School of Agriculture and Food Security

Epidemiological and genetic analysis of quantitative resistance to gray leaf spot (cercospora zeina) in elite maize (zea mays l) genotypes

2026-04-02T13:02:19Z

Epidemiological and genetic analysis of quantitative resistance to gray leaf spot (cercospora zeina) in elite maize (zea mays l) genotypes NYANAPAH, James Osare Maize has a significant and increasingly crucial role in global food security systems, but the threat of gray leaf spot (GLS) disease, caused by Cercospora zeina, persists and continues to impact its yields on a global scale.Forty-eight inbred lines of maize from the International Maize and Wheat Improvement Center (CIMMYT)were sorted into 6 sets and factorial crosses of each set generated according the North Carolina mating design II. The lines alongside their crosses evaluated across 12 environments to characterize partial disease resistance to artificial GLS epidemics,temporal progress of the disease, genetic association of resistance with 9 phenological traits, and combining abilities alongside heterotic effects of the inbred lines for resistance. Eight measures of resistancethat includedstandardized area under disease progress curve (SAUDPC), and weighted mean absolute rate of disease increase (ρ) were examined. SAUDPCs were the most efficient infection measure, buttheir variability were best explained (R2 = 93.9%) by disease ratings between the VT (full tassel emergence preceding pollen shed) and R4 (dough stage) stages of development. Individual disease ratings at R4 were almost as effective as SAUDPCs in characterizing genotype reactions.The Levenberg-Marquardt algorithm, along with integration of data eyeballing and gridding to determine starting parameter values, were the best methods for estimating the nonlinear regression model that accurately fit the gray leaf spot (GLS) epidemics.The generalized version of the Richards model outperformed all other growth curve models examined except in some instances where its curve shape parameter matched the fixed curve shape models that best fit any particular epidemic. Goodness of fit of the monomolecular, Gompertz, logistic and exponential models varied with the resistance of entries and favorability of the trial environments to GLS development. Genotypic and phenotypic correlations of SAUDPC were strongest with the Stay-green characteristic (SGR) (r = −0.87). The magnitude and direction of coheritability estimates mirrored trends in genotypic and phenotypic correlations. The covariation of GLS resistance with agronomic traits was mainly due to the direct effects of days to anthesis (DTA) and days to silking (DTS), and the indirect effects of stay-green capacity (SGR) and silking-maturity interval (SMI). General combining ability (GCA) and specific combing ability (SCA) effects were significant. However, the GCA effects were more important than SCA effects signifying the preponderance of additive gene action. Although this was confirmed by significant correlations between GCA effects and per seresistance of inbred parents, the correlations were not strong enough to be of predictive value. Estimates of potence ratio suggested that non-additive effects were due to multiple loci and alleles with recessive, dominance, over-dominance, and various types of epistasis. These findings indicate that comparative analysis of GLS epidemics should be based on the generalized Richards model and breeding for resistance should prioritizereciprocal recurrent selection, pedigree selection, restricted index selection, multiple population improvement, and multistage selection depending on the genetic background of the sources of resistance. PhD Thesis

Biological and economic performance of peanut-based meals As alternatives to dietary fishmeal in pond cultured Nile Tilapia (Oreochromis niloticus L.) In Uganda

