NRU :: Browsing by Author "Asea, Godfrey"

Browsing by Author "Asea, Godfrey"

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Agronomic Evaluation of Alternative Lowland Rice Varieties for Farmers in Uganda; A Case of Aromatic Rice
(Journal of Food Security, 2022) Alibu, Simon; Obura, Morish; Ekebu, James; Nampamya, Doreen; Lamo, Jimmy; Asea, Godfrey; Tae-Seon, Park
Rice has recently become an important crop for tackling food insecurity and poverty in Uganda. Over three-quarters of the country's local rice production occurs in irrigated and rain-fed lowlands in eastern and northern Uganda. However, breeding programs and seed systems have only partially met farmers' expectations for new lowland rice varieties and seeds recently, so farmers are sticking with old varieties. However, a new high-yielding, early-maturing, and most importantly, aromatic variety, NARORICE-1, released in 2019, seems to offer a new ray of hope for lowland rice farmers. This study compared the agronomic performance of NARORICE-1 and two promising KAFACI lines to a popular farmer's variety, WITA-9, in central, eastern, and northern Uganda. These varieties were evaluated for growth and yield response to higher seedling counts per hill when transplanted. Doho was the most productive location with an average rice yield of 6.1 t ha–1, significantly higher than NaCRRI and Olweny with 3.9 and 3.7 t ha–1, respectively. The yield performance of NARORICE-1 was comparable to that of the popular farmer's variety WITA-9. Increasing the number of seedlings per hill from three to seven during transplanting had no clear effect on the paddy yield of NARORICE-1. Besides higher yield potential, NARORICE-1's other additional beneficial traits such as aroma, shorter growing time, and higher milling efficiency have made it one of the growers' favorites.
Comparison of Response to Nitrogen between Upland NERICAs and ITA (Oryza sativa) Rice Varieties
(Journal of Agricultural Science, 2012) Onaga, Geoffrey; Asea, Godfrey; Lamo, Jimmy; Kikafunda, Joseph; Bigirwa, George
Average yields of upland rice are the lowest in Uganda, and most of the productivity gains attributed to improved varieties are related to increased area of production from clearing virgin lands for rice production. In a bid to optimize productivity, we compared the effect of four nitrogen fertilizer treatments: 0, 40, 80 and 120 kgN/ha and two variety types (ITAs (Oryza sativa) and NERICAs (New rice for Africa)) on grain yield and yield parameters in four locations. Combined analysis of variance revealed that nitrogen fertilizer increased mean grain yields from 2116-5200 kg/ha in the NERICAs and 2331-5100 kg/ha in the ITAs. In all the study areas, NERICA 4 and NARIC 2 outperformed NARIC 1 and NERICA 1, and yield trends were consistent over the years suggesting that the two varieties respond better to N fertilizer application. However, the productivity gains are probably related to genetic potential of the varieties rather than the N fertilizer effect, as reflected by the consistent relative performance between 0 N and other N rates. The heavier grains of NARIC 2 and NERICA 4 suggest greater dry matter accumulation before heading, as these varieties have a longer period of vegetative growth. The significant interaction of location x fertilizer and location x variety reveals the need for evaluating the nitrogen-supplying power of soils in the various cropping systems in the country.
