Agronomy

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Agronomic performance and combining ability estimates of yellow maize inbred lines under adequate and deficit moisture conditions
(Springer, 2022) Amegbor, I. K.; Abe, A.; Adjebeng‑Danquah, J.; Adu, G. B.; Oteng‑Frimpong, R
Breeding for drought tolerance and increased grain yield is vital in mitigating the threat posed by recurrent drought stress on maize production, as well as tackling malnutrition with plant-based food products. The study was conducted to assess the combining ability of yellow maize lines and the performance of their single-cross hybrids under drought and rain-fed conditions. A total of 24 yellow maize inbred lines from CSIR-Savanna Agricultural Research Institute Maize Improvement Programme gene pool were selected and inter-mated using North Carolina II mating design to generate 96 single-cross hybrids. The 96 hybrids together with four advanced hybrids used as checks (a total of 100 hybrids) were evaluated under drought and rain-fed conditions for two years using a 10 × 10 lattice design with two replications. The hybrids differed significantly in their grain yield (GY) and agronomic performance under the growing conditions. In the present study, drought stress reduced GY by 50.3%. The general combining ability (GCA) and specific combining ability (SCA) for GY and its related traits were significant. Even though additive and non-additive gene actions controlled the inheritance of the traits, additive gene action was found to be more important than non-additive genetic effects. Hybrids 27, 81 and 68 on the other hand 89, 18 and 26 were identified as the outstanding genotypes under drought and rain-fed conditions, respectively. These hybrids should be extensively evaluated under varied conditions and commercialized to enhance food insecurity in sub-Saharan Africa.
Agronomic performance of tropical × tropical and tropical × temperate single-cross maize hybrids in Ibadan, Nigeria
(Obafemi Awolowo University, Ile-Ife, Nigeria, 2018) Abe, A.
The productivity of tropical maize could be improved by the introgression of beneficial alleles from temperate germplasm. Ten tropical × temperate and two temperate × temperate single cross hybrids were developed and evaluated for their performance alongside four tropical × tropical hybrids. The tropical × temperate hybrids were developed by crossing the temperate inbred lines B73 and Mo17 as males to the tropical inbred lines 4001, 4008, 9613, 9432 and KU1409. The experimental design was randomized complete block with three replicates. Data were collected on seedling emergence, flowering traits, grain yield and yield components and subjected to analysis of variance. Significant genotypic differences were observed among the hybrids for all measured traits. The tropical × tropical crosses had significantly higher grain yield, ear width, kernel weight and kernel depth than the crosses involving the tropical × temperate inbred lines. However, the tropical × tropical hybrids had lower emergence percentage, but higher emergence index and emergence rate index than the tropical × temperate hybrids. Grain yield ranged from 3.38 (Mo17 × B73) to 6.02 t/ha (4001 × 4008) and was in the order temperate × temperate < tropical × temperate < tropical × tropical hybrids. On average, tropical × B73 hybrids had higher grain yields than tropical × Mo17 hybrids. Four of the tropical × temperate hybrids (4001 × B73, 4008 × B73, KU1409 × B73 and 9432 × Mo17) had grain yields equal to or above the overall average. These hybrids have considerable potential and could be exploited to improve and broaden the grain yield of tropical maize.
Assessing effect of marker-based improvement of maize synthetics on agronomic performance, carotenoid content, combining ability and heterosis
(MDPI (Multidisciplinary Digital Publishing Institute), 2020) Iseghohi, I.; Abe, A.; Meseka, S.; Mengesha, W.; Gedil, M.; Menkir, A
Vitamin A deficiency (VAD) is a serious problem in sub-Saharan Africa (SSA) and other parts of the world. Understanding the effect of marker-based improvement (MARS) of two maize synthetics (HGA and HGB) representing different heterotic groups on their agronomic performance, carotenoid content, and combining abilities could help identify suitable sources to develop divergent inbred lines for optimizing heterosis. This study involved three selection cycles each of the two synthetics and their nine varietal-cross hybrids together with a released check variety was conducted across four diverse locations in Nigeria in 2018 and 2019. Environment and hybrid effects were significant on grain yield and other agronomic traits as well as provitamin A content and other carotenoids. Genetic improvement per cycle of MARS in the parental synthetics was 15% for provitamin A, 25% for β-carotene and 26% for lutein in HGA and 4% for grain yield, 3% for zeaxanthin and 5% for α-carotene in HGB. Grain yield and agronomic traits of the two maize synthetics were controlled by additive and non-additive gene effects, while provitamin A content and other carotenoids were mainly controlled by additive gene effects. Some selection cycles which were high in grain yield and provitamin A content were identified as potential sources of new and divergent maize inbred lines in maize breeding programs. Some varietal-cross hybrids expressed significant mid-parent heterosis for grain yield and moderate mid-parent heterosis for provitamin A, β-carotene and xanthophylls. These hybrids could be commercialized at reasonable prices to small-scale farmers in rural areas that are most affected by vitamin A deficiency.
