Department of Biotechnology
http://41.89.164.27:8080/xmlui/handle/123456789/192
2024-03-28T13:25:14ZIDENTIFICATION OF DROUGHT TOLERANT KENYAN BRACHIARIA ECOTYPES USING DROUGHT TOLERANCE INDICES
http://41.89.164.27:8080/xmlui/handle/123456789/2101
IDENTIFICATION OF DROUGHT TOLERANT KENYAN BRACHIARIA ECOTYPES USING DROUGHT TOLERANCE INDICES
Awalla, B. J.; Were, B. A; Binnot, J.
Drought is one of the major abiotic stress factors limiting agricultural productivity globally. Brachiaria also known as signal grass is a native of sub-tropical and tropical Africa and important in livestock production. The grass has many advantages including; high biomass, high nutritional value, adaptation to drought and low fertility soils, sequestration of carbon, enhanced nitrogen uses efficiency and low greenhouse gas emissions. Emergence of climate change with increased global temperatures has led to prolonged drought which has adversely affected the improved Brachiaria hybrids. Locally available ecotypes are a rich source of unique genes and characteristics that could be key in developing drought resilient hybrids. The objectives of this study were to i) assess the effectiveness of various indices in selection of drought tolerant Kenyan Brachiaria ecotypes, ii) evaluate the relationship between the indices and iii) to identify high yielding and stable ecotypes under stressed condition. The design of the experiment was completely randomized design (CRD) with three replications in a factorial arrangement (3 x 25). A total of 11drought tolerance indices; tolerance (TOL), stress Tolerance Index (STI), mean productivity (MP), yield stability index (YSI), Geometric Mean Productivity (GMP), stress susceptibility index (SSI), Yield Index (YI), harmonic Mean (HM), drought intensity index (DII), modified stress tolerance k1 and modified stress tolerance k2 were calculated based on shoot biomass production under non-stressed (YP) and stressed (YS) conditions. Rank means, rank sum and standard deviation were also used to identify the tolerant materials. In the previous experiment, various physiological parameters were scored which included; leaf relative water content, relative chlorophyll content using SPAD -502 Chlorophyll meter (Minota Co), leaf fresh weight, leaf dry weight and leaf relative water content. Relative water content was also estimated and comparative scores were done between control, medium and extreme or water deficit experiments. Based on all the indices and ranking, BrK 1, BrK 6, BrK 7, BrK13 and BrK 18 were the most tolerant in stressed condition. These ecotypes can be recommended for planting in areas prone to drought. More studies on the identified tolerant ecotypes are essential to ascertain whether the materials hold unique genes that could later be introgressed into various breeding schemes to confer tolerance.
2023-06-01T00:00:00ZDiscovery of genomic regions associated with grain yield and agronomic traits in Bi-parental populations of maize (Zea mays. L) Under optimum and low nitrogen conditions
http://41.89.164.27:8080/xmlui/handle/123456789/2091
Discovery of genomic regions associated with grain yield and agronomic traits in Bi-parental populations of maize (Zea mays. L) Under optimum and low nitrogen conditions
Kimutai, Collins; et al.
Low soil nitrogen levels, compounded by the high costs associated with nitrogen
supplementation through fertilizers, significantly contribute to food insecurity,
malnutrition, and rural poverty in maize-dependent smallholder communities of
sub-Saharan Africa (SSA). The discovery of genomic regions associated with low
nitrogen tolerance in maize can enhance selection efficiency and facilitate the
development of improved varieties. To elucidate the genetic architecture of grain
yield (GY) and its associated traits (anthesis-silking interval (ASI), anthesis date (AD),
plant height (PH), ear position (EPO), and ear height (EH)) under different soil
nitrogen regimes, four F3 maize populations were evaluated in Kenya and
Zimbabwe. GY and all the traits evaluated showed significant genotypic
variance and moderate heritability under both optimum and low nitrogen
stress conditions. A total of 91 quantitative trait loci (QTL) related to GY (11)
and other secondary traits (AD (26), PH (19), EH (24), EPO (7) and ASI (4)) were
detected. Under low soil nitrogen conditions, PH and ASI had the highest number
of QTLs. Furthermore, some common QTLs were identified between secondary
traits under both nitrogen regimes. These QTLs are of significant value for further
validation and possible rapid introgression into maize populations using markerassisted
selection. Identification of many QTL with minor effects indicates
genomic selection (GS) is more appropriate for their improvement. Genomic
prediction within each population revealed low to moderately high accuracy
under optimum and low soil N stress management. However, the accuracies
were higher for GY, PH and EH under optimum compared to low soil N stress. Our
findings indicate that genetic gain can be improved in maize breeding for low N
stress tolerance by using GS.
