Browsing by Author "Twesigye, Charles K."

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Corm damage caused by banana weevils Cosmopolites sordidus (Germar) collected from different banana growing regions in Uganda
(Springer Nature: Agriculture & Food Security., 2018-10-19) Twesigye, Charles K.; Ssekatawa, Kenneth; Kiggundu, Andrew; Tushemereirwe, Wilberforce; Matovu, Enock; Karamura, Eldad
In this study, both healthy tissue culture plantlets and maiden suckers of the Nakitembe cultivar were used to assess the damage level variation caused by banana weevils collected from different banana growing regions. Seventy-nine (79) tissue culture plantlets and fifty (50) suckers were established in buckets in a randomized complete block design for 5 months. Ten adult weevils (5 females and 5 males) were introduced at the base of each plant, and the buckets were covered with a weevil proof mesh. Weevil damage was estimated as a percentage at 60 days after the weevil introduction by estimating the peripheral damage (PD), total cross section corm damage (XT) and above the collar damage (ACD). Results: The results showed high differences in the PD, XI, XO and XT caused by weevils from the different zones. PD and XT ranged from 4.8–50.4 to 4.2–43.8%, respectively, caused by weevils collected from Kabale and Rakai, Kabale and Wakiso, respectively, while XI and XO varied from 0.0–42.9 to 8.3–40.4%, respectively, caused by banana weevils collected from Kabale and Rakai, Kabale and Rakai, respectively. Banana weevils from Rakai caused the highest ACD of 40.4% and no such damage was caused by banana weevils collected from western Uganda. Average ACD in suckers was 19.6% and significantly higher than that in tissue culture plants (8.5%). Conclusions and recommendations: Corm damage assessment suggests the existence of banana weevil biotypes but it is recommended that follow-up studies be carried out to confirm this phenomenon.
Effect of Land Use Activities on Water Quality and Vegetation Cover Change in Nsooba - Lubigi Wetland System, Kampala City
(East African Journal of Biophysical and Computational Sciences, 2024-10-07) Twesigye, Charles K.; Igunga, Kennedy; Nakayinga, Ritah
An assessment of the effect of land use activities on water quality and vegetation cover change in Nsooba - Lubingi Wetland System in Kampala city was conducted between July and October 2020. In order to achieve the set objectives, twelve locations were selected from the Nsooba - Lubingi Catchment. The physico-chemical characteristics of water along the catchment area were determined by standard analytical methods. The average values for Total Dissolved Solids across all the land-use types of wetland, built up areas and agriculture were lower than the National Standard (750 mg/l). A similar pattern of the land-use was observed for the parameters Total phosphorous, Biological oxygen demand, Chemical oxygen demand, Total suspended solids and Total organic carbon, where the observed average values were all below the National Standards of 10 mg/l, 50mg/l, 70mg/l, 50mg/l and 50mg/l, respectively. The Total Nitrogen average value for built-up areas (11.27 mg/l) was higher than the national standard of 10 mg/l while the remaining land use types of wetland (8.05mg/l) and agriculture (5.96mg/l) were below that of the recommended standard. GIS and Remote sensing techniques were used to analyze highresolution satellite imagery captured during 1998, 2008 and 2018. Wetland coverage declined by approximately 5 hectares (47.2% to 14.58%) from 1998 to 2018. Although most of the measured parameters were below the National standard specified by the Uganda National Environmental Management Authority apart from Total Nitrogen for built-up areas, there is need for close monitoring of the water quality in Nsooba - Lubingi catchment to ensure public health safety. The increased built-up environment in the Nsooba - Lubigi wetland affects ecosystems services of the wetland. The buffer zones for flood control and sewage treatment have been turned into built-up environment. The results from this study suggest a need to protect the Nsooba - Lubingi catchment for its important ecosystems services of flood control and sewage treatment.
Soil Moisture Content Suitability for Coffee Growing under Climate Change Scenarios in Uganda
(2024-11-13) Kobusinge, Judith; Twesigye, Charles K.; Kagezi, Godfrey H.; Ssembajwe, Ronald; Arinaitwe, Geofrey
Background: Previous studies have looked at suitability of Arabica coffee with less emphasis on Robusta coffee. Secondly, they looked at coffee suitability in terms of temperature and rainfall. Methods: This study examined the effect of climate change on soil moisture content for coffee growing in Uganda, using historical (1990-2022) and projected (2025-2050) data from Terraclimate and eight Global Climate Models (GCMs). Soil moisture was analyzed in relation to coffee crop moisture thresholds at the root zone to simulate historical and future coffee suitability under two scenarios: Shared Socio-economic Pathways (SSPs) 245 and 585. Results: Soil moisture content in Uganda was characterized by high variability in highland areas during the March to May season among years. Furthermore, there were both decreasing and increasing trends averaging at ±1mm/Month. The future was on the other hand dominated by increasing trends over the western region and eastern-northern regions under SSP245 and SSP585 respectively averaging at 0.2mm/Month. Suitability analysis for 1990-2022 revealed that 71% of Uganda was highly suitable for coffee, while future predictions indicated an increase in suitable areas to 74% under SSP245 and 81% under SSP585. Conclusion: Generally, the higher moisture content associated with climate change will result in increased suitability of coffee by 10%, however, characterized by shifting area suitability especially for the mid-northern and south western regions where a reduction and gain in suitability is expected, respectively. This study highly the importance of identification and adaptation of site-specific soil moisture conservation practices, especially in the unsuitable areas.
Variation among banana weevil cosmopolites sordidus (Germar) populations in Uganda as revealed by AFLP markers and corm damage differences
(Agriculture & Food Security., 2018-10-23) Twesigye, Charles K.; Ssekatawa, Kenneth; Kiggundu, Andrew; Tushemereirwe, Wilberforce; Matovu, Enock
The banana weevil Cosmopolites sordidus (Germar) is a major production constraint of bananas and plantains (Musa spp.) in the world. Differences in damage levels and pesticide response across regions led to the postulation that there might be considerable variation between banana weevil populations (biotypes) with varying levels of virulence. One of the most sustainable options for banana weevil control is the use of host plant resistance. While new resistant varieties are being developed through both conventional crossbreeding and biotechnology, there is a need to assess the genetic variation of banana weevil populations from eastern, central, southern, southwestern and midwest regions of Uganda to determine whether there are biotypes with different virulence levels. This would help guide new control strategies to target all the possible biotypes. The amplified fragment length polymorphism (AFLP) technique was used to analyze population genetic diversity using four primer combinations (EcoRI/MSeI). Results: Analysis of molecular variance results presented no evidence to support significant genetic variability among the banana weevil populations from eastern, central, southern, southwestern and midwest regions. Practically, all the genetic variation was found to reside within populations (97% for sites and 98% for regions), with only approximately 3% and 2% residing among populations of sites and regions, respectively. Conclusions and recommendations: AFLP markers clustered the banana weevils into two distinct populations consequently supporting the hypothesis of possible presence of banana weevil biotypes in Uganda. However, attempts should be made to make follow-up studies on the seemingly unique population of eastern Uganda using more robust molecular techniques to establish whether the eastern Uganda population constitutes a different biotype.