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Information on the genetic and agronomic relationship among the crop characters is important for the breeding programs. This study aimed at determining the relationship among grain yield, popping expansion and other agronomic characters in 19 popcorn lines evaluated in replicated trials at two locations. Correlation analysis was carried out to determine the relationship between agronomic traits while multiple stepwise regression analyses was used to determine the contribution of other agronomic traits to grain yield. Results showed that plant and ear heights as well as cob length exhibited positive and significant association with grain yield. Popping volume showed negative and significant association (-0.45**) with grain yield while 100-grain mass had a negative and significant correlation (-0.37**) with popping volume. Stepwise multiple regression analysis showed that ear height, cob length, plant aspect and 100-grain mass contributed a total of 53.66 % to variation in grain yield, with ear height contributing the highest portion (22.51 %). Cluster analysis grouped popcorn lines into four different clusters, where ‘Small Pearl Shaped’ and ‘Popcorn 33-1-Y’ belonged to cluster II and IV, respectively, showing how divergent they are and possible utilization for hybrid formation. Improvement for popcorn should focus on identifying lines with acceptable level of popping volume and improved on their grain yield and yield attributes.

Breeding for yield and quality requires the assessment of the seed metrics and vigour traits. This study, therefore, assessed the variability and inter-dependence of grain yield (GY), seed morphometric and vigour traits in hybrid maize. Seeds of 75 early maturing hybrid maize varieties were evaluated for morphometric traits and quality in four replicates. A field trial laid out in a randomised complete block design with three replicates was also conducted in Ibadan, Nigeria, to determine the grain yield of the hybrids. Data collected on the GY, seed dimension and quality were subjected to analysis of variance. The least significant difference was used to separate means. Relationships among the GY, seed morphometric and vigour traits were determined using correlation coefficients, while principal component (PC) analysis was performed for variability among the hybrids. Significant differences (P

A study was conducted to investigate genetic variability in physiological seed quality using viability and vigour tests which were conducted at the seed testing laboratory of Institute of Agricultural Research and Training (IAR&T), Moor Plantation, Ibadan. The investigational materials consisted of twelve genotypes of maize of different maturity-early, intermediate and late collected from the International Institute of Tropical Agriculture (IITA), Ibadan and IAR&T, Moor Plantation, Ibadan, respectively. The experimental design used was completely randomize design (CRD) and data was collected for some viability and vigour traits and the data collected were subjected to analysis of variance. Significant differences were found among all the maize genotypes for the characters under observation. Hundred seed weight ranged from 24.6-29.3 g, 18.5-26.6 g, 22.9-29.1 g, standard germination ranged from 54.0-100.0%, 16.0-92.0%, 50.0-100% and accelerate ageing germination also ranged from 6.0-96.0%, 7.0-84.0%, 0-90.0% in the early, intermediate and late- maturing genotypes, respectively. Conductivity ranged from 5.34-17.10 µS/cm/g, 13.7-91.7 µS/cm/g and7.06-33.6 µS/cm/g with mean values of 11.14, 39.23 and 14.05 µS/cm/g in the early, intermediate and late-maturing genotypes, respectively. Variability was smaller in the late-maturing genotypes for Root Number (RN) and Shoot Length (SLT) but higher for both early and late- maturing genotypes. It was concluded from this study that seeds of early-maturing genotypes had significantly higher physical and physiological quality parameters. All the early materials used for the study tend to be homogenous for all the traits measured and selection should be practiced for hundred seed weight to increase yield potential in maize varieties.

Background: Lowering the nitrogen demand is the most cost effective and sustainable option to increase grain yield of maize in poor fertility soil. Aim: This study was conducted to estimate the variability and inter-traits’ association of white and yellow hybrid maize in soil nitrogen-nutritional stress and optimal conditions. Materials and Methods: 150 white and 66 yellow single cross hybrid maize were evaluated in contrasting soil (stress and optimal) N conditions in Ibadan in 2014 and 2015. The trial for the white maize was laid out in 19 × 8 lattice design while the yellow maize was experimented in randomized complete block design. Each trial was replicated three times. Data were collected on days to anthesis (DTA), days to silking (DTS), plant height (PH), ear height (EH), anthesis-silking-interval (ASI) and grain yield (GY) were estimated while leaf senescence (LS), plant aspect (PASP) and ear aspect (EASP) were scored. Data collected were subjected to analysis of variance while variances and broad sense heritability were calculated and rated. Results: Greater variability existed among white maize than the yellow maize for the traits. Inheritance of the traits can be predicted in optimal N than stress condition. Additive genes action was responsible for inheritance of DTA and DTS while both additive and non-additive control the GY, PH, EH and LS of the white maize in both N conditions. For yellow maize, the DTA and DTS were controlled by additive genes action in both N conditions. The GY, ASI, PH, EH and LS were governed by both additive and non-additive genes actions in N stress condition. Additive genes action is responsible for inheritance of PH and EH while both additive and non-additive actions govern inheritance of GY, ASI and LS in optimal condition. The GY had positive relationship with the DTA, DTS and LS in both N conditions for the white maize while the GY positively correlated with PH, EH and LS in N stress, but with ASI only in optimal condition for the yellow maize. Conclusion: Grain yield, flowering, height and leaf senescence can be used in selecting maize for nitrogen-use-efficiency.

