Browsing by Author "Gibson, Paul"
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Item Additive Main Effects and Multiplicative Interactions Analysis of Yield Performances in Cowpea Genotypes under Ugandan Environments(International Journal of Advanced Research (IJAR), 2017) Agbahoungba, Symphorien; Karungi, Jeninah; Talwana, Herbert; Badji, Arfang; Kumi, Frank; Mwila, Natasha; Edema, Richard; Gibson, Paul; Rubaihayo, PatrickYield in legumes is the result of many plant processes, which are usually expressed in yield and have been shown to be affected by management, genotype and environment. The objectives of this study were to assess the extent of genotype x environment interaction and to select the stable cowpea genotypes in Ugandan environments over seasons. Seventy-two cowpea genotypes were evaluated for yield in three locations and two seasons in Uganda. The yield data were subjected to analysis of variance and additive main effects and multiplicative interactions (AMMI) analysis. The results showed a highly significant (P<0.001) genotype by location and by year (season) interaction effects for grain yield, with 69.16% of the total variation attributable to environmental effects, 5.36% to genotypic effects and 12.74% to G x E interactions effects. Genotype MU9 had the highest yield (854.68 kgha-1) but was only adapted to specific environments (Arua 2015B and 2016A). Hence, genotypes WC 30, NE 45, NE 31, NE 51 which were equally high yielding, stable and adapted to the tested environments, and should be recommended for genetic improvement of cowpea germplasm in Uganda.Item Combining ability and heritability analysis of sweetpotato weevil resistance, root yield, and dry matter content in sweetpotato(Frontiers Media S.A., 2022-09) Mugisa, Immaculate; Karungi, Jeninah; Musana, Paul; Odama, Roy; Alajo, Agnes; Chelangat, Doreen M; Anyanga, Milton O; Oloka, Bonny M.; Gonçalves dos Santos, Iara; Talwana, Herbert; Ochwo-Ssemakula, Mildred; Edema, Richard; Gibson, Paul; Ssali, Reuben; Campos, Hugo; Olukolu, Bode A; Guilherme; Yencho, Craig; Yada, Benard; da Silva Pereira, Guilherme; Yencho, CraigEfficient breeding and selection of superior genotypes requires a comprehensive understanding of the genetics of traits. This study was aimed at establishing the general combining ability (GCA), specific combining ability (SCA), and heritability of sweetpotato weevil (Cylas spp.) resistance, storage root yield, and dry matter content in a sweetpotato multi-parental breeding population. A population of 1,896 F1 clones obtained from an 8 × 8 North Carolina II design cross was evaluated with its parents in the field at two sweetpotato weevil hotspots in Uganda, using an augmented row-column design. Clone roots were further evaluated in three rounds of a no-choice feeding laboratory bioassay. Significant GCA effects for parents and SCA effects for families were observed for most traits and all variance components were highly significant (p ≤ 0.001). Narrow-sense heritability estimates for weevil severity, storage root yield, and dry matter content were 0.35, 0.36, and 0.45, respectively. Parental genotypes with superior GCA for weevil resistance included “Mugande,” NASPOT 5, “Dimbuka-bukulula,” and “Wagabolige.” On the other hand, families that displayed the highest levels of resistance to weevils included “Wagabolige” × NASPOT 10 O, NASPOT 5 × “Dimbuka-bukulula,” “Mugande” × “Dimbuka-bukulula,” and NASPOT 11 × NASPOT 7. The moderate levels of narrow-sense heritability observed for the traits, coupled with the significant GCA and SCA effects, suggest that there is potential for their improvement through conventional breeding via hybridization and progeny selection and advancement. Although selection for weevil resistance may, to some extent, be challenging for breeders, efforts could be boosted through applying genomics-assisted breeding. Superior parents and families identified through this study could be deployed in further research involving the genetic improvement of these traits.Item Combining ability for resistance to rice yellow mottle virus disease in interspecific and intraspecific rice Genotypes(African Journal of Crop Science, 2015) Munganyinka, Esperance; Edema, Richard; Lamo, Jimmy; Gibson, Paul; Rukundo, PlacideEstimates of combining ability for resistance to rice yellow mottle virus disease (RYMV) were obtained in the green house of National Crops Resources Research Institute, Uganda. The study involved forty-one F2’s diallel crosses and their five intraspecific and four interspecific parental lines. Effects of both general combining ability (GCA) and specific combining ability (SCA) for RYMV reactions were significant, with a