Developing Lowland Rice Germplasm with Resistance to Multiple Biotic Stresses through Anther Culture in Uganda
(The Korean Society of International Agriculture, 2015) Lamo, Jimmy; Gyoung-rae, Cho; Ininda, Jane; Kofi Ayirebi, Dartey Paul; Ekebu, James; Ekobu, Moses; Alibu, Simon; Okanya, Stephen; Oloka, Bonny; Otim, Michael; Asea, Godfrey; Kyung-Ho, Kang
The lowland rice genotypes grown in Uganda were introduced in the 1970s. These genotypes (now landraces) are threatened by multiple biotic stresses namely; Rice Yellow Mottle Virus (RYMV) disease, Bacterial Leaf Streak(BLS). Bacterial Leaf Blight (BLB), and Rice Blast (BL). There are currently no rice lines with multiple resistance to these stresses although attempts have been made to develop them through hybridization involving cultivated, local and introduced lines and four varieties with tolerance to RYMV have been released. The use of potential resistance donor such as the traditional African cultivated rice, Oryza glaberrima, could be an alternative approach to furnish multiple resistance to the cultivated rice. The rice germplasm developed from a cross of an Oryza glaberrima from Niger Delta and Milyang23, a high-yielding Korean rice variety were evaluated for multiple resistance in Uganda as a Korea-Africa Food & Agriculture Cooperation Initiative (KAFACI)-Alliance for a Green Revolution in Africa (AGRA) joint cooperative project, “Enhancement of High Yielding Rice Germplasm in African Countries through Anther Culture Breeding”. Milyang23 was back crossed 4 times with Oryza. glaberrima and fixed through anther culture in Korea. An evaluation of 50 lines generated showed that up to 98%, 92%, 88% and 88% of the test plants showed resistance to the RYMV, BLS, BLB and BL diseases, respectively. There was no symptoms of the four diseases in 74% of the genotypes tested. The plants that showed symptoms of the three diseases had scores of not more than 3 on a 1 to 9 scale. This preliminary finding demonstrates that these generations of rice lines could help solving the current problem of susceptibility to multiple diseases.
Effects of plant density on the performance of selected African upland rice varieties
(African Journal of Agricultural Research, 2017) Matsumoto, Shunsuke; Tsuboi, Tatsushi; Asea, Godfrey; Miyamoto, Kisho; Maruyama, Atsushi; Takagaki, Michiko; Kikuchi, Masao
The effects of plant density on yield and yield components in upland rice cultivation were examined by conducting a series of field experiments in Central Uganda, using three African and one Japanese improved upland rice varieties. The estimation of plant-density response functions with respect to yield components and yield revealed that an increase in plant density significantly decreased the number of panicles per hill, number of spikelets per panicle, and 1000-grain weight, and significantly increased the number of panicles per square meter. The percentage of filled grain was not affected by plant density. Compared to the Japanese variety, the three African varieties were characterized by more numbers of panicles/hill, less numbers of spikelets/panicle, higher grain-filling ratio and lighter 1000-grain weight, but differences in the degrees of response to plant density were less distinct between them. Rice yield increased in the range of plant density tested, though the marginal increase in yield due to an increase in plant density by 1 hill/m2 diminished from 100 kg/ha at the plant density of 11 hills/m2 to 30 kg/ha at 33 hills/m2. No significant differences were found among the four varieties for the level of yield as well as for its degree of positive response to plant density. The yield components that determined the increase in yield were the number of panicles per square meter and the number of spikelets per panicle, or combined together, the number of spikelets per square meter, which was estimated to reach the maximum at the plant density of 35 hills/m2. When the differences among the treatments in the costs of seeds and weed-control were considered, the optimum plant density was found to be 22 hills/m2 (plantspacing of 30 cm × 15 cm), lower than the plant density that gives the maximum yield.
Efficacy of Event MON 87460 in drought-tolerant maize hybrids under optimal and managed drought-stress in eastern and southern africa
(Elsevier B.V, 2014-03) Obunyali, Caleb O; Pillay, Kiru; Meisel, Barbara; Ndou, Eric N; Mashingaidze, Kingstone; Sserumaga, Julius Pyton; Asea, Godfrey; Mwimali, Murenga; Tende, Regina; Beyene, Yoseph; Mugo, Stephen; Okogbenin, Emmanuel; Oikeh, Sylvester O.
