Browsing by Author "Abe, A."

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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.
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
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.
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 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.
Genetic parameters, prediction, and selection in a white guinea yam early-generation breeding population using pedigree information
(Wiley Periodicals, Inc. on behalf of Crop Science Society of America, 2020-12) Asfaw, A.; Aderonmu, D. S.; Darkwa, K.; Koeyer, D. D.; Agre, P.; Abe, A.; Olasanmi, B.; Adebola, P.; Asiedu, R.
Better understanding of the genetic control of traits in breeding populations is crucial for the selection of superior varieties and parents. This study aimed to assess genetic parameters and breeding values for six essential traits in a white Guinea yam (Dioscorea rotundata Poir.) breeding population. For this, pedigree-based best linear unbiased prediction (P-BLUP) was used. The results revealed significant nonadditive genetic variances and medium to high (.45–.79) broad-sense heritability estimates for the traits studied. The pattern of associations among the genetic values of the traits suggests that selection based on a multiple-trait selection index has potential for identifying superior breeding lines. Parental breeding values predicted using progeny performance identified 13 clones with high genetic potential for simultaneous improvement of the measured traits in the yam breeding program. Subsets of progeny were identified for intermating or further variety testing based on additive genetic and total genetic values. Selection of the top 5% progenies based on the multi-trait index revealed positive genetic gains for fresh tuber yield (t ha−1), tuber yield (kg plant−1), and average tuber weight (kg). However, genetic gain was negative for tuber dry matter content and Yam mosaic virus resistance in comparison with standard varieties. Our results show the relevance of P-BLUP for the selection of superior parental clones and progenies with higher breeding values for interbreeding and higher genotypic value for variety development in yam.
Genetic variability for and tolerance to anaerobic germination in rice (Oryza sativa L.)
(Taylor & Francis, 2021) Asante, M. D.; Ipinyomi, S. O.; Abe, A.; Adjah, K. L.; Aculey, P.; Bam, R. K.; Manneh, B.
Poor germination and seedling establishment under flooded conditions is a major bottleneck in the direct-seeding system of rice. The objectives of this study were to determine the genetic variability for traits associated with anaerobic germination and identify tolerant genotypes. One hundred rice genotypes were screened. Data were collected on survival percentage, shoot length, root length, length of plant above water, and seedling vigor index. Six clusters, which were generally related to the ability of the genotypes to tolerate anaerobic germination, were detected. The first two principal components accounted for 91.1% of the total variation, with survival percentage, seedling vigor index and shoot length being the main discriminatory traits. Genotypic coefficient of variation ranged from 18.21% for shoot length to 50.89% for seedling vigor index. Shoot length and seedling vigor index recorded high broad-sense heritability estimates (>60%), with accompanying high genetic advance as percent of mean (>20%); the latter ranged from 23.12% for root length to 82.21% for seedling vigor index. The high heritability, along with high genetic advance, particularly for shoot length and seedling vigor index, indicated that selection for these traits should be effective in improving tolerance to anaerobic germination. Five tolerant genotypes (OBOLO, ART68-12-1-1-B-B, ART64-31-1-1-B-B, CRI-1-21-5-12, and CRI-Enapa) with high survival percentage (≥70%) under anaerobic conditions were identified. These genotypes could be used to improve commercial rice varieties for tolerance to anaerobic germination.
Genetic variability, heritability and correlations for milling and grain appearance qualities in some accessions of rice (Oryza sativa L.)
(Springer, 2020-06) Adjah, K. L.; Abe, A.; Adetimirin, V. O.; Asante, M. D.
