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  1. Home
  2. Browse by Author

Browsing by Author "Asea, G."

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    Does root cutting in seedlings before transplanting affect growth and yield of lowland rice (Oryza sativa L.)?
    (ScienceOpen Posters, 2019) Alibu, S.; Asea, G.; Lamo, J.; Otim, M.; Ekobu, M.; Onaga, G.; Adur, S.; Tsuboi, T.
    Lowland rice cultivation is just beginning to take root in much of Sub-Sahara Africa, but transplanting is unpopular as it is labor-intensive and labor is becoming scarce and expensive. A substantial share of labor and time goes into preparing rice seedlings before transplanting, including carefully uprooting and washing the seedlings to minimize root injury. This study examined whether cutting the roots of rice seedlings before transplanting affects growth and yield of lowland rice.
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    Farmers’ Perceptions On Maize Ear Rots And The Prospects For Breeding Farmer Preferred Varieties In Uganda
    (In Proceedings of The Second RUFORUM Biennial Meeting, 2010) Tembo, L.; Okori, P.; Asea, G.; Gibson, P.
    Maize ear rots are a major constraint to maize production globally, and yield loses of up to 70% have been reported in Uganda. Developing varieties resistant to ear rots is a practical strategy that provides better insurance for the small scale farmers. To enhance the adoption of varieties, farmers’ perceptions should be included early in the breeding programme. In this study a survey was done in four districts of Uganda to examine farmers’ perception on ear rots and their views on agronomic desirable traits. High yield and earliness were the most preferred traits by the farmers.
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    Genetic Basis of Maize Resistance to Multiple Insect Pests: Integrated Genome-Wide Comparative Mapping and Candidate Gene Prioritization
    (Genes, 2020) Badji, A.; Kwemoi, D. B.; Machida, L.; Okii, D.; Mwila, N.; Agbahoungba, S.; Kumi, F.; Ibanda, A.; Bararyenya, A.; Solemanegy, M.; Odong, T.; Wasswa, P.; Otim, M.; Asea, G.; Ochwo-Ssemakula, M.; Talwana, H.; Kyamanywa, S.; Rubaihayo, P.
    Several species of herbivores feed on maize in field and storage setups, making the development of multiple insect resistance a critical breeding target. In this study, an association mapping panel of 341 tropical maize lines was evaluated in three field environments for resistance to fall armyworm (FAW), whilst bulked grains were subjected to a maize weevil (MW) bioassay and genotyped with Diversity Array Technology’s single nucleotide polymorphisms (SNPs) markers. A multi-locus genome-wide association study (GWAS) revealed 62 quantitative trait nucleotides (QTNs) associated with FAW and MW resistance traits on all 10 maize chromosomes, of which, 47 and 31 were discovered at stringent Bonferroni genome-wide significance levels of 0.05 and 0.01, respectively, and located within or close to multiple insect resistance genomic regions (MIRGRs) concerning FAW, SB, and MW. Sixteen QTNs influenced multiple traits, of which, six were associated with resistance to both FAWandMW, suggesting a pleiotropic genetic control. Functional prioritization of candidate genes (CGs) located within 10–30 kb of the QTNs revealed 64 putative GWAS-based CGs (GbCGs) showing evidence of involvement in plant defense mechanisms. Only one GbCG was associated with each of the five of the six combined resistance QTNs, thus reinforcing the pleiotropy hypothesis. In addition, through in silico co-functional network inferences, an additional 107 network-based CGs (NbCGs), biologically connected to the 64 GbCGs, and di erentially expressed under biotic or abiotic stress, were revealed within MIRGRs. The provided multiple insect resistance physical map should contribute to the development of combined insect resistance in maize.
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    Genetic Diversity among Tropical Provitamin A Maize Inbred Lines and Implications for a Biofortification Program
    (Cereal research communications, 2019) Sserumaga, J.P.; Makumbi, D.; Warburton, M.L.; Opiyo, S.O.; Asea, G.; Muwonge, A.; Kasozi, C.L.
