Abstract Seagrass meadows provide numerous ecosystem services and their rapid global loss may reduce human welfare as well as ecological integrity. In common with the other ‘blue carbon’ habitats (mangroves and tidal marshes) seagrasses are thought to provide coastal defence and encourage sediment stabilisation and surface elevation. A sophisticated understanding of sediment elevation dynamics in mangroves and tidal marshes has been gained by monitoring a wide range of diferent sites, lo...
Abstract Biological control of plant diseases through the addition of microbial biocontrol agents and the promotion of earthworms can be an environmentally friendly alternative to the chemical control of plant diseases. However, possible risks with biocontrol agents and their interactions with earthworms and other soil biota have not been well studied. The aim of this study was to assess whether the beneficial bacterium Bacillus amyloliquefaciens and the earthworms Aporrectodea caliginosa or...
Abstract : There is growing interest in carbon stocks and flows in seagrass ecosystems, but recent global reviews suggest a paucity of studies from Africa. This paper reviews work on seagrass productivity, biomass and sediment carbon in Africa. Most work was conducted in East Africa with a major geographical gap in West Africa. The mean above-ground, below-ground and total biomasses from all studies were 174.4, 474.6 and 514 g DW m-2, respectively with a global range of 461–738 g DW m-2. M...
Abstract The root knot nematode, Meloidogyne is one of the most economically damaging plant parasitic nematode groups, and are widely distributed in Kenyan agro-ecosystems. The aim of this study was to determine the diversity of Meloidogyne species in Kenyan sweet potato fields and identify sweet potato varieties that exhibit resistance to M. incognita. Meloidogyne species were collected from Nyanza, Western, Eastern and Central Provinces of Kenya. Mitochondrial DNA was used to differentiate...
Abstract Kenya’s Vision 2030 identifies agriculture as one of the key sectors to deliver sustainable economic growth and improved livelihoods for the poor in the rural areas. However, the sector continues to face several endemic and emerging constraints that require special attention. During the first two decades after independence, Kenya’s economy grew at an average rate of 6 percent per year and this was substantially driven by a robust agriculture sector. However, until about five yea...
Abstract Woody debris accumulations are important ecological components in low order forested streams. They provide forage and refuge for a macroinvertebrates, which are key trophic components for riverine fish. The occurrence of woody debris in tropical streams is however threatened by large scale destruction of catchment forests thereby threatening the riverine biodiversity. Despite their importance, the current status of woody debris accumulations in tropical forested streams is unknown. ...
Abstract Naromoru is a semiarid area in Central Kenya, occurring on the leeward side of Mt. Kenya. Its water sources include a few permanent rivers such as Nairobi River, intermittent streams and a large number of undrainable water reservoirs. Most of the undrainable water resources have been stocked with fish but their utilization for fish rearing has generally remained very low. The purpose of this study was therefore to examine the water quality status of the dams to assess their suitabil...
Abstract Resistance to Coffee Berry Disease (CBD) in Coffea arabica cv. Ruiru 11 is known to be controlled by among others, the T (Ck-1) gene from Robusta coffee (Coffea canephora Pierre). The cultivar reportedly presents significant variability in resistance to CBD. Previous work identified a microsattelite marker Sat 235 which was linked to CBD resistance and mapped it onto the introgressed C. canephora fragment which carries the Ck-1 gene. This study was aimed at utilizing the Sat 235 mar...
Abstract Majority of reported work on coffee breeding primarily concerns agronomic improvement that directly impinges on coffee quality. However, it is crucial that coffee breeding programmes for disease resistance also include coffee quality improvement since consumer awareness about the quality of different coffees has increased. The aim of this study was to determine the variation and associations of cup quality parameters and resistance against Coffee Berry Disease (CBD) in Coffea arabic...
Abstract Coffee Leaf Rust (CLR) is a fungal disease caused by Hemileia vastatrix Berk et Br. and is one of the major diseases of coffee. It causes premature leaf fall, yield loss and even death of the tree in severe cases. Coffee genotypes respond differently to biotic factors. This study was aimed at identifying potential sources of resistance genes to the disease. Forty five Coffea arabica L accessions were evaluated for their response to CLR under field conditions. CLR infection was asses...
Abstract Nutrient enrichment is one of the most serious threats to wetland ecosystems. Information is lacking, particularly concerning the response of wetland plants species in Kenya in regard to nutrient enrichment of wetlands. Understanding the mechanisms and adaptations that allow only certain species to thrive in the potentially stressful wetland environment requires the study of the biology of these plants. This study was carried out to investigate the growth and nutrient uptake among s...
Abstract Physical characteristics of green coffee bean have been reported to affect beverage quality to some extent. The objective of this study was to assess the beverage quality and green bean physical characteristics of forty two arabica coffee genotypes and to determine the relationship between the two attributes. Green bean physical characteristics were assesed through actual measurements, grading and weighing while beverage quality was determined by a panel of seven judges using the pr...
Abstract Climatic variability is the main factor responsible for the fluctuations in the coffee yield in the world. The relationships between the climatic parameters and the agricultural production are quite complex, because environmental factors affect the growth and the development of plants under different forms during the phenological phases of the coffee crop. Such environmental factors include reduced rainfall and high temperatures both of which majorly contribute to drought. This pape...
Abstract Biochemical composition appears to be influenced by both genetic factors and plant growth conditions. The main objective of this study was to evaluate the biochemical composition of selected Ruiru 11 sibs and its relationship with cup quality. Thirty four (34) Ruiru 11 sibs grown in three different locations in Kenya were used in this study. The experiment was laid out in a Randomized Complete Block Design with three replications. Coffee cherries were picked during the peak harvesti...
Abstract Knowledge of the effects of environment and genotype by environment (GxE) interaction is important to breeders in making decisions regarding the release of new cultivars. Five Coffea arabica lines coded CR8, CR22, CR23, CR27 and CR30 have been developed by Coffee Research Foundation and are currently being tested for release in various coffee growing zones in Kenya. The objective of this study was to determine the performance of the five advanced breeders’ lines under varying envi...