Assessing intraspecific variability and diversity in African yam bean landraces using agronomic traits
(MDPI, 2022-04) Olomitutu, O. E.; Abe, A.; Oyatomi, O. A.; Paliwal, R.; Abberton, M. T.
Landraces are repositories for potential beneficial traits which could be used to develop varieties with enhanced qualities. Optimal utilization of the available large collection of landraces of African yam bean (AYB) presently conserved at the Genetic Resource Center, International Institute of Tropical Agriculture, Ibadan (GRC-IITA), requires an assessment of the magnitude and nature of genetic diversity within the germplasm. One hundred and ninety-six AYB accessions were evaluated during the 2018 and 2019 cropping seasons in three agro-ecologies of Nigeria, using a 14 X 14 triple lattice design. The accessions were assessed for fourteen agronomic traits. Accession, environment, and accession X environment interaction effects were significant (p < 0.05) for all the traits. Variances due to environment and accession X environment interaction were higher than the genotypic variances. Similarly, estimates of phenotypic coefficient of variation (PCV) were higher than genotypic coefficient of variation (GCV) for all traits. Broad-sense heritability ranged from 17.1% (days to maturity) to 66.4% (seed length). Seed yield per plant had positive significant genotypic correlation with all the studied traits, except pod length and seed length. The first three principal components accounted for 59.7% of the total variation among the accessions and comprised of the 14 traits. Five major clusters were delineated based on phenotypic characteristics. Genetic variation was present among the AYB accessions, and these results will be useful for setting breeding goals and conservation approaches.
CHARACTERIZATION AND EVALUATION OF SELECTED SOILS OF SOUTHERN NIGERIA FOR RUBBER (Hevea brasiliensis, Muell. Arg.) CULTIVATION
(2011-07) ORIMOLOYE, J.R.
Successful land management for tree crop production requires good knowledge of the soil variation and suitability for specific tree crops. Most of the traditional rubber growing areas in Nigeria have not been evaluated for their suitability and production potential. Characterisation and evaluation of the land for rubber production was therefore conducted. Soils of two rubber producing areas: Iyanomo, Edo State and Akwete, Abia State were characterised and evaluated using local, United States Department of Agriculture (USDA Soil Taxonomy) and FAO systems. Conventional parametric and non-parametric land suitability evaluation systems as well as Geographic Information System (GIS) methods were used to generate suitability ratings for rubber cultivation. Dry rubber yield from existing plantations on the two sites obtained in the 2005/2006 and 2006/2007 cropping seasons were used to validate the suitability ratings. Effects of soil and weather parameters on rubber yield were determined. Influence of the three stages of development of rubber plantations on soil properties were compared with forest and arable land use types. Data were analysed using descriptive statistics, correlation, concordance, path analysis and ANOVA at p = 0.05. The soils studied were classified as Alagba, Orlu, Kulfo and Ahiara series at Iyanomo and Uyo, Calabar and Etinan Series at Akwete. The soils were in the Ultisol and Inceptisol soil orders of the Soil Taxonomy. The Ultisols covered 73.1 % and 70.9 % of the study area at Iyanomo and Akwete respectively; while Inceptisol covered 26.9 % and 29.1 % at Iyanomo and Akwete respectively. Soil maps produced by GIS and conventional method were not significantly different. Parametric and non-parametric land suitability evaluation rated 73.1 % and 26.9 % of studied area at Iyanomo as moderately suitable (S2) and marginally suitable (S3) respectively but 70.9 % and 29.1 % of Akwete site as S3 and not suitable (NS) respectively. The GIS method however rated 88.0 % of the Iyanomo site as highly suitable (S1) and 12.0 % as S2 and 52.8 % and 47.2 % of Akwete site as S1 and S2 respectively. Correlation between soil classes and actual rubber yield were not significant in 2005/2006 and 2006/2007 cropping seasons but soil classes significantly correlated with yield index in 2006/2007 season for both sites. Observed yield index ranged between 79.9 – 124.0 in 2005/2006 and 71.4 – 195.1 in 2006/2007 and were higher than the expected indices from conventional evaluation systems. Correlation coefficients of rainfall (r = 0.340*), humidity (r = - 0.245**), and path analyses revealed that relative humidity, K, bulk density and porosity were factors that significantly affect rubber yield. Majority of the soils were Ultisols and Inceptisols and were suitable for rubber production. Suitability evaluation with Geographic Information System is better than conventional methods in predicting yield of rubber.
Effects of drought stress on grain yield, agronomic performance, and heterosis of marker-based improved provitamin-A maize synthetics and their hybrids
(Taylor&Francis, 2021) Iseghohi, I.; Abe, A.; Meseka, S.; Mengesha, W.; Gedil, M.; Menkir, A.
