Natural Sciences
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- ItemEffects of chemical and organic fertilizer treatments on bacterial populations and diversity from selected maize fields in Lusaka province.(The University of Zambia, 2024) Lubasi, NamasikuMicrobes are the primary agents responsible for the biogeochemical cycling of nutrients, promoting plant development, and suppressing disease. However, not much is known about how chemical fertilizers affect the populations, distribution and survival of soil microorganisms which are essential for enhancing soil structure in soils. To gain a better understanding of the effects of chemical fertilizers on bacterial community diversity, soil samples were collected from 20 representative locations in Lusaka Province of Zambia to investigate how soil bacterial diversity is shaped following the application of chemical (compound D) and organic (manure) fertilizers. The sampling was done between May to June after farming season. Soil physicochemical properties were analyzed. Genomic DNA was extracted from purified sub-cultured bacteria using Qiagen DNA extraction kit and PCR amplified using 16S rRNA primers and amplicons were sequenced. Analysis of variance (ANOVA) was carried out using Minitab (version 17.1.0.0) and a phylogenic tree was generated in MEGA 11. Little variation was recorded in soil temperature which ranged between 29 – 32˚C and the only exception was in soil temperatures of samples collected from the eastern farms (East 1 – East 5) for both organically and chemically fertilized maize fields. The pH of chemically fertilized soils ranged from 4.9 – 6.78 while organically fertilized soils had higher pH ranging from 6.77 – 7.05. The ANOVA test showed that variance in the soil moisture content and organic matter significantly affected and shaped the bacterial communities of the soils. The isolated soil bacteria were predominantly Gram-positive. The colonies mainly composed of bacteria with bacillus and cocci cell shape. Oligotrophic bacteria dominated in chemically fertilized soils. Different fertilization treatments had different impacts on the soil bacterial communities. Chemically fertilized soils had metabolic and stress-resistant bacteria including Exiguobacterium auratiacum, Gottfriedia acidiceleris, Mycrobacterium paludicola, Lysinibacillus fusiformis and Peribacillus frigoritolerans capable of metabolizing polysaccharides and proteins. Soils to which organic fertilizers were applied had copiotrophic bacteria including Actinobacteria and Arthrobacter capable of degrading unusual polymeric compounds. Therefore, it is important to understand the dynamics of chemical and organic fertilizers on soil bacteria to help devise agricultural practices that maintain soil health and fertility as well as maintain good crop yields. Keywords: Bacterial diversity, chemical fertilizer, organic fertilizer, oligotrophic, copiotrophic.
- ItemDiversity of fungal and fungi-like pathogens of tomato (solanum lycopersicum) from selected parts of Lusaka province.(The University of Zambia, 2023) Mweemba, GodfreyFungal and fungi-like pathogens including Cladosporium fulvum, Alternaria alternate, and Alternaria solani class dothideomycetes are major pathogens of solanaceous crops such as tomato (Solanum lycopersicum) where they cause significant losses. To contribute to the understanding of the extent to which fungal pathogens affect tomato productivity in a major tomato-growing part of Zambia, the study tested the hypothesis that various fungal and fungi-like pathogens are circulating in tomato-growing areas of Lusaka and show morphological, molecular and virulence diversity. Tomato tissue showing diverse disease symptoms including leaf spotting, stem rotting and fruit damage were collected from farmers’ fields in various parts of Lusaka Province. Surface-sterilised tissue was cultured on potato dextrose agar to analyse the morphological diversity of isolates. Purified isolates were used in infection studies to fulfill Koch’s postulates and to analyse the variations in virulence of the isolates. Genomic DNA was extracted from the purified fungal isolates and PCR-amplified using primers targeting the internal transcribed spacer region (ITS). The Sanger dideoxy chain termination sequencing method was used to sequence the PCRamplified genomic DNA. Taxonomic identification of isolates from this study indicate that Alternaria alternata, Epicoccum nigrum and Cladosporium fulvum are some of the tomato pathogens circulating in the study area showing diversity in virulence and morphological characteristics. Selected isolates were found to have varying levels of virulence on Tengeru tomato variety. From 20 plants whose leaves were inoculated with pathogens from each study site, the means lesion diameters were found to be 5.9mm for samples from University of Zambia agriculture research field, 8.29mm for isolates from 13Miles and 6.095mm for those from Kafue. Molecular phylogeny analysis of the sequenced ITS amplicons by the maximum likelihood criterion revealed relatedness between isolates from similar regions of the study area as well as those from various regions of the study area. Results from this study will be useful for tomato breeders and farmers as they conduct breeding projects and use fungicides to control the pathogens circulating in the study area.
