School of Agriculture and Food Security

Economic performance and effect of cage-fish farming on Livelihoods of Lake Victoria basin communities in Siaya county, Kenya

2023-12-21T14:19:05Z

Economic performance and effect of cage-fish farming on Livelihoods of Lake Victoria basin communities in Siaya county, Kenya NAMAEMBA, Christine Cage fish farming has been considered as an important approach in increasing productivity and improving livelihoods and has grown rapidly along the Lake Victoria shores and is projected to increase productivity significantly in order to address the diminishing fish supply. Efficient utilization of limited resources is paramount to increasing productivity as well as the impacts of cage farming on livelihoods. However, despite its potential to increase productivity, there still exist a supply gap between the actual achieved yields and the potential yields. Moreover, there is dearth information on effect of cage fish farming on livelihood capitals as well as perception of stakeholders. The overall study objective was to evaluate the economic performance and effects of cage-fish farming on the livelihoods of the communities in Siaya County. Specifically, the study assessed technical efficiency, determined factors influencing technical efficiency of cage- fish farming, evaluated the effects of cage-fish farming on livelihoods of communities and assessed the perceptions of fish stakeholders on cage-fish farming in Siaya County. The study adopted Cobb-Douglas production theory and Sustainable livelihood approach. Descriptive research design was used and multistage sampling technique employed to select the two datasets. Data was collected from cage-fish farmers (n= 292) and from fish stakeholders (n= 217). Primary data was collected using structured questionnaires. Descriptive statistics, Stochastic Frontier Approach and censored to bit regression were used to determine technical efficiency and factors influencing technical efficiency. Sustainable Livelihood index was used to evaluate the effect of cage-fish farming on livelihoods, whereas Principle Component analysis was used to assess the perceptions of fish stakeholders on effects of cage-fish farming. Mean technical efficiency was estimated to be 65%, indicating a possible enhancement of production at the present state of technology and input level to achieve in the short run increased technical efficiency by 35% through adoption of best practices. The combined effect of operational and farm-specific factors that influences technical efficiency significantly were labour, feed, cage size, age, education level, source of capital and cage location (beach and geographical). Sustainable livelihood index of 57% was derived from the study. This demonstrates that the livelihoods in the region had improved from cage-fish farming. Physical capitals were most improved at 73.3%, followed by financial capitals (59.1%) and social capital was least at 44.9%. The study revealed that economic, health, social and environmental perceptions on cage-fish farming were the key considerations and had a total explained variance of 61%. From this study, it is evident that cage-fish farming is important to the livelihoods of both cage farmers and other fish stakeholders due to its positive effect on livelihood changes thus cage-fish farming is a critical strategy for investment. It is therefore important to address the efficient utilization of inputs and factors that influence technical efficiency for increased productivity. Cage-fish farming should be encouraged by providing the necessary production skills for improved cage performance. Furthermore, farmers should diversify their sources of capital to facilitate the adoption of larger cages and enhance marketing for enhanced bargaining power. There is a need for government ministries, departments and agencies, stakeholders, and financial institutions to come up with initiatives or formulate financial products for cage-fish farming investment to provide easy access to farming capital.

Replacement of soybean meal in the diet of Nile tilapia (oreochromis Niloticus) by black soldier fly (hermetia illucens) larvae meal and the cost implications