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 Africa (SSA). However, frequent drought is a major abiotic factor that retards maize growth, resulting in yearly fluctuations in grain yield. Development of provitamin A-enriched maize varieties resilient to recurrent drought stress could enhance and stabilize maize grain yield. This study was conducted to assess the effects of managed drought stress (MDS) on the performance and heterosis of some marker-based improved provitamin A maize synthetics and their varietal-cross hybrids. The maize synthetics and their varietal-cross hybrids, along with a drought-tolerant check (PVASYN13), were evaluated under MDS and well-watered (WW) conditions at Ikenne, Nigeria, for two years. Genotype and year effects were significant for grain yield and some agronomic traits under MDS and WW conditions. Grain yield was reduced by 56% under MDS. Grain yield was significantly correlated with days to anthesis, days to silking and anthesis-silking-interval under MDS but not under WW condition. Under MDS, three varietal-cross hybrids (PVASYNHGBC0/PVASYNHGAC0, PVASYNHGBC2/ PVASYNHGAC0, PVASYNHGBC0/ PVASYNHGAC1) had similar grain yields and tolerance indices as the drought-tolerant check, whereas PVASYNHGBC1/PVASYNHGAC2 produced 12.5% more grain yield than the check. Three of the varietal-cross hybrids (PVASYNHGBC0/PVASYNHGAC0, PVASYNHGBC0/PVASYNHGAC1 and PVASYNHGBC1/PVASYNHGAC2) had significant mid-parent heterosis for grain yield under the two test conditions, and were recommended for developing drought-tolerant varieties to com-bat VAD in drought-prone environments of SSA
EFFECTS OF INTEGRATED USE OF VETIVER GRASS STRIPS AND MULCH ON SOIL EROSION AND MAIZE GRAIN YIELD IN IKENNE, NIGERIA
(2016-07) ARE, KAYODE
Soil erosion is a major threat to sustainable agriculture in the humid tropics. Management practices adopted to control soil erosion and improve soil quality include mulching and the use of Vetiver Grass Strips (VGS). Integrating VGS with mulch could be more effective in controlling soil erosion than VGS or mulching alone. However, information on the effectiveness of combined utilisation of VGS and Vetiver Mulch (VM) in controlling soil erosion and improving crop yield is scanty. Therefore, this study was carried out to quantify the effects of integrating VGS and VM on soil erosion, soil quality and maize Grain Yield (GY). Three soil erosion control experiments were conducted on a Rhodic Kandiudult soil with 7% slope, in Ikenne, using maize as test crop. Treatments in each experiment were laid out in a randomised complete block design with three replications. The potential of VGS spaced at 10 m intervals (10VGS) and 6 t/ha of VM (VM6) in reducing runoff, soil and nutrient losses was evaluated. Treatment with No Vetiver grass (NV) served as control. Runoff and soil loss were measured. Carbon, nitrogen and phosphorus contents of eroded sediment were determined using standard methods. In another experiment, 10VGS and VGS spaced at 20 m intervals (20VGS) were integrated with VM of 2 (VM2) and 4 (VM4) t/ha as: 10VGS+VM2, 10VGS+VM4, 20VGS+VM2 and 20VGS+VM4. The four integrated treatments and 10VGS, 20VGS, VM2, VM4, VM6 and NV were evaluated for their effectiveness in reducing erosion. Data were collected on soil loss and maize GY. Soil Physical Quality Index (SPQI) was estimated using the soil management assessment framework. Also, 10VGS+VM4, 10VGS, VM6 and NV were assessed for their effectiveness in reducing nitrate-N and phosphate-P in runoff. The nitrate-N and phosphate-P concentrations were determined using standard methods, and Eutrophic Quality Index (EQI) estimated. Data were analysed using descriptive statistics and ANOVA at α0.05. Runoff from 10VGS, VM6 and NV were 20.5±5.4, 16.9±6.7 and 30.9±2.3 mm while soil losses were 337.5±9.9, 402.5±40.0 and 1079.0±18.3 kg/ha, respectively. Carbon, nitrogen and phosphorus contents of eroded sediments for VM6 (12.65 g/kg, 1.25 g/kg and 7.60 mg/kg) and NV (16.90 g/kg, 1.70 g/kg and 8.30 mg/kg) were higher than for 10VGS (11.05 g/kg, 1.15 g/kg and 7.30 mg/kg). Soil loss was lowest under 10VGS+VM4 (1.48±0.06 t/ha/yr) and highest under NV (7.49±0.94 t/ha/yr). Soil loss increased in the order of 10VGS+VM4 <10VGS+VM2 <10VGS
EFFECTS OF POSTHARVEST HANDLING METHODS AND STORAGE CONDITIONS ON STORABILITY OF PEPPER (Capsicum frutescens L.) FRUITS IN SOUTHWEST NIGERIA
(2014-08) ADEWOYIN, OLUYINKA BENEDICTA,
