Kenyatta University (KU) is a public research university with its main campus in Nairobi County, Kenya. It acquired the status of university in 1985, being the third university after University of Nairobi (1970) and Moi University (1984). As of October 2014, it was one of 23 public universities in the country.
Uncertain rainfall onset complicates maize establishment in eastern Kenya, where both grain and stover contribute to farm livelihoods. We evaluated pre-rain dry-soil sowing, rainfall-triggered wet sowing and delayed sowing over five seasons at water-limited Machang’a and wetter Kiamaogo. Sowing treatment was assigned to split-plot main plots and locally predominant maize varieties to subplots, with three replications and repeated observation of the same physical plots. Site-specific mixed models quantified grain yield, stover yield, harvest index, establishment, productive-cob formation and grain-yield failure, while sowing-specific rainfall exposure was reconstructed for all ten site–season environments. At Machang’a, dry sowing increased grain yield by 51–86% relative to wet or delayed sowing in the 2009 short rains and 2010 long rains. In three other seasons, 94.4–100% of plots failed to produce grain despite established plants and measurable stover, showing that vegetative biomass could persist under conditions that prevented grain production. At Kiamaogo, sowing responses varied among variety–season combinations. Delayed sowing increased stover by 1.96–3.69 Mg ha⁻¹ in six of 15 combinations and reduced harvest index by 0.086–0.125 in four of 15 combinations, indicating shifts in biomass allocation rather than a consistent grain-yield advantage. Across sites, treatment responses reflected strong interactions among environment, season and variety. The study shows that sowing-time strategies can substantially alter both grain production and residue supply in rainfed maize systems and provide a field basis for developing climate-informed sowing strategies under variable rainfall.
Although above ground biomass (AGB) inventory provides critical information for sustainable ecosystem management, credible metrics assaying AGB remain a significant challenge. Projecting AGB dynamics, can be enhanced by understanding technological processes and products, thereby isolating the “myths from reality”. Generally, “myths” tacitly presuppose map aptness, whereas “reality” create awareness to proceed with caution by exhibiting imperfections that not only enhance knowledge but create new opportunities for innovation on remedial strategies. Other than data issues (i.e., complexity, heterogeneity, scarcity, accessibility), factors influencing scientific integrity and accuracy in AGB quantification include efficacy of measurement tools, robustness of algorithm, and systemic error in generalized map products smoothened after mosaicking. Here, AGB quantification at variable scales particularly for heterogeneous landscapes are explicated, and limitations of generalization exposed. Consideration is given to the mixed pixels challenge in digital imagery with emphasis on related technology flaws that exacerbate misclassification. The effects of heterogeneity in ground dataset and contribution to product accuracy are explicated. A case study of an unadulterated detailed AGB map output from multi-platform datasets is previewed to show real map aspect prior to generalization which is ordinarily subjective. Future opportunities are advanced for transferable metrics and models that incorporate a minimum data set of key covariates and fusion of multi-platform datasets.
In sub-Saharan Africa, there is growing interest in conservation agriculture practices, including reduced tillage (e.g., ripping), residue retention, and crop diversification, but their effects on soil moisture and penetration resistance in sub-humid regions remain unclear. This study investigated the effect of ripping, residue retention, cropping systems, and fertilizer management on soil moisture, penetration resistance, and maize (Zea mays L.) grain yield in a sub-humid zone of western Kenya. The study was conducted in a long-term experiment in western Kenya, using a split-split-split plot design with tillage in the main plot, while residue retention, cropping systems, and fertilizer application were the sub-plots, sub-sub-plots, and sub-sub-sub-plots, respectively. There were nine treatments and four replications. Soil moisture, penetration resistance, and maize grain yield were measured between 2023 and 2024. Residue retention resulted in significantly (p < 0.001) higher soil moisture (52.93-55.09 mm) in the 0- to 90-cm soil depth than residue removal (25.98-28.91 mm). Maize-soybean rotation also had significantly higher (p < 0.001) soil moisture in the 0- to 90-cm soil depth (41.42-45.08 mm) than the continuous maize (36.29-41.07 mm). The penetration resistance in the wet period ranged between 90 and 320 pounds per square inch (PSI), and between 200 and 492 PSI during the dry period. Ripping resulted in 12% higher maize grain yields than hand digging. Maize-soybean rotation had a higher (p < 0.001) maize grain yield (3.93 t/ha) than continuous maize system (1.57 t/ha). Nitrogen application at 90 kg N/ha in a continuous maize and 60 kg N/ha in maize-soybean rotation systems resulted in 118% and 85% higher maize grain yield, respectively, than when no nitrogen was applied. Similarly, applying phosphorous (60 kg P/ha) and potassium (60 kg K/ha) in maize-soybean rotation increased maize grain yield by 40% more than when potassium (60 kg K/ha) was applied as the only nutrient. Therefore, residue retention and ripping significantly improve soil health by enhancing moisture retention and reducing penetration resistance. Farmers in the sub-humid western Kenya region can increase maize yields by adopting maize-soybean rotation, applying appropriate fertilizers (nitrogen, phosphorous, and potassium, each nutrient applied at the rate of 60 kg/ha), and implementing residue retention and ripping, especially under low rainfall conditions.
Paraquat is a widely used but highly toxic herbicide which persists in aquatic environments due to its chemical stability, posing a significant risk to the ecosystems and human health. Conventional wastewater treatment methods are often ineffective in removing such recalcitrant compounds, necessitating the use of alternative approaches. This study investigates the degradation of paraquat in aqueous solutions using gamma irradiation from a cobalt-60 source, exploring its potential as an advanced oxidation process for environmental remediation. Paraquat solutions were irradiated at doses ranging from 1 to 8 kGy, and degradation was monitored using UV-Visible spectroscopy, chemical oxygen demand (COD), and total organic carbon (TOC) analysis. The results obtained show a 98
The Meliaceae (mahogany family) comprises over 740 species across 58 genera distributed predominantly in tropical and subtropical regions, many of which possess significant ecological, economic, and medicinal value. Intensified deforestation, overexploitation, and climate change have severely reduced natural populations, necessitating effective strategies for conservation, genetic improvement, and sustainable utilization. In vitro regeneration technologies—including micropropagation, somatic embryogenesis, and genetic transformation—provide essential tools for large-scale multiplication, germplasm conservation, and functional genomics of these high-value tree species. This review synthesized over three decades of research on in vitro regeneration systems developed for major Meliaceae genera, highlighting trends in explant selection, regeneration pathways, and hormonal responsiveness across taxa. Comparative analysis revealed a consistent reliance on cytokinin-driven shoot induction and auxin-mediated rooting, alongside persistent challenges related to explant maturity, phenolic exudation, genotype dependency, and low transformation efficiencies. Recent advances in stable transformation systems and stress-mitigating culture strategies demonstrated increasing feasibility of molecular improvement in selected species. The review identified key future directions, including diversification of plant growth regulators, integration of stress modulators, development of bioreactor-based propagation systems, and application of genome-editing technologies to improve regeneration fidelity and scalability. Collectively, these advances positioned Meliaceae biotechnology as a critical enabling platform for reforestation, conservation, and climate-resilient forestry.
