Faculty of Science, Engineering and Technology

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Implication for in situ conservation of indigenous species with special reference to wild Coffea arabica L. population in Mount Marsabit Forest, Kenya
(Universidad Autónoma de Yucatán (UADY), 2011) Eunice W. Githae; Charles K. K. Gachene; David W. Odee
Mt. Marsabit forest is the only forest in Kenya where Coffea arabica L. (Rubiaceae) occurs naturally in wild populations. This forest however is highly fragmented and decreasing at a rapid rate due to anthropogenic activities. This study assesses the diversity and structure of species of conservation concern with reference to wild coffee as basis for management, conservation and use of wild genetic resources in Kenya. A botanical inventory and diversity study identified 52 species of trees and shrubs, 12 species of herbs and six species of climbers and lianas were recorded and belonged to 35 families and 64 genera. Rubiaceae (Coffee family) was the richest family with nine species followed by Euphorbiaceae with six species. Rinorea convallarioides (Bak.f.) Eyles ssp. marsabitensis Grey-Wilson (Violaceae), an endemic species, and Drypetes gerrardii Hutch. (Euphorbiaceae), were the two most important species, accounting for more than third of the combined importance value. Coffea arabica was dominant in the forest undergrowth with a higher density occurring in the open patches where it was competing with other shrubs and small trees in the undergrowth. The success and future management and conservation strategy of this forest depend on how to conserve the forest genetic resources especially of this wild species.
Influence of Socio-economic Factors on Prevalence of Ochratoxin A in Dry Coffee Cherry in Tharaka Nithi County, Kenya
(Kenya Horticultural Society, 2024-12) Tabitha K. Gitonga; Eunice W. Githae; Moses M. Muraya; Olivia A. Njiri
Coffee is a vital cash crop worldwide, contributing significantly to foreign exchange earnings and offering potential health benefits. However, concerns over contamination with mycotoxins, particularly Ochratoxin A (OTA), have grown due to its serious health risks. This study investigated the influence of socioeconomic factors on the prevalence of OTA in dry Coffee Cherry from Tharaka Nithi County, Kenya. A cluster random sampling method was used to collect the dry coffee cherry samples and survey data from 143 farmers across three agroecological zones, employing a semi-structured questionnaire. Pathogens were isolated on Potato Dextrose Agar (PDA) media and OTA production assessed according to the International Commission on Microbiological Safety for Foods. Data was analysed using the SPSS version 28 and SAS version 9.4. The study found out that socio-economic factors significantly (p < 0.05) influenced coffee farming practices and prevalence of OTA. Ochratoxin A prevalence was strongly associated with agro-ecological zones, farm size, and altitude. Larger farms and lower altitudes were linked to higher OTA risks. Gender, farm size and coffee variety also influenced OTA contamination levels. The study revealed that 88.3% of coffee farmers recognized mold in dry coffee cherries, yet 22.8% consuming moldy cherries, with 64.1% unaware of the health risks. Additionally, 87.6% of farmers identified poor drying and storage practices as key contributors to OTA contamination. Key indicators of contamination included discoloration, moldy smell, and moldiness with wetness. Roasting practices varied, with 35.1% roasting dried cherries after fermentation. The study highlights significant socioeconomic factors influencing OTA contamination in coffee. To mitigate risks, it is recommended to improve farmers' awareness of mold-related health risks and implement targeted interventions in high-risk areas to reduce OTA prevalence.
Long-distance gene flow in Acacia senegal: Hope for disturbed and fragmented populations
(Wiley, 2023-06-29) Stephen F. Omondi; Eunice W. Githae; Damase P. Khasa
Even though pollen and seed dispersals are some of the important factors that determine tree species survival across landscapes, gene dispersal data of important tropical dryland tree species such as Acacia senegal that are undergoing various population disturbances remain scarce. Understanding patterns of gene dispersal in these ecosystems is important for conservation, landscape restoration and tree improvement. We investigated pollen and seed mediated gene flow in two A. senegal populations of contrasting state (less disturbed and heavily disturbed) using nine microsatellites and 128 genotyping-by- sequencing single nucleotide polymorphism (SNPs) multilocus genotypes of two growth stages (juvenile and adult trees) and their spatial locations. We performed parentage assignments using likelihood approach and undertook spatial genetic structure (SGS) analyses for the two growth stages through correlation among kinship coefficients and geographical distances between pair of individuals. The SNPs showed higher resolving power and assignment rates than microsatellites; however, a combination of the two marker-types improved the assignment rate and provided robust parentage assessments. We found evidence of long-distance (up to 210 m) pollination events for both populations; however, the majority of seed dispersal was found closer to the putative maternal parent. On average, parentage analysis showed high amounts of pollen (40%) and seed (20%) immigration in both populations. Significant positive SGS was found only for the adult cohorts in the less disturbed population for distance classes 20 and 40 m, indicating historical short-distance seed dispersals. Our results suggest long-distance gene flow within the species and we recommend conservation of remnant and isolated populations or individual trees to promote genetic connectivity.
Soil physicochemical properties under Acacia senegal varieties in the dryland areas of Kenya
(Academic Journals, 2011-08) Eunice W. Githae; Charles K. K. Gachene; Jesse T. Njoka
Acacia senegal is a multipurpose drought-tolerant tree or shrub legume and is commonly used in agroforestry systems in sub-Saharan Africa for gum arabic production and soil fertility improvement. Despite its wide distribution in Kenya, there has not been exhaustive evaluation on the effects of the extant varieties (kerensis, leiorhachis and senegal) on soil properties under their canopies for sustainable utilization of the species. Three sites in the drylands of Kenya representing the three varieties were selected for assessment. Soil samples were collected under tree canopies at a depth of 0 to 25 cm and were compared with the soils from the open canopies. There were significant differences in soil physicochemical properties among the three varieties (P<0.05 and P< 0.01). Soil nutrients under the canopies were higher than in the open canopies mainly due to effects of litter accumulation. The three varieties have beneficial effects on soil nutrient status in their natural ecosystems and would most likely improve crop productivity in agroforestry systems as well as enhance herbage productivity in the rangelands. The varieties growing under different soil types may have an effect on their gum Arabic production and quality.

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