Pepper a perishable seasonal fruit, requires storage to extend its shelf-life. Appropriate postharvest handling and storage prolong longevity and preserve quality of Pepper Fruit (PF). However, there is dearth of information on its handling and storage in Southwest Nigeria. Therefore, the effects of postharvest handling methods and storage conditions on storability of PF were investigated. Two hundred Pepper Fruit Marketers (PFM) were randomly selected from pepper markets in Ibadan, Oyo State (Sasa and Bodija), Iwo, Osun state (Erunmu, Odo-Ori, and Station) and Akure, Ondo State (viz: Isikan, Oja-Oba, Sasa, NEPA and Isolo). Structured questionnaire was used to determine the socioeconomic characteristics of PFM and postharvest handling methods. Capsicum frutescens grown on the Teaching and Research Farm, University of Ibadan was harvested with and without pedicels at 10 and 100% ripeness. Postharvest handling was evaluated by comparing packaging in perforated polyethylene, non-perforated polyethylene and aluminium-foil before storing in either Ambient Conditions (AC) of 21.9-33.5°C and 58-62% Relative Humidity (RH); Refrigerator (4.0°C and 40-45% RH) or Evaporative Coolant Structure (ECS) (18 - 20°C and 70-75% RH). Pepper fruits were heat-sterilised, parboiled and unparboiled before oven-drying or sun-drying in order to determine the effect of processing on proximate and Vitamin C Content (VCC). Percentage Weight Loss (WL) was calculated. Firmness (FM) and Decay Level (DL) were evaluated on a scale of 1 to 4 and General Appearance (GA) on scale of 1 to 5. Data were analysed using descriptive statistics, correlation coefficient and ANOVA at p < 0.05. The average age of PF marketers was 45 years with male predominance (56%). Majority (69.0%) spread PF on cemented floor to minimise deterioration; Sixty-six percent removed spoilt fruits to reduce infection. Seventy-four percent sourced PF from middlemen these were inappropriately transported in commuter vehicles with used grain sack. Fruits were marketed at 100% ripeness without pedicels. Evidence of deterioration due to presence of insect larvae and rottenness was observed from the 5th day after storage. The shelf-life of PF harvested with pedicels at 10% ripeness and stored in refrigerator, ECS and AC was 27, 20 and 6 days, respectively, while shelf life of PF harvested at 100% ripeness was 21, 14, and 3 days, UNIVERSITY OF IBADAN LIBRARY iii respectively. In contrast, the shelf-life of PF harvested without pedicel at 10% ripeness was 21, 18 and 5 days while for 100% ripeness, it was 18, 15 and 2 days respectively. The WL, DL, GA and firmness of fruits harvested at 10% with pedicels and stored in refrigerator was 14.3%, 3.2, 4.0 and 3.5. The PF packaged in the aluminium-foil had significantly longer shelf life (30 days) than those packaged in perforated polyethylene (21 days) and non-perforated polyethylene (15 days). Parboiled-sundried pepper was significantly higher in crude protein (15.2%), fat (11.3 %), capsaicin (27.8%), and VCC (9.6 mg/100 g) compared to oven-dried pepper. Heat-sterilised fruits had the lowest nutrient contents. Storability of PF was best at 10% ripeness with pedicel. Parboiled-sundried method conserved nutrients better than other techniques. Keywords: Pepper storability, Postharvest handling, Capsicum frutescens. Word count: 487
Effects of pre-storage treatments on sprouting and nutritional quality of ginger (zingiberofficinalerosc) rhizomes in different storage periods
(International Peer Reviewed Journal and book Publishing, 2016) Olaniyi, J. O.; Olusoga, S.; Babatola, L. A.; Atanda, T. T.
Purpose: Ginger rhizomes are highly susceptible to damage during postharvest storage due to soil borne pathogenic disorder. Experiments were conducted to evaluate the effects of prestorage treatments required for sprouting and maintaining the quality of ginger plant in different storage periods at the Teaching and Research Farm, Ladoke Akintola University of Technology, Ogbomoso. Method: The rhizomes were treated with four different pre-storage treatments viz.,control, hydrated lime, - Mancozeb, and 100ml of Trichodermaharzianum solution at different storage periods of one, two and three months. The experiment was arranged in a complete randomized designand laid out in a randomized complete block design with three replicates. Data were collected on percentage sprouting, plant height, number of leaves, leaf area and nutritional quality of ginger rhizomes. Data were subjected to analysis of variance using Statistical Analysis System Software (SAS, 2005). Differences among treatment means were compared using Least Significance Difference (LSD) at 5% probability level. Results: The storage periods significantly (P≤0.05) influenced the percentage sprouting andgrowth parametersof ginger at various sampling period. Highest growth of 9.05cm was recorded from ginger plant stored for three months while the least value of 6.94cm was obtained from rhizomes stored for one month. The pre-storage treatments significantly (P≤0.05) influenced the percentage sprouting, weight loss and growth parameters of ginger at various sampling period. Highest percentage sprouting (94.3%) was recorded from rhizomes treated with 100 ml Trichodermaharzianim solution followed by rhizomes treated with hydrated lime (88.3 %) while lowest percentage sprouting (61.5 %) were recorded from control. Highest percentage weight loss of 46.3% was recorded from control followed by hydrated lime (35.58 %) while the lowest percentage weight loss of 33.93 % was recorded from 100 ml Trichodermaharzianim solution. Conclusions: In conclusion, rhizomes treated with Trichodermaharzianim solution for a period of three months before planting produced better sprouting and enhanced the growth quality of ginger on the field
EFFECTS OF SOME FIELD PRACTICES ON THE YIELD AND QUALITY OF CASSAVA (Manihot esculenta Crantz) PLANTING MATERIAL
(2011) Yomeni, M. O.
