Study of anthracnose (Colletotrichum lindemuthianum) resistance and its inheritance in Ugandan dry bean germplasm.

Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2006.The common bean (Phaseolus vulgaris L.) is an important crop grown widely in Uganda. It is also an important source of income for smallholder farmers particularly women. Despite its importance, production in the cool highland regions is constrained by anthracnose disease which causes losses in both the quantity and the quality of beans produced. The principal aim of this research was to elucidate on the status of dry bean anthracnose and the genetics governing its resistance. A participatory rural appraisal study was conducted to explore farmers' knowledge, experience, problems and cultivar preferences in association with managing dry bean anthracnose disease. This study revealed that anthracnose is an important constraint to production which is not controlled in any way. Although farmers have varying cultivar preferences, they use mostly home saved seed and only 1% could access improved seed. The study suggested the need for practical approaches in the provision of quality anthracnose resistant seed in consideration of farmers' preferences and the dynamics of their rural livelihoods. A study was conducted to determine the variability of the anthracnose (Colletotrichum lindemuthianum) pathogen in some of the major bean growing regions of Uganda. Use was made of a set of 12 internationally accepted anthracnose differential cultivars to identify the physiological races present. The results obtained indicated the presence of eight races with one race (767) being dominant and most aggressive. Differential cultivars AB 136 and G2333 were resistant to all the eight races, and can be utilised as potential sources of resistant genes. A germplasm collection of mostly Ugandan accessions was screened for anthracnose resistance. Using the area under disease progression curve as the tool for assessing disease severity, eleven accessions were identified that posses good levels of anthracnose resistance. The yield loss attributed to the anthracnose disease was determined on three susceptible Ugandan market-class dry bean cultivars and two resistant cultivars. The results showed that the yield of susceptible cultivars was reduced by about 40% and an almost equivalent yield was lost due to poor quality seed. In comparison, the yield lost by the resistant cultivars was not significant. The study suggested the use of resistant cultivars as the best solution in combating anthracnose resistance. Three susceptible Ugandan market class dry bean cultivars and six resistant cultivars were used for the study of the inheritance of resistance to the anthracnose pathotype 767 in a complete 9x9 diallel design. The results clearly indicated that the resistance was predominately conditioned by additive gene action. It was also established that epistatic gene action was important. More than one pair of genes displaying partial dominance were responsible for determining resistance and the maternal effect did not have an influence on resistance. Additionally, the result showed that some of susceptible cultivars combined very well with the resistant cultivars and that anthracnose resistance heritability estimates in both the narrow and broad sense were high. These results suggested that the use of simple pedigree breeding procedures such as backcross selection could be useful in improving anthracnose resistance levels in the Ugandan market class varieties

Effectiveness of pyramided genes in conferring resistance to anthracnose disease in common bean populations

Anthracnose disease (Colletotrichum lindemuthianum (Sacc. et. Magn) Lams. Scrib.) is one of the most devastating diseases that constrain common bean production in Uganda. A cascading pedigree pyramiding scheme was used to develop common bean populations to evaluate the effectiveness of pyramided and single resistance genes (Co-42, Co-43, Co-5, and Co-9) on disease development. Detached leaf trifoliates of F4:6 genotypes were screened with four C. lindemuthianum races (352, 713,767 and 2047). Disease severity data were subjected to ANOVA. Races, genotypes and Race x Genotype interaction were significant. Genes Co-42 and Co-5 conferred resistance to the four races and the gene pyramids Co-42+Co-5+Co-9 and Co-42+Co-5 had the lowest severity scores. Gene Co-43 conferred resistance to race 352 and weak resistance to race 713; whereas gene Co-9 conferred resistance to race 352. Co-43+Co-9 gene pyramid showed resistance only to race 352. The Co-42 and Co-5 genes conferred resistance to all the four races 352, 713, 767 and 2047. The single gene Co-42 was not significantly different from the pyramids Co-42+Co-5+Co-9 and Co-42+Co-5 (P<0.01). Similarly, the Co-5gene was not significantly different from Co-42+Co-5, Co-42+Co-9 and Co-5+Co-9 pyramids. The Co-9gene showed antagonism in all pyramids. These results indicate that pyramiding of resistance genes would be effective for disease management in Uganda, but pyramids with Co-9 gene would be less effective

