Knowledge of the magnitude of genetic variability, heritability and genetic gains in selection of desirable characters could assist the plant breeder in ascertaining criteria to be used for the breeding programmes. Ten open pollinated maize varieties were evaluated at the Teaching and Research farm, University of Ilorin, Nigeria, during 2005 and 2006 cropping seasons to estimate genetic variability, heritability and genetic advance of grain yield and its component characters. The effect of genotype and genotype by year interaction were significant for ear weight and grain y ield, while the effect of year was highly significant (P< 0.01) for all the characters. High magnitude of phenotypic and genotypic coefficient of variations as well as high heritability along with high genetic advance recorded for grain yield, number of grains ear -1 , ear weight, plant and ear heights provides evidence that these parameters were under the control of additive gene effects and effective select ion could be possible for improvement for these characters. Tze Co mp3 C2, Acr 94 Tze Co mp5, Tze Co mp 4-Dmr Srbc2 and Acr 90 Pool 16-Dt were identified as outstanding genotypes for maize grain yield and should be tested at mu ltilocation for their y ield performance.

Quality protein maize (QPM) combining the enhanced levels of lysine and tryptophan with high grain yield and desirable agronomic traits could reduce food insecurity and malnutrition in West and Central Africa. Twenty-two varieties of QPM and two local checks were evaluated for agronomic characteristics and nutritional qualities in the southern Guinea savanna of Nigeria for two years (2009 and 2010). Though crude protein levels are good indicators of quality, amino acid composition analyses, especially lysine and tryptophan that would provide a final proof are in progress. The genotypes comprised five open pollinated varieties (OPVs), nine inbred lines, eight hybrids and two local varieties. Differences among the varieties were significant (P<0.01) for grain yield, days to tasselling as well as plant and ear heights, while year x variety interaction was only significant (P<0.05) for days to tasselling. Most of the QPM inbred lines (CML 437, CML 490 CML 178) and hybrids (Dada-ba, ART98-SW5-OB, ART98-SW4-OB and TZPB-OB) have superior performance for grain yield, other yield attributes and nutritional qualities compared with the OPVs and local checks. These inbreds could be potential sources of favorable alleles useful for future maize breeding, while the hybrids could be evaluated in different environments of Nigeria for comparative advantages in different environments and quality of the grains to be released to farmers.

Context: Development of early maturing maize cultivars that remain productive under low N fertilizer farming system, consistent with the farmers’ technologies is a prerequisite to improving adoption of new varieties without increasing production cost. Objective: To assess the performance of ten early open pollination maize varieties (OPVs) and their F1 hybrids for grain yield and nitrogen use efficiency (NUE), and also identify productive cultivars under low N fertilizer regimes. Materials and Methods: The trials were set up in a split plot arrangement with three N fertilizer levels (0, 45 and 90 kg N ha-1) as main plot and the genotypes as sub-plot. Each plot within N level was four-row, laid out in a randomized complete block design of four replications. Ten OPVs were crossed in a half diallel to generate 45 F1 hybrids during 2004 and 2005 growing seasons. Planting were carried out on 20th July, 2005 and 2nd July, 2006. Agronomic characters studied were grain yield, maize establishment count, days to 50% tasselling and silking as well as plant and ear heights. Results: The year 2005 growing season was better for all observed characters amongst all the genotypes than the year 2006. Although, expressions of these traits in the hybrids were relatively higher than the OPVs including the grain yield. The total increase in grain yield observed was 1.72 t ha-1 and 1.95 t ha-1 for OPVs and hybrids respectively on application of 90 kg ha-1 over no N-application. However, NUE was optimum at 45 kg N ha-1 in both groups. Grain yield and NUE correlated positively with growth characters measured except for days to 50% silking. Higher genetic gains were recorded for plant and ear heights. Conclusion: Two drought tolerant varieties (Acr 90 Pool 16-Dt and Tze Comp3 Dt) that combined well with specific cultivars for grain yield and NUE probably have gene pools for low N-tolerance. DOI: http://dx.doi.org/10.3329/jbs.v19i0.13000 J. bio-sci. 19 43-52, 2011

AbstractMaintaining yield stability in the African yam bean (AYB) (Sphenostylis stenocarpa) under year-to-year variability is crucial to its sustained productivity. Exploring yield stability in crops is vital in identifying how stable and consistent the yield of such crops is. Cultivation of AYB, an underutilized traditional legume in a specific environment, will further popularize the crop and enhance the acceptance as a cheap protein source thereby reducing hunger and malnutrition especially in regions where climate change has negatively affected legume crop production. Field trials were carried out to study the performance of 23 AYB genotypes in four-year environments. Two seeds of each genotype were sown in a single 5 m row plot spaced at 1 m between and within rows; the trial was conducted during the cropping season of 2011, 2012, 2013, and 2014 and was laid out in a randomized complete block design (RCBD) with three replications. At harvesting, five plants from each row were separately harvested; seeds of all the sampled plants in each plot were bulked and weighed, and the seed yield per plant was then determined. A combined analysis of variance (ANOVA) was performed to test for the significance of genotypes, year, and genotype by year interaction. Before combined ANOVA, a test for homogeneity of residual variances was performed using Bartlet’s test; stability of the genotypes over the years was ascertained numerically and graphically using additive main effects and multiplicative interaction and Genotype X Genotype X Environment interaction (GGE) biplot analyses. Rainfall distribution between 680 and 1,700 mm with an average temperature of 28.50°C under sandy-clay soil type supported high and stable seed yield production in AYB. This environment was found adequate during the 2014 (E1) growing season. Genotypes TSs118, TSs12, TSs109, TSs148, TSs5, TSs61, and TSs69 produced an above-average mean yield across the years and were found to be productive and stable in all the year environments. TSs82 and TSs6 with above-average mean seed and tuber yield can be considered for cultivation where seed and tuber dual-purpose production is to be maximized, while TSs111, TSs49, and TSs96 with high tuber yield ranking above average total tuber yield can be further enhanced for tuber production.

A field experiment was conducted at Landmark University Omu-Aran, Nigeria from June to November 2017 and repeated at the same time in the year 2018 on a nematode infested soil to evaluate the effects of different amounts of Siam weed compost on the performance of root-knot nematode (RKN) infested tomato. The compost was applied a week before planting as soil amendment at the amount of 0.0, 0.5, 1.5, and 2.0 t·ha−1, while carbofuran was applied at the rate of 3.0 kg·ha−1. Four weeks old tomato seedlings cultivar ‘Roma VF’, which is susceptible to RKN, was transplanted to already prepared soil. Results of the experiment showed that the compost, especially in the amount 2 t·ha−1 and carbofuran at 3 kg·ha−1, brought about significant reduction of the population of RKN in soil and roots, and a significant increase in the growth and yield of tomato. The result of the experiment showed that Siam compost can be used for the managing root-knot nematodes in tomato cultivation, as an environmentally safe factor.