2023-12-21T14:08:01Z

Replacement of soybean meal in the diet of Nile tilapia (oreochromis Niloticus) by black soldier fly (hermetia illucens) larvae meal and the cost implications MAKOKHA, Simon Shati Soybean meal (SBM) is a plant protein derivative, which is widely used in Nile tilapia (Oreochromis niloticus) feed formulation. However, as a major plant protein source, SBM creates a food-feed competition with a growing demand for both aquaculture and terrestrial animals. In addition, soybean is characterized by deficiency in methionine and cystine, low nutrient digestibility and lesser nutrient bio-availability that limits inclusion levels hence compromising optimal fish growth. It is the limitations of SBM that have prompted search for other alternative protein sources, for fish feed production. This study investigated the effect of replacing SBM with black soldier fly larvae meal (BSFLM) on the growth performance, feed utilization, carcass body composition and amino acid concentration of O. niloticus. Three isonitrogenous (30% crude protein) diets containing BSFLM in varying proportions of 0% (BSFLM0), 50% (BSFLM50) and 100% (BSFLM100), were formulated to replace SBM. A commercial diet (COMM0) sourced from the local market was used as a positive control. Male sex-reversed O. niloticus juveniles of mean weight 20.88± 0.16 g were stocked in 12 cages (8m3) each at a density of 12.5 fish m-3.The cages were suspended in earthen ponds (150 m2) with four cages per pond. Fish were hand fed at 5% (28 days), 3% (54 days) and 2.5% (84 days) of the body weight twice a day (1000hrs and 1600hrs). Significant differences (P < 0.05) were found in the final body weight, body weight gain (BWG), specific growth rate (SGR), feed conversion ratio (FCR), survival rate and Fulton’s condition factor (K). The best growth performance and feed utilization was recorded in fish fed on BSFLM100.The diets had significant (P < 0.05) effects on body composition and amino acid profiles of the experimental fish. Fish fed on BSFLM100 exhibited highest levels of crude protein of the fish carcasses with highest values for phenylalanine, threonine, Isoleucine, lysine, proline and glutamic acid amino acids. On enterprise budget analysis, replacing SBM with BSFLM at 50% and 100% reduced the cost of culturing O. niloticus by 8.8% and 12%, respectively compared to control diet COMM0. The study demonstrated that BSFLM is a cost-effective alternative to SBM in the diets of O. niloticus hence can replace soybean meal up to 100% without negative effect on growth and carcass body composition.

Extent of farmers’ participation in agricultural development projects, perceived project sustainability and their effects on poverty situation in Kakamega county, Kenya.

2023-09-13T12:30:17Z

Extent of farmers’ participation in agricultural development projects, perceived project sustainability and their effects on poverty situation in Kakamega county, Kenya. OKUMU, Janet Julie In recent years the agriculture sector has been highly affected by increasing climate variability and enhanced exposure to extreme weather events. These changes have reduced productivity and led to greater instability in production in the agricultural sector and consequently resulted to increased poverty among the people who primarily rely on rain-fed agriculture for their livelihoods. The government of Kenya and other international development organizations therefore invested massive resources into agricultural development projects due to their contribution towards food security and poverty reduction. However, despite billions of dollars spent on agriculture projects, most of these projects are partially active or the efforts have ultimately ended in halt or failure. Furthermore, farmers’ participation in their own projects has not yet attained the acceptable levels that qualify to imply full participation and high levels of poverty still persists among the rural households. This study aimed at determining the extent of farmers’ participation in agricultural development projects, perceived project sustainability and their effects on poverty situation in Kakamega County. The study sought to determine socio-demographic and institutional factors influencing extent of farmers’ participation in agricultural development projects, determine socio-economic and institutional determinants of perceived sustainability of agricultural development projects and determine the effect of extent of farmers’ participation and perceived project sustainability on poverty situation in Kakamega County. Cochran’s formula for unknown heterogeneous population size was used to determine 384 respondents. Using cross-sectional research design, structured questionnaires were used to obtain primary data from 384 farmers both project participants and non-participants. Interview schedules were also conducted on 12 sub-county agriculture officers as key informants. Systematic sampling technique was employed to select farmers from the sampling frame of all farmers provided at every sub county. From the Tobit regression model analysis, it was established that extent of farmers’ participation in agricultural development projects was positively influenced by the type of project funders and the number of climate smart practices offered by the projects whereas it was negatively influenced by the frequency of extension visits by other extension service providers, distance to the market and legal land ownership status. The ordered probit results demonstrated that the perceived sustainability of the projects was positively influenced by the number of practices adopted from the project, longevity of farmers’ participation and training while it was negatively influenced by legal land ownership status, farming experience and adoption cost. The stepwise regression results revealed that extent of farmers’ participation in projects had a significant positive effect on the poverty situation of farmers at 1 % level of significance while farmers’ perception on sustainability of agricultural projects did not have a significant effect. The study recommends up scaling of agricultural development projects to non-benefiting communities through partnerships between the national government and international agencies funding agriculture in order to offer a wide variety of new climate smart agricultural practices and also enhance high farmer participation in terms of both longevity and high climate smart practice adoption. The projects should also be designed under a bottom-up approach that allows prior assessment of the needs and capabilities of the local farmers. This assists in the development of climate smart agriculture practices and training that is tailored to suit farmers’ different needs and capabilities. In addition they should also explore opportunities for cost-sharing among farmers through collective action or by providing subsidies backed by local institutions that will continue to offer quality training, extension services and other forms of support beyond the project period.