Participatory Evaluation of Common Bean for Drought and Disease Resilience Traits in Uganda

The use of genetic resources to respond to occurring and unpredictable climatic changes is one of the coping mechanisms for small scale farmers in Africa. This paper summarizes findings of a participatory action research (PAR) project evaluating different common bean (Phaseolus vulgaris) varieties with nine farmer groups across nine villages in two CCAFS sites of Rakai and Hoima districts in Uganda. Six and fifteen bean varieties including local landraces, farmer variety (commonly grown by farmers), Uganda officially released varieties and new germplasm bearing different characteristics were evaluated with over 300 farmers in replicated trials in the first season of 2012, and two seasons of 2013, respectively. The study provides evidence that breeders and farmers look out for similar traits, with yield being the major driver, and in most cases end up with the same results with a few discrepancies. Some key lessons emerged from the findings. First, making blanket variety and management recommendations to cover large physical areas is erroneous. Site and context specific recommendations, especially in the view of the variability in climatic conditions and soils are probably the best option. Second, the results highlight the need for plasticity in bean varieties (i.e. ability to change structure and function when exposed to changes in the environments hence suitability to a wide range of environments) in addition to having farmer preferred traits. Lastly, the project also highlighted the ability, capacity and willingness of farmers to adopt and adapt new technologies in the face of varying climate scenarios

Presented at the Third International Tropical Agriculture Conference (TROPAG 2019), Brisbane, Australia, 11–13 November 2019

Common bean fresh pod is a niche market product consumed worldwide including in Eastern Africa region. It is more preferred to dry bean due to the fresh taste and ease to cook. A lot of research has been done on production and disposition of dry bean product; however, little information is available on production and marketing of fresh bean pod in Uganda. The general observation indicates wide consumption of fresh bean pods however, there is limited information on its entire value chain, yet, its value cannot be undermined. Based on this background, a reconnaissance study was undertaken in Mpigi district, a major fresh bean growing area and eight retailing markets within Uganda’s capital, Kampala, to understand the economic feasibility of fresh bean pod market. Using qualitative approaches, farmer and market analysis was conducted to explore and understand fresh bean market dynamics. The results show that there are over 10 varieties being sold for fresh pod, unstandardized weight measures are being used, and price variation of over 50%. Additionally, unsatisfied demand for fresh pod beans is 45%. The results indicate existence of a lucrative fresh pod market valued at more than USD 2.0 million within Kampala and suburbs. It was also revealed that production faces significant gaps in seed availability to ensure consistent quality supply to the market while at selling points, bronzing effect was a major challenge leading to product deterioration. Thus, interventions are needed to eliminate the existing production and marketing challenges for a sustainable fresh bean pod business

Inheritance of resistance to common bacterial blight in four selected common bean (\u3ci\u3ePhaseolus vulgaris\u3c/i\u3e L.) genotypes

Common 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\u27s (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

Accroître l’accès des femmes à des marchés ables grâce à la commercialisation collective

English version available in IDRC Digital LibraryCultivate Africa’s Future Fund (CULTIAF

Increasing women’s access to reliable markets through collective marketing

French version available in IDRC Digital LibraryWhile some household challenges emerged from collective marketing, the project enabled women to participate in male-dominated marketing activities and to benefit from the income generated. The project identified 65 mixed farmer groups and linked them to the Community Enterprise Development Organization (CEDO) which supplies bean seed on credit to farmer groups to produce grain on a contractual basis. Group marketing has been identified as one of the most viable ways of increasing women’s participation in agricultural marketing and improving their access to market information, as well as strengthening their bargaining power.Cultivate Africa’s Future Fund (CULTIAF

Phenotypic and genotypic screening for rust resistance in common bean germplasm in Uganda

Peer Revie