Increasing demand, soil cultivation pressure and adverse climate change effects necessitated maize production in nitrogen stress soils. This study examined the general combining ability (GCA) of 12 maize inbreds and specific combining ability of their crosses for agronomic traits under varied nitrogen conditions. GCA accounted for 53% of the variation for grain yield (GY) under stress and 40% under optimal condition. GCA contributed over 59% for days to anthesis (DTA) and days to silking (DTS), anthesis-silking-interval (ASI) and ear aspect (EASP) under both conditions. BD74-165 and BD74-161 had positive significant GCA for GY under stress with TZEI12 under optimal and BD74-222 under both conditions. TZEI13 and TZEI16 had positive significant GCA for DTA and ASI under stress, and TZEI12, TZEI11 and BD74-161 under optimal. Additive genes control DTA, DTS and PH; non-additive genes were responsible for ASI, PASP and EASP while both additive and non-additive genes governed inheritance of GY, EH and leaf-senescence (SEN) under stress. Inheritance of GY, ASI, PH, PASP and EASP were due to non-additive genes; DTA and DTS to additive genes while additive and non-additive genes control EH and SEN under opti­mal condition. Inbreds with significant GCA can be parents for GY improvement under respective conditions. Keywords: Combining ability; diallel; low nitrogen; maize lines; stress tolerance

Water stress is one of the major abiotic factors affecting crop growth and development at every growth stages. Effects of water deficit on the vegetative growth stage of four maize varieties consisting of two Quality Protein Maize varieties (ILE1OB and ART98SW6OB) and two drought tolerant checks (TZPBSR and DTESTRSYN) were evaluated under the screen house conditions at the Institute of Agricultural Research and Training (I.A.R & T), Moor Plantation, Ibadan. Maize seeds were sown in 20 L plastic pots filled with 15 kg top soil, which were subjected to four watering regimes of 25, 50, 75 and 100% field capacities (FC). The experimental design was a 4 × 4 factorial fitted into CRD with four replications. Data were collected on days to germination, number of leaves per plant, leaf area, plant height, stem diameter, leaf extension rate, biomass yield and water use efficiency. The result showed that days to germination were prolonged as the moisture availability decreases, while water use efficiency increased as the moisture level reduced. Reduction in moisture availability caused significant reduction in the other evaluated parameters. At 25% FC DTESTRSYN was superior in leaf area, number of leaves per plant, days to germination and water use efficiency, TZPBSR had highest values for stem diameter and biomass yield, while ILE1OB was superior in plant height, stem diameter, leaf and stem extension rate. ILE1OB competes favourably with the drought tolerant checks and performed better than ART98SW6OB. Adequate moisture condition is fundamental for normal growth and development in maize crops.