Comparative effects of maize-soybeans and maize-desmodium intercropping systems on yield of component crops and rainfall use efficiency in western Kenya

2023-06-22T15:15:24Z

Comparative effects of maize-soybeans and maize-desmodium intercropping systems on yield of component crops and rainfall use efficiency in western Kenya OSIEYO, Samuel Murunga Inadequate soil moisture ensuing from climate change and variability limits the effectiveness of legumes to increase maize production. Soybeans and desmodium are legumes intercropped with maize to control striga weed, improve soil fertility and prevent soil degradation. However, there exists need to determine their comparative effect on yield and rainfall use efficiency when intercropped with maize in rain-fed maize production. The main objective of this study was to compare the effect of maize-soybeans (MS) and maize-desmodium (MD) intercropping systems on yield and rainfall use efficiency in Western Kenya. The specific objectives sought to compare the effect of maize monocrop (M), MS and MD intercrops on soil moisture trends; determine effect of M, MS and MD intercrops on maize energy yield and; determine the effect of M, MS and MD intercrops on rainfall use efficiency. The study was carried in two sites in Busia and Vihiga during the planting seasons in the year 2015. This was experimental research with treatments of MS intercrop; MD intercrop; and M monocrop. Each treatment was replicated three times in RCBD arrangement. Each experimental plot measured 30 m2. Freshco 425 IR maize, Soybeans HB 19 and Greenleaf desmodium varieties were used. On site rainfall data was collected using rain gauge. Volumetric soil moisture content was measured at 7 days intervals at 5cm, 25cm and 45cm depths using theta probe type ML2X equipment. Crop yields were determined from 15m2 net plot areas by weight for maize and soybeans, and as dry matter weight for desmodium. Yield energy values were determined in kJ using bomb calorimetry to standardize yield units for maize, soyabeans and desmodium then expressed in kJ ha. -1. One-way ANOVA was performed using R software version 3.1.2 to determine whether the cropping systems had effect at 5% level of significance. Tukey Honestly significant difference was used to separate the treatment means that were significantly different. Statistically there were no significant differences in soil moisture trends in the cropping systems in season I and II at both sites. Maize energy yields were also not significantly different in both seasons in the two sites. Statistically significant differences in RUE (P<0.05) only existed in Busia site in season II in favour of intercropping. There was no yield advantage of growing maize as a single crop. Maize can be intercropping with soybeans and with desmodium at the current recommended maize population of 44,000 plants ha-1. Masters Thesis

Effect of inorganic and organic nitrogen sources on the yield, agronomic efficiency and land equivalent ratio of sorghum - groundnut cropping systems in Migori County, Kenya

