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Identifying efficient testers for separating maize (Zea mays L.) inbred lines into heterotic groups can facilitate the development of superior hybrids. Striga-resistant yellow-maize inbred lines de...

Provitamin A-enriched maize (Zea mays L.) is an important complementary food staple for combating vitamin A deficiency (VAD) in high maize-producing and maize-consuming countries of sub-Saharan Afr...

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 recomm...

Adoption of improved maize (Zea mays L.) varieties in the rainforest agro-ecology of Nigeria largely depends on yielding potential and resistance to common foliar diseases. The present study aims at assessing the combining ability of a set of adapted and exotic drought-tolerant maize inbred lines under irrigated and rainfed conditions in Nigeria. Ninety-six hybrids generated using a North Carolina Design II scheme, and four checks were evaluated in a 10 × 10 triple lattice with three replications under full irrigation in the dry seasons of 2010 and 2011 and under natural disease inoculation in the rainy seasons of 2011 and 2012. Hybrids differed significantly for all measured traits. Both general combining ability (GCA) and specific combining ability (SCA) were mostly highly significant (P 70%). EXL03, EXL06, EXL16, ADL33, and AD...

Aflatoxin contamination caused by Aspergillus flavus infection of corn is a significant and chronic threat to corn being used as food or feed. Contamination of crops at levels of 20 ng g(-1) or higher (as regulated by the USFDA) by this toxin and potent carcinogen makes the crop unsalable, resulting in a significant economic burden on the producer. This review focuses on elimination of this contamination in corn which is a major US crop and the basis of many products. Corn is also "nature's example" of a crop containing heritable resistance to aflatoxin contamination, thereby serving as a model for achieving resistance to aflatoxin contamination in other crops as well. This crop is the largest production grain crop worldwide, providing food for billions of people and livestock and critical feedstock for production of biofuels. In 2011, the economic value of the US corn crop was US$76 billion, with US growers producing an estimated 12 billion bushels, more than one-third of the world's supply. Thus, the economics and significance of corn as a food crop and the threat to food safety due to aflatoxin contamination of this major food crop have prompted the many research efforts in many parts of the world to identify resistance in corn to aflatoxin contamination. Plant breeding and varietal selection has been used as a tool to develop varieties resistance to disease. This methodology has been employed in defining a few corn lines that show resistance to A. flavus invasion; however, no commercial lines have been marketed. With the new tools of proteomics and genomics, identification of resistance mechanisms, and rapid resistance marker selection methodologies, there is an increasing possibility of finding significant resistance in corn, and in understanding the mechanism of this resistance.

Maize (Zea mays L.) is an important food crop in the Guinea savannas of Nigeria. Despite its high production potential, drought, Striga hermonthica parasitsim, and poor soil fertility particularly nitrogen deficiency limit maize production in the savannas. Breeders at IITA have developed drought- and Striga-tolerant cultivars for testing, dissemination, and deployment in the region. Information on the response of these cultivars to N fertilization is, however, not available. This study evaluated grain yield, total N uptake (TNU), N uptake (NUPE), N utilization (NUTE), and N use efficiency (NUE) of selected maize cultivars along with a widely grown improved maize cultivar at two locations in the Guinea savannas of northern Nigeria. Maize grain yield increased with N application. The average grain yield of the maize cultivars was 76% higher at 30, 156% higher at 60, and 203% higher at 120 kg N ha−1 than at 0 kg N ha−1. This suggests that N is a limiting nutrient in the Nigerian savannas. Five drought-tolera...

Maize (Zea mays L.) landraces in the northern Guinea savanna and Sudan savanna in West and Central Africa appear to have some drought-adaptive traits. This study was initiated to assess the level of improvement in yield potential and other agronomic traits achieved under drought stress (DS) and in multiple locations (ML) after introgression of alleles from maize landraces into an elite maize variety (AK9443-DMRSR) via backcrossing. Six backcross (BC) populations together with recurrent parent (AK9443-DMRSR), a commercial hybrid (Oba Super-II), and an improved variety (TZLCOMP4C1) were evaluated under controlled DS and full irrigation (FI) during the dry seasons of 1999 and 2000, as well as in seven ML trials. No significant differences were observed among genotypes for grain yield and most of the traits measured under DS and FI. Significant differences were recorded among genotypes for grain yield and other agronomic traits measured in ML and across 11 environments. Drought stress reduced grain yields of ...

