Browsing by Author "Msolla, Susan Nchimbi"

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Assessment of the effects of water stress on seed yield of common bean genotypes
(African Journal of Agricultural Research, 2020) Claude Rubyogo, Jean; Mbiu, Julius Peter; Msolla, Susan Nchimbi; William, Magdalena N.
Drought stress is among the most important abiotic factors that contribute to the significant yield reduction of common bean (Phaseolus vulgaris L.). Due to unreliable and poor distribution of rainfall, drought tolerance has become the important train in common bean in bean growing areas. The objective of this study was to evaluate 16 common bean genotypes for drought tolerance under three moisture regimes and identify genotypes with specific traits that improved tolerance to drought that could be recommended for released and become useful parents in the breeding programs. The experiment was conducted in Maruku, Bukoba under screen- house. Based on the drought stress indices which includes drought tolerance index (DTI), Harvest Index (HI) SMC 162, DAB 602, SSIN 1128, DAB 378, DAB 362 and SMR 101 had performed better than other tested genotypes. Also, the results showed that genotypes DAB 582, SRC 59, DAB 602, SSIN 1240, SMC 24, SMR 101 and DAB 362 were drought tolerant with lower and high value of the DSI and YSI respectively. Therefore, the later genotypes can be used in the future breeding programs as the parent for drought tolerance and also can used as a new varieties by farmers.
Characterization of the common bean host and Pseudocercospora griseola, the causative agent of angular leaf spot disease in Tanzania
(African Journal of Plant Science, 2016) Chilagane, Luseko Amos; Msolla, Susan Nchimbi; Kusolwa, Paul Mbogo; Porch, Timothy Gabriel; Diaz, Luz Miryam Serrato; Tryphone, George Muhamba
Angular leafspot (ALS), caused by the fungus, Pseudocercospora griseola, is one of the most important disease of common bean in Tanzania. Breeding for resistance to this disease is complicated by the variable nature of the pathogen. In Tanzania, a thorough analysis of the variability of this pathogen is lacking which limits breeding for durable resistance. This work aimed at characterizing P. griseola in relation to its host in Tanzania. A sample collection of both P. griseola and common bean was conducted in the 2013 and 2014 growing seasons from nine regions. Single spore isolation was performed for P. griseola isolates and DNA was extracted from both P. griseola mycelium and bean leaves from which the pathogen was collected. For characterization of the gene pool origin of the host, Phaseolin DNA marker was evaluated and for the pathogen, the Internal Transcribed Spacer region (ITS) and the Actin gene sequences were evaluated. Phylogenetic analysis showed the presence of 69.7% Andean and 30.3% Mesoamerican strains of P. griseola in Tanzania. The common bean host genotypes showed a similar distribution with 84.2% Andean and 15.8% Mesoamerican. In both cases, Andean strains of the pathogen and Andean bean genotypes outnumbered Mesoamerican. In relation to the common bean genotypes, Andean genotypes were more susceptible to ALS as compared to Mesoamerican genotypes. There were few strains that were of Andean origin but were pathogenic on Mesoamerican common bean genotypes, a group that has previously been termed Afro-Andean. Geographically, most of the regions of Tanzania had only Andean strains except for Kagera where 60% were Mesoamerican strains, and in Arusha and Tanga, where 50 and 33% were Mesoamerican, respectively. Only three regions, Kagera, Mbeya and Rukwa, were found to grow Mesoamerican beans. The findings of this study are important in setting basic objectives for breeding for angular leaf spot disease in Tanzania.
Diversity among yellow seeded common beans in Tanzania
(Science Publishing Group, 2023-01-17) Bunmi, Olasanmi; Urassa, Fadhila Ahmed; Msolla, Susan Nchimbi
Common bean is globally the most important leguminous crop for direct human consumption. In Tanzania, it is the most inter-cropped leguminous crop especially with maize. Characterization of common beans is important for genetic improvement and ex-situ germplasm conservation since it allows identification and awareness of key features of the genotypes. The common beans grown in Tanzania are of different seed colours such as red, red mottled, grey, white, yellow, brown etc. Yellow bean is one of the most traded bean types in Tanzania but there is limited information on diversity of the varieties cultivated across the country. Therefore, the objective of this study was to assess the diversity of yellow seeded common beans found in Tanzania. The study was carried out at Sokoine University of Agriculture, Morogoro, Tanzania in 2022. Thirty-two yellow bean genotypes collected from different regions of Tanzania were assessed for diversity using quantitative and qualitative traits. The trials were carried out in the screen house and on the open field. The data collected were subjected to analysis of variance, cluster, principal component, and correlation analyses. Sixteen genotypes were characterized as determinate plant type while the remaining sixteen were classified as indeterminate. About 75% of the genotypes had cuboid shape while 12.5% had kidney and oval shapes. About 78% of the genotypes were dominated by green cotyledon colour while 90% had white hypocotyls colour. The cluster analysis grouped the genotypes into five groups in both field and screen house. The first four principal components accounted for 51.8% of the variation observed on the field and 61.9% in the screen house. There were strong correlations among many important traits which will allow indirect selection for some complex traits. The positive correlation observed between number of locules and number of seed per pod (r = 0.87) indicates that number of locules can be used to determine the density and seed yield. There was high level of diversity among the yellow bean genotypes evaluated in this study for quantitative and qualitative traits. The scientific information obtained from this study will be useful in breeding programmes for improvement of yellow seeded beans in Tanzania for the traits.
Molecular marker-assisted backcrossing of anthracnose resistance genes into common beans (Phaseolus vulgaris L.) varieties
(Scientific Research Publishing Inc., 2021-05-26) Uwera, Annuarite; Musoni, Augustine; Assefa, Teshale; Rusagara, John Nzungize; Msolla, Susan Nchimbi
Anthracnose, caused by Colletotrichum lindemuthianum, is a major disease of common bean and results in high yield loss. Due to the high degree of pathogenic variability of the fungus and the continual emergence of new races, genetic resistance in the host is not durable. Gene pyramiding using Marker Assisted Selection (MAS) is proposed as a viable approach to improve the durability of major genes conditioning resistance to anthracnose. In this study a common bean line Urugezi x AND 1062 susceptible to anthracnose but already improved for Pythium root rot resistance was improved for an thracnose resistance through a backcross breeding program. Genotypic selec tion was done in Rubilizi laboratory in Kigali, Rwanada whereas phenotypic selection was conducted in an anthracnose hotspot at Rwerere, a research Centre of the Rwanda Agricultural and Animal Resources Development Board (RAB). Analysis of variance for effect of bean varieties and anthracnose isolates on disease expression showed significant differences (p < 0.001) among varieties and isolates and for the interaction between isolates and va rieties. Developed BC2F1 plants were 41% of them resistant and 59% suscepti ble to anthracnose. However, the observed proportion of 26 resistants and 37 susceptible in BC2F1 plants didn’t fit the goodness of fit of the expected pro portion of 75 resistants to 25 susceptible. Only 41% of BC2F1 plants inherited the resistance genes and were phenotypically resistant. Presence of SCAR-markers, SAB3 and SBB14, in the developed resistant lines h suggested successful resistance transfer of anthracnose resistance genes.