2023-06-08T14:02:31Z

Effect of inorganic and organic nitrogen sources on the yield, agronomic efficiency and land equivalent ratio of sorghum - groundnut cropping systems in Migori County, Kenya KHAGUL, Ladona Nyanga Persistent droughts, soil infertility and reduced land sizes are major limitations to agricultural productivity in Migori County. Intercropping drought tolerant legumes with cereals such as sorghum and groundnuts is one of the coping strategies that have been proposed but the effectiveness of these systems particularly under various sources of nitrogen (N) is not clear. A study was therefore conducted at Nyabisawa and Piny Oyie in Migori County during the long rains of 2019 to establish the effect of inorganic and organic N sources on the yield and yield components, land equivalent ratio (LER) and agronomic efficiency (AE) of sorghum - groundnut cropping systems. A Randomised Complete Block Design (RCBD) replicated thrice was used. Treatments included: sole sorghum, sole groundnut and sorghum - groundnut intercrop supplied with N from two sources, that is, organic (farmyard manure (FYM)) and inorganic (urea). Crops in the sole sorghum and sorghum - groundnut intercrop received N at rates of 40 and 80 kg/ha from each source and 40 kg N/ha provided by urea combined with FYM in equal amounts (20 kg N/ha from each source). Sole groundnuts received at 20 kg N/ha from each source and 20 kg N/ha provided by urea combined with FYM in equal proportions (10 kg N/ha from each source). There was a zero N input treatment for each cropping system. Sowing was at the onset of the rains and harvesting done at physiological maturity. The effectiveness of intercropping was determined using LER while the agronomic efficiency was determined using AE. All data were subjected to analysis of variance and the significant treatment means were separated using LSD (p ≤ 0.05.) Synergism was observed where use of 40 kg N/ha from combined sources significantly increased the sole sorghum plant heights above the unfertilized sole sorghum and also gave the tallest plants at 4, 6 and 8 WAP and the highest sorghum grain and stover yields at Nyabisawa and Piny Oyie. In the intercrop however, the use of N from urea at 40 and 80 kg N/ha from urea and 80 kg N/ha from FYM became important considering the higher demand for minimal resources available in the intercrop. The unfertilized intercropped sorghum had the shortest plants and lowest grain and stover yields in both sites due to the N deficiency which had not been managed thus the need to supply N to the crops so as to improve their yields. In groundnuts, the yields of sole groundnuts to which 20 kg N/ha from urea was applied were significantly superior compared to those supplied with 20 kg N/ha from FYM. Only FYM applied at 20 kg N/ha on sole groundnuts significantly increased the groundnut pods per plant and the biomass yields above the unfertilized sole groundnuts at Nyabisawa. Intercropping was beneficial (LER>1) where 0 kg N/ha, 80 kg N/ha from urea and 80 kg N/ha from FYM were applied. The AEs decreased with increasing N rates in the sole sorghum, while in the intercrop, they increased with increasing N rates. This was observed where sole sorghum that received 40 kg N/ha from urea and the combined sources had significantly higher AEs than those that received 80 kg N/ha from urea and FYM at Nyabisawa and those that received 80 kg N/ha from FYM at Piny Oyie. In the intercrop, it was noted that where 80 kg N/ha from urea and FYM was supplied, the AEs were significantly higher than those which received 40 kg N/ha from combined sources at Nyabisawa and Piny Oyie. In sole groundnuts however 20 kg N/ha from urea had a significantly higher agronomic efficiency compared to all the other treatments since the crops needed N before they were well established to start fixing their own N. In conclusion, the application of 40 kg N ha–1 from combined sources in sole sorghum, 20 kg N ha–1 from urea in sole groundnuts and either 80 kg N ha–1 from urea or FYM on the intercropped sorghum and groundnuts gave the best yields and could be recommended to farmers for adoption especially when production is done under similar conditions

Assessing the contribution of fisheries management strategies on compliance to fisheries regulations by fisher folk in lake Victoria: a case study of Busia county, Kenya