- ItemTrends in extreme temperature and precipitation events over Zambia for the period 1981-2021.(The University of Zambia, 2025) Zulu, MemoryHuman activities such as burning fossil fuels, cutting down forests and livestock farming have caused an increase in the earth’s surface temperature by 1.0 °C since the preindustrial levels. Warmer temperatures over time are altering global weather patterns. These alterations have been resulting in more frequent and intense extreme weather events that were previously unheard of in many regions, including Zambia. Extreme weather events such as hot spells, dry spells, flash floods, etc. pose many risks to water availability and food security. Agriculture in Zambia heavily relies on rainfall. The shifting patterns of temperature and precipitation in Zambia have led to reduced crop yields, failed harvests, and challenges in animal farming. Consequently, food security is now at risk. The frequent occurrences of extremely hot days, floods, and droughts have severe implications on the livelihoods of many individuals and pose serious harm to the infrastructure such as roads, dams, and schools in the country. The districts are affected differently by the extreme weather events. Therefore, it is crucial to understand the annual trends in extreme temperature and precipitation events based on daily historical and current meteorological observations at a finer resolution for assessing climate change vulnerability at the local (district) scale and consequently designing local adaptation strategies. This study conducted a comprehensive evaluation of annual/seasonal trends in some selected extreme weather events by utilizing the ERA5 data set of resolution 0.5 x 0.5 degrees for the period 1981-2021. The research investigated the annual trend in the frequency of days with maximum temperature exceeding 35°C ( very hot day) as well as the maximum daily temperature across regions in Zambia. The study partitioned the regional domain of Zambia into three climate zones based on mean total seasonal rainfall. Findings reveal significant increases in both the frequency of days with maximum temperature exceeding 35°C and annual maximum daily temperature most especially in climatic zone 1 indicating urgent implications for agriculture and ecosystems. In terms of precipitation, the study examined seasonal total rainfall and the seasonal frequency of days when daily rainfall exceeds 20mm and 30mm thresholds. Results indicated a general decrease in seasonal total rainfall during the October, November and December (OND) season, and increasing trends regardless of some fluctuating patterns observed in the January, February and March (JFM) season. The analysis identified districts that are hotspots of the considered extreme weather events emphasizing the need for region-specific adaption strategies to address the negative impacts of weather events. These findings contribute to a broader understanding of Zambia’s climate dynamics and underscore the necessity for informed decision-making to enhance resilience against changing climatic conditions. Keywords: Trends, Temperature, Precipitation, Extreme Events, ETCCDI Climate Indices.
- ItemNatural regeneration of Miombo trees after shifting cultivation: a case study of Chibombo and Rufunsa districts, Zambia.(The University of Zambia, 2024) Ngoma, ChandaThe objective of the study was to assess the regeneration of Miombo woodlands after shifting cultivation in Chibombo and Rufunsa districts in comparison to undisturbed woodland. The study analysed different descriptors that characterize the woodland including: species composition, diversity, richness, stem density and mode of regeneration. To achieve these objectives, three sites were selected. In each site, 40 circular plots of radius 10 meters were sampled. All trees within the plot were identified and counted. Trees that were ≥0.6cm in height were measured for height and diameter. The main stems were counted and the mode of regeneration for each shoot was recorded. The GENSTAT and Python were used to analyse the data. The Shannon Diversity Index was used to assess species diversity. The Non-Metric Multidimensional scaling (NMDS) results show that there is some separation between the sites, particularly between Chibombo and the other two sites, suggesting that Chibombo might have a distinct species composition compared to Mfunganisha and Nyampande. However, the Analysis of Similarlity (ANOSIM) like analysis suggests that the observed differences in species composition are not statistically significant (p-value is 0.10). Analysis of species diversity revealed that Chibombo had the highest species diversity with H‟=2.83 and D=0.11. The undisturbed woodland recorded H‟=2.68 and D=0.13 while Rufunsa had the lowest diversity with H‟=2.60 and D=0.12. However, the undisturbed woodland had the highest species richness (60); Rufunsa recorded 43 while Chibombo had the least with 40. Generally, the species diversity was quite high in all three sites, an indication of good recovery in terms of species. Determination of stem density revealed that Rufunsa had the highest number of stems per hactor (10417), higher than the undisturbed woodland which recorded 9063 stems ha-1 while Chibombo recorded the lowest number of stems of 3165 stems ha-1 . An analysis of mode of regeneration showed that root sucker is the most dominant mode of regeneration, followed by stump and seed regeneration in both sites. This can be attributed to the type of shifting cultivation and the farming equipment which favours root sucker. No mature trees were recorded in both sites accounting for the low number of seed regeneration. The study revealed a potential for Miombo woodland to recover provided the fallow period is followed and the regenerating Miombo trees are not exploited for other use such as poles and fibre before maturity. Further, there is need to educate farmers on the importance of coppice with standards. While this study has provided insights into species diversity and stem density, further research should investigate additional indicators of recovery, such as soil health, carbon sequestration, and the presence of keystone species.
- ItemGrowth and mortality of buka fish, lates stappersii (boulenger, 1914) in the southern part of lake Tanganyika, Zambia.(The University of Zambia, 2024) Nonde, ElvisPopulation growth parameters and mortality rates of Lates stappersii were investigated for the southeast and southwest arms of Lake Tanganyika, Zambia from April, 2022 to August, 2022. Exploitation ratio was studied. Furthermore, water quality parameters were investigated. Fish samples were procured from purse-seine fishers in Mpulungu and Nsumbu sectors of the lake. A total of 1,526 specimens with 642 females and 884 males for both sites were collected, examined and analyzed. The von Bertalaffy growth model was used to determine fish growth. The FordWalford plots were used to estimate the von Bertalanffy growth parameters (Asymptotic length , and growth coefficient, ). Exploitation ratios (E) were computed from estimated mortality rates (total mortality coefficient, Z; natural mortality coefficient, M and fishing mortality coefficient, F). To test for statistically significant differences, T-test analysis was used. It was established that there was no significant difference in growth parameters between samples collected from Mpulungu and Nsumbu areas of Lake Tanganyika. No statistical differences were observed in two of the water quality parameters; dissolved oxygen and temperature between the two areas. There was a difference in water transparency between the two areas. It was Further observed that fishing mortalities and exploitation ratios were consistently high and not significantly different between the two areas. The study therefore, established that both areas are inhabited by the same population of Lates. stappersii. From these results it is recommended that a fishery management strategy should not redistribute or focus on increasing fishing units in Nsumbu area to those in Mpulungu because this will not result in corresponding catch yields but will only increase the current overexploitation of the stock.