2024-02-14T14:30:56Z

Biological and economic performance of peanut-based meals As alternatives to dietary fishmeal in pond cultured Nile Tilapia (Oreochromis niloticus L.) In Uganda MUSITA, Augustus Apollo Increasing price of dietary fishmeal is offsetting the excellent growth and yield induced in farmed Nile tilapia subsequently reducing the corresponding cost-effectiveness. Replacement of the dietary ingredient with better or comparable substitutes has become necessary in many countries including Uganda. In light of the phenomenon, a study was conducted in Busoga sub-region of Eastern Uganda to evaluate the biological and economic performance of pondcultured Nile tilapia (Oreochromis niloticus L.) fed on peanut-based meals as alternative to dietary fishmeal. Sample surveys supplemented by field experiments attained all the specific objectives of the study from January 2016 to March 2017. The specific objectives of the study related the following performance indicators in Nile tilapia fed on the test diets; biomass production (g/pond), Feed Conversion Ratios, Relative Growth Rates (%), Net Fish Yields (g/pond), Survival Rates (%), Economic Conversion Ratios and Profit Indices. The surveys that valuated the test feeds and fish products occurred in sampling units in local commodity markets in Iganga municipality and along the main roads network respectively. The fish pond input and output valuations (USD/Kg) were conducted directly and indirectly respectively. The field experiments aimed at measuring targeted responses induced by test diets in Nile tilapia. Each of the two experimental sites at Busoga University farmland consisted of rectangular shaped earthen ponds. Two experimental sites A and B were stocked in the dry and wet seasons respectively. The replication of Site A at Site B aimed at mitigating the effect of weather on fish production. Forty-eight mono-sex fish fingerlings were stocked in sixteen pond units of uniform size (3.0 x 4.0 x 1.0 cubic meters) at each site. Among the stocked ponds, one acted as a fish reserve pond for mitigating the risk of fish loss in the earthen ponds. Mean body weights at stocking were 22.2 and 21.7 grams for the sites A and B respectively. Test diets were Iso-caloric throughout the experiments (5.3627 Kcal/g) and isonitrogenous; 30% and 25% Crude Protein for the first twelve and latter weeks respectively. Dietary treatments included the fishmeal-based diet (control) and two peanut-based diets; peanut meal and mixed plant meal-based diets. The locally available commercial feed for grow-out Nile tilapia containing 25% Crude Protein was the control diet throughout the feeding trials. The results indicated that only unionized ammonia affected fish biomass production negatively. Survival Rates in Nile tilapia were the only performance indicators that were insignificantly different (p 0.05) across all the dietary treatment groups. Other Insignificant differences (p 0.05) among other indicators of performance were restricted were restricted the fishmeal and mixed plant-based diets. With exception to the Survival Rates, the peanut-based diet exhibited significantly poorer (p 0.05) results than the fishmeal-based diet. The lack of significant differences (p>0.05) across all tested biological and economic performance indicators implied that the mixed plant meal based and fishmeal-based diets exhibited comparable performances. Therefore, among the peanut-based meals, only the mixed plant-meal should completely substitute the conventional fishmeal-based diet in the pond cultured Nile tilapia in Uganda. PhD Thesis

Assessment of vulnerabilities to drought, impact and adaptation options in pastoral production systems in Laisamis, Marsabit county, Kenya