Improving maize productivity in the savannas of West Africa will depend on improving soil fertility and ensuring the efficient use of inputs and the relevant maize varieties tolerant to low nitrogen (N) that have been developed for this region. Several cycles of full-sib family selection that combine agronomic performance under low N with yield under high N to maximize gains under both environments have been used to improve three such developed populations. Evaluation of different cycles of selection revealed that desirable changes in gene frequencies had taken place after three cycles of selection in two of the three populations, leading to a yield gain of over 200 kg/ha/cycle under 30 kg N/ha and over 270 kg/ha/cycle under 90 kg N/ha. Trends in performance of the third population under low N simply indicated that additional cycles of selection would be required to shift gene frequencies significantly in the direction of increased yield production. This yield gain did not adversely affect other agronomic...

Sorghum (Sorghum bicolor [L.] Moench) is one of the most important cereal crops grown in the dry savannas and semi-arid regions of West Africa under rain-fed conditions. Although total sorghum production in Nigeria has increased over the years, the average grain yield on farmers' fields has remained low. A two-year trial was conducted to evaluate the effect of planting dates on three exotic sorghum cultivars (P9402, P9405, and PSL985061) and an improved local cultivar (KSV 8) under natural infestation with Striga hermonthica in northeast Nigeria. At Nzuda, the highest yield was obtained when planting was carried out on 19 July 2006 and on 5 July 2007. The decline in yield in 2007 as planting dates increased was largely due to early cessation of rain, which affected grain yield. At Sabon-Gari, KSV 8 and P9402 produced comparable grain yields that were higher than the yields of other cultivars at all planting dates. Grain yields of KSV 8 and P9402 were greater for 5 July than for the other planting dates an...

The majority of farmers in sub-Saharan Africa (SSA) depend on maize (Zea mays L.), which is mostly grown in drought-prone areas. Understanding the inheritance of drought tolerance would help in developing drought-tolerant maize hybrids that would help increase maize production under erratic rainfalls. Twenty-four maize inbred lines were subjected to NC design II to generate 96 single-cross hybrids. The 24 inbred lines and their 96 hybrids were evaluated under managed drought-stress conditions between 2002 and 2005 at Ikenne, Nigeria. The objectives of this study were to determine the effects of drought-susceptible and drought-tolerant inbred lines on performance of their hybrids, investigate mode of inheritance of drought tolerance, and determine the relationship between parental lines and their hybrids. Most crosses with at least one drought-tolerant parent produced tolerant hybrids, and the crosses between susceptible inbred lines produced susceptible hybrids. General combining ability (GCA) accounted f...

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...

A major problem that usually confronts the breeder is ensuring that there is sufficient genetic variability in a population for the trait being improved because this determines the breeding schemes to use for improvement and whether or not sufficient progress could be made. Three hundred full-sib families from cycle 3 of the early maturing yellow endosperm maize (Zea mays L.) population, TZE-Y Pop DT STR, were evaluated under artificial Striga hermonthica infestation at Mokwa and Abuja, Nigeria in 2003. The objectives of this study were to investigate the type of gene action involved in the inheritance of S. hermonthica resistance in TZE-Y Pop DT STR C3, determine the extent of genetic variability available in the population after three cycles of S1 recurrent selection, and the phenotypic and genetic correlation coefficients among the traits used for selecting for resistance to S. hermonthica. Estimates of dominance variances were larger than additive genetic variances for grain yield, plant heig...

Iron deficiency is estimated to affect over one‐half the world population. Improving the nutritional quality of staple food crops through breeding for high bioavailable iron represents a sustainable and cost effective approach to alleviating iron malnutrition. Forty‐nine late maturing tropical elite maize varieties were grown in a lattice design with two replications in three locations representing three agroecologies in West and Central Africa to identify varieties with high levels of kernel‐Fe. Bioavailable iron was assessed for some varieties selected for high Fe concentration in kernel and improved agronomic traits using an in vitro digestion/Caco‐2 cell model. Significant differences in kernel‐Fe and ‐zinc concentration were observed among varieties (P