The use of cassava stems as planting materials is limited by scarcity, poor quality, high cost and inappropriate field techniques (land preparation, planting spacing, and field maintenance). To enhance the supply of stem for planting cassava varieties, the existing production practices were evaluated and techniques for increasing the number and quality of cassava planting materials were investigated.Seventy-four cassava farms, purposively selected in 11 major cassava growing
Evaluation of bread wheat (Triticum aestivum L.) genotypes for drought tolerance using morpho-physiological traits under drought- stressed and well-watered conditions
(Springer Nature, 2023-05) Sewore, B. M.; Abe, A.; Nigussie, M.
Increasing frequency of drought spells occasioned by changing climatic conditions, coupled with rise in demand for bread wheat, calls for the development of high yielding drought resilient genotypes to enhance bread wheat production in areas with moisture deficit. This study was designed to identify and select drought-tolerant bread wheat genotypes using morpho- physiological traits. One hundred and ninety-six bread wheat genotypes were evaluated in greenhouse and field experiments, under well-watered (80% of field capacity) and drought- stressed (35% of field capacity) conditions, for two years. Data were collected on five morphological traits (flag leaf size, flag leaf angle, flag leaf rolling, leaf waxiness and resistance to diseases) and 14 physiological traits. Relative water content (RWC), Excised leaf water retention (ELWR), Relative water loss (RWL), Leaf membrane stability index (LMSI), as well as Canopy temperature depression (CTD) at heading (CTDH), anthesis (CTDA), milking (CTDM), dough stage (CTDD) and ripening (CTDR) were estimated. Similarly, leaf chlorophyll content (SPAD reading) was recorded at heading (SPADH), anthesis (SPADA), milking (SPADM), dough stage (SPADD), and ripening (SPADR). Significant (p<0.01) genotypic differences were found for the traits under both well-watered and drought-stressed conditions. Associations of RWL with SPADH, SPADA, SPADM, SPADD and SPADR were significant (p<0.01) and negative under both watering regimes. The first three principal components accounted for 92.0% and 88.4% of the total variation under well-watered and drought- stressed conditions, respectively and comprised all the traits. The traits CTDD, CTDM, CTDR, SPADH, SPADA, SPADM, SPADD and SPADR with genotypes Alidoro, ET-13A2, Kingbird, Tsehay, ETBW 8816, ETBW 9027, ETBW9402, ETBW 8394 and ETBW 8725 were associated under both conditions. Genotypes with narrow flag leaves, erect flag leaf angles, fully rolled flag leaves, heavily waxed leaves, and resistant to disease manifested tolerance to drought stress. The identified traits and genotypes could be exploited in future breeding programmes for the development of bread wheat genotypes with tolerance to drought.
EVALUATION OF MEHLICH - 3 AS A MULTIPURPOSE EXTRACTANT OF PHOSPHORUS AND POTASSIUM USING BELL PEPPER (Capsicum annuum L.) IN SOME NIGERIAN SOILS
(2016-09) OLUWAYOMBO, OLAWALE OLUFUNMI
Use of single soil specific extractants to determine plant available phosphorus and exchangeable potassium for crops such as bell pepper, are costly, laborious and time wasting. Bell pepper, rich in antioxidants, requires phosphorus and potassium for high quality fruit yield. Mehlich-3 (M3), a multi-purpose extractant could extract phosphorus and potassium simultaneously. However, M3 has not been evaluated and adapted for Nigerian soils. Therefore, M3 as a multi-purpose extractant of P and K from soil for bell pepper was evaluated. Phosphorus and potassium extractions were carried out on soil (0–15 cm) samples from 12 purposively selected sites belonging to eight soil series across three agro-ecological zones (derived savanna, humid forest and northern guinea savanna) of Nigeria. Bray 1 (B1), Bray 2 (B2) and Olsen were used to extract phosphorus; 1M Ammonium acetate pH 7.0 (AAc) was used to extract potassium, while M3, Ammonium hydrogen flouride+DTPA (ABD) and modified M3 (MM3) were used to extract phosphorus and potassium simultaneously. Concentrations of phosphorus and potassium extracted by different extractants were determined using standard procedures. In the screenhouse, pots were filled with 3 kg each of the 12 soil samples and laid in a completely randomised design (n=108). Bell pepper was grown at one plant per pot for four weeks. Phosphorus and potassium uptakes were determined. Field experiment was conducted on Egbeda, Apomu and Jago soil series for three cropping seasons to determine critical range of soil phosphorus and potassium and