2022-12-19T15:42:29Z

Assessment of vulnerabilities to drought, impact and adaptation options in pastoral production systems in Laisamis, Marsabit county, Kenya JIDDAH, Choke. Chufe Dry lands are home to about 25–30% of the global population, or around two billion people, 90% of those who live in developing countries. The same report indicates that 40% of the human population of both Africa and Asia live in such these areas. Dry lands cover 80 % of Kenya‘s land surface in Kenya and 100% of the study area. Drought is a major disaster causing huge damages to humanity, the environment and the economy at global, continental, national and in the study area. Despite making considerable progress on monitoring, forecasting and mitigation of droughts across the world, there are still gaps in drought vulnerability assessment, determining drought impacts and adaptation options. The evidence of gaps is the too frequent and severe drought without adequate interventions. Therefore, the purpose of this study was to assess vulnerabilities to drought, impact and adaptation options of pastoralists’ production systems in Laisamis Sub-County, Marsabit County. The specific objectives of the study were to: Assess magnitude of vulnerabilities to drought in pastoral production system; assess the impact and find out the adaptation options to drought in pastoral production system. The study employed a crosssectional research design which was used to provide systematic and accurate facts about households, the community and describes current situation. Stratified random sampling approach was used to obtain the primary data. The minimum sample size of 376 households was calculated using Taro Yamane (1967:886) simplified formula. The study targeted 6,182 households in four locations in Laisamis Sub-County, Marsabit County, Kenya. The unit of analysis was the households heads which were interviewed. Secondary data were obtained from relevant public reports, agricultural reports, statistical abstracts and publications from development partners. The household Vulnerability Index was calculated using Principal Component Analysis (PCA).This was done by subtracting average adaptation indices and exposure and sensitivity indices. Primary data on drought adaptation options and impacts of drought were obtained through questionnaires. The study considered various biophysical and socio-economic factors to calculate Vulnerability Index. Weights for different indicators to calculate the Household Vulnerability Index (HVI) were used. Data analyses were done using frequencies, percentages, Pearson correlation coefficient, cross tabulations and Chi square tests. The presentations of results were done in form of narrative, graphs, tables, pie and bar charts. Household vulnerability was assessed in this study. The results show that 2.3 % of the households were highly vulnerable, 32.6 % were moderately vulnerable and 65.1 % less vulnerable. The overall drought vulnerability index for the study area was 0.46, indicating moderate vulnerability. Drought adaptation options were identified. Drought impacts was measured through Drought Index indicating 53 % for the study area resulting in less available pasture, low livestock population, high livestock mortality, low meat and milk production. It can be concluded that understanding the vulnerability of households to drought is indispensable for decision-makers to device adaptation strategies for long-term resilience building of pastoral households. The study concluded minimum external interventions are required for resilience building in the study area. PhD Thesis

Assessing the correlation between interannual climate Variability and land cover change, and flow regime of sub-catchments, and their impact on communities of the Mara river basin, Kenya

2022-12-19T15:24:01Z

Assessing the correlation between interannual climate Variability and land cover change, and flow regime of sub-catchments, and their impact on communities of the Mara river basin, Kenya MNGUBE, FREDRICK MHINA Climate variability and Land Cover Changes (LC) have negative consequences on watershed management. Whereas, the role of climate variability on land cover changes and stream flow regimes have affected people’s livelohoods and caused resources use conflicts in the Mara river basin, little is known of their impact at the sub-catchment level where majority of communities live, hence the need to fill this gap. The main objective of this study was to determine correlation between inter-annual climate variability, land cover changes and flow regimes and socioeconomic status of communities of the Mara River Sub-catchments, Kenya. The specific objectives were to; determine the correlation between rainfall and temperature variability and LC in Amala, Nyangores, Talek and Sand river sub-catchments of the Mara River tributaries, Kenya; evaluate the effects of land cover changes on stream flow of Amala and Nyangores tributaries of the Mara River, Kenya; forecast future changes in LC for the Amala, Nyangores, Talek and Sand River sub-catchments of the Mara River, Kenya; assess the effects of land cover changes on the socio-economic status on the communities of Amala, Nyangores, Talek and Sand River subcatchments of the Mara River, Kenya. Empirical and cross-sctional designs were used. Rainfall and temperature, Landsat images for LC and the Normalized Difference Vegetation Index (NDVI) and soil data were obtained from websites. The socio-economic data and focused Group Discussion (FGD) were collected using questionnaire from sample size of 422 adults derived from target population of 1,000,000. Mann-Kendall test was used to establish trends in climate, coefficient of determination used to measure the correlation between climate variables, LC changes and stream flows. Markov Chain model used to forecast future LC. A generalized linear model was used to correlate drivers of LC and stream flows. Results indicated that LC classes correlated with temperature and rainfall in different ranges (r = 0.23 to 0.99). Temperature showed strong correlation with built-up areas (r = 0.99), and weaker with grasslands (R2 = 0.23). Rainfall showed positive correlation with bare land (R2 = 0.98) and weaker with grasslands (R2 = 0.02). Annual flow ranged between R2 = 0.07 to 0.99). The strongest correlation was observed in built up areas (R2 = 0.99) and the weakest in grassland land (R2 = 0.07). Change detection matrix showed significant but varying degrees changes by 2027. Majority of the household (89.7%) reported having noticed changes in LC in the past 30 years, unpredictable rainy pattern and increase in temperature were the main drivers of LC and stream flows. FGD participants observed irregular rainfall patterns and increase in temperature, and were supportive of environmental protective measures to reverse negative land cover changes. There was a correlation between temperature and rainfall and land cover change. LC dynamics affected mean annual water flows in Nyangores and Amala. The simulated results indicated there were high water flows in built areas and lowest in grasslands. Future LC projection showed significant increase in grassland and reduced cropland. Types of trees planted, irregular rain pattern and increased temperature were the the drivers of LC change. The study recommends adaptation to temperature and rainfall variability; a multidisciplinary approach towards the hydrologic processes that maintain ecological health and communities’ livelihood; suitable land use practices to improve future land cover; and an integrated plan to address the drivers of LC changes.