2023-10-01T00:00:00ZPERFORMANCE EVALUATION OF A PROTOTYPE VARIABLE PITCH IRISH POTATO GRADER
http://41.89.164.27:8080/xmlui/handle/123456789/2055
PERFORMANCE EVALUATION OF A PROTOTYPE VARIABLE PITCH IRISH POTATO GRADER
KIBOR, DAVID TIROP
The manual grading of potatoes in Kenya has resulted in inconsistencies, quality variations and financial losses for small-scale farmers due to low market prices for ungraded products. To mitigate these challenges, this study aimed to develop and evaluate the performance of a cost-effective potato grading machine to enhance uniformity and overall quality of potato tubers. The research involved determining the physical and mechanical properties of Shangi potato variety. The prototype potato grader consisted of a feeding hopper, conveyor belt, grading unit, and collection trays. Grading capacity, grading efficiency, and mechanical damage index were assessed by varying grading unit speeds, angles of inclination and feed rates. The results showed that the grading capacity increased with higher grading unit speeds, inclination angles, and feed rates. The optimal operating conditions were observed at a grading unit speed of 4 rpm, an inclination angle of 0 degrees, and a feed rate of 3400 kg/hr. The prototype potato grader achieved a commendable grading capacity of 3968 kg/hr, with an efficiency of 89.34% and a low mechanical damage index of 2.94%. The results demonstrate that the potato grading machine effectively enhances grading while minimizing mechanical damage. This grading machine offers efficiency a practical and sustainable solution for small-scale farmers to produce high-quality graded potatoes in line with market demands. It is recommended that future research may include further optimization by exploring various grading unit speeds, feed rates, and inclination angles. Implementing padding on the collection trays could further reduce mechanical damage. Additionally, investigating alternative power sources may enhance the grader's versatility and extending testing to other fruits and vegetables would broaden its applicability in the agricultural industry.
2023-10-01T00:00:00ZMORPHO-GENETIC DIVERSITY OF GAMMA IRRADIATED DOLICHOS BEAN (Lablab purpureus (L.) Sweet) GENOTYPES FOR CLIMATE CHANGE ADAPTATION.
http://41.89.164.27:8080/xmlui/handle/123456789/2043
MORPHO-GENETIC DIVERSITY OF GAMMA IRRADIATED DOLICHOS BEAN (Lablab purpureus (L.) Sweet) GENOTYPES FOR CLIMATE CHANGE ADAPTATION.
