Theses
https://hdl.handle.net/20.500.12478/6559
2024-03-28T14:32:05ZPhysicochemical parameters and functional properties of flours from advanced genotypes and improved cassava varieties for industrial applications
https://hdl.handle.net/20.500.12478/7948
Physicochemical parameters and functional properties of flours from advanced genotypes and improved cassava varieties for industrial applications
Chimphepo, L.
Cassava has potential for many industrial uses, which provide an opportunity for more rewarding markets. Therefore, significant research on improved varieties, targeting industrial applications, is required as a possible approach to spur improvements in the value chain. In addition, the promotion of cassava for production, targeting industrial applications, requires information on yield and stability performance of cassava genotypes and varieties in a diverse range of environments. To this end, this study evaluated the physicochemical parameters and functional properties of ten (10) improved cassava genotypes for fast-tracking adaptable and preferred cassava genotypes for industrial use as well as the effect of interaction of genotypes and varieties with environment on such physicochemical parameters and functional properties. The genotypes were collected from a multi-location (Uniform yield Trial) trial of the IITA breeding program in Malawi. Their flour samples were analysed for various physicochemical parameters and functional properties compared with currently marketed High Quality Cassava Flour (HQCF). Results show that genotype effect on overall quality characteristics endearing to industrial applications was significant, allowing identification of industry preferred genotypes. Starch and amylopectin content are the major determinants of variability in the cassava flours' functional properties, such as water and oil absorption capacities, solubility, and swelling power. Overall, genotypes I020452 and I010040, and the released variety Sagonja have a high starch and amylopectin content, high bulk density, and all the analysed functional properties. These genotypes showed comparable/or superior functional properties to market HQCF. On the other hand, the results showed that environments (E) and genotypes (G) and their interaction (G x E) effects were highly significant(P < 0.001) in explaining the variance of the physcochemical parameters and functional properties. Environment played a major role in influencing dry matter (on fresh root weight basis), bulk density and solubility. However, genotype and environment interaction played a major role in influencing starch content, amylopectin content, swelling power, and WBC. Based on interaction principal component analysis of G x E, I010040, MM06/0045 and TMSL110080 genotypes and Mbundumali, Mpale and Sagonja varieties were the most selected for both improved stability and better response according to AMMI. I010040 showed higher levels of starch related properties (starch and amylopectin content, bulk density, OAC, solubility and swelling power) whereas Mbundumali is high yielded higher dry matter content (on fresh root weight basis) and also WBC and TMSL110080 was the highest yielding in dry matter content (on fresh root weight basis). Therefore, these cassava genotypes and varieties can be targeted for cultivation in wide range of environments in the semi-arid climates and similar agro-ecologies for production of high quality cassava flour (HQCF) and starch for various industrial applications.
2021-08-01T00:00:00ZEffective communication for disseminating soil and water management practices to bring about sustainable smallholder agriculture in Tanzania: case study of Manyara and Dodoma regions
https://hdl.handle.net/20.500.12478/7941
Effective communication for disseminating soil and water management practices to bring about sustainable smallholder agriculture in Tanzania: case study of Manyara and Dodoma regions
Ndibalema, G.