Household allocation of labor time in two types of Smallholder farming Systems in rural Kenya

2022-03-16T13:19:39Z

Household allocation of labor time in two types of Smallholder farming Systems in rural Kenya MONICA, Awuor Ayieko The study analyzed the effects of gender and farming systems on time allocated to work by agricultural households in rural Kenya. A total of 289 participants were selected from Njoro and Kikuyu divisions. spot observations, personal observations, questionnaires, and focus groups methods were used to collect data. Ecological zones influenced the ~~ount of time allocated to work. Households in Njoro spent less time on work than households in Kikuyu. Females spent more time on household and agricultural work than males. Younger males spent more time in agriculture than female; of the same ages. Female-heads were not different from other women on time they allocated to work. Respondents from female-headed households spent more time in agriculture and household production and less time in income generation than their counterparts from two-parent households. Presence of a husband in a household made members worked more hours doing household activities than when he was away. Age and educational attainment influenced the time females allocated to work. For males, the factors were age, educational attainment, type of family and the size of farm. For every additional year in age, females contributed increasing amounts of time to household and agricultural production while males' time iv decreased. To cope with bad weather and economic hardships, livelihood strategies such as reducing consumers, shifting members' maintenance responsibilities, increasing sources of income and depending on remittances were used. Men were conscious of their reduced time allocated to work in the home, acknowledged the role of women in agricultural production and allowed their spouses to make management and production decisions on their farms. Women were performing male designated chores, conscious of their roles in households subsistence, bias in traditional division of labor and its consequences and were seeking alternative solutions to manage the effects of emigration of men. Mothers were m0re liberal than fathers in allocating gender designated responsibilities to their children. Boys contributed more time to agriculture than male adults and even their counterpart females. Division of labor in the communities were based on relative power, social ideology, and moral economy.

Farmer-Led Soil Conservation Initiative in adeveloping Country Setting: The Case of the Claveria land care association in Claveria, Misamis oriental, Philippines

2022-03-16T12:55:01Z

Farmer-Led Soil Conservation Initiative in adeveloping Country Setting: The Case of the Claveria land care association in Claveria, Misamis oriental, Philippines AGUSTIN, Arcenas In the middle of 1996, a group of 20 fanners in Claveria, Misamis Oriental, formed an organization called the Claveria Land Care Association (CLCA) under the support and patronage of the International Centre for Research on Agroforestry (lCRAF). The objective of the organization was to promote the use of contour plowing through a farmer-to-fanner approach. By the year 2000, the CLCA had members in 105 sitios while the absolute number of adopters of contour plowing has almost doubled from the previous number of adopters. The CLCA is credited for the phenomenal rise in fanners that have switched to contour plowing in Claveria. This study investigates the CLCA phenomenon by: (1) documenting the events .leading to fanner awareness of soil erosion problems.in Claveria and the options available to combat them; (2) documenting its evolution from a low-key fanner organization to a high-profile promoter of soil conservation; (3) determining the characteristics and activities of the CLCA sub-chapters that made significant influence on adoption of contour plowing; (4) determining the characteristics of the farmers who perceive themselves as members of the CLCA; (5) determining the parcel and fanner characteristics that influence adoption; and (6) identify the future challenges that the CLCA sitio-based organizations face. Using primary data collected from a survey of274 randomly-selected farmers from 45 sitios in the municipality of Claveria, a probit analysis was done to determine the statistical association between perception of membership, and the farmers' socio-economic characteristics, ties with the community and participation in community activities, The probit analysis was also utilized to test the statistical relationship between adoption of contour plowing, and the variables farmers' socioeconomic traits, parcel characteristics and perception of membership. The results indicate that attendance in cross-visits and sitio meetings, and those that lived close to Claveria are more likely to perceive themselves as members of the CLCA. Further, number of parcels tilled by the farmer, attendance in training and sitio meetings, slope of the parcel tilled, and the area of the parcel have a significant statistical association with contour farming adoption. The study also found that the CLCA lacks self-sufficiency in funds generation and needs to lock down on the membership selection criteria and benefits in order to sustain its activities in the future. The CLCA's mechanism for participatory governance and democratic selection of its leaders is well in place. The results and insights gained from the findings of this research paper are relevant for policy makers and development project designers in creating programs and schemes aimed at catching the "elusive" adopters of technology -- traditional farmers from the developing countries.