KIMNO, STEPHEN KIPCHIRCHIR
Dolichos bean (Lablab purpureus (L.) Sweet 2n=22 or 24 is a multipurpose legume mainly grown and used as a pulse, forage feed and in soil amendment for nitrogen fixation and green manure. Practically, it still yields below estimated potential of over 5000 kgha-1. Induced crop mutagenesis is a safer conventional breeding method and has played a major role in increasing global food security. The main objective of the study was to contribute to climate change adaptability through gamma ray irradiation of dolichos bean genotypes and selection of climate smart allelic accessions. Specific objectives were to: evaluate the effect of gamma irradiation doses on morpho-agronomic traits of mutant dolichos bean accessions, assess genetic variability estimates, determine the genetic diversity, and evaluate nutritional and mineral composition and to evaluate the adaptability potential of mutant accessions in north rift Kenya. Four dolichos bean varieties (maridadi, cream, black I and black II) were irradiated with 300 gy and 400 gy gamma rays in 2018 in Austria. The M1 to M4 generations of the accessions of four dolichos bean genotypes were advanced by forward genetics protocol at University of Eldoret in 2019 through 2021.M2 accessions were evaluated for effect of mutation and genetic estimates, 95 M3s for genetic diversity based on 20 SSR markers, 24 M4s were screened for nutritional and mineral composition and yield and adaptability potential. The results showed that dose 300gy and 400gy significantly (p=0.05) increased leaf length, raceme length, dry seed yield per plant and plant height across the accessions. Qualitative phenotypic variations were present in all mutant accessions except black I. There was a higher genetic estimate variability for the yield associated traits measured for eldo maridadi than for eldo black I indicating difference in genotype and impact of mutation. Genetic diversity of 95 accessions based on microsatellite markers produced 20 polymorphic primers mapping an average of 5.25 alleles per locus, polymorphic information content of 0.58 with analysis of molecular variance (AMOVA) among population of 45% and among and within individuals 54% and 1%.The nutritional test showed that accession BF032 (28.86±0.18%), MT076 (74.88±0.59%), BF137 (9.69±0.34%), MT049 (12.55±0.57%) and BT188 (449.69±0.02 kcal) had significantly higher percent crude protein, carbohydrate, crude fat, crude fibre and energy. WT018, BT114 and BT039 had significantly higher phosphorous, potassium, calcium and zinc (0.58±0.21mg/l, 2.81±0.00 mg/l, 175.65±2.27 mg/l and 3.64±2.29 mg/l respectively). Accessions BT188 (3919 kgha-1), MT049 (3315 kgha-1), GT032 (3512 kgha-1) and WT026 (4462 kgha-1) were identified as adaptable and best yielding while Baringo as the best location for dolichos production. The use of gamma irradiation in generating genetic variability in Kenyan dolichos bean genotypes for climate change adaptation was effective. The best accessions on nutrition and yield adaptability are an important genetic resource for building resilience to climate change in Kenya.
2023-10-01T00:00:00ZEvaluation of Proximate and Mineral Composition of Mutant Dolichos Lablab (Lablab purpureus L.) Accessions in Kenya
http://41.89.164.27:8080/xmlui/handle/123456789/1973
Evaluation of Proximate and Mineral Composition of Mutant Dolichos Lablab (Lablab purpureus L.) Accessions in Kenya
Kimno, S. K.; et al.
Plant breeding through induced mutation technology is a potent method to creating new variants of
food crops with of desirable phenotypic, genetic and biochemical functions. It is a catalyst in
developing improved crop varieties where classical hybridization or selection have limitations. It has
been used to improve nutrition quality and higher yield in a number of legumes. Dolichos Lablab
(Lablab purpureus L) is multipurpose legume that has not been exploited extensively for food
nutritional properties through breeding. The purpose of the study was, therefore, to generate
awareness that nutritional status of D. Lablab could be improved through mutation induction and be
a good source of food components essential for good health. Twenty-four dolichos Lablab
germplasms including 20 mutant accessions and 4 commercial genotypes were evaluated for
proximate values and mineral contents in Kenya in 2021 based on Association of Official Analytical
Chemists (AOAC). Data analysis was based on least significant difference (P = .05).The revealed
percent moisture, ash crude fat, crude fibre, crude proteins and total starch content ranged :
7.35% -11.84%, 1.09 -2.90%, 3.35% - 8.05% , 8.86 - 12.70% , 20.03% - 28.87% and 25.50% -
39.00% .The mineral content of phosphorous (P), potassium(K) and calcium (Ca) ranged from
27mg - 57mg, 132mg -297mg and 7mg - 19mg. A significant positive correlation between ash
levels to P and K concentration and on P to K concentration. The result of analysis ranked 9
(WT026, WT018 ,MT110 , BT188 , BT032, BT114, MT076 BT137,GT09) different accessions that
positively contributed to the nutritional content of the investigated dolichos lablab accessions.
Further research on the superior accessions can be done on yield potential, resistance to biotic and
abiotic constrains, sensory preferences or used in bio fortification of existing genotypes.