preponderance of GCA effects. Of parental lines used in this study, Naric 1, Nerica 6 and WAC 116 were good combiners for transferring resistance genes to their progenies. In this study, most genotypes with good resistance were good general combiners expect Gigante, that despite its good mean performance, combined badly for resistance to RYMV. The crosses with the best resistance were Naric 1x Gigante, Naric 1x Nerica 6, Nerica 6 x Nerica 4 and Nerica 1 x Nerica 6. From this study, we suggest that selection of parents as donors for resistance should consider both GCA and parental performance. On the basis of predominant additive genetic effects observed in the present study, we believe that combinations of interspecific parents may be used to produce rice varieties resistant to RYMV, and that selection in early selfing generations should be effective.Item Continuous Storage Root Formation and Bulking in Sweet potato(Gates Open Research, 2019) Bararyenya, Astere; Tukamuhabwa, Phinehas; Gibson, Paul; Grüneberg, Wolfgang; Ssali, Reuben; Low, Jan; Odong, Thomas; Ochwo-Ssemakula, Mildred; Talwana, Herbert; Mwila, Natasha; Mwanga, RobertSweetpotato (Ipomoea batatas (L.) Lam, family Convolvulaceae.) is one of the most important food crops worldwide, with approximately 106 million tons produced in almost 120 countries from an area of about 8 million ha and an average global yield of 11.1 tons/ha (FAO, 2016). Asia is the world’s largest sweetpotato producing continent, with 79 million tons, followed by Africa (FAOstat, 2016). About 75% of this global production is from China alone. A total of 21.3 million tons is produced in Africa, with 48% from the Great Lakes region. In East Africa, the crop is the second most important root crop after cassava and has played an important role as a famine-relief crop during its long history and has recently been reevaluated as a health-promoting food (Low et al., 2017). Uganda ranks as the fourth largest sweetpotato producer in the world after China, Nigeria and Tanzania, with a production of 2.1 million t. In Africa, Uganda is ranked third after Nigeria and Tanzania. Sweetpotato is one of the main staple crops in the food systems of Uganda, Rwanda, and Burundi with a per capita consumption of 50.9, 80.1 and 57.0 kg, respectivelyItem Estimates of combining ability and heritability in cowpea genotypes under drought stress and nonstress conditions in Uganda(Journal of Plant Breeding and Crop Science, 2017) Mwale, Saul Eric; Ochwo Ssemakula, Mildred; Sadik, Kassim; Alladassi, Boris; Rubaihayo, Patrick; Gibson, Paul; Singini, Wales; Edema, RichardCowpea is an important source of food and income for small scale farmers in Uganda. Production is, however, affected by both biotic and abiotic stresses. Drought stress has recently emerged as a serious concern due to the effects of climate change. This study was therefore undertaken to estimate the general and specific combining ability effects of parents and crosses as well as estimate the heritability of delayed leaf senescence, seed yield and its components under drought stress. Five drought tolerant genotypes were crossed with four drought sensitive genotypes in a North Carolina II mating design. The study revealed that drought tolerance is conditioned by both additive and non-additive genetic effects with the predominance of non-additive genetic effects for seed yield, 100 seed weight and number of pods per plant. Delayed leaf senescence was however, controlled by additive genetic effects, implying that progenies performance could be predicted from parents General Combining Ability (GCA) effects. The cultivars SECOW 5T, IT93K-452-1 and IT98K-205-8 were good combiners for drought tolerance. The F2 families: SECOW 3B x IT98K-205-8, SECOW 5T x IT98K-205-8, SECOW 4W x IT98K- 205-8 and SECOW 1T x IT98K-205-8 had positive Specific Combining Ability(SCA) effects in seed yield, number of pods per plant and 100 seed weight, implying that they performed better than what was predicted by their parents GCA effect. As such, they are promising cross combinations that can be advanced for later generation selection.Item Evaluation of Cowpea Genotypes for Resistance to Fusarium redolens in Uganda(American Journal of Plant Sciences, 2017) Wanjala Namasaka, Roy; Tusiime, Geoffrey; Orawu, Martin; Gibson, Paul; Nyiramugisha, Josiane; Edema, RichardFusarium redolens, a virulent fungus which causes damping off, leaf yellowing, wilting and root rots has recently been devastating cowpea fields in Uganda. This study aimed at identifying cowpea genotypes that are resistant to Fusarium redolens. Therefore, ninety cowpea genotypes were evaluated two times against a highly virulent Fusarium