Poor milling and grain appearance is a common feature of locally produced rice (Oryza sativa L.) in West Africa. Development of genotypes with high yield and uniform milled grain size will enhance the market for the locally produced rice. One hundred rice accessions were evaluated to assess genetic variability, heritability and correlations for 11 milling and appearance quality traits and grain yield. The field was laid as a 10 9 10 alpha lattice design with three replications following standard cultivation practices. ANOVA revealed significant differences for the traits studied. The genotypic and environmental variances showed significant differences for all characters studied. Phenotypic coefficient of variation was greater than its corresponding genotypic coefficient of variation for each studied trait. Heritability at broad-sense varied from 14.1% for milling degree to 73.8% for milled grain length-to-width ratio (L/W). Genetic advance as percent of mean ranged from 2.2% for brown rice recovery to 129.6% for percentage of grain with chalkiness (PGWC). In general, genotypic correlations ranged higher than their corresponding phenotypic correlations. Brown rice recovery had significant positive phenotypic and genotypic correlations with milling recovery and head rice recovery. Consequently, brown rice recovery, milling recovery and L/W could be used as selection criteria for the improvement of head rice recovery. Genotypes BETIA and CRI-AMANKWATIA had the desirable PGWC and degree of chalkiness, therefore, they are recommended for the improvement of high yielding varieties with high amount of chalkiness.
Genetic variability, heritability and genetic advance in shrunken-2 super-sweet corn (zea mays L. saccharata) populations
(Academic Journal, 2019-04) Abe, A.; Adelegan, C. A.
Inbred line development requires information on the nature and magnitude of genetic variability and transmissibility of desired trait in source populations. In this study, the level of genetic variability, heritability and genetic advance of thirteen agronomic and fresh yield traits among twelve shrunken-2 super-sweet corn populations were evaluated. Field experiments were conducted for two years in Ibadan, Nigeria using a randomised complete block design with three replicates. Estimates of genetic variability components, broad-sense heritability and genetic advance were computed for each trait. All the traits exhibited significant genotypic differences. Genotypic variance was significant for number of marketable cobs, yield of cobs, number of cobs, number of kernel rows, husk cover, ear height and days to anthesis, while environmental variance was significant for all the traits. Phenotypic coefficients of variation were higher than the corresponding genotypic coefficients of variation for all traits. Broad sense heritability ranged from 22.2% for anthesis-silking interval to 85.1% for husk cover. The genetic advance was high (32.7%) for husk cover, medium (12.0%) for yield of cobs and low for other traits. Genetic variability was present among the shrunken-2 super-sweet corn populations. Opportunities abound for further improvement of the populations and extraction of lines for hybrid seed production.
Genetic variation for nitrogen-Use efficiency among selected tropical maize hybrids differing in grain yield potential
(Taylor & Francis, 2012) Abe, A.; Menkir, A.; Moose, S. P.; Victor, O. A.; Olaniyan, A. B
Low soil nitrogen (N) and sub-optimal N fertilizer applications result in poor grain yield (GY) in maize. Genotypes with improved N-use efficiency (NUE) are particularly beneficial to low-input agriculture. Information on the relative importance of the main components of NUE will facilitate genetic improvement of tropical maize for NUE. This study evaluated genetic variation for NUE among tropical maize hybrids selected for contrasting responses to N. The hybrids were grown in replicated trials from 2006 to 2008 where plots received either no (0 kg N/ha), low (30 kg N/ha), or high (90 kg N/ha) levels of supplemental N. The results documented significant genetic variation for GY and measured NUE component traits among the hybrids, as well as significant interactions between hybrid and N level for all traits except nitrogen harvest index. Under low N, NUE, NUPE, and NUTE increased by 61%, 21%, and 42%, respectively. Grain yield was significantly and positively correlated with NUE, NUPE, and NUTE at both low N and high N. Both NUPE and NUTE were significantly and positively correlated to NUE. Five hybrids (4001/4008, KU1409/4008, KU1409/9613, 4008/1808, and 1824/9432) produced similar GY at both low N and high N but differed in their NUPE and NUTE. Genetic variation was present among the maize hybrids studied for NUE and its components. Although both NUPE and NUTE contributed to high grain yield, the relative importance of the two traits to NUE varied with genotype and level of N.
Genome-wide association study revealed SNP alleles associated with seed size traits in African yam bean (sphenostylis stenocarpa (hochst ex. A. rich.) harms)
(MDPI, 2022-12) Olomitutu, O. E.; Paliwal, R.; Abe, A.; Oluwole, O. O.; Oyatomi, O. A.; Abberton, M. T.