2021-08-01T00:00:00ZCharacterization of effect of Gamma ray on morpho-Agronomic traits of dolichos Lablab (Lablabpurpureus I.) sweet
http://41.89.164.27:8080/xmlui/handle/123456789/1970
Characterization of effect of Gamma ray on morpho-Agronomic traits of dolichos Lablab (Lablabpurpureus I.) sweet
Kimno, S. K.; et al.
Lablab purpureus (L.) Synonym Dolichos lablab (L.) Sweet; is a minor and an important multipurpose legume. Despite this it classified as an orphaned crop hence few studies on its improvement have been undertaken. Limited studies have been carried out on use of mutation on dolichos improvement. Four elite Lablab genotypes coded G1, B1, M5 and W7 were mutagenized with two doses of gamma radiation 300Gy and 400 Gy with objective to study the effect of mutation on various agronomical traits at M2 generation. Data on effect of irradiation on lablab was collected 10 randomly selected plants of on each plot .The traits evaluated were leaf length, leaf width, number of raceme per plant, raceme length, pod length, pod width, plant height, dry seed yield per plant and seed length and seed width. For these traits mean of mutant plants was significantly different from mean of control plants at P≤0.05. Mutant accessions of B1, M5 and W7 genotypes exhibited wide mutation spectra after mutagenesis of albino, leafiness, upright single stem, seedless pod, short dwarf pod, variegated leaf, variation in flower colour, variation in
growth habit, leaf shape, seed colour. Gamma irradiation doses of 300 Gy and 400 Gy were potent in mutagenesis of the studied dolichos lablab. The agronomically diverse mutants are an important resource for dolichos improvement through breeding and genetic studies. Mutants with variegated leafs and flower colour can be used in the landscaping while those different seed colour could be used in the improvement of sensory and cooking qualities of other native dolichos lablab beans
2021-09-01T00:00:00ZGenetic Variability, Heritability and Genetic Advance of Yield and Yield Contributing Characters in Putative M2 Dolichos Bean (Lablab purpureus L.) Accessions
http://41.89.164.27:8080/xmlui/handle/123456789/1963
Genetic Variability, Heritability and Genetic Advance of Yield and Yield Contributing Characters in Putative M2 Dolichos Bean (Lablab purpureus L.) Accessions
Kimno, S. K.; et al.
Dolichos bean (Lablab purpureus L.) is a multipurpose, orphan leguminous crop in Kenya .It is characterized with narrow genetic diversity and low yield output. Use of nuclear techniques such as gamma ray induction in breeding for improved genetic variability is an effective approach in improvement of this important crop. Studies on genetic variability estimates of two Kenyan dolichos bean accessions were undertaken as the pre-requisites for selection of potential high yielding putative accessions for production. This study was conducted between May 2020 and October 2020
at biotechnology department, University of Eldoret research field, Kenya. 0gy, 300gy and 400gy mutant accessions of Eldo maridadi and Eldo black I respectively were raised in Randomized Complete Block Design (RCBD) with three replications. Data was collected either on plot basis or from randomly taken 3 plants on days to 50% flowering, leaf length, number of flower buds per race , raceme length (cm) , plant height (cm), number of nodes per raceme , pod length (cm), 100 seed weight (g), dry seed yield (g). The data collected for each quantitative trait was subjected to analysis of variance (ANOVA) for simple lattice design. There was high PCV and GCV coupled with high heritability in, raceme length (cm), plant height (cm), number of nodes per raceme, pod length (cm), 100 seed weight (g), dry seed yield per plant (g) in Eldo black I accession traits than in Eldo maridadi .The different accession following mutation did exhibit difference in trend of genetic variability estimates. An indication of genotypic differences, response to mutation, lesser influence of environment in expression of the traits, prevalence of additive gene action in their inheritance and amenability of the traits to simple selection. Eldo maridadi accessions exhibited high to low heritability with low genotypic advance as percent of mean in evaluated traits thus direct selection on this traits may not beneficial. Other traits or further improvements on yield potentiality and yield traits on the accessions of this genotype are suggested by creating variation and selection.