Abstract Frequent drought events due to climate change have become a major threat to maize (Zea mays L.) production and food security in Africa. Genetic engineering is one of the ways of improving drought tolerance through gene introgression to reduce the impact of drought stress in maize production. This study aimed to evaluate the efficacy of Event MON 87460 (CspB; DroughtGard®) gene in more than 120 conventional drought-tolerant maize hybrids in Kenya, South Africa, and Uganda for 3–6 years under managed drought-stress and optimal conditions and establish any additional yield contribution or yield penalties of the gene in traited hybrids relative to their non-traited isohybrids. Germplasm used in the study were either MON 87460 traited un-adapted (2008–2010), adapted traited DroughtTEGO® (2011–2013) or a mix of both under confined field trials. Results showed significant yield differences (p < 0.001) among MON 87460 traited and non-traited hybrids across well-watered and managed drought-stress treatments. The gene had positive and significant effect on yield by 36–62% in three hybrids (CML312/CML445; WMA8101/CML445; and CML312/S0125Z) relative to non-traited hybrids under drought, and without significant yield penalty under optimum-moisture conditions in Lutzville, South Africa. Five traited hybrids (WMA2003/WMB4401; CML442/WMB4401; CML489/WMB4401; CML511/CML445; and CML395/WMB4401) had 7–13% significantly higher yield than the non-traited isohybrids out of 34 adapted DroughtTEGO® hybrids with same background genetics in the three countries for ≥ 3 years. The positive effect of MON 87460 was mostly observed under high drought-stress relative to low, moderate, or severe stress levels. This study showed that MON 87460 transgenic drought tolerant maize hybrids could effectively tolerate drought and shield farmers against severe yield loss due to drought stress. The study signified that development and adoption of transgenic drought tolerant maize hybrids can cushion against farm yield losses due to drought stress as part of an integrated approach in adaptation to climate change effects.
Exploration of rainfed rice farming in Uganda based on a nationwide survey: Evolution, regionality, farmers and land
(African Journal of Agricultural Research, 2013) Haneishi, Yusuke; Okello, Stella E.; Asea, Godfrey; Tsuboi, Tatsushi; Maruyama, Atsushi; Takagaki, Michiko; Kikuchi, Masao
Based on a nationwide survey of rice growing households, this paper explores how rainfed rice cultivation evolved in Uganda, how diverse it is in different regions of the country, what categories of farmers have adopted it, and how it has been integrated into their traditional cropping patterns. We find that the diffusion of rainfed rice cultivation accelerated at around the turn of this century when upland New Rice for Africa (NERICA) was introduced in the agro-ecological zones receiving annual rainfall of 1000 mm or more. The growth rate of area under rainfed rice cultivation from 2000 to 2009 was 14% year-1 in the lowest zone and as high as 31% year-1 in the highest zone. Rice was grown predominantly by smallholders. Farmers growing rainfed rice, upland and lowland alike, cultivated on average 2 ha of farm land, of which one-third (0.6 ha) was planted to rice, and the sizes of cultivated area and rice planted area of around 70% of farmers were below these averages. In terms of land tenure systems, rice was a crop of more importance in areas where the traditional customary tenure systems still remained, and the incidence of leasehold land tenure was higher for rice cultivation than for other crops.
Exploration of rainfed rice farming in Uganda based on a nationwide survey: Regionality, varieties and yield
(African Journal of Agricultural Research, 2013) Haneishi, Yusuke; Maruyama, Atsushi; Asea, Godfrey; Okello, Stella E.; Tsuboi, Tatsushi; Takagaki, Michiko; Kikuchi, Masao
Using a nationwide survey of rice growing farmers in Uganda, this study examined how farmers grow rice under rainfed conditions in various agro-climatic zones, and how rainfed rice cultivation performs in terms of yield, and what factors determine the level of rice yield. The study found that Nerica 4 and Supa were the two major varieties planted by rainfed rice farmers, the former in upland and the latter in lowland. High seeding rate, low fertilizer-chemical application and high labor intensity characterized rainfed rice cultivation in Uganda, though distinct regionality existed in fertilize-chemical application and labor intensity. The high marketed ratio of rice produce also characterized rice farming. The estimation of yield functions revealed that rainfall, the amount of seeds and fertilizers applied, lowland and small farmers were positive determinants of rice yield per hectare, that the potential for high yield existed in western regions of the country, and that there were some minor lowland rice varieties that performed better than popular Nerica 4 and Supa. The estimation also revealed that rice plots under the traditional tenure systems yield less, and those under the leasehold system yield more, than those under the formalized freehold and private mailo systems.