Sesamum Indicum L. crop origin, diversity, chemistry and Ethnobotany

2022-03-10T11:20:46Z

Sesamum Indicum L. crop origin, diversity, chemistry and Ethnobotany BEDEGIAN, Dorothea

Effects, of some terrestrial weeds, termites and snails on growth and yield of the cichlid fish oreochromis niloticus L.

2022-02-09T09:00:22Z

Effects, of some terrestrial weeds, termites and snails on growth and yield of the cichlid fish oreochromis niloticus L. OTIENO, , Owiti Dickson The major aim of aquaculture (farming and husbandry of fish and shellfishes) is to boost the production of fish in ~the attempt <...to satisfy human need for food and protein. qne of the most important challenges in any aquacultural enterpri 't> is the need for cost-effective fish feeds; t~is item being the mos( e~ensive item in fish farming. As a result, the search for suitable feeds (economically and nutritionally effective; based on locally available ingredients) for culture fisheries continues in many laboratories throughout the world. A number of materials have been subjected to investigations and tests to find out their suitability as possible food source for fish. These include, several species of plants, animals, domestic refuse (especially kitchen refuse) and by-products from manufacturing and food processing industries. The materials that have attracted attention in these regard include grains, oil Seed cakes, plants (seeds, fruits and vegetative parts i-Ie aves ), insects (and other invertebrates including earthworms, Achantina), housefly larvae, silkworm larvae, slaughter-house byproducts, brewery wastes, and poultry by, products. In the present study, the effect of three terrestrial plants (Amaranthus caudatus, Bi dens pilosa, and Galins og a p aviflor ay and two invertebrates (termites, Hodotermes sp. and. the giant African snail, Ach antino fulica) on growth in the cichlid fish, Oreochromis niloticus L. have been investigated, by the following steps; analyses of the nutrient contents of each of the test feed mate-rial; diet formulation; digestibility studies; and, effects on growth. The nutrient contents determined by the method of the Weende Proximate Analyses (the Method of the Association of Official Analytical Chemists, 1984) reveals that these feeds are high in crude protein contents ranging from 27.5 % in Amaranthus, 29.6 % in Galins oga, 30.5 % in Bi dens , 48.3 % in Hodotermes to 74.2% 2 in the Achantina (exluding shell). The amino acid profile (by the method of gas-liquid chromatography) show that the Hodotermes and the Achantina can be good sources of essential amino acids in formulated diets especially for supplementation to plant p':r2teins. Digestibilities of the nutrients investigated by the indirect method using the inert chromium oxide (Cr203) as a marker, and casein as reference diet reveal high apparent digestibilities in both the animal and plant matter, (except Amaranthus), with significant differences at PO.05 level noted between diets and nutrients. During digestibility trials, it was observed that the Am ar anthus diet was generally rejected resulting in negative growth values. Apparent digestibility coefficients (%) for protein, fat and energy in the test diets were: Amaranthus 72.97, 80.87 and 72.69; Bidens 84.30,83.17, and 78.03; Galinsoga 83.90,87.82, and 76.31; Termite 82.19, 96.19, and 85.01; and Achantina 93.49, 97.19. and 93.96 respectively. From the analyses of the nutrient contents and their .digestibilities in the plant and animal materials of the present experiments, it has been concluded that the H odotermes and Achantina may be selected for inclusion in the supplementary diet for b. nil oticus on the primary basis of amino acid composition rather than the crude protein content. Because of the general rejection of Amaranthus during digestibility trials, its further investigations were regarded unnecessary and thus it had to be eliminated by the end of the digestibility-trial-stage. In growth studies, feeding experiments were designed to examine the effects of Bi dens, Galinsoga termite and Achantina on weight gain, feed conversion, ichthyornass productivity in Oreochromis. niloticus. O. niloticus weighing 15.3 g to 18.9 g average weights were used to stock 24 holding cages (80 fish per cage) placed in a pond. The fish were fed to seven experimental diets; each diet given to three replicated groups. One group, also in 3 triplicate, were held without any supplementary feeding to serve as control. The feeding experiments lasted ninety-one days, during which period, the growth parameters (lengths and weights) were measured fortnightly. '-' The average weights at the end of the feeding period ranged from 48.5 g in the control; 53.7 g in Galinsoga; 56.3 gin Galinsogaltermite; 57.7 g in Bi dens; 59.3 g in Bidensltermite 66.8 g in Galinsogalsnail; 67.8 g in BidenslGalinsogaltermite/snail to 75.5 g in the Bidens/snail based diets. Bidens-meallsnail-meal based diets resulted in the best growth performance (weight gain, mean daily growth rate, specific growth rate) and biomass productivity. No significant differences (P > 0.05) were observed in feed conversion ratios and conversion efficiencies. Details of the methods and results are presented and discussed. It has been concluded that Bi dens pilosa, Achantina and Hodotermes can be effectively used as supplementary feeds, to the Nile tilapia Oreochromis niloticus. It was further concluded that Amaranthus caudatus is not a suitable material as feed ingredient in . the diets for O. niloticus. Donation

