https://repository.seku.ac.ke/handle/123456789/14 2026-09-10T07:47:08Z 2026-09-10T07:47:08Z Gumo, Pius Sakha, Michael Otieno, Erick O. Wambua, Judy M. Ishmael, Kamtoi Gitari, Harun Gweyi-Onyango, Joseph https://repository.seku.ac.ke/handle/123456789/8433 2026-09-09T13:16:56Z 2025-12-30T00:00:00Z

Sorghum varieties invariably show improved water use efficiency coupled with morpho-physiological characters under limiting water conditions Gumo, Pius; Sakha, Michael; Otieno, Erick O.; Wambua, Judy M.; Ishmael, Kamtoi; Gitari, Harun; Gweyi-Onyango, Joseph Climate change has affected several aspects of sustainable food production and food security. One of the major challenges of climate change is the prolonged drought that has led to water stress in crops, including sorghum (Sorghum bicolor L. Moench), in arid and semi-arid areas of Kenya. A study was conducted at the Nadapal irrigation scheme in Turkana County, Kenya, to determine the crop's performance under different water application regimes. Principal component analysis was used to compare phenotypic andgenotypic characteristics and to study ontogenetic morphological integration leading to variation in sorghum yields. A path coefficient analysis was applied to estimate correlations between yield and yield-related traits and to determine the direct and indirect effects of these traits on yield per plant. It also enabled the identification of causal factors and other overlapping factors. The experimental design was a randomized complete block design (RCBD) with three replicates. From the analysis of variance, a highly significant and positive strong correlation was observed for seed index and plant height (r = 0.76) as well as head weight and grain yield (r = 0.74). Surprisingly, water use efficiency (WUE) showed a negative correlation with all other measured parameters. These kinds of interactions amongst WUE and other yield components depend on whether greater WUE is associated with equivalent carbon gain while using less water or greater carbon gain while using equivalent amounts of water (or a combinationof the two). The correlation and path coefficient analyses carried out demonstrated that head weight, head length, and seed index were important selection criteria for high grain yields in sorghum. There were direct and indirect effects of the parameters on sorghum yield. This study evaluated other important correlations among sorghum characteristics that breeders can exploit to enhance the production of high-yielding sorghum cultivars. It revealed overlapping characteristics among head weight, head length, and seed index in relation to grain yield. As a result, these components could serve as selection criteria to improve sorghum seed yield DOI:https://doi.org/10.52756/ijerr.2025.v49.011

2025-12-30T00:00:00Z Sakha, Michael Gitari, Harun Maitra, Sagar Mutua, Lydia Wambua, Judy M. Gweyi-Onyango, Joseph https://repository.seku.ac.ke/handle/123456789/8432 2026-09-09T13:02:44Z 2026-01-01T00:00:00Z

Soil properties as key drivers of greenhouse gas emissions and climate change Sakha, Michael; Gitari, Harun; Maitra, Sagar; Mutua, Lydia; Wambua, Judy M.; Gweyi-Onyango, Joseph Greenhouse gas (GHG) emissions from the agricultural sector play a significant role in global warming and climate change. Soils act as both sources and sinks of greenhouse gases (GHGs), including nitrous oxide (N2O), carbon dioxide (CO2) and methane (CH4). While previous studies have largely examined the contribution of agriculture and land-use change to anthropogenic GHG emissions, the contribution of specific soil properties to GHG emissions remains less clear. Therefore, this review synthesizes previous studies not only on broader soil properties but also highlights specific soil variables and their interactions within these broader categories that contribute to individual GHGs and regulate their production and emissions. We conclude that soil physical, biological, and chemical properties are important drivers of GHG emissions. Physical properties include soil temperature, bulk density, water content, soil structure, texture and porosity. Biological properties, particularly biological processes and chemical properties, including soil pH, organic matter, soil carbon, cation exchange capacity (CEC) and micronutrient availability, interact to regulate GHG production, consumption and emissions. Understanding these soil-specific controls is therefore essential for developing effective and context-specific strategies for reducing GHG emissions and enhancing the mitigation potential of agricultural soils. DOI: https://doi.org/10.52756/ijerr.2026.v51.005