2023-03-01T00:00:00ZIDENTIFICATION OF NEW MOLECULAR MARKERS FOR DIVERSITY ANALYSIS AND BREEDING FOR EARLY MATURITY AND DETERMINATE LABLAB (LABLAB PURPUREUS) VARIETIES
http://41.89.164.27:8080/xmlui/handle/123456789/1736
IDENTIFICATION OF NEW MOLECULAR MARKERS FOR DIVERSITY ANALYSIS AND BREEDING FOR EARLY MATURITY AND DETERMINATE LABLAB (LABLAB PURPUREUS) VARIETIES
KAMAU, ELIEZAH MAINA
Lablab (Lablab purpureus (L.) Sweet) is a grain legume crop commonly grown in Africa and India and is used as human food, animal feed, in soil conservation, enhancing soil fertility and in weed management. In Kenya, most farmers grow landraces which are inherently low yielding and have other undesirable attributes like long maturity duration and indeterminate growth habit. The status of genetic diversity of the local lablab germplasm and how it relates to materials from other regions remain unclear. Unavailability of novel breeding selection tools such as molecular markers and lack of adequate information on the inheritance pattern of important traits have also hampered the crop improvement in Kenya. The objectives of the study were therefore: to develop new molecular markers for lablab; to assess the genotypic diversity of local, exotic and wild lablab accessions using simple sequence repeats, diversity array technology (DArT) and single nucleotide polymorphism (SNP) molecular markers; to identify the inheritance pattern of selected lablab qualitative traits and establish the linkage relationship of the genes controlling them; determine the heritability estimates, genetic gain and character association of important traits of determinate lablab. Transcriptome sequencing using 454 Titanium FLX system of mRNA isolated from leaves and shoots of lablab samples, was conducted to discover genic-SSRs and to develop SSR markers. Eight of these new developed SSR markers were used to characterize 189 lablab accessions. SilicoDArT and SNP markers were developed using DArTSeq technology and used to characterize 240 lablab accessions. The genetics of growth habit and other qualitative traits were studied in three generations (F1, F2 F3) of eight lablab populations. Selected F5 lines with determinate growth habit were grown using RCBD design at KALRO Thika and Katumani to determine heritability estimates, genetic gain and character association. Results indicated that there were 446 genic SSRs from 3140 assembled lablab contigs indicating an overall density of 202 SSR per Mbp. SSR primer pairs designed from the contigs sequences amplified on lablab genome. The gene diversity among the 189 accessions based on SSR loci ranged from 0.26 to 0.52 with an average of 0.38, with germplasm collected from Kenya showing a moderate genetic diversity of 0.36. Higher genetic diversity (He<0.5) was detected within the Ethiopian and South Africa populations. A total of 15,601 polymorphic DArT markers and 11,431 SNP markers were identified each with average reproducibility and genotype call rate of more than 90%. Based on both DArT and SNP markers the 240 lablab was of narrow genetic diversity with the expected mean heterozygosity of 0.030 (DArT) and 0.039 (SNP). However, genetic differentiation was most pronounced between the cultivated and the wild accessions. The growth habit in lablab is under control of three genes which could be temperature dependent. The genes controlling stem growth habit and time to flowering in lablab are linked. The study identified, moderate to high heritability, genetic advance estimates and significant positive correlations of pods per plant, raceme per plant, plant height, pod width, racemes per pod and number of flower nodes. The newly developed molecular markers are useful in grouping lablab genotypes into related clusters that breeders can use to enhance lablab productivity. Selection for high number of units of pods per plant, raceme per plant, plant height, pod width, racemes per pod and can be effective when targeting to develop high seed yielding determinate varieties.