Farmer-led soil conservation initiative in a developing Country setting: the case of the claveria land care Association in claveria, misamis oriental, Philippines

2022-01-17T08:10:58Z

Farmer-led soil conservation initiative in a developing Country setting: the case of the claveria land care Association in claveria, misamis oriental, Philippines ARCENAS, Agustin In the middle of 1996, a group of 20 fanners in Claveria, Misamis Oriental, formed an organization called the Claveria Land Care Association (CLCA) under the support and patronage of the International Centre for Research on Agroforestry (lCRAF). The objective of the organization was to promote the use of contour plowing through a farmer-to-fanner approach. By the year 2000, the CLCA had members in 105 sitios while the absolute number of adopters of contour plowing has almost doubled from the previous number of adopters. The CLCA is credited for the phenomenal rise in fanners that have switched to contour plowing in Claveria. This study investigates the CLCA phenomenon by: (1) documenting the events .leading to fanner awareness of soil erosion problems.in Claveria and the options available to combat them; (2) documenting its evolution from a low-key fanner organization to a high-profile promoter of soil conservation; (3) determining the characteristics and activities of the CLCA sub-chapters that made significant influence on adoption of contour plowing; (4) determining the characteristics of the farmers who perceive themselves as members of the CLCA; (5) determining the parcel and fanner characteristics that influence adoption; and (6) identify the future challenges that the CLCA sitio-based organizations face. Using primary data collected from a survey of274 randomly-selected farmers from 45 sitios in the municipality of Claveria, a probit analysis was done to determine the statistical association between perception of membership, and the farmers' socio-economic characteristics, ties with the community and participation in community activities, The probit analysis was also utilized to test the statistical relationship between adoption of contour plowing, and the variables farmers' socioeconomic traits, parcel characteristics and perception of membership. The results indicate that attendance in cross-visits and sitio meetings, and those that lived close to Claveria are more likely to perceive themselves as members of the CLCA. Further, number of parcels tilled by the farmer, attendance in training and sitio meetings, slope of the parcel tilled, and the area of the parcel have a significant statistical association with contour farming adoption. The study also found that the CLCA lacks self-sufficiency in funds generation and needs to lock down on the membership selection criteria and benefits in order to sustain its activities in the future. The CLCA's mechanism for participatory governance and democratic selection of its leaders is well in place. The results and insights gained from the findings of this research paper are relevant for policy makers and development project designers in creating programs and schemes aimed at catching the "elusive" adopters of technology -- traditional farmers from the developing countries. Donation