2023-03-17T13:43:46Z

Assessing the contribution of fisheries management strategies on compliance to fisheries regulations by fisher folk in lake Victoria: a case study of Busia county, Kenya ODENDE, Timothy Fisheries resources in Lake Victoria have been under immense pressure leading to over utilization and decline of fish. Fisheries resources support livelihoods, generate income, ensure food security, and provide raw materials used in animal feeds and pharmaceutical industry. However, fisheries resources have faced ecological challenges in many freshwater lakes worldwide. Lake Victoria’s ecological health has been deteriorating due to overfishing, use of illegal fishing gears and fishing methods. Fisheries management strategies and regulations have been enacted to regulate fishing in Lake Victoria. However, it was not known whether these strategies could enhance fisher folks’ compliance to fisheries regulations. In addition, Busia County government introduced aggregated farming practices as income diversification. However, it was unknown whether these alternative farming practices could improve fisher folks’ compliance with fisheries regulations. Therefore, the goal of this study was to evaluate the impact of fisheries resources management strategies on fishermen's compliance to fisheries regulations in Busia County, Kenya's Lake Victoria. The objectives were to: Examine the perceptions of fisher folks towards the types of fisheries management strategies and fisheries regulations; determine the relationship between types of punitive measures and compliance with fisheries regulations; and determine the relationship between categories of alternative livelihoods and compliance with fisheries regulations. Descriptive cross-sectional research design was used in this study. The study population consisted of 4200 participants including fishermen, boat owners, fish merchants, regional manufacturers of fishing gear, and equipment dealers. The sample size of 324 respondents was calculated using Kothari (2004) formula. Primary data was gathered from 13 landing beaches in the Samia and Bunyala sub counties using structured questionnaires, Key informant interviews and focus group discussions. Frequencies and percentages were used to present the data, and the Chi-square test of independence and Spearman Rank correlation were used to investigate the relationships between the variables. The results showed that respondents strongly agreed (r=0.714) that current laws and regulations were easy to understand but the approaches used were ineffective. In addition, the respondents strongly agreed (r=0.896) that even though fishermen are aware of fisheries regulations, they are forced by hard economic conditions to violate income diversification approaches. Types of punitive measures such as closed seasons, fish landing areas restrictions, fishing areas restrictions, fishing methods restrictions and gear size restrictions showed a statistically significant (p < 0.01) association with compliance to fisheries regulations. Moreover, alternative livelihoods: Aggregated horticulture farming (χ26=30.35, p=0.00003), aggregated dairy and poultry farming (χ26=21.38, p=0.0016) and aggregated aquaculture farming (χ26=94.79, p=0.0000) showed statistically significant association with compliance to fisheries regulations. In conclusion, stakeholders had positive attitude towards fisheries management strategies and regulations. Low compliance to fisheries regulations led to dwindling fish stocks. Strengthening punitive measures and aggregated farming practices could enhance compliance. There was need to create awareness on fisheries management strategies and regulations, and build capacity on aggregated farming practices to enhance compliance with fisheries requlations among the fisherfolks. Masters Thesis

Effect of subsidy program on fertilizer usage and maize-grain Productivity among small-scale farmers in Kakamega county, Kenya

2022-12-19T14:45:32Z

Effect of subsidy program on fertilizer usage and maize-grain Productivity among small-scale farmers in Kakamega county, Kenya Mulupi, Dennis Kimoso The continuous use of land over some time has undermined the availability of soil nutrients globally. The decline in soil fertility is among the main challenges facing crop productivity, especially in Africa. To counter the soil nutrients issue, farmers are required to intensify the application of fertilizers. However, inorganic fertilizer application rates in Sub-Sahara Africa remain low compared to other developing regions. A number of government-led interventions and strategies have been introduced to raise fertilizer usage. One policy instrument so far implemented is the fertilizer subsidy program for small-scale farmers. Despite, the criticisms on targeting and voucher allocation procedures, fertilizer subsidies continue to be implemented by national and county governments in Kenya. However, there has not been much achievement in the overall crop yields, especially for maize where productivity is declining despite the continued subsidies for fertilizer as reported in the Kakamega County Integrated Development Plan. This study sought to estimate the proportions of subsidized fertilizer utilized, determine the socio-economic factors affecting the proportions of subsidized fertilizer utilized in the overall inorganic fertilizer usage, and determine the effect of the subsidized fertilizer program on maize-grain productivity among small-scale maize farmers in Kakamega County. The study adopted rational choice theory and theory of production using a Cobb-Douglas function to estimate maize-grain yields attained by farmers. This study was done in Malava and Mumias East Sub-counties on a study population of 44,098 farmers targeting 80% of farmers practicing maize farming; representing the sub-counties with the highest and least number of farmers in Kakamega County. The study employed a crosssectional survey design using semi-structured questionnaires to obtain data from 300 farmers, selected using a multi-stage sampling technique. Descriptive statistics were used to estimate proportions of subsidized fertilizer utilization, a Tobit regression model to determine the socialeconomic factors influencing proportions of subsidized fertilizer utilized, and a two-stage probit and Tobit approach controlling for program selection bias to determine the effect of the fertilizer subsidy program on maize-grain productivity. Results revealed that the average proportion of subsidized fertilizer utilized was 59.48% among subsidy program participants. Moreover, the findings showed higher average fertilizer usage of 85.6 kg/ha among the program participants compared to 74.9 kg/ha for non-participants. The proportion of subsidized fertilizer usage by farmers was significantly influenced by the farm size under maize, household size, quantities of seeds planted, age and education level of the household head, distance to the input market, and amount of credit borrowed. Tobit model results showed that subsidy program participation led to an increase in maize-grain productivity by 32.3%, after controlling for actual fertilizer quantities, seed quality, and household socio-economic characteristics. The average maize productivity was 2.216t/ha with Malava having a significantly higher average of 2.265t/ha compared to Mumias East at 2.11t/ha. Farmers who benefited from the subsidy program had average productivity of 2.46t/ha significantly higher than non-participants who had an average of 1.97t/ha. However, despite this positive effect, the fertilizer subsidy program in Kakamega County has not been able to increase maize yields to the potential production levels (5.5 t/ha), since the average fertilizer usage is still low as compared to what is recommended for the county for it to make an impact on productivity. The study recommends the subsidy program as a good strategy to attain the recommended application rates of 200 (NPK) and 150 (CAN) kg/ha as the participants have higher fertilizer application rates. Moreover, policymakers need to consider the socio-economic factors of small-scale farmers when formulating policies on allocation, as they are the main target for the program to attain optimal fertilizer application, and increased maize productivity.

