Browsing by Author "Stanley Tamusange Nkalubo"

Now showing 1 - 4 of 4

Genetic clustering, and diversity of African panel of released common bean genotypes and breeding lines
(Springer Nature, 2023-03-08) Winnyfred Amongi; Stanley Tamusange Nkalubo; Mildred Ochwo‐Ssemakula; Arfang Badji; Isaac Onziga Dramadri; Thomas Lapaka Odongo; Ephraim Nuwamanya; Phineas Tukamuhabwe; Paulo Izquierdo; Karen Cichy; James Kelly; Clare Mukankusi
Common bean is a grain legume of global importance especially for proteins and micronutrients. The crop is a staple food in sub-Saharan Africa, where it has gained importance in iron bioforti cation for people prone to anemia. However, biotic and abiotic constraints, long cooking time, and high phytic acid and polyphenols both of which affect bioavailable iron, hinder the production and health benefits. To inform breeding decisions, the study determined genetic diversity and population structure within 725 breeding lines, varieties, or landraces mostly from Uganda and South America. Genotyping by sequencing and diversity array technology (DarTseq) were used to generate single nucleotide polymorphic markers on Set1 (427) and Set2 (298) germplasm, respectively. The germplasm were grouped into Andean and Mesoamerican gene pools, with the latter as the larger subpopulation. Analysis of molecular variance revealed 46% (Set1) and 50% (Set2) of genetic variation among the subpopulations, with fixation indices (FST) of 0.54 (Set1) and 0.71 (Set2) among Andean and Mesoamerican beans, respectively. The overall germplasm’s gene diversities were 0.206 (Set1) and 0.332 (Set2). Admixtures were the most diverse (0.193) in both sets of germplasm. The germplasm exhibited high genetic diversity and as a result they have a high potential for use in plant breeding. Inter- gene pool crosses within and across market classes are possible and considering both approaches is expected to increase diversity to realize genetic gain. The structure and polymorphic information generated provided useful perspectives for genomic breed- ing and genome-wide association study using the population.
Genetics of Drought tolerance in common bean genotypes adapted to Ugandan conditions
(J. Plant Breed. Crop Sci., 2015-01-21) Winnyfred Amongi; Stanley Tamusange Nkalubo; Paul Gibson; Richard Edema; Mildred Ochwo-Ssemakula
Common bean (Phaseolus vulgaris L.) is an important source of food and income for majority of households in Sub-Saharan Africa. However, bean production in Uganda is being affected by drought which has resulted from recent changes in climate. Developing high-yielding and drought-tolerant bean cultivars would significantly contribute to increased and stable yields in drought-prone environments. However, prior research was not focused on breeding for drought tolerance in bean in Uganda. Thus, this study sought to elucidate the genetics governing the inheritance of drought tolerance in Ugandan bean genotypes, through establishing the mechanism of inheritance of this trait in the genotypes relevant to Uganda. Five drought-tolerant and three drought-sensitive genotypes were hybridized using a NCII mating design. The findings of the study indicated that drought tolerance is controlled by both additive and non-additive gene action with more predominance of additive gene effects for seed yield, pod weight, seed and pod and number. Further findings also revealed that the genotypes SEN 99 and NABE 15 are good combiners for drought tolerance.
Host and Seasonal Effects on the Abundance of Bean Leaf Beetles (Ootheca spp.) (Coleoptera: Chrysomelidae) in Northern Uganda
(Insects, 2022-09-18) Moses Lutaakome; Samuel Kyamanywa; Pamela Paparu; Samuel Olaboro; Charles Halerimana; Stanley Tamusange Nkalubo; Michael Hilary Otim
Bean leaf beetles (BLBs) (Ootheca spp.) are serious legume pests in Uganda and sub-Saharan Africa, but their ecology is not well understood. We planted host plants, viz., common bean, cowpea, and soybean, in an experiment in the hotspot areas of Arua and Lira districts in Northern Uganda in order to assess their influence on the density of adults and immature stages of BLBs in different seasons. Overall, the number of adults, larvae, and pupae were higher in cowpea than common bean and soybean plots. The number of adults were highest in cowpea (29.5 adults/15 plants) in Arua during the long rainy season (2018A). The number of adults did not differ significantly during short rains (season B) in 2017 and 2018. Similarly, in Lira district, the highest number of adult BLBs was in cowpea (4.6 beetles) compared to the common bean (2.7 beetles) and soybean plots, with a peak at four weeks after planting (WAP). During 2018A, larvae of BLBs first appeared at five WAP and seven WAP and peaked at 13 WAP and 11 WAP in Arua and Lira, respectively. The pupae were present in the soil after the harvesting of crops during 2018A, but peaked at seven WAP and eight WAP in 2018B season in Arua and Lira, respectively. The occurrence of below-ground adults in 2018B followed the peak abundance of pupae, although this was delayed until six WAP in Arua compared to Lira. We conclude that cowpea is the most preferred by adults and larvae compared to common bean and soybean. Similarly, the first rain season (2018A) attracted higher abundance and damage than the second rain season. Management of the BLBs should thus take into consideration avoidance of host crop rotation and dealing with the below-ground stages.
Prevalence and variability of the common bean rust in Uganda
(Afr. J. Agric. Res., 2017-01-06) Blessing Adanta Odogwu; Stanley Tamusange Nkalubo; Clare Mukankusi; Pamela Paparu; Rubaihayo Patrick; James Kelly; Steadman James
Uganda is the second largest producer of dry beans (Phaseolus vulgaris L.) in Africa, but common bean rust caused by Uromyces appendiculatus (Pers. Unger), is negatively impacting the production of the crop. There is little information on the occurrence and identity of the rust pathotypes present in the country. Consequently, a field survey was carried out during the 2015 second planting season in fifteen districts, representing the areas of high beans production in Uganda. High common bean rust incidence and severity were observed in the low altitudes and the South-Western Highlands of Uganda. Wakiso and Hoima districts had the highest rust disease incidence 72 and 76% respectively and severity rates of 6 and 5.5, respectively. Rust disease incidence was uniformly high on commercial genotypes and landraces. Similarly, high rust disease incidence and severity were observed in the bean-maize– groundnut cropping system. Twenty-three single rust isolates were collected in Uganda and inoculated on 11 bean rust differentials and Ouro Negro (Ur-14) genotypes. Six rust pathotypes were identified and these included 2-0, 4-0, 50-0, 5-1, 4-33 and 63-19. Five of the pathotypes were of Andean origin and only pathotype 4-33 was of Mesoamerican origin. The rust pathotype 63-19 showed similar pathogenic characteristics with the Puerto Rico rust race 19-63. This study provides critical baseline information to integrate breeding and crop protection in the efforts to develop an overall strategy for the management of common beans in Uganda.