.) hybrids have been developed and commercialized in the Nigeria savannas, but limited informationis available on how they perform at plant densities higher than the recommended density of 53,333 plants ha-1. Therefore, field trials were conducted in northern Nigeria in 2015 and 2016 at two locations with contrasting rainfall amount to evaluate the performance of selected maize hybrids at plant densities of 53,333 and 88,888 plants ha-1. All maize hybrids had higher grain yields, total dry matter, ears m-2, and number of grains m-2 at 88,888 than at 53,333 plants ha-1 at both locations. The magnitude ofincreases in yield when plant density was increased to 88,888 plants ha-1 was, however, higher for the new hybrids than for the old commercial hybrids. In Tudun Wada, five hybrids produced significantly higher mean grain yields than the remaining hybrid sat both plant densities. One of the hybrids (M1227-12) produced the highest grain yield at both planting densities at this location. In Samaru Zaria, the hybrid M1227-12 produced the highest grain yield only at 53,333 plants ha-1 at this location, whereas M0926-8 produced the highest yield at 88,888 plants ha-1. The 500-grain weight was 7-8% lower at 88,888 plants ha-1 than at 53,333 plantsha-1, which was offset by a significant increase in grain number. Our results showed that farmers in the Nigeria savannas can increase planting density of hybrid maize to 88,888 plants ha-1 and significantly increase their yields. [ABSTRACT FROM AUTHOR]

Insect pests are major constraint to cowpea production in northern Nigeria causing yield losses up to 70%. Several cowpea varieties have been developed and delivered to farmers by IITA over the past four decades. These varieties have varying degrees of resistance to insect pest attacks. A field study was established in northern Nigeria to determine the response to insecticide spraying of old cowpea varieties developed in the late 1970s and new varieties developed in the 2000s in order to determine whether new varieties have lesser requirement for spraying with insecticides than the old ones. The result revealed that the new cowpea varieties developed in the 2000s require more spraying than the old varieties developed in the 1970s. Infestations by the insect pests, maruca (Maruca virataFabricius) and flower thrips (Megalurothrips sjostedtiTrybom) were significantly less at zero and 1 spray for old varieties than for the new varieties. Old varieties also produced significant higher grain yield at zero and 1 spray compared with new varieties. Newer varieties require more spray to maximise yield gain. [ABSTRACT FROM AUTHOR]

Field studies were conducted in northeast Nigeria to evaluate the response of early and late-maturing maize varieties infested with natural populations of Striga to different rates of nitrogen (N) fertilizer. There were significant reductions in the number of emerged Striga at 120 kg N ha-1 for the early varieties and at 60 and 120 kg N ha-1 for the late varieties. The number of emerged Striga only significantly differed among the late varieties. Averaged across varieties, grain yield of the early varieties was 144% higher at 60 kg N ha-1 and 192% higher at 120 kg N ha-1 than without added N. For the late varieties the increase in grain yield was 85% higher at 60 kg N ha-1 and 144% higher at 120 kg N ha-1 than without added N. Among the early varieties, TZE COMP4 C3 had significantly lower grain yield than the other varieties. Among the late varieties, grain yields of 8338-1-1 and TZB-SR were significantly lower than in the other varieties. Our results show that the application of 60-120 kg N/ha to Striga resistant or tolerant varieties may reduce damage and increase grain yield. Higher economic rates of return was obtained at N rates of 60-120 kg N/ha than the other rates. [ABSTRACT FROM AUTHOR]

The cultivation of soybean is increasing in the savannas of Nigeria due to its widespread use in the food and feed industry. Production is, however, constrained by low soil phosphorus (P) levels in northeast Nigeria. This study evaluated four soybean varieties for their response to three rates of P in two agro-ecozones in 2004 and 2005. Experimental design was a split-plot arrangement of treatments with three replications. The main plots were assigned the P treatments and subplots were soybean cultivars randomised within the main plots. The studies found that soybean responds to P application but differences between 20 and 40 kg P/ha were not significant, despite low test P levels. This may be due to limitations in other nutrients. More studies are needed to determine the synergistic effect of P and other nutrients on soybean growth and yield. Soybean growth and seed yield were lower in 2004 than in 2005 because trials were established comparatively late in 2004 and crops were therefore affected by late season moisture stress. There is, therefore, a need to establish the appropriate time for planting soybean in these zones. Late maturing varieties produced higher yields than early maturing varieties in 2005 probably due to early planting which allowed full use of the growing season. [ABSTRACT FROM AUTHOR]