optimum fertiliser rates using M3. Phosphorus (0, 30, 45 and 60 kg/ha) and potassium (0, 15, 30 and 45 kg/ha) were applied in a split plot arrangement in a randomised complete block design, replicated thrice. Fruit yield of bell pepper was measured. Data were analysed using descriptive statistics, correlation and quadratic regression at α0.05. Phosphorus extracted by B1, B2, Olsen, ABD, MM3 and M3 were 8.34±1.22, 11.19±2.62, 5.11±1.68, 30.33±4.32, 15.68±3.48 and 14.41±4.32 mg/kg, respectively, while potassium extracted by AAc, ABD, MM3 and M3 were 0.47±0.02, 0.21±0.02, 0.36±0.05 and 0.59±0.09 cmol/kg, respectively. Phosphorus and potassium uptakes were 2.34±0.5 and 22.62±2.28 g/kg, respectively. Significant correlations exist between extracted phosphorus and potassium with their uptakes, except ABD for potassium. Correlations of phosphorus and potassium extracted by M3 with their uptakes were the highest (r=0.95), while the lowest was in B1 (0.78) for phosphorus UNIVERSITY OF IBADAN LIBRARY iii and MM3 (0.93) for potassium. The yields (t/ha) of bell pepper across seasons were 15.02±0.51 (Egbeda), 14.19±0.36 (Apomu) and 5.15±0.40 (Jago). Fruit yield was significantly influenced by applied fertilisers with phosphorus lowest in Apomu (r2=0.65) and highest in Jago (r2=0.99), for potassium, the least was in Jago (r2=0.52) and highest in Egbeda (r2=0.99). Critical ranges of phosphorus and potassium in the soils were 15 (Apomu) to 20 (Jago) mg/kg and 0.20 (Apomu) to 0.25 (Jago) cmol/kg, respectively. Optimum phosphorus and potassium concentrations for bell pepper were 45 kg/ha and 30 kg/ha, respectively. Mehlich-3 is a good simultaneous extractant of phosphorus and potassium across the agro-ecological zones. It is therefore recommended for evaluating soil phosphorus and potassium. Keywords: Multipurpose soil extractants; Mehlich-3 extractant; Phosphorus uptake; Bell pepper yield; Word count: 494
Field performance of shrunken-2 super-sweet corn populations derived from tropical field maize × shrunken-2 super-sweet corn crosses in Ibadan, Nigeria
(Academic Journal, 2019-05) Abe, A.; Lasisi, O. A.; Akinrinbola, O. J.
The conversion of tropical field corn genotypes into sweet corn could broaden the genetic base and improve yield and adaptation of sweet corn varieties. In this study, the performance of shrunken-2 (sh2) super-sweet corn populations derived from crosses between a sh2 population and tropical field corn genotypes were evaluated in Ibadan. experiments were conducted using randomised complete block design with three replicates. Data were collected on agronomic and fresh ear yield traits, and then subjected to analysis of variance. Significant genotypic differences were observed among the populations with most of the derived populations significantly superior to the donor population for most of the traits. Yield of marketable cobs ranged from 5.80 to 7.63 t/ha (mean = 6.84 t/ha). Six derived populations had significantly higher yield of marketable cobs than the donor population. On the average, 83.1% of the number of cobs harvested was marketable. Husk cover scores ranged from 2.8 to 6.8, with all the derived populations having significantly lower husk cover scores than the donor population. The results indicated that the conversion of the field corn genotypes into super-sweet corn was effective in the development of new super-sweet corn populations. The observed genetic differences could be exploited in further breeding programmes.
Genetic analysis and heterotic grouping of quality protein maize (Zea mays L.) inbred lines and derived hybrids under conditions of low soil nitrogen and drought stress
(Springer Nature, 2023-02) Owusu, G. A.; Abe, A.; Ribeiro, P. F.
Quality Protein Maize (QPM) varieties are rich in lysine and tryptophan, but suffer reduced grain yield (GY) in West and Central Africa (WCA) due to low soil nitrogen (low-N) and intermittent drought stress (DS). Development of stress-tolerant QPM hybrids will enhance sustainable maize production and improve nutritional health in WCA. Knowledge of combining ability, gene action and heterotic grouping of QPM inbred lines are crucial to successful breeding strategies for the development of superior hybrids with enhanced nutritional values. The objectives of this study were to: (i) determine the combining ability for GY and yield-related traits among 13 newly developed QPM inbred lines, and (ii) assign the QPM inbred lines to distinct heterotic groups based on general combining ability effects of multiple traits under low-N and DS conditions. Seventy-eight single cross hybrids were generated through half-diallel mating of 13 QPM inbred lines.