Seed Dormancy and Comparative Longevity in two Sub-Species of Vernonia Galamensis(Nairobiensis& Afromontana Var. Gibbosa) (Cass.) Less

2021-10-14T06:44:21Z

Seed Dormancy and Comparative Longevity in two Sub-Species of Vernonia Galamensis(Nairobiensis& Afromontana Var. Gibbosa) (Cass.) Less ONDIEKI, Desterio Nyamongo Vernofliagalamensis (Cass.) Less. is a potential industrial oil crop whose seeds contain 35-45% of triglyceride oil rich in vernolic acid, a naturally epoxidized fatt~ acid with low viscosity. Naturally epoxidized, vernolic acid is a potential useful raw material for manufacturing paints and coatings. Exploitation of V galamensis as a crop is however hampered by poor seed retention and ill understood seed dormancy characteristics. To address the issues of seed retention, seed maturation studies were conducted with a view to establishing morphological markers of seed maturity that shall enable determination of the optimum seed harvesting point. Changes in seed colour were monitored during seed development. Seeds harvested at different maturity levels were subjected to desiccation and germination evaluationto tease the onset of germinability dormancy and storability. In addition, changes in seed water status and seed mass during seed development were monitored to establish the point at which seeds acquired mass maturity. It was found that a "scorched earth" (dark brown) achene colour largely denoted a common indicator of mass maturity to the extent that no seed lot registered any appreciable increase in dry weight subsequent to achievement of this colour. It thus appears reasonable to recommend that harvesting of seeds be undertaken once the achene colour turns scorched earth in order to minimise seed losses due to natural dispersal. In regard to dormancy, seeds harvested at the point of natural dispersal and dried to equilibrium water content at 20°C and 18 - 20% relative humidity were subjected to a variety of dormancy release experiments namely: soaking, de-coating, chilling, alternating temperature after-ripening and gibberellic acid & potassium nitrate treatments, to determine the nature of dormancy and develop appropriate germination testing protocol. The percent germination data were arcsine transformed and subjected to analysis of variance. The results showed that seeds of v MASENO UNIVERSITY S.G. S. LIBRARY the subsp nairobiensis were more dormant than those of the subsp afro montana var. gibbosa. Similarly, seeds harvested from Muguga (with a cooler climate) were shown to be more dormant than those harvested from Maseno (warmer climate). The observed significant positive \ germination response due to nipping, decoating and soaking implicate the role of the seed pericarp in regulating dormancy and/or germination. However, the observed positive response due to 2-weeks of cold chilling at SOC, alternating temperatures, after-ripening, light exposure, potassium nitrate and gibberellic acid (GA3) treatment, point to the nature of dormancy as being of the non-deep physiological type. Moreover, the results of the thermo-gradient plate experiment confirm this non-deep physiological dormancy as being of type II, according to the classification by Baskin and Baskin. Seed soaking for at least 24 hours seems to be the most pragmatic protocol for use by farmers to enhance seed germination in their fields. The same procedure may also be used in laboratory seed germination testing. Alternatively, chilling for at least two weeks at SOC can be used to overcome seed dormancy prior to incubating at 30/2S or 2SI17°C.