Factors Influencing Genomic Prediction Accuracies of Tropical Maize Resistance to Fall Armyworm and Weevils
(Plants, 2021) Badji, Arfang; Machida, Lewis; Kwemoi, Daniel Bomet; Kumi, Frank; Okii, Dennis; Mwila, Natasha; Agbahoungba, Symphorien; Ibanda, Angele; Bararyenya, Astere; Ndapewa Nghituwamhata, Selma; Odong, Thomas; Wasswa, Peter; Otim, Michael; Ochwo-Ssemakula, Mildred; Talwana, Herbert; Asea, Godfrey; Kyamanywa, Samuel; Rubaihayo, Patrick
Genomic selection (GS) can accelerate variety improvement when training set (TS) size and its relationship with the breeding set (BS) are optimized for prediction accuracies (PAs) of genomic prediction (GP) models. Sixteen GP algorithms were run on phenotypic best linear unbiased predictors (BLUPs) and estimators (BLUEs) of resistance to both fall armyworm (FAW) and maize weevil (MW) in a tropical maize panel. For MW resistance, 37% of the panel was the TS, and the BS was the remainder, whilst for FAW, random-based training sets (RBTS) and pedigree-based training sets (PBTSs) were designed. PAs achieved with BLUPs varied from 0.66 to 0.82 for MW-resistance traits, and for FAW resistance, 0.694 to 0.714 for RBTS of 37%, and 0.843 to 0.844 for RBTS of 85%, and these were at least two-fold those from BLUEs. For PBTS, FAWresistance PAs were generally higher than those for RBTS, except for one dataset. GP models generally showed similar PAs across individual traits whilst the TS designation was determinant, since a positive correlation (R = 0.92***) between TS size and PAs was observed for RBTS, and for the PBTS, it was negative (R = 0.44**). This study pioneered the use of GS for maize resistance to insect pests in sub-Saharan Africa.
Farmer’s Knowledge and Perceptions on Rice Insect Pests and Their Management in Uganda
(Agriculture, 2016) Alibu, Simon; Otim, Michael H.; Okello, Stella E. A.; Lamo, Jimmy; Ekobu, Moses; Asea, Godfrey
Rice is a new crop in Uganda, but has quickly grown in importance. Between 2000 and 2010, total area under rice cultivation in the country grew by 94% from 140,000 ha. Changes in the agro ecosystem due to expansion in rice area may have altered the pest status of rice insect pests. However, far too little attention has been paid to assessing the prevalence and importance of rice insect-pests in Uganda. In this study, we interviewed 240 lowland-rice farming households from eight districts within the north, east and central regions of Uganda about their perceived insect-pest problems and control measures employed, if any. A semi-structured questionnaire was used. The farmers ranked rice insect pests as the most important biotic constraint in rice production, with stem borers and the African rice gall midge (AfRGM) perceived to be the 1st and 2nd most detrimental insect pests, respectively. In spite of this, only 36% of the respondents could positively identify symptoms of AfRGM damage on rice plants, while 64% were familiar with stem borer damage. Over 60% of interviewed farmers expressed confidence in the effectiveness of insecticides for controlling rice insect pests. Cultural control measures were not popular among the farmers.