Genetic analysis and yield assessment of maize hybrids under low and optimal nitrogen environments
(Elsevier Ltd., 2022) Amegbor, I. K.; Abe, A.; Adjebeng‑Danquah, J.; Adu, G. B.
Development of maize hybrids that possess tolerant genes to low soil nitrogen is critical for long-term maize production in areas with low soil fertility. In this study, estimates for combining ability effects for grain yield and secondary traits of selected inbred lines, identify potential parents for hybrid development and yield potential of the crosses under sub-optimal and optimal N environments. One hundred hybrids were evaluated under suboptimal and optimal N environments for two years. The experimental layout was a 10 X 10 alpha lattice design with two replications for two experiments. The results obtained showed that, the genotypes evaluated varied for grain yield and the characters measured under sub-optimal and optimal N conditions. Grain yield reduction due to N stress was 40.9%. General and specific combining ability (GCA) and (SCA) effects for mean squares varied for grain yield demonstrating the importance of additive and non-additive genetic effects for the hybrids evaluated under the study conditions. Even though significant variations were detected for GCA and SCA, GCA which is the additive gene action component mainly controlled the heritage of grain yield under both conditions. Inbred line 15 was identified as the superior parent with positive and significant GCA for grain yield under sub-optimal N. Genotypic correlation studies displayed that grain yield was positively correlated with ears per plant under sub-optimal N and was also positively associated with anthesis-silking interval under high N. The hybrids 52, 75, 81 and 37 were identified to be significantly superior in terms of grain yield, ASI and EPP under the two-contrasting conditions. The results suggest that, there is a need for development of low N tolerant inbred lines and hybrids for production under soils with low N status in the Guinea savanna of Ghana for high grain yield to be realised.
Genetic analysis of agronomic and fall armyworm-resistance traits in maize hybrids with varying levels of resistance to stem borers
(Multidisciplinary Digital Publishing Institute (MDPI), 2022) Job, A.; Iseghohi, I.; Abe, A.; Yahaya, M.; Olayiwola, R.; Akinwale, R.; Obisesan, O.; Igyuve, M.
Stem borer (SB) and more recently, fall armyworm (FAW) are serious economic pests in maize production in sub-Saharan Africa. It is hypothesized that SB-resistant germplasm may confer resistance against FAW. However, the performance of SB-resistant lines in hybrid combinations and the inheritance of FAW-resistant traits under variable FAW infestations have not been reported. This study was conducted to (i) obtain information on the inheritance of agronomic and FAW-resistant traits under variable FAW infestations; (ii) identify hybrids combining high grain yield (GYLD) and stability under FAW infestations; and (iii) determine the effects of FAW damage on GYLD. Three SB-resistant lines (1393, CKSBL10060 and CML 331) as testers and six open-pollinated varieties (OPVs) as lines were crossed in a line tester scheme to generate eighteen test crosses. The test crosses together with two tester x tester crosses and two checks were evaluated under artificial FAW infestation (AI), natural infestation (NI) and pesticide-protected condition (PC) in Nigeria. Additive and nonadditive effects were significant for GYLD, most agronomic and FAW-resistant traits under AI and NI, except ear damage (EDAM) scores under NI, whereas only the non-additive effect was significant for GYLD under PC. Two testers (1393 and CKSBL10060) combined significant and positive GCA effects for GYLD with desirable GCA effects for FAW-resistant traits under AI and NI, whereas CML 331 combined significant and negative GCA effects of GYLD with undesirable GCA effects of FAW resistance under the test conditions. Three OPVs (AWR SYN-W2, AMATZBR-WC4 and TZB-SR) had a significantly positive GCA effect for GYLD and a desirable GCA effect for either leaf damage (LDAM) or EDAM score under AI. The FAW LDAM and EDAM significantly reduced GYLD under AI but not under NI. Three test crosses (AMATZBR-WC4 x CKSBL10060, TZB-SR x CKSBL10060 and TZBR Comp 1-WC2 x 1393) combined high yield with stability and FAW tolerance across the test conditions and thus were recommended for further testing.
Genetic analysis of grain yield and agronomic traits of quality protein maize inbred lines and their single-cross hybrids under drought stress and well-watered conditions
(Elsevier, 2022) Owusu, G. A.; Ribeiro, P. F.; Abe. A
Drought-tolerant maize hybrids are crucial to enhance productivity in West and Central Africa. The objectives of this study were to (i) determine the combining abilities of tropical quality protein maize (QPM) inbred lines, (ii) identify hybrids with outstanding yield performance under drought stress (DS) and well-watered (WW) condi-tions, and (iii) identify drought-adaptive traits for index selection under DS. Seventy-eight hybrids developed from a diallel cross among 13 QPM inbred lines were evaluated under DS and WW conditions. The hybrids differed significantly (p ≤0.05) for grain yield (GY) and other traits. General combining ability (GCA) and specific combining ability (SCA) were significant for GY and other traits. Four hybrids (CRIZEQ-24 ×CRIZEQ-77, CRIZEQ-44 ×CRIZEQ-77, CRIZEQ-14 ×CRIZEQ-49, and CRIZEQ-24 ×CRIZEQ-40) were identified with outstanding GY performance under DS. Days to anthesis, ear aspect, number of ears per plant and plant aspect were important traits for selection under DS.