This study investigated effective communication for disseminating soil and water management (SWM) practices for sustainable smallholder agriculture. Higher uncertainties in precipitation and land degradation are potentially the most limiting reasons for poor performance of rainfed agricultural sectors in Tanzania. Despite the increased focus on sustainable intensification of African agriculture and an increase of agricultural innovations with potential to alleviate these, adoption by smallholder farmers is slow. This includes soil and water management practices designed to minimize land degradation and increase productivity which few farmers implement. Studies note that although researchers generate good technologies, the lack of appropriate communication strategies, tools and methodologies lead to poor extension information and technologies resulting in low adoption of the innovations. Therefore, to find a solution to this problem, this study was guided by four research questions: 1) How is the communication flow between stakeholders through channels for disseminating SWM practices? 2) What are the common and preferred communication channels in disseminating SWM practices? 3) What are the motivations for using the communication channels in disseminating SWM practices? 4) How can the communication on disseminating of SWM practices be improved to support sustainable agriculture? The study was conducted in Kongwa District in Dodoma Region and Babati District, Manyara Region of Tanzania. A net-map tool, questionnaires and semi structured interviews were used to collect both qualitative and quantitative data for this study. Mass media and interpersonal communication are used in disseminating SWM practices information to farmers in Babati and Kongwa districts. But farmers preferred interpersonal channels as sources of SWM information including from extension officers, researchers, fellow farmers, village meetings and mobile phones. The preference was because these channels are not only informative compared to mass media but they are interactive and inclusive, which gives farmers the opportunity for giving feedback on the information disseminate. This influences farmers to not only to get information but also trigger their learning and adoption of the innovation. Agricultural exhibition events should be organised at village or ward levels to provide practical backstops against which the experts can deliver information and knowledge to farmers, and give opportunity to farmers to access knowledge. It will be helpful to increase the number of extension officers who will facilitate effective communication and dissemination of the information as they seem to be an important link for interpersonal between farmers and other agricultural stakeholders.
2019-05-01T00:00:00ZPhysiological responses of cowpea (Vigna unguiculata L. Walp) varieties to Rhizobia inoculation, phosphorus application and sequential cropping system in Minna, Nigeria
https://hdl.handle.net/20.500.12478/7911
Physiological responses of cowpea (Vigna unguiculata L. Walp) varieties to Rhizobia inoculation, phosphorus application and sequential cropping system in Minna, Nigeria
Adediran, O.A.
Cowpea is the most important grain legume in Nigeria but the yield obtained on farmers’ fields is far below the potential yield of the crop. This study aimed at exploiting rhizobia inoculation, phosphorus application, varietal differences and sequential cropping system to improve the productivity and profitability of cowpea per unit area in Minna, Nigeria. A glasshouse and two field experiments were conducted between 2015 and 2017. The glasshouse experiment was a factorial combination of four nitrogen sources (uninoculated, inoculated with USDA 3451 and USDA 3384 rhizobia strains and 90 kg N ha-1), soils collected from 20 locations in the Nigerian savannas and two varieties of cowpea (IT93K-452-1 and IT99K-573-1-1) replicated three times and laid in a completely randomized design. The first of the field experiments conducted on three farmers’ fields in Minna was a factorial combination of three nitrogen sources (uninoculated, inoculated with USDA 3451 and USDA 3384 rhizobia strains), three phosphorus rates (control, 20 kg P ha-1 and 40 kg P ha-1) and three varieties (IT93K-452-1, IT99K-573-1-1 and TVX-3236) in the first year. In the second and third year of planting, the strains were replaced with BR 3262 and BR 3267 and 90 kg N ha-1 was added as part of the treatments. The treatments were laid in randomized complete block design. The second field experiment evaluated the performance of six cowpea varieties (IT93K-452-1, IT99K-573-1-1, TVX-3236, Kanannado, Oloyin and IT90K-76) in cowpea sequential cropping system. Data were collected on growth, yield, nodulation and physiological parameters. The results revealed that the cowpea varieties successfully formed symbiosis with the introduced rhizobia strains in all the locations. Rhizobia inoculation increased nodulation in 11 out of the 20 locations with percentage increase ranging from 4 to 43%. Plants fertilized with 90 kg N ha-1 had significantly higher biomass yield than the inoculated and uninoculated plants which had similar biomass yield. Phosphorus significantly (P≤0.05) increased the photosynthetic activities, nodulation, N-fixation, growth and yield of the cowpea varieties in the three years with application of 20 kg P ha-1 increasing grain yield by 49-95% over the control. Significant interactions exists between rhizobia inoculation, phosphorus and varieties on some growth and yield attributes. IT99K-573-1-1 maintained the highest productivity among the varieties however, TVX-3236 appeared to be more P efficient having significantly higher growth rate, nodule weight and grain yield at lower P rates. Number of pods per plant had the highest correlation coefficient with grain yield in the three years (r=0.79). Crop growth rate (CGR), leaf area index (LAI) and quantum yield of photosystem II (Phi 2) explained 67.29% of the variation in grain yield (R2= 67.29%) and these three physiological parameters could significantly predict the grain yield. All the varieties were successfully planted in two sequence in each growing season except Kanannado and there was significant variation in the growth and yield attributes of the cowpea varieties in sequential cropping system. IT93K-452-1, IT99K-573-1-1, TVX-3236 and IT90K-76 all had significantly higher (P≤0.05) grain yield and profitability with gross margin ranging between ₦407,910 and ₦1,131, 967 than Oloyin and Kanannado varieties which had gross margin range of -₦123,065 and ₦88,931. Similarly, double cropping of these four varieties increased the gross margin by an average of 115% in 2016 and 140% in 2017 over the traditional system of planting once. It can be concluded from these results that N limits the productivity of cowpea in some soils of Nigerian savannas and rhizobia inoculation with highly effective strains than what was used in this study can overcome this limitation. CGR, LAI and Phi 2 could be exploited to increase the grain yield of cowpea through agronomic practices and plant breeding programs. Application of 20 kg P ha-1 is sufficient for the optimum performance of cowpea in the study area and double cropping of improved, early and medium maturing varieties of cowpea per season is capable of increasing the productivity and profitability of cowpea in the study area.
2019-10-01T00:00:00ZUtilisation des champignons entomopathogenes et des pieges a pheromones dans la lutte contre Sahlbergella singularis Haglund, 1895 (Hemiptera : Miridae), bio-agresseur du cacaoyer au Cameroun
https://hdl.handle.net/20.500.12478/7909
Utilisation des champignons entomopathogenes et des pieges a pheromones dans la lutte contre Sahlbergella singularis Haglund, 1895 (Hemiptera : Miridae), bio-agresseur du cacaoyer au Cameroun
Mahot, H.C.
Le cacao fait partie des produits qui font vivre plus de 3 millions de personnes au Cameroun. Malgré l’objectif gouvernemental qui vise 600.000 tonnes de fèves de cacao par an à l’horizon 2020, la production cacaoyère reste faible en raison de la pression des maladies et des ravageurs. Dans l’entomofaune nuisible associée au cacaoyer, les hémiptères et précisément les Miridae constituent le groupe d’insectes le plus préjudiciable. De nos jours, la recherche des alternatives à la lutte chimique contre les mirides est un challenge. Les champignons Beauveria bassiana et Metarhizium anisopliae et les pièges à phéromones suscitent de plus en plus d’espoirs et constituent des issues importantes en lutte biologique et en lutte semiochimique. Ce travail a évalué le pouvoir insecticide des isolats de B. bassiana et de M. anisopliae vis-à-vis de Sahlbergella singularis dans le but de mettre au point et sélectionner des formulations de biopesticides. Il a essentiellement évalué l’attractivité des pièges de differentes couleurs, appâtés aux phéromones, vis-à-vis de S. singularis et déterminé l’impact de ces pièges à phéromones sur sa densité et ses dégâts en milieu réel. Les isolats de Beauveria bassiana et Metarhizium anisopliae testés avec la méthode par immersion et celle par ingestion ont montré un potentiel insecticide intéressant au laboratoire