Genetic distance among doubled haploid maize lines and their testcross performance under drought stress and non-stress conditions
(Euphytica, 2013) Beyene, Yoseph; Mugo, Stephen; Semagn, Kassa; Asea, Godfrey; Trevisan, Walter; Tarekegne, Amsal; Tefera, Tadele; Gethi, James; Kiula, Barnabas; Gakunga, John; Karaya, Haron; Chavangi, Andrew
In contrast to conventional inbreeding that takes up to seven generations to develop inbred lines, the doubled haploid (DH) technology allows production of inbred lines in two generations. The objectives of the present study were to: (a) evaluate testcross performance of 45 doubled haploid lines under drought stress and non-stress conditions (b) estimate heritabilities for grain yield and other traits and (c) to assess the genetic distance and relationship among the DH lines using 163,080 SNPs generated using genotyping-by-sequencing (GBS). The 45 hybrid and five checks were evaluated using a 10 9 5 alpha lattice in six drought stress and nine well-watered environments in Kenya, Uganda, and Tanzania. Differences in trait means between the drought stress and well-watered conditions were significant for all measured traits except for anthesis date. Genetic variances for grain yield, grain moisture, plant height and ear height were high under well-watered environments while genetic variance for anthesis date, root lodging and stalk lodging were high under drought stress environments. Combined analyses across drought stress and well-watered environments showed that ten top hybrids produced 1.6–2.2 t/ha grain yield under well-watered condition and 1–1.4 t/ha under drought stress condition higher than the mean of the commercial checks. Genetic distance between pairwise comparisons of the 38 of the 45 DH lines ranged from 0.07 to 0.48, and the overall average distance was 0.36. Both cluster and principal coordinate analysis using the genetic distance matrix calculated from 163,080 SNPs showed two major groups and the patterns of group was in agreement with their pedigree. Thirteen (13) of the best hybrids are currently in National Performance Trials testing, an important step towards commercialization in Kenya, Tanzania and Uganda.
Genetic gain and cost efficiency of marker-assisted selection of maize for improved resistance to multiple foliar pathogens
(Molecular breeding, 2012) Asea, Godfrey; Vivek, Bindiganavile S.; Lipps, Patrick E.; Pratt, Richard C.
Northern corn leaf blight (NCLB) caused by Exserohilum turcicum, gray leaf spot (GLS) caused by Cercospora zeae-maydis and maize streak caused by maize streak Mastrevirus (MSV) are the most destructive foliar diseases limiting maize production in sub-Saharan Africa. Most foliar diseases of maize are managed using quantitative (partial) resistance, and previous studies have reported quantitative trait loci associated with host resistance (rQTL). Our objective was to compare the genetic gain and costs resulting from phenotypic, genotypic, and markerassisted selection of partially inbred lines derived from many families for resistance to infection
Genotype by environment interaction effects on grain yield of highland maize (Zea mays L) hybrids
(Maydica, 2018) Ninsiima Kayaga, Hellen; Ochwo-Ssemakula, Mildred; Kagoda, Frank; Mahulé Elysé Alladassi, Boris; Asea, Godfrey; Gibson, Paul; Edema, Richard
Maize varieties adapted to highland environments are generally scarce in East and Central Africa (ECA) since most breeding efforts have focused on mid-altitude maize. As a result, farmers in the highlands of Uganda mainly grow varieties that are bred for the mid-altitude zones. Since these maize varieties are not adapted to highland conditions, their productivity in this region rarely exceeds 2 t ha-1. This study was aimed at determining the effect of genotype by environment interactions (GEI) on the grain yield of highland maize hybrids. The study was conducted in three highland locations of Uganda in the maize growing season of March to October 2015. Thirty-six F1 hybrids and two checks were arranged in a 2 x18 (0, 1) alpha lattice design with two replications. Hybrid by location interaction had highly significant differences (P ≤ 0.001) and explained 46.2% of phenotypic variance. Genotype by environment interactions (GEI), thus, had a strong effect on grain yield. Analyses revealed two maize megaenvironments, with AMH701-9/AMH703-22 hybrid emerging the best genotype in Kachwekano and Kalengyere (6.69 t ha-1 and 14.30 t ha-1), and AMH701-9/AMH701-20 hybrid being the best in Buginyanya (14.39 t ha-1). Efforts to breed for high yielding maize cultivars for the highland areas of Uganda should therefore focus more on specific adaptation than broad adaptation.