Characterization of the genetic diversity of Cercospora zeina in Kenya and mapping the qtl for resistance to gray leaf spot and Turcicum leaf blight in maize

2022-12-19T13:58:08Z

Characterization of the genetic diversity of Cercospora zeina in Kenya and mapping the qtl for resistance to gray leaf spot and Turcicum leaf blight in maize OMONDI, Dennis. Oduor Gray leaf spot (GLS) caused by Cercospora zeina in Africa and Turcicum leaf blight (TLB) caused by Exserohilum turcicum are a major threat to maize production due to the associated grain yield losses. Resistance in the currently grown maize hybrids could be overcome by high levels of genetic diversity that characterizeC. zeina and E. turcicum populations. However, little is known concerning the population structure and diversity of C. zeina in Kenya. The objectives of this study were firstto characterize the genetic diversity of C. zeina. Secondly to map the quantitative trait loci (QTL) conditioning resistance to GLS and TLB in the double haploid (DH) population from CML511×CML546. The genetic diversity of C. zeina and the role of sexual recombination in this population was determined by collecting GLS infected maize leaves from four counties in Kenya. The genomic DNA for the 129 successful isolates were assayed using previously designed mating type (MAT) primers and genotyped using 11 microsatellite markers. The CTB7 (cercosporin toxin biosynthesis 7) test confirmed that all the isolates sampled were C. zeina as they all produced PCR products of 618 bp. The population exhibited high levels of gene diversity (He=0.445), slightly high gene flow (Nm=3.85) and high level of polymorphism. In addition, the four counties were characterized by nearly equal distribution of the two mating types, providing evidence that it could be undergoing sexual recombination. Occurrence of sexual recombination could be responsible for the high genetic diversity. STRUCTURE analysis revealed that the population clustered into four sub-groups according to the four counties. The PhiPT value of0.15 (p=0.001) corroborated with AMOVA tests was significant to provide evidence for partial population differentiation. QTL mapping was achieved by evaluating the DH population in Maseno and Kabianga in a 5×46 alpha lattice design during the long rains of 2018 and 2019. The disease incidence for the plots were scored on a scale of 1-9 and the best linear unbiased predictions determined using META-R statistical software. Marker genotyping of the population was performed using 1250 markers in diversity arrays technology (DArTseq). Linkage map construction and QTL analysis were conducted in QTL IciMapping v4.1. Nine GLS resistance QTLs were mapped on the chromosomal bins 1.06, 1.07, 1.11, 2.04, 2.06, 3.04, 3.05, 4.1 and 7.04.Fourteen TLB resistance QTLs were detected on the chromosomal bins 1.02, 1.08, 2.05, 2.06, 2.07, 3.01, 3.04, 4.02, 4.08, 5.03, 6.05, 7.03, 8.08 and 10.04. The QTLs were detected in at least two environments. The highest phenotypic variance was conditioned byqGLS1_190(16.60%) for GLS and qTLB8_171 for TLB (13.65%). Disease resistance was negatively correlated with flowering time suggesting higher resistance in the late maturing genotypes. These findings will enhance proper identification of the pathogen causing GLS and GLS management programs. The identified QTLs and their flanking markers could be validated and fine mapped in future work for use in breeding for resistance to GLS and TLB. Masters Thesis