    Insights into the diversity and relationships among elite breeding materials are an important component in maize improvement programs. We genotyped 63 inbred lines bred for high levels of provitamin A using 137 single nucleotide polymorphism markers. A total of 272 alleles were detected with gene diversity of 0.36. Average genetic distance was 0.36 with 56% of the pairs of lines having between 0.30 and 0.40. Eighty-six percent of the pairs of lines showed relative kinship values <0.50, which indicated that the majority of these provitamin A inbred lines were unique. Relationship pattern and population structure analysis revealed presence of seven major groups with good agreement with Neighbour Joining clustering and somewhat correlated with pedigree and breeding origin. Utilization of this set of provitamin A lines in a new biofortification program will be aided by information from both molecular-based grouping and pedigree analysis. The results should guide breeders in selecting parents for hybrid formation and testing as a short-term objective, and parents with diverse alleles for new breeding starts as a long-term objective in a provitamin A breeding program.
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    Genomic Prediction of Tropical Maize Resistance to Fall Armyworm and Weevils: Genomic Selection Should Focus on Effective Training Set Determination
    (ResearchGate, 2020) Badji, A.; Machida, L.; Kwemoi, D. B.; Kumi, F.; Okii, D.; Mwila, N.; Agbahoungba, S.; Ibanda, A.; Bararyenya, A.; Nghituwamhata, S. N.; Odong, T.; Wasswa, P.; Otim, M.; Ochwo-Ssemakula, M.; Talwana, H.; Asea, G.; Kyamanywa, S.; Rubaihayo, P.
    Genomic selection (GS) can accelerate variety release by shortening variety development phase when factors that influence prediction accuracies (PA) of genomic prediction (GP) models such as training set (TS) size and relationship with the breeding set (BS) are optimized beforehand. In this study, PAs for the resistance to fall armyworm (FAW) and maize weevil (MW) in a diverse tropical maize panel composed of 341 double haploid and inbred lines were estimated. Both phenotypic best linear unbiased predictors (BLUPs) and estimators (BLUEs) were predicted using 17 parametric, semi-parametric, and nonparametric algorithms with a 10-fold and 5 repetitions cross-validation strategy. n. For both MW and FAW resistance datasets with an RBTS of 37%, PAs achieved with BLUPs were at least as twice as higher than those realized with BLUEs. The PAs achieved with BLUPs for MW resistance traits: grain weight loss (GWL), adult progeny emergence (AP), and number of affected kernels (AK) varied from 0.66 to 0.82. The PAs were also high for FAW resistance RBTS datasets, varying from 0.694 to 0.714 (for RBTS of 37%) to 0.843 to 0.844 (for RBTS of 85%). The PAs for FAW resistance with PBTS were generally high varying from 0.83 to 0.86, except for one dataset that had PAs ranging from 0.11 to 0.75. GP models showed generally similar predictive abilities for each trait while the TS designation was determinant. There was a highly positive correlation (R=0.92***) between TS size and PAs for the RBTS approach while, for the PBTS, these parameters were highly negatively correlated (R=-0.44***), indicating the importance of the degree of kinship between the TS and the BS with the smallest TS (31%) achieving the highest PAs (0.86). This study paves the way towards the use of GS for maize resistance to insect pests in sub-Saharan Africa.
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    Inheritance of resistance to bacterial blight and implication for rice improvement in Uganda
    (RUFORUM, 2010) Habarurema, I.; Asea, G.; Lamo, J.; Gibson, P.; Edema, R.
    Bacterial blight caused by Xanthomonas oryzae pv.oryzae, is a destructive disease of rice worldwide. Resistant varieties are the best option to avert the disease. Thirty resistance genes identified face a wide genetic diversity exhibited by the pathogen. Information on local isolates is not available and genetic mechanism for resistance harbored in Ugandan germplasm is unknown. Experimental sites were Makerere University and NaCRRI. Differential cultivars from Africa Rice were used to group Ugandan isolates. Seven parents were crossed into a half diallel to produce F1 and F2 progenies for determining the inheritance of resistance through inoculation. Preliminary results are reported.

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