Seed size is an important yield and quality-determining trait in higher plants and is also crucial to their evolutionary fitness. In African yam bean (AYB), seed size varies widely among different accessions. However, the genetic basis of such variation has not been adequately documented. A genome-wide marker-trait association study was conducted to identify genomic regions associated with four seed size traits (seed length, seed width, seed thickness, and 100-seed weight) in a panel of 195 AYB accessions. A total of 5416 SNP markers were generated from the diversity array technology sequence (DArTseq) genotype-by-sequencing (GBS)- approach, in which 2491 SNPs were retained after SNP quality control and used for marker-trait association analysis. Significant phenotypic variation was observed for the traits. Broad-sense heritability ranged from 50.0% (seed width) to 66.4% (seed length). The relationships among the traits were positive and significant. Genome-wide association study (GWAS) using the general linear model (GLM) and the mixed linear model (MLM) approaches identified 12 SNP markers significantly associated with seed size traits across the six test environments. The 12 makers explained 6.5–10.8% of the phenotypic variation. Two markers (29420334|F|0-52:C>G-52:C>G and 29420736|F|0-57:G>T-57:G>T) with pleiotropic effects associated with seed width and seed thickness were found. A candidate gene search identified five significant markers (100026424|F|0-37:C>T-37:C>T, 100041049|F|0-42:G>C-42:G>C, 100034480|F|0-31:C>A-31:C>A, 29420365|F|0-55:C>G-55:C>G, and 29420736|F|0-57:G>T-57:G>T) located close to 43 putative genes whose encoding protein products are known to regulate seed size traits. This study revealed significant makers not previously reported for seed size in AYB and could provide useful information for genomic-assisted breeding in AYB.
Green ear yield potential of tropical field maize at two levels of nitrogen fertiliser application in Ibadan, Nigeria
(Experimental Institute for Cereal Research, 2015) Abe, A.; Akinrinola, T. B.
Green maize plays a significant role in the social and economic life of the peoples of the humid forest and derived savannah agro-ecologies of West and Central Africa. Appropriate strategies for its production would contribute significantly to sustainable agriculture. Fourteen tropical field maize genotypes, consisting of hybrids and open pollinated varieties (OPVs), were evaluated in field trials for green ear yield at two levels (30 and 60 kg ha-1) of nitrogen fertilizer application during the main cropping seasons of 2012 and 2013. A factorial in a split plot design with three replications was used. Fertilizer levels were main plots and maize genotypes subplots. Highly significant genotype, N level and genotype × N level effects were observed for all traits considered. The range in yield of marketable cobs at 30 kg N ha-1 and 60 kg N ha-1 were 98.4% and 108.6% of the respective means. The number and yield of ears, yield of cobs and number and yield of marketable cobs were significantly reduced at 30 kg N ha-1. The percentage reduction in yield of marketable cobs was 55.9%. Yield of marketable cobs and other measured green ear yield variables at 30 kg N ha-1 for OPVs were significantly higher than for the hybrids, while the differences were not significant at 60 kg N ha-1. Suwan-1 STR produced the highest number and yield of marketable cobs per hectare both at 60 kg N ha-1 and across N levels. At 30 kg N ha-1, the top yielding genotypes were ACR97 TZL COMP1 C2 (2.82 t ha-1), TZE COMP3 C2 (2.71 t ha-1) and 9044-27 STR (2.51 t ha-1), while the best three genotypes at 60 kg N ha-1 were Suwan-1 (6.56 t ha-1), AK96DMR-L-SR-W (5.91 t ha-1) and 9144-4 (5.28 t ha-1). Yield of marketable cobs in this study at 30 and 60 kg N ha-1 was 46.5 and 49.1% of the yield of ears ha-1, respectively. Genetic variation for green ear yield was present among the maize genotypes studied and this was greatly influenced by the level of N fertiliser application.