redolens (isolate from Zombo in Paidha district) in the screen house in 2016. Genotype effect was highly significant (P < 0.001) for root rot severity. Based on the Index of Susceptibility (IS), three genotypes (Asontem, Dan1 LA and IT89KD-88) remained resistant (IS < 3.5) over the two screening periods, 72 moderately resistant (3.5 ≤ IS < 6.5) and 11 susceptible (IS ≥ 6.5). Resistance was found to be enhanced by presence of lateral roots above or at the ground level. Further results suggested a difference in genetic control of resistance to root rots and seed rots caused by Fusarium redolens . All the released varieties tested (SECOW 1 T, SECOW 2 W, SECOW 3 B, SECOW 4 W and SECOW 5 T) had moderate resistance to Fusarium redolens . Correlation analysis revealed root rot severity was strongly correlated to disease incidence (+0.64, P < 0.001), to proportion of plants with lateral roots (−0.56, P < 0.001), to amount of leaf chlorophyll (−0.53, P < 0.001) and to proportion of plants that died prematurely due to Fusarium redolens infection (+0.45, P < 0.001). No significant correlation was detected between root rot severity and proportion of plants that germinated. The established resistance could be exploited for improvement of farmer preferred cowpea varieties towards Fusarium redolens resistance in Uganda.Item Flowering problems and their possible solution in cassava breeding(Journal of Scientific Agriculture, 2020) Ibrahim, Yasmin; Baguma, Yona; Abincha, Wilfred; Gibson, Paul; Edema, Richard; Bisikwa, JenipherSix elite cassava clones were chosen from cassava breeding program at the National Crops Resource Research Institute (NaCRRI) based on their flowering characteristics and seed set. The clones were planted in randomized complete block experimental design with 3 replications. The floral biology of these cassava clones were studied, focusing on morphological traits and developmental timing. Since cassava develops branches in levels, data was sourced from the 1st level of branching through the 4th level of branching. The result indicated that days to branching generally varied among all the genotypes studied, indicating the need to use different planting dates for different genotypes to ensure synchronization of flowering. The time difference among genotypes from branching to visible inflorescence was not larger than one and a half days and this difference did not seem be a factor for synchronization. The general number of female flowers was low in all genotypes across branching levels. This suggests there is a need to apply techniques that could enhance flowering in cassava. Conversely, the number of male flowers outnumbered the female flowers, suggesting that male flower production may not be a limiting factor to hybrid seed production. Male flower opened 20 to 30 days later after the opening of the female flowers. This calls for delayed planting of the early flowering genotypes when used as female parent. It was recommended that in order to synchronize flowering, the late flowering genotypes have to be planted ahead of the early flowering genotypes. In addition, applying techniques such as growth regulators, red light and finding the most optimal locations for flowering is recommended for further study as a way of enhancing flowering among cassava genotypes.Item Genetic Gains for Yield and Virus Disease Resistance of Cassava Varieties Developed Over the Last Eight Decades in Uganda(Frontiers in Plant Science, 2021) Manze, Francis; Rubaihayo, Patrick; Ozimati, Alfred; Gibson, Paul; Esuma, Williams; Bua, Anton; Alicai, Titus; Omongo, Chris; Kawuki, Robert S.Achieving food security for an ever-increasing human population requires faster development of improved varieties. To this end, assessment of genetic gain for key traits is important to inform breeding processes. Despite the improvements made to increase production and productivity of cassava in Uganda at research level, there has been limited effort to quantify associated genetic gains. Accordingly, a study was conducted in Uganda to assess whether or not genetic improvement was evident in selected cassava traits using cassava varieties that were released from 1940 to 2019. Thirty-two varieties developed during this period, were evaluated simultaneously in three major cassava production zones; central (Namulonge), eastern (Serere), and northern (Loro). Best linear unbiased predictors (BLUPs) of the genotypic value for each clone were obtained across environments and regressed on order of release year to estimate annual genetic gains. We observed that genetic trends were mostly quadratic. On average, cassava mosaic disease (CMD) resistance increased by 1.9% per year, while