2022-02-01T00:00:00ZSOIL EROSION PREDICTION USING MODIFIED UNIVERSAL SOIL LOSS EQUATION (MUSLE) IN TUGEN HILLS, BARINGO, KENYA
http://41.89.164.27:8080/xmlui/handle/123456789/1733
SOIL EROSION PREDICTION USING MODIFIED UNIVERSAL SOIL LOSS EQUATION (MUSLE) IN TUGEN HILLS, BARINGO, KENYA
CHESIRE, ATHANUS KOMEN
Soil erosion by water is one of the primary causes of land degradation and occurs throughout the world. Soil erosion is contributing negatively to the already declining agricultural productivity thereby negatively influencing people’s livelihoods and economic empowerment. Therefore, there is need to understand erosion processes, quantify sediment yield, identify and rank critical sources on spatial domain of sediment. This will help in formulation of prioritized catchment conservation strategies. This study focused on estimation of sediment yield from Tugen Hills particularly Saimo catchment in Baringo County using Modified Universal Soil Loss Equation (MUSLE) model with a view to develop an understanding of inter-relationships between soil erosion and sediment yield. The input model parameters of runoff volume (Q) and peak flow rate (qp) were determined from runoff plots of dimensions 4.8m by 2m set up in the catchment with average slope of 2%. Soil erodibility factor (K) was calculated mathematically based on soil samples collected. Cover management (C) was obtained by percentage cover and support practice (P) factor was determined through observation and use of conversion table. Apart from determination of model parameters, the study calibrated and validated MUSLE for use in future studies within Saimo catchment and other catchments with similar characteristics. The mean bulk densities for top soil and bottom soil are 1.05g/cm2 and 1.07 g/cm3. The total value for fine sand and silt gives 37.1%. The saturated hydraulic conductivity varied from 8.0 μm/s to 41.3 μm/s with a mean value of 24.1 μm/s. There were only two classes high and moderately high translating to code 2 and 3, respectively. The analysis of variance (ANOVA) of the observed data showed that rainfall intensity affected the sediment yield production in the runoff plots and that there was no evidence to suggest that the soil homogeneity in the runoff plots affected the sediment yields. The observed and simulated MUSLE model values for calibration were PBIAS (0.83), R2 (0.75), r (0.87) and KGE (-0.20) and those for validation were NSE (0.96), PBIAS (-0.44), R2 (0.60), r (0.78) and KGE (0.46). Hence it can be concluded that the MUSLE model can be used successfully as an effective tool in soil conservation management. Future work for several seasons is however needed in order to capture different slopes and the varying climatic conditions for the model to be robust and to be used widely.
2022-10-01T00:00:00ZPRODUCTION, STORAGE AND QUALITY CHARACTERISTICS OF SWEET POTATO VARIETIES
http://41.89.164.27:8080/xmlui/handle/123456789/1686
PRODUCTION, STORAGE AND QUALITY CHARACTERISTICS OF SWEET POTATO VARIETIES
YEGO, ROMANA C.
Sweet potato (Ipomeabatatas) is an important subsistence crop in Eastern Africa and is fast becoming an important supplementary staple food in Kenya. It is harvested fresh but the shelf life is short. Little is known in regard to storability of local varieties grown by farmers and its effect on culinary characteristics and nutritional value. The main objective of the study was to evaluate the production, processing, utilization and effect of various storage methods on preservation of nutritional quality (βeta -carotene) of sweet potatoes in Kabras and Kabondo wards. The study adopted a cross sectional survey and experimental research designs using 211 sweet potato farmers who were a stratified random sample. A questionnaire was used to collect data on production, processing and utilization of the sweet potato. The storage experiment involved the use of pit and clamp storage methods. The nutritional quality of the stored sweet potato, particularly the effect of storage on Trans –βeta carotene content cis-isomers, was determined by UV-Spectrophotometer. Data was analyzed using the Statistical Package for Social Sciences (SPSS V.20). T-test and ANOVA for the various variables were determined. The study results showed that 73.3% of the respondents in Kabondo and 86.7% in Kabras; 91.7% were women 64.2% and 39.7 of the farmers in the two study areas preferred the yellow local variety of sweet potatoes and grew sweet potatoes twice a year. There was no significant difference in the mean βeta carotene levels in selected sweet potato varieties stored under pit and clamp methods (p≤ 0.05). The clamp storage method was generally better than the pit storage method as it had fairly higher sensory trait means as compared to the pit storage method, using a five unit hedonic scale. There is need for use of improved storage methods as this will boost food and livelihood security at household, community and national level and also to address nutritional problems.
2022-06-01T00:00:00Z