contre les larves de S. singularis. Ils ont causé des mortalités pouvant atteindre des taux de 100%. Les épreuves biologiques ont permis de retenir quatre des six isolats fongiques sur la base des concentrations létales 50 (CL50) ; des temps létaux 50 (TL50) et 90 (TL90) et deux isolats BIITAC6.2.2 et MIITAC11.3.4, après le test de transmission horizontale. Les paramètres croissance végétative, sporulation, germination et biomasse fongiques ont démontré que le glycérol, l’huile de soja, l’huile de palme raffinée et l’huile de coton ont une bonne compatibilité avec les souches de champignons selectionnées. Ces mêmes paramètres ont servi à sélectionner la formulation de type Emulsion Inverse (EI), qui a mieux conservé la viabilité des spores de B. bassiana et de M. anisopliae pendant 18 semaines d’une part et, d’autre part, la température de 25oC qui est la plus favorable à la conservation des formulations. Les toxicités des conidies de B. bassiana et de M. anisopliae formulées en laboratoire avec l’huile de soja et avec l’huile de palme raffinée ont été avérées avec des taux moyens de mortalité des mirides compris entre 76% et 84%. L’espèce B. bassiana a montré un effect insecticide relativement plus élevé que M. anisopliae; la pathogénicité de ses conidies formulées a indiqué, en cacaoyère, une efficacité certaine. Ainsi, l’insecticide de B. bassiana formulé à base d’huile de soja a significativement réduit les populations de mirides comparé au témoin. Cette réduction a atteint un taux de 100% au bout du trente-sixième jour d’essai. La viabilité des conidies de B. bassiana sur les feuilles de cacaoyer se maintient et ne se perd considérablement qu’après un mois post-application, soit une perte de 72% au bout de deux mois. La persistance de l’activité insecticide de B. bassiana sur les cabosses de cacaoyer, au bout de deux mois post-application, a été induite malgré les conditions abiotiques. Le type de formulation influence l’efficacité du champignon comme agent de bio-contrôle, sa facilité d'application et sa durée de conservation. Ces atouts, à prendre en compte dans la mise au point d’une formulation fongique, sont importants dans une stratégie phytosanitaire de contrôle de populations des insectes ravageurs. Parallèlement à l’investigation d’une stratégie de lutte biologique par ces champignons, l’optimisation de l’utilisation des pièges par l’intégration du paramètre « couleurs » a été menée à Ayos et à Konye. D'après les réactions comportementales des mirides, toutes les couleurs de pièges utilisées ont été attractives avec une préférence pour le piège vert. La préférence pour les pièges verts s’est expliquée par le mimétisme de la couleur du matériel végétal. En tout, 4191 mirides ont été échantillonnés dans les deux localités d’étude soit 3826 dans les parcelles avec pièges et 368 dans les parcelles sans pièges (témoin). Les profils des courbes de pluviométrie, de température et d’humidité relative n’ont pas toujours coïncidé avec celui de la dynamique de population de S. singularis qui n’a pas trouvé une explication directe par ces facteurs abiotiques. Ces derniers semblent influencer plutôt l’état physiologique du cacaoyer qui, à son tour, détermine la dynamique spatio-temporelle de S. singularis dans les plantations cacaoyères. La prévalence des dégâts sur la plante hôte (cabosses) dus à S. singularis a été moins élevée dans les parcelles avec pièges (essai) comparées aux parcelles témoins. Dans la localité d’Ayos, le taux moyen de cabosses affectées a été de 1,7 % dans les parcelles essais contre 3,6% dans les témoins tandis qu’à Konye, il a été de 1,3 % contre 5,5% respectivement. La sévérité des dégâts de S. singularis chez la plante hôte (cabosses) dans les parcelles témoins a été plus importante que celle dans les parcelles essais, soit 1,06% et 0,53% à Ayos contre 1,63% et 0,42% à Konye respectivement. Les niveaux élevés de prévalence des dégâts et de sévérité dans les parcelles témoins comparées aux parcelles traitées suggèrent que l’utilisation du piégeage réduit les dommages causés par les mirides sur les cabosses bien que le niveau de captures de S. singularis mâles dans les pièges appâtés, n'a pas montré une réduction considérable des dégâts sur les cabosses de cacaoyer. Cocoa is one of the products that provide important incomes for more than 3 million people in Cameroon. Despite the government's target yield of 600,000 tons by 2020, cocoa production remains low due to diseases and pests. In the insect wildlife pest associated with cocoa trees, Hemiptera specially Miridae are the most damaging group of insects. Research for alternatives