2026-01-01T00:00:00Z Muui, Catherine W. Muasya, Reuben M. Lelei, David K. Maitra, Sagar Gitari, Harun I. https://repository.seku.ac.ke/handle/123456789/8431 2026-09-09T12:44:08Z 2026-08-30T00:00:00Z

Soil properties and rainfall variability as determinants of yields for sorghum landraces Muui, Catherine W.; Muasya, Reuben M.; Lelei, David K.; Maitra, Sagar; Gitari, Harun I. There is a decline in crop yields due to climate change. Drought and low-soil-fertility-tolerant crops could enhance food production. The objective of this study was to assess the effects of rainfall patterns and soil properties on yields of sorghum landraces. Rainfall and yield data were obtained from the Ministry of Agriculture and the meteorological department. Soil properties from farmers' farms and experimental sites were determined. Experiments were laid out in a Randomized Complete Block Design. Accessions were grown in selected locations in the Eastern, Nyanza and Coastal regions. Data were subjected to analysis of variance using R statistical software. Reduced rainfall periods recorded low yields. However, on station (2019), yields were higher, though rainfall was very low. Farmers' farms recorded pH (6.3–6.8), OC (0.6–1.2%), phosphorus (36.5–50.0ppm), nitrogen (0.1–0.2%) and potassium (1.1–1.6 Cmol/kg). Sodium was highest in the east (0.8 Cmol/kg), calcium (4.0 Cmol/kg), and magnesium (1.4 Cmol/kg) in Nyanza. Manganese and copper were highest in Nyanza, while high iron and zinc were observed in eastern and coastal regions, respectively. At planting, Taita Taveta farm recorded significantly high nitrogen, whereas phosphorus and calcium were highest in KALRO Katumani. Kitaakya ivuui Makueni (b) and Nyakabala Siaya (a) performed best in at least two regions. Though rainfall had an impact on yields, optimum agronomic practices and accession yield potential increased yields under low rainfall. Low on-farm yields could be attributed to low organic carbon and nitrogen. Use of accessions with high yield potential could enhance food security under low moisture and nutrient-depleted soils. DOI:https://doi.org/10.52756/ijerr.2026.v51.001

2026-08-30T00:00:00Z Akuja, Thomas E. Kirambia, Rosemary K. Xavier, Briggx Nchogu https://repository.seku.ac.ke/handle/123456789/8425 2026-08-31T17:09:18Z 2026-08-25T00:00:00Z

Assessing the general performance and marketability of onions under different areas on s, ca and mg supplementation in Kenya Akuja, Thomas E.; Kirambia, Rosemary K.; Xavier, Briggx Nchogu Onion (Allium cepa) is a vital crop serving both as a dietary staple and a source of income for farmers, with significant market benefits. However, its potential as a functional food is limited by poor growth, low yields, and reduced bioactive compounds, which diminish marketability. Therefore, this research aimed to investigate the effects of sulfur (S), calcium (Ca), and magnesium (Mg) supplementation on onion growth, yield, and bioactive compounds. A Randomized Complete Block Design (RCBD) was adopted across major onion production areas in Kenya: Kisaju-Kajiado and Koma-Machakos. Experimental treatments included varying levels and combinations of S, Ca, and Mg supplementation. Preliminary tests including Levene's, Kolmogorov-Smirnov, Durbin-Watson, Shapiro-Wilk, Cox and Snell, Nagelkerke, and McFadden tests were performed to assess normality, linear and multinomial regression, and collinearity using SPSS software. Analysis of Variance (ANOVA) was performed, and where significant differences were found, Post Hoc tests were conducted. Significant differences were observed, leading to rejection of the null hypothesis. The treatment with S, Ca, and Mg at 40 kg/ha significantly produced the best performing onions as well as market returns on the 'Red Creole' onion variety. Kisaju-Kajiado was also found to be the optimal location for onion production, with high return-on-investment profits. This research is recommended for farmers intending to improve onion performance and marketability. The study concludes that S, Ca, and Mg supplements significantly improve onion growth, yield, and bioactive compounds, thereby increasing marketability. DOI: https://doi.org/10.51583/IJLTEMAS.2026.150700150

2026-08-25T00:00:00Z