annual genetic improvements in harvest index (0.0%) and fresh root yield (5 kg per ha or 0.03% per ha) were non-substantial. For cassava brown streak disease (CBSD) resistance breeding which was only initiated in 2003, average annual genetic gains for CBSD foliar and CBSD root necrosis resistances were 2.3% and 1.5%, respectively. It’s evident that cassava breeding has largely focused on protecting yield against diseases. This underpins the need for simultaneous improvement of cassava for disease resistance and high yield for the crop to meet its current and futuristic demands for food and industry.Item 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, RichardMaize 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.Item Identification of Blast Resistant Genotypes among Drought Tolerant Finger Millet in Uganda(East African Nature and Science Organization, 2020-11-03) Aru, John Charles Aru; Wanyera, Nelson; Okori, Patrick; Gibson, PaulFinger millet is an important food security crop among many subsistence farmers living in marginal and especially semi-arid regions of Eastern Africa. However, crop production is affected mainly by terminal drought and blast disease caused by fungus Pyricularia grisea. Both collectively lead to over 90% grain yield loss depending on environmental conditions, cropping systems and varietal differences. Therefore, resistance breakdown remains high owing to variability in the blast pathogen and weather conditions. Stable varieties should possess both blast resistance and drought. In order to initiate breeding for multiple resistance to blast on drought-tolerant background, a study was conducted to identify variability for blast resistance from adapted germplasm as an initial step in developing a breeding strategy for incorporating resistance. Thirty genotypes from drought-prone agro-ecologies and including mini core germplasm from NARO-NaSARRI national Finger Millet improvement programme were assessed. They were screened using a local virulent pathogen isolate (NGR1) from Ngora, representing Teso major farming system and is a hot spot for the blast. The screening was under controlled conditions from in Makerere University Agricultural Research Institute (MUARIK) in 2012b. The results showed significance (p<0.01) for Area Under Disease Progressive Curve (AUDPC). Subsequently, the study identified IE927, Seremi1, Seremi3, Sec220 and Kabale as highly resistant to foliar blast infection comparable to Gulu-E a standard broad-spectrum resistant check and they could be used to improve finger millet for blast resistance. Meanwhile DR33, IE9 and IE2576 as most susceptible compared to non-race -specific susceptible check E11 from Uganda.Item Identification of candidate genes associated with resistance to bruchid (Callosobruchus maculatus) in cowpea(Plant Breeding, 2019) Miesho, Belay; Hailay, Mehari; Msiska, Ulemu; Bruno, Awio; Malinga, Geoffrey M.; Obia Ongom, Patrick; Edema, Richard; Gibson, Paul; Rubaihayo, Patrick; Kyamanywa, SamuelCowpea is an important legume crop widely grown in sub‐Saharan Africa for food and feed. However, it is largely challenged by bruchid, a serious storage pest resulting in losses in quantity and quality of grains. Therefore, this research was designed to contribute to the breeding of cowpea resistance to bruchid through the identification of candidate genes associated with resistance to bruchid. A total of 217 mini‐core cowpea accessions were genotyped and phenotyped for their reactions to bruchid. To determine the genomic regions linked with bruchid resistance, 41,948 polymorphic SNP markers were used. Genome‐wide association study identified 11 SNPs linked to the average number of eggs, holes, insect emergence and development period and Dobie susceptibility index. Gene search via Phytozome identified six candidate genes (Vigun08g132300, Vigun08g158000, Vigun06g053700, Vigun02g131000, Vigun01g234900 and Vigun01g201900) associated with the resistance traits. These candidate genes could be incorporated into the farmers preferred but susceptible cowpea varieties to bruchid. The SNP markers associated with the resistance traits can be used in marker‐assisted breeding for accurate and rapid screening of cowpea resistant genotypes to bruchid.Item Identification of rice genotypes tolerant to submergence at seedling stage in Uganda(Journal of Plant Breeding and Crop Science, 2019) Bildadi Mlaki, Anna; Gibson, Paul; Edema, Richard; Habineza, Jean Claude; Mwanje, Gerald; Lamo, Jimmy; Nuwamanya, EphraimFloods have destroyed over 2000 acres of rice in Uganda which affected yield and caused losses to farmers. This problem is more pronounced when fields are not well leveled, and the mode of irrigation is by surface flooding. Majority of lowland rice fields in East African region are of this nature and are thus prone to yield losses. There are no submergence tolerance varieties identified in Uganda, so far. To address this problem, breeding for submergence tolerance is the most ideal and promising strategy in rice. As a first step, genotypes tolerant to submergence need to be identified which is the objective of this study. 