Propagation of Uapaca Kirklana Using Tissue· Culture Techniques

2022-03-24T09:15:26Z

Propagation of Uapaca Kirklana Using Tissue· Culture Techniques MALIRO., Moses F.A A study on propagation of Uapaca kirkiana using tissue culture-techniques was done G ' at Bunda College of Agriculture. Experiments were conducted on In Vitro and In Vivo seed germination; axillary shoot proliferation using seedling stem nodal sections; direct organogenesis and callus development from stem shoot sections, adult tree leaf and cotyledonous explants; and root development. Explants were fruits obtained from a local market, some fruits direct from trees and adult tree explants were obtained from Uapaca kirkiana provenance near the College. Treatments in the seed germination experiments included surface sterilization of seeds with four different concentrations of sodium hypochlorite (NaOel) and four exposure times; primary and secondary seed-coat removal; split-plot treatments of two fruit sources (market and direct from trees) as main factors, and two seed germination media - Murashige & Skoog (MS) and Woody Plant Medium (\VPIYf) as subplot factors. Another seed germination experiment was set up in a green house with the two fruit sources as main factors and primary seed-coat removal and non-removal as sub- factors. The axillary shoot proliferation experiment used seedling stem nodal sections as explants. Treatments included 0, 5, 10, 20, 40, 80, and 160 mg/l of kinetin growth regulator supplement on WPM media in a preliminary test. A detailed experiment followed with a split-plot design which included five indole butyric acid (IBA) levels (0.0,0.25,0.50, 1.00,2.00 mgll) as main factors and the same five levels of kinetin as sub-factors. The direct organogenesis and callus experiments tested three types of tree organs which included adult stem shoot sections, leaf sections and cotyledonous VI leaf sections. MS basal salts media were supplemented with 2mgll lAA +2mgll kinetin+ 1Omgll inositol and White vitamins and glycine + 80mg(l adenine sulphate + IOmg/1tyrosine for direct organogenesis; and 2mglllAA + O.5mgJIkinetin for callus development. Explants for rooting experiment were obtained from axillary shoot proliferation plantIets and tested on rooting media in a split-plot design. The main factors were two basal salts (MS and \VPM) and subfactors were five IBA growth regulator levels (0.0 IBA, 0.5 IBA, 0.5 IBA + 0.5 NAA + 0.5 BAP, 1.0 IBA and 2.0 IBA in mgll. The containers used for media were 25mm x 150mm belli co tubes with 20 ml quantities. Each treatment had N=20 cultures. Incubation of cultures was done under 16 hours light illumination at 4511EM~-1 except for callus cultures which were incubated under 24 hour darkness. Temperatures were maintained within the range of 25 to 28°C. The data collected was subjected to Analysis of Variance and regression analysis where necessary. "... ,. Optimum concentration of NaOCl "for surface sterilization for the U kirkiana seeds was 2% for 20 minutes. Removal of both primary and secondary seed-coats promoted the number of aseptic seedlings. The !viS medium gave significantly higher frequency of normal seedlings (90%) and multiple seedlings/seed (90%) than \VPM medium in the first experiment. When the experiment was repeated the effect of the two media did not significantly differ. Primary seed-coat removal improved in vivo germination from 55% to 780/0and from 35% to 95% for market fruits and fruits direct from trees respectively. The seeds exhibited apomixis with a maximum of 9 seedlings/seed for VIl in vitro, and 2 seedlings/seed for in vivo germination. The high number of shoots that developed per axillary nodal bud section was achieved with supplementation of 0.50 mg/l kinetin alone (1.3 shoots) or combined with 0.25 mg/l IBA (I.Ishoots), 2.0 mgll kinetin alone (1.1shoOLS)or combined with 0.5 mgll IBA (1.3 shoots). The direct organogenesis and callus cultures did not regenerate into adventitious plantlets but just developed callus and embryoids. The stem sections had a high callus development frequency (67.5% partial and 15% full) followed by cotyledonous sections (27.5% partial and 200/0 full). Adult tree leaf explant callus development failed because all cultures had fungal contamination. The subcultured calli proliferated fastest on \VPM supplemented with 3.0 mg/l IAA. Higher ratios of kinetin to auxin (IAA) slowed calli proliferation. In the rooting experiments, MS media containing 1.0 and 2.0 mg/l IBA promoted rooting at 65% (1.7 roots/plantlet) and 60% (1.3 roots/plantlet) respectively, than lower levels of IBA. The MS media promoted better rooting (0.7roots/plantlet) than the WPM media (0.4 roots/plantlet). Further investigation on media protocols to improve adventitious axillary shoot proliferation and rooting performance to ensure high field survival of the U. kirkiana plantlets is suggested. Chemical names used: 6-furfurylaminopurine (kinetin); benzyladenine (BA); N6-benzylaminopurine (BAP); 1 H-indole-3-butyric acid (IBA); 2-naphthaleneacetic acid (NAA); indole-3-acetic acid (IAA); and gibberellic acid (GA3)·