Genotype by environment interactions and agronomic performance of doubled haploids testcross maize (Zea mays L.) hybrids
(Euphytica, 2016) Sserumaga, Julius Pyton; Oikeh, Sylvester O.; Mugo, Stephen; Asea, Godfrey; Otim, Michael; Beyene, Yoseph; Abalo, Grace; Kikafunda, Joseph
In vivo production of maternal haploid plants and advancement in chromosome doubling technology has led to rapid production of doubled haploid homozygous lines. These in turn have boosted rapid advancement in most breeding programs. This has resulted in production of a large number of maize hybrids which need testing across production environments to select the most suitable hybrids for release and cultivation. The objective of this study was to assess the genotype 9 environment interactions (GE) for grain yield and other agronomic traits and evaluate the performance of 44 recently developed doubled haploids (DH) testcross hybrids along with six checks across five locations in Uganda. Significant mean squares for environment (E), genotype (G) and GE were observed for all studied traits. Environment explained 46.5 % of the total variance, while G and GE contributed 13.2 and 7.2 %, respectively. Genetic correlations among locations were high (0.999), suggesting little GE among environments. The 10 best testcross hybrids had a 49.2 %average grain yield advantage over the six checks at all locations. DH hybrids CKHDHH0887, CKDHH0878, CKDHH 0859, WM1210, CKDHH0858, and WM1214 were the most stable, across locations. The DH testcross hybrids produced higher grain yield and possessed acceptable agronomic traits compared to the commercial hybrids developed earlier. Use of the best DH testcross hybrids, well targeted to the production environments, could boost maize production among farmers.
Grain yield performance and flowering synchrony of CIMMYT’s tropical maize (Zea mays L.) parental inbred lines and single crosses
(Euphytica, 2016) Worku, Mosisa; Makumbi, Dan; Beyene, Yoseph; Das, Biswanath; Mugo, Stephen; Pixley, Kevin; Ba¨nziger, Marianne; Owino, Fidelis; Olsen, Michael; Asea, Godfrey; Prasanna, Boddupalli M.
Maize production constraints in sub-Saharan Africa (SSA) are being addressed by CIMMYT and partners through an array of projects, focusing on developing and evaluating parental inbred lines and single-crosses as well as formulating, evaluating and releasing high-yielding and stress resilient hybrids adapted to different agro-ecologies. The objectives of the present study were to (1) evaluate the grain yield performance of parental elite inbred lines developed over the years, and single crosses; and (2) ascertain the flowering synchrony among inbred lines and singlecross hybrid parents. Parental inbred lines and singlecrosses were evaluated at seven locations in two countries in 2014. Combined analysis of variance revealed differences (P\0.01) among genotypes for grain yield (GY) and among different years/era of release of the inbred lines. The improvement in GY of inbred lines was estimated to be 1.4 %per year. Under irrigated conditions GY of some single-cross hybrids was over 16 t ha-1. Some single-cross and inbred line parents showed acceptable flowering synchrony, good producibility, and stable performance across testing environments, suggesting that these have high potential for seed production. Further research is needed to determine the physiological and morphological characteristics that contributed to the GY improvement in the parental inbred lines. Information generated from this study will enhance the use of CIMMYT’s tropical mid-altitude parental germplasm by breeders working in both private and public breeding programs for developing and deploying high-yielding maize hybrids for the benefit of small-scale farmers in SSA.
Grain-yield stability among tropical maize hybrids derived from doubled-haploid inbred lines under random drought stress and optimum moisture conditions
(Crop and Pasture Science, 2018) Sserumaga, Julius Pyton; Beyene, Yoseph; Pillay, Kiru; Kullaya, Alois; Oikeh, Sylvester O.; Mugo, Stephen; Machida, Lewis; Ngolinda, Ismail; Asea, Godfrey; Ringo, Justin; Otim, Michael; Abalo, Grace; Kiula, Barnabas
Drought is a devastating environmental stress in agriculture and hence a common target of plant breeding. A review of breeding progress on drought tolerance shows that, to a certain extent, selection for high yield in stress-free conditions indirectly improves yield in water-limiting conditions. The objectives of this study were to (i) assess the genotype environment (GE) interaction for grain yield (GY) and other agronomic traits for maize (Zea mays L.) across East African agro-ecologies; and (ii) evaluate agronomic performance and stability in Uganda and Tanzania under optimum and random drought conditions. Data were recorded for major agronomic traits. Genotype main effect plusGE(GGE) biplot analysis was used to assess the stability of varieties within various environments and across environments. Combined analysis of variance across optimum moisture and random drought environments indicated that locations, mean-squares for genotypes and GE were significant for most measured traits. The best hybrids, CKDHH1097 and CKDHH1090, gave GY advantages of 23%and 43%, respectively, over the commercial hybrid varieties under both optimum-moisture and random drought conditions. Across environments, geno typic variance was less than the GE variance for GY. The hybrids derived from doubled-haploid inbred lines produced higher GY and possessed acceptable agronomic traits compared with the commercial hybrids. Hybrid CKDHH1098 ranked second-best under optimum-moisture and drought-stress environments and was the most stable with broad adaptation to both environments. Use of the best doubled-haploids lines in test cross hybrids make-up, well targeted to the production environments, could boost maize production among farmers in East Africa.