29 rice genotypes were morphological characterized in screen house and field conditions while 34 rice genotypes were molecularly characterized. Results suggested significant differences in the performance of genotypes both in the screen house and under field conditions in which varieties Swarna, IRRI SUPA 3 and KOMBOKA showed approximately 80% and above survival rate with Swarna variety ranking first. Molecular characterization of rice genotypes revealed that, out of 34 genotypes, 30 genotypes scored presence for Sub 1A-2 allele while, four genotypes were neither Sub1A-1 nor Sub 1A- 2 alleles. None of the tested genotypes were carrying Sub 1A-1 allele.Item Inheritance of cowpea resistance to flower thrips in Uganda germplasm(Journal of Plant Breeding and Crop Science, 2018) Agbahoungba, Symphorien; Karungi, Jeninah; Badji, Arfang; Sadik, Kassim; Gibson, Paul; Edema, Richard; Assogbadjo, Achille E.; Rubaihayo, Patrick R.Flower thrips [Megalurothrips sjostedti (Trybom)] is the most damaging insect pest on cowpea. However, information regarding the nature of gene action governing the inheritance of resistance to thrips is not available for cowpea genotypes in Uganda. This study was carried out to determine the inheritance pattern of cowpea resistance to flower thrips. Five resistant cowpea genotypes and three susceptible genotypes were crossed in full diallel mating design. F2 progenies were evaluated along with the parents in alpha lattice design with two replications under natural thrips infestation at Kabanyolo, Arua and Serere in Uganda. Combining ability analysis was performed using method one and model one of diallel analysis. The results showed that the environmental effects were highly significant (P<0.001). Additive, dominance and epistasis effects had major contributions. The broad sense heritability varied from 18 to 42% for thrips damage scores and from 0 to 6% for thrips counts. The estimates of narrow sense heritability were low for thrips damage score (2 to 18%) and thrips counts (0 to 9%). Genotypes TVU-1471 and TVU-1509 were identified as good transmitters of resistance to flower thrips. Crosses TVU-1509 x NE5, TVU-473 x Sanzi, TVU-123 x Sanzi, TVU-123 x TVU-473, and TVU-473 x TVU-1509 presented significant (P<0.05) and negative SCA effects for thrips damage scores and thrips counts and would be the most useful in breeding as some of their progenies would have high resistance to flower thrips. This study provides the basis of an efficient breeding program of cowpea for flower thrips resistance.Item Inheritance of resistance to brown spot disease in upland rice in Uganda(Journal of Plant Breeding and Crop Science, 2017) Mwendo, Marco Martin; Ochwo-Ssemakula, Mildred; Mwale, Saul Eric; Lamo, Jimmy; Gibson, Paul; Edema, RichardBrown spot disease caused by Bipolaris oryzae [Breda de Haan (Shoem.)] is one of the most important diseases affecting rice (Oryza sativa L.) worldwide. Host plant resistance is considered an effective, cheap and environment friendly means of managing this disease. Nine rice genotypes with varying resistance levels were crossed in a full diallel mating design including reciprocals and parents. Parents, reciprocals and F2 progenies were evaluated in an alpha lattice design in the screen house and field trials at the National Crops Resources Research Institute in Uganda in 2013-2014. The objectives of the study were to determine the mode of inheritance for resistance to brown spot disease and characterize segregation patterns of specific F2 progenies. Significant (P ≤0.001) variation for brown spot resistance occurred among the tested genotypes. The general combining ability (GCA) and specific combining ability (SCA) effects of brown spot disease scores were both significantly different (P≤0.001), indicating that both additive and non-additive genetic effects were present. There was, however, a predominance of non-additive genetic effects in the genetic control of brown spot resistance as shown by low estimates of baker’s ratio (0.29) and narrow sense coefficient of genetic determination (0.24), implying that progeny performance could not be predicted from parents GCA effects as it was better only in specific crossing combinations. Segregation patterns also indicated