to chemical control of mirids has today become a challenge. The use of the entomopathogenic fungi Beauveria bassiana and Metarhizium anisopliae and pheromone traps are increasingly of interest and are important output in biological and semiochemical control. This work has assessed the insecticidal potential of fungal isolates of B. bassiana and M. anisopliae against Sahlbergella singularis to develop and select biopesticide formulations. It has specially evaluated the attractiveness of the baited colored traps by S. singularis and determined the impact of these pheromone traps on their density and their damages in natural environments. Beauveria bassiana and Metarhizium anisopliae isolates tested through immersion and ingestion methods showed interesting insecticidal potential in the laboratory against S. singularis larvae. They have caused mirid death that could reach the average rates of 100%. Bioassays tests and the evaluation of lethal concentrations 50 (LC50) and lethal times 50 (TL50) and 90 (TL90) allowed the screening of four fungal isolates between the six tested. However, only two strains, namely BIITAC6.2.2 and MIITAC11.3.4 were transmitted horizontally. Fungal vegetative growth, sporulation, germination and biomass have shown that glycerol, soybean oil, refined palm oil and cottonseed oil have good compatibility with fungi. These same parameters also helped to select the Reverse Emulsion (EI) formulation, which better preserved the viability of B. bassiana and M. anisopliae spores for 18 weeks in one hand and in the other hand to choose the temperature of 25ºC, which is the most favourable for the conservation of the formulations. Toxicity of B. bassiana and M. anisopliae conidia formulated in the laboratory with soybean oil and refined palm oil have been proven with the mirid mortality average rates ranged from 76% to 84%. B. bassiana was relatively more toxic to mirids than M. anisopliae; the pathogenicity of its formulated conidia has indicated an incontestable efficacy in cocoa field. The mycoinsecticide of B. bassiana, formulated with soybean oil, significantly reduced mirid populations compared to the control. This reduction reached an average rate of 100% after thirty-six days of product application. The viability of B. bassiana conidia on cocoa leaves is maintained and it is significantly lost only a month after application; either a losses of 72% after two months. The persistence of insecticidal activity of B. bassiana on cocoa pods two months after application was induced despite abiotic conditions. The type of formulation affects the efficacy of the fungus as a bio-control agent, its safe application and its shelf life. These assets are to be considered in the development of fungal formulation as it is essential in a phytosanitary strategy of insect pests population control. Beside the investigation of a biological control strategy by B. bassiana and M. anisopliae, the optimization of trap using by color integration was also carried out in the localities of Ayos and Konye. According to the behavioral reactions of the mirids, all trap colours were attractive with preference for the green trap. The preference for green traps was explained by the imitation of the colour of the plant material. A total of 4191 mirids were sampled in the two study sites, 3826 in the plots with traps (treated) and 368 in the plots without traps (control). The profiles of the rainfall, temperature and relative humidity curves did not always coincided with those of the S. singularis population’s dynamics which have not found a direct explanation in these abiotic factors variation. These abiotic factors seem to influence the physiological state of the cocoa tree, which could determine the spatio-temporal dynamics of S. singularis in cocoa plantations. The prevalence of host plant damage (pods) caused by S. singularis was lower in trap plots (treated) compared to control plots. In Ayos, the average rate of affected pods was 1.7% in treated plots compared to 3.6% in controls, while in Konye, it was 1.3% compared to 5.5% respectively. The severity of damage of S. singularis in the pods in control plots was greater than the one in treated plots, i.e. 1.06% and 0.53% in Ayos against 1.63% and 0.42% in Konye respectively. The high levels of damage prevalence and severity in the control plots compared to treated plots suggest that the use of trapping method reduce the damage caused by mirids on pods despite the fact that the level of catches of S. singularis male by pheromone traps did not shown a considerable reduction in damage of cocoa pods.
2019-01-01T00:00:00Z