Indirect selection for resistance to Stenocarpella maydis and Fusarium graminearum and the prospects of selecting for high-yielding and resistant maize hybrids
(Plant Breeding, 2016) Tembo, Langa; Asea, Godfrey; Gibson, Paul T.; Okori, Patrick
Stenocarpella maydis and Fusarium graminearum affect grain yield and quality as a result of mycotoxins produced. A negative association of yield with resistance to cob rots has been reported. The objectives of this study were therefore to investigate the influence of cob characteristics on the response to F. graminearum and S. maydis disease reaction and evaluate the prospects of direct selection for high-yielding and resistant maize hybrids. In this study, the pathogens were directly introduced to the cob through toothpick inoculation. Correlation of husk cover to diseaseseverity of each pathogen, separately toothpick inoculated, was significant(P < 0.01). However, the low r values (<0.45) of traits associated with the response to inoculation by S. maydis and F. graminearum imply that indirect selection would not be beneficial for obtaining the type of resistance shown under inoculation. Several hybrids combined good yields with at least moderate resistance to both pathogens.
Inheritance of Yield and Yield-related Traits in Highland Maize Hybrids of Uganda
(Journal of crop science and biotechnology, 2017) Ninsiima Kayaga, Hellen; Kagoda, Frank; Ochwo-Ssemakula, Mildred; Mahulé Elysé Alladassi, Boris; Asea, Godfrey; Gibson, Paul; Edema, Richard
Although many studies have been conducted on gene action of grain yield and yield related traits in maize, none of them focused on highland maize in Uganda. This study was conducted to establish the gene action controlling inheritance of yield and its related traits in highland maize hybrids. Thirty-six F1 hybrids generated from a 9 x 9 half diallel mating design, were planted with two local checks in three highland locations; Kalengyere, Kachwekano, and Buginyanya with two replications using a 2 x 19 alpha (0, 1) lattice design. Results showed that inheritance of ear length and anthesis-silking interval was controlled by both additive and non-additive gene action while the inheritance of days to anthesis, days to silking was mainly controlled by additive gene action. The inheritance of grain yield and other yield related traits was greatly influenced by environment and genotype x environment interaction. Considering the great influence of the environment and genotype x environment interaction on most of the traits including grain yield, further testing in additional locations over more seasons and broadening the genetic base of the parents is encouraged.
Magnaporthe oryzae populations in Sub-Saharan Africa are diverse and show signs of local adaptation
(bioRxiv, 2020) Onaga, Geoffrey; Suktrakul, Worrawit; Wanjiku, Margaret; Quibod, Ian Lorenzo; Domelevo Entfellner, Jean- Baka; Bigirimana, Joseph; Habarugira, George; Murori, Rosemary; Asea, Godfrey; Ismail, Abdelbagi M.; Jantasuriyarat, Chatchawan; Oliva, Ricardo
Rice blast caused by Magnaporthe oryzae is one of the most economically damaging diseases of rice worldwide. The disease originated in Asia but was detected for the first time in Sub-Saharan Africa (SSA) around 100 years ago. Despite its importance, the evolutionary processes involved in shaping the population structure of M. oryzae in SSA remain unclear. In this study, we investigate the population history of M. oryzae using a combined dataset of 180 genomes. Our results show that SSA populations are more diverse than earlier perceived, and harbor all genetic groups previously reported in Asia. While M. oryzae populations in SSA and Asia draw from the same genetic pools, both are experiencing different evolutionary trajectories resulting from unknown selection pressures or demographic processes. The distribution of rare 32 alleles, measured as Tajima’s D values, show significant differences at the substructure level. Genome-wide analysis indicates potential events of population contraction strongly affecting M. oryzae in SSA. In addition, the distribution and haplotype diversity of effectors might suggest a process of local adaptation to SSA conditions. These findings provide additional clues about the evolutionary history of M. oryzae outside the center of origin and help to build customized disease management strategies.