that resistance to brown spot was controlled by one or two dominant genes. The reciprocal effects for the crosses were significantly different (P ≤ 0.05), suggesting that cytoplasmic genetic effects modified the expression of resistance. Care should, therefore, be taken when selecting female parents during hybridization. Family-based breeding programs would also be effective for improving resistance to brown spot in rice varieties adapted to Uganda.Item Inheritance of resistance to common bacterial blight in four selected common bean (Phaseolus vulgaris L.) genotypes(Journal of Plant Breeding and Crop Science, 2017) Alladassi, Boris M. E.; Nkalubo, Stanley T.; Mukankusi, Clare; Mwale, Eric S.; Gibson, PaulCommon bacterial blight (CBB) is the most serious bacterial disease of common bean in Uganda. It causes severe yield losses of up to 62%. Genetic resistance is the most effective option for controlling CBB in smallholder common bean production systems. This study was carried out to determine the inheritance pattern of CBB resistance in leaf and pod of four new resistance sources. The four resistant and four susceptible genotypes were crossed in a half-diallel mating design. F1 individuals were advanced to F2 and evaluated with the parents, in a randomized complete block design replicated twice. Combining ability analysis was performed according to Griffing's (1956) method IV and model 1 using Genstat 12th. General combining ability effects were significant whereas specific combining ability was not suggesting that resistance to CBB in leaf and pod was primarily controlled by additive genes effects. The estimated narrow sense coefficient of genetic determination was moderately high (0.65) for the resistance in leaf and high (0.83) for resistance in pod suggesting that early-generation selection would be effective. Baker’s ratio estimates were relatively high for resistance in leaf (0.79) and pod (0.9) suggesting that hybrids’ performance can be predicted based on the parents’ general combining ability (GCA) effects.Item 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, RichardAlthough 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.Item Microsatellites markers associated with resistance to flower bud thrips in a cowpea F2 population derived from genotypes TVU-123 and WC36(African Journal of Biotechnology, 2018) Agbahoungba, Symphorien; Karungi, Jeninah; Sadik, Kassim; Gibson, Paul; Edema, Richard; Assogbadjo, Achille E.; Rubaihayo, Patrick R.Breeding for resistance to flower bud thrips (Megalurothrips sjostedti) in cowpea has been hindered by the quantitative nature of resistance. To identify simple sequence repeat (SSR) markers associated with resistance to flower bud thrips that could be used for marker-assisted breeding, a F2 population was generated from a cross between genotypes TVU-123 (resistant) and WC36 (susceptible). The population was evaluated for thrips damage scores, thrips counts, and pods number per plant under artificial infestation. Sixty-six microsatellites markers were screened between the two parental lines and seven polymorphic markers were used for genotype 100 F2 plants. Single marker analysis was used to evaluate an association between the markers and traits. Transgressive segregation among the F2 plants for resistance to flower thrips was observed. A significant negative relationship was observed between thrips damage scores and pods number per plant. Markers CP37/38 and CP215/216 were significantly associated with thrips damage scores and thrips counts, respectively. The two markers explained 7 and 11.2% of the total variation in thrips damage scores and thrips counts with positive and negative effects, respectively. Mainly additive gene effects were observed. A more detailed study using more markers on these loci should provide better understanding of this complex trait.Item New sources of sorghum resistant genotypes to downy mildew disease in Uganda(BIODIVERSITAS, 2019) Kumi, Frank; Badji, Arfang; Mwila, Natasha; Odong, Thomas; Ochwo-Ssemakula, Mildred; Tusiime, Geoffrey; Gibson, Paul; Biruma, Moses; Prom, Louis K.; Cuevas, Hugo E.; Agbahoungba, Symphorien; Rubaihayo, PatrickKumi F, Badji A, Mwila N, Odong T, Ochwo-Ssemakula M, Tusiime G, Gibson P, Biruma M, Prom KL, Cuevas HE, Agbahoungba S, Rubaihayo P. 2019. New sources of sorghum resistant genotypes to downy mildew disease in Uganda. Biodiversitas 20: 3391-3397. Sorghum downy mildew (SDM) disease is still prevalent in Uganda at varying levels of incidence and severity. In this study, a total of 100 sorghum genotypes, five (5) from (U.SA, India, and Sudan) and 95 genotypes from Uganda were evaluated for resistance to downy mildew and