Genetic analysis of zinc, iron and provitamin a content in tropical Maize (zea mays L.)
(MDPI, 2023-01) Udo, E.; Abe, A.; Meseka , S.; Mengesha, W.; Menkir, A.
Breeding maize with high contents of zinc, iron and provitamin A (PVA) could be effective in mitigating micronutrient deficiency in developing countries with a high reliance on maize-based diets. Information on the mode of inheritance of zinc, iron, PVA and grain yield (GY) would facilitate the development of varieties with enhanced contents of these nutrients. Twenty-four yellow to orange maize inbred lines and their 96 F1 hybrids generated using North Carolina Design II, were evaluated alongside four checks for two years at two locations in Nigeria. The effects of environment, hybrid and inbred line were significant for GY and contents of zinc, iron and PVA. The GY, and contents of zinc, iron and PVA of the hybrids ranged from 1.49 to 6.05 t ha􀀀1, 22.51 to 33.33 mg kg􀀀1, 20.04 to 29.65 mg kg􀀀1 and 3.55 to 15.28 _g g􀀀1, respectively. Additive gene effects controlled the accumulation of PVA and Fe, whereas both additive and non-additive gene effects controlled the inheritance of Zn and GY. Inbred lines with high general combining ability for GY and single or multiple micronutrients were identified, and could be used to develop hybrids and synthetics that combine high GY with high micronutrient content. Six hybrids combined high GY with high contents of all three micronutrients, and are recommended for further evaluation and possible release. Our study revealed the feasibility of enriching maize with multiple micronutrients without compromising grain yield.
Genetic control of total phenolic content and some kernel compositional traits in purple maize
(International Journal of Plant Breeding and Genetics, 2022-06) Oladipo, T. G.; Abe, A.
Purple maize kernels are rich in phytochemicals and nutrients which can be exploited to promote human health. A better understanding of the genetic mechanisms controlling these qualities, which could also be dependent on the choice of parents and their role in the cross, is important for their improvement. This study was conducted to: investigate the nature and relative importance of gene effects involved in the inheritance of total phenolic content (TPC) and proximate composition in reciprocal crosses between two maize lines (UIp01 and TZi3) with purple and white kernels, respectively using generation mean analysis. Kernels of F1, F2 and backcross generations derived from UIp01 × TZi3 and TZi3 × UIp01 and the parents were assessed for TPC and proximate composition following standard procedures. Analysis of variance revealed that the populations differed significantly for all traits, except moisture content. Reciprocal differences were observed only for TPC indicating the influence of maternal parent in its inheritance. Heritability estimates were moderate (0.4-0.5) to high (0.7-0.9) for most traits. Results showed the importance of non-additive effects over additive effects for starch and fat contents, and varying levels of additive and non-additive effects for TPC, moisture, protein, ash and fiber contents.
Genetic diversity and population structure of cowpea [vigna unguiculata (L.)Walp.] germplasm collected from Togo based on DArT markers
(MDPI, 2021-08) Gbedevi, K. M.; Boukar, O.; Ishikawa, H.; Abe, A.; Ongom, P. O.; Unachukwu, N.; Rabbi, I.; Fatokun, C
Crop genetic diversity is a sine qua non for continuous progress in the development of improved varieties, hence the need for germplasm collection, conservation and characterization. Over the years, cowpea has contributed immensely to the nutrition and economic life of the people in Togo. However, the bulk of varieties grown by farmers are landraces due to the absence of any serious genetic improvement activity on cowpea in the country. In this study, the genetic diversity and population structure of 255 cowpea accessions collected from five administrative regions and the agricultural research institute of Togo were assessed using 4600 informative diversity array technology (DArT) markers. Among the regions, the polymorphic information content (PIC) ranged from 0.19 to 0.27 with a mean value of 0.25. The expected heterozygosity (He) varied from 0.22 to 0.34 with a mean value of 0.31, while the observed heterozygosity (Ho) varied from 0.03 to 0.07 with an average of 0.05. The average inbreeding coefficient (FIS) varied from 0.78 to 0.89 with a mean value of 0.83, suggesting that most of the accessions are inbred. Cluster analysis and population structure identified four groups with each comprising accessions from the six different sources. Weak to moderate differentiation was observed among the populations with a genetic differentiation index varying from 0.014 to 0.117. Variation was highest (78%) among accessions within populations and lowest between populations (7%). These results revealed a moderate level of diversity among the Togo cowpea germplasm. The findings of this study constitute a foundation for genetic improvement of cowpea in Togo.