Response of selected sorghum (sorghum bicolor (l.) Moench) genotypes to striga hermonthica (del.) Benth in western Kenya

2021-06-30T08:48:54Z

Response of selected sorghum (sorghum bicolor (l.) Moench) genotypes to striga hermonthica (del.) Benth in western Kenya OCHIEL, Dauglas Claoudious ABSTRACT Sorghum (Sorghum bicolor (L.) Moench) is an important staple food crop in western Kenya, but its yields are low due to many constraints including; pest and diseases, drought, soil acidity, and parasitic weed Striga hermonthica. In recent years, Striga has been a major cause of yield reduction in western Kenya owing to declining soil fertility and susceptibility of existing cultivars. Several control options such as chemical, biological and cultural methods have been utilized but only with little success realized. This has created renewed interest in resistance breeding for its proper management. The objectives of this study were to: determine the numbers of induced and maximum distance of germinated Striga seeds under laboratory conditions and assess the response in yield components and yield in the selected sorghum genotypes under field Striga hermonthica infestation. A total of 21 sorghum genotypes, 7 obtained from each institution; International Crop Research Institute for the Semi-Arid Tropics, Rongo and Maseno Universities were evaluated in Agar Gel (AG) experiment in Maseno botanical laboratory and in an on-farm trial at Kadel and Nyahera under natural Striga infestation. The AG experiment and field trials were respectively set up in three replications in a completely randomized design and randomized complete block design. Variance analysis (ANOVA) and mean field Striga counts, numbers of induced germinated Striga seeds, Striga damage ratings, maximum distance of the germinated Striga seeds, and yield components and yield were analyzed using a Statistical Analysis System (SAS) software package (release 6.1) tested for significance at 5% level and means separated using L.S.D 5%. Significant differences (p<0.001) were realized both in the fields (plant height, dry shoot biomass yield, grain yield, field Striga count, and Striga damage ratings) and in the AG experiment with respect to maximum germination distance and numbers of induced germinated Striga seeds. Among the sorghum genotypes evaluated, T53B, N57, N68, C26, IESV 92036-SH, T30B, and Uyoma 47 white genotypes had stable yields under Striga infestation in the two sites whereas Nyadundo1, Nyadundo 2, and Uyoma 8 were susceptible. In the AG experiment, E117B, T30B, Uyoma 8, Uyoma 42 STR, and T53B induced high numbers of germinated Striga seeds with maximum germination distances (MGD). In contrast, Uyoma 47 Brown, IESV 92038/2-SH, and IESV 92036-SH sorghum genotypes induced the germination of few Striga seeds with low MGD. This study has identified and selected four Striga tolerant (T53B, N68, N57, and T 30B) and three resistant ( C 26, Uyoma 47 Brown, and IESV 92036-SH) sorghum genotypes which can be utilized in further research programs or adopted to improve sorghum productivity in the highly Striga infested regions of western Kenya. Masters Thesis