other agronomic traits during the second growing season of 2016 (August-December). The experiment was conducted in two locations at Makerere University Agricultural Research Institute at Kabanyolo (MUARIK) and Abi-Zonal Agricultural Research and Development Institute (Abi-ZARDI) research station at Arua. The experimental design used was 10 x 10 alpha lattice design with three replicates. Data were collected on plant disease incidence (PDI), plant disease severity (PDS), area under disease progress curve (AUDPC), days to 50% flowering, plant height, 1000 seed weight, and grain yield. Results for analysis of variance showed highly significant differences (P < 0.001) in genotypes, location, and AUDPC, yield and yield components. Disease incidence varied significantly (P < 0.001) between locations, and Arua recorded highest disease incidence and severity of 80.6 and 2.8, respectively. Results from correlation analysis showed a highly significant (P < 0.001) positive association of downy mildew disease incidence with AUDPC (0.835) which suggests that the severity of SDM disease increased with disease incidence, whiles significant (P < 0.001) negative correlation was recorded for days to 50 % flowering (-0.302), 1000 seed weight (-0.471), and grain yield (-0.585), suggesting that grain yield and yield component decreased significantly with increase in SDM incidence and severity. Two resistant (PI 656061 and PI 533831) and four moderately resistant (E 40, MAKSO 8, PI 655990 and Epuripur) genotypes were identified from this study. These genotypes were recommended for sorghum breeding program against downy mildew disease.Item Participatory farmers’ selection of common bean varieties (Phaseolus vulgaris L.) under different production constraints(Plant Breeding, 2018) Bruno, Awio; Katungi, Enid; Nkalubo, T. Stanley; Mukankusi, Clare; Malinga, G. Maxwell; Gibson, Paul; Rubaihayo, Patrick; Edema, RichardOn-farm evaluation of 15 common bean varieties was undertaken with nine farmer groups under two fertilizer applications levels in four subcounties of Hoima and Rakai districts for two seasons to select farmers’ desired and undesired varieties. Farmers’ votes for acceptance and rejection of varieties at podding stage were converted to a preference index, and analysis of variance was conducted to examine differences in farmers’ preference indices among subcounties and combined across subcounties, seasons, management and gender. Management had no-significant influence on the way farmers selected varieties in the subcounties. Choice of varieties varied significantly (p ≤ .001) between seasons and gender in the different subcounties. Variety Masindi Yellow Long and Farmers’ seed (Kaduli), and the introduced KATB1 were accepted by farmers due to their medium seed size, desired seed colour and potential of varietal adaptability to their farm conditions. Varieties NABE2, ROBA1 and RWR719 were deselected due to possession of traits less desired in the market. These results demonstrate the need for breeding programmes to involve diverse stakeholders in capturing the diverse traits preferences in varietal development process.Item Population diversity of rice bacterial leaf blight isolates in Uganda(Asian Journal of Plant Science and Research, 2013) Habarurema, Innocent; Edema, Richard; Gibson, Paul; Lamo, Jimmy; Asea, Godfrey; Séré, Yacouba; Gasore, Elie R.The deployment of resistant cultivars is the best option to control bacterial leaf blight (BLB) and requires an understanding of the pathogen diversity. BLB caused by Xanthomonas oryzae pv.oryzae is a destructive disease of rice (Oryza sativa L.) in Uganda. Unfortunately, detailed information on Ugandan pathogen populations is not available. A set of 21 differential rice genotypes that have known resistance genes were used in a split plot design to test for differential virulence of six different isolates of X.oryzae pv.oryzae obtained from seed samples collected from Eastern Uganda. Statistical analysis showed diversity among isolates. The susceptibility of the differentials with two to four-gene combinations and the resistance of IR24 to Ugandan isolates were unusual and, therefore suggested a different pattern between Asian and Ugandan isolates at pathological level. Although the isolates were fewer in number, attempts to classify them into pathogenic races gave rise to 6 different races, as each isolate caused a particular virulence pattern on the differentials. The six races formed two significantly different (p ≤ 0.05) groups of one race (UX041) and five races (UX051, UX00, UX050, UX058 and UX044). These races would be used in screening rice germplasm available and/or newly introduced to Uganda.