Modest Ag-Extension and Access to Seeds of Aromatic Rice Can Boost Returns of Smallholder Farmers in Uganda, A Case Study
(Agriculture, 2022) Alibu, Simon; Obura, Morish; Ekebu, James; Nampamya, Doreen; Lamo, Jimmy; Asea, Godfrey; Tae-Seon, Park
Limited farmer access to quality seeds of improved varieties and knowledge gaps in good agronomic practices are the major factors limiting rice productivity among smallholder farmers in Uganda. Promoting high yielding aromatic rice varieties alongside good agronomic practices can unlock commercial opportunities for smallholder farmers in rice cultivation, given that 80% of rice consumers in Uganda prefer aromatic rice, which is in short supply. This case study highlights a project’s achievements to accelerate the adoption of improved aromatic rice varieties among smallholder farmers in Uganda. This project supported a few selected farmers with the seed of a new aromatic rice variety, NARORICE-1, and equipped them with agronomic skills to raise their yields from an average of 3.1 to 4.1 t/ha. Line transplanting was identified as a crucial technology to increase rice yields among smallholders. Costly and inaccessible crop-enhancing inputs such as seeds and fertilizers, and an unfair distribution of irrigation water were the two main obstacles farmers face in rice production. Farmers valued NARORICE-1 for its aroma, high yield, and early maturity. The project’s training of a community seed producer improved farmers’ access to NARORICE- 1 seeds, increasing its adoption by 20% in two years. NARORICE-1 is much more in demand than any other variety and attracts a better price, making it an ideal innovation for increasing productivity and farmer’s incomes. An effective seed system and continuous farmer training are vital for accelerating impact.
Molecular characterization of tropical maize inbred lines using microsatellite DNA markers
(Maydica, 2014) Sserumaga, Julius P.; Makumbi, Dan; Ji, Hyeonso; Njoroge, Kiarie; Wanjohi Muthomi, James; Chemining’wa, George N.; Si-myung, Lee; Asea, Godfrey; Kim, Hakbum
An insight on diversity and relationships among germplasm is important in any breeding program for crop improvement. The main objectives of our study were to: (i) determine the level of genetic diversity within mid altitude maize inbred lines resistant to weevils, aflatoxin accumulation and drought, (ii) to suggest potential heterotic groups using their genetic structures and distance based on cluster analysis with the aim to generate broad based source germplasm for mid altitude maize breeding program with combined traits of importance against Aflatoxin accumulation. In this study, 25 SSR markers were used to finger print forty two maize inbred lines to assess the genetic diversity, genetic relationships, and their population structure. A total of 184 alleles were identified at all the loci with an average of 7.36 and a range between two and 19 alleles per locus. The major allele frequency varied from 0.17 to 0.90 with an average of 0.49 while the minor allele frequency varied from 0.10 to 0.83 with an average of 0.51. The gene diversity values varied from 0.18 to 0.92 with an average of 0.65. Average heterozygosity percentage of the inbred lines was 4%, ranging from 0% to 2%, indicating the low level of heterozygosity within the inbred lines. The average polymorphism information content (PIC) was 0.61. A dendrogram constructed using unweighted Neighbour Joining algorithm suggested three heterotic groups among the inbred lines. The three heterotic patterns based on the SSR markers need to be verified by field testing to confirm what appears to be promising alternative heterotic patterns. The fixed pattern detected using SSR markers could potentially contribute towards effective utilization of the inbred lines for the exploitation of heterosis and formation of genetically diverse sources population.

Browsing by Author "Asea, Godfrey"

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