The experiment was conducted to characterize cowpea (Vigna unguiculata (L.) genotypes based on morphological characters. The experiment was carried out at the screen house of the Institute of Agricultural Research and Training (IAR&T), Moor Plantation, Ibadan in 2015 and 2016 using nine (9) cowpea varieties. Soil was sieved with 2mm sieved and sterilized. The experiment was laid out in Completely Randomized Design (CRD) with four replicates. Morphological data were collected based on descriptor for cowpea (IBPGR, 1983). For quantitative traits, analysis of variance revealed that genotype and years effect mean squares from pooled data were highly significantly different for days to first and 50% flowering (P ˂ 0.01), interaction between genotype and years effect also had significant effect on days to first and days to 50% flowering (P ˂ 0.05).Higher significant values were obtained for terminal leaf width, pod weight, pod length, days to physiological maturity, total seed weight per plant, 100 seed weight and number of seed per plant in 2015 than the year 2016. However there were no significant differences obtained for terminal leaf length, pod per peduncle, number of pod per plant, seed length, seed width, seed thickness, and number of seed per pod in both years. Qualitative characters results show thatgenotypic effect, year effect and their interactions were not significant for plant vigour. Modupe, Ife 98-12, Oloyin-Pelebe, Ife BPC, Oloyin-Nla and Sokoto genotypes had intermediate twining tendency. Drum and Mulla had pronounced twining tendency while Ife Brown had no twining tendency. Based on pooled cluster analysis the dendrogram grouped the varieties in two different major clusters A and B. Cluster A comprised of seven genotypes; Oloyin-Nla, Oloyin-Pelebe, Sokoto, Ife BPC, Modupe, Ife 98-12 and Ife Brown. Cluster B comprised of two genotypes; Drum and Mulla. This implies that genotypes within the same cluster had similar genetic background, while genotypes in cluster A are distant on the chromosome as compare to genotypes on cluster B respectively.Keywords: Genetic evaluation, Vigna unguiculata, Cowpea, Morphological Characters

Reduction in germination of crop seeds due to depletion of food reserves and decline in synthetic activity due to ageing has become a serious concern to groundnut growers who need adequate, high quality seeds to sustain groundnut production. Therefore, to stimulate farmers’ interest in groundnut production, an experiment was conducted to evaluate some groundnut varieties for their tolerance to seed ageing stress, with a view to recommending varieties that can be considered for production in tropical countries. Seeds of nine elite groundnut genotypes, sourced from The International Crops Research Institute of Semi-Arid Tropics (ICRISAT), Kano and three other genotypes sourced from local seed dealer in Ibadan, Nigeria were subjected to seed quality assessments in the seed testing laboratory of Institute of Agricultural Research and Training, Ibadan. The seed lots were subjected to accelerated ageing procedures of 42 °C temperature and 100% relative humidity for 24 hours. Twenty-five seeds of each genotype were drawn from each genotype in three replicates at 3, 6, 12 and 24 hours of ageing. The drawn samples were reassessed to determine their tolerance ability to ageing stress. Percentage germination was transformed using arc-sine before the data on preliminary seed germination and seedling vigour data and seed ageing data were subjected to analysis of variance (ANOVA) using SAS™ Means were separated using Duncan Multiple Range Test (DMRT) at 5% level of significance while k-means non-hierarchical clustering analysis was used to group the genotypes based on their response to the ageing. Result showed that seeds of the groundnut genotypes differ in their response to ageing stress factors. Seeds of ‘Samnut-24’, ‘Samnut-25’ and ‘Ex-Dakar’ (R) were found to be more tolerant to ageing stress while ‘Samnut 22’ and ‘Boro White’ were susceptible to ageing stress. Optimum ageing for 24 hours is recommended for testing seeds of groundnut varieties for storage tolerance

Presence of genotypic differences in maize ( Zea mays L.) grain yield in multi-environments would help plant breeders to make logical decisions in improvement programmes of the crop. Hence, the grain yield performance, heterosis and stability in hybrid maize in varied soil nitrogen (N) conditions in Nigeria were assessed using multiple biometrical techniques. Grain yield performance, heterosis and stability of 150 single cross hybrid maize were assessed with checks in severe N stress, N stress and optimal conditions in a replicated trial laid out in 19 × 8 lattice design for 2 years. The grain yield was subjected to analysis of variance for each N condition and combined across years. Heterosis was estimated for the trait, additive mean effects and multiplicative interaction (AMMI); and genotype + genotype × environment (GGE) models were used to analyse the hybrids’ yield stability. The AMMI captured 93.7%; while GGE bi-plot accounted for 88.7% of total variation among the hybrids. Eight hybrids had high yields across the N conditions. Genotypes and environments affected heterosis for grain yield. Hybrids TZEI7×BD74-399, BD74-179×BD74-55 and BD74-175×BD74-147 were the most ideal genotypes for the N conditions; while severe N stress condition was ideal test environment. Hybrid BD74-170×BD74-31 adapted most to N stress; while TZEI1×BD74-399 adapted most to severe N stress and to optimal conditions. Based on yield, heterosis and stability, hybrids involving inbred line BD74-171 were recommended for N stress; while those with inbred lines TZEI1, TZEI4 BD74-170, BD74-128, BD74-179 and BD74-175 were adapted to N stress and optimal conditions. Key words: AMMI, GGE biplot, Zea mays