Browsing by Author "Muraya, M.M"

Now showing 1 - 3 of 3

ASSESSMENT OF TOMATO FARMING STRATEGIES, DISEASES KNOWLEDGE AND MANAGEMENT PRACTICES AMONG FARMERS’ IN KIRINYAGA COUNTY, KENYA
(Chuka university, 2022) Ogolla, O. F; Onyango, O.B; Muraya, M.M; Mulambula, S
Diseases are hindrance to tomato production in Kirinyaga, Kenya. However, information on farmer’s disease knowledge to warrant pesticide use, disease predisposing factor such as varietal choice, seed source and irrigation system is scanty. This study assessed the association between tomato varieties grown, farming strategies, farmers’ socio characteristic, disease knowledge, diseases management practices, legal status and sources of pesticides used in tomato farming, knowledge of biological control agents with the agroecological zones in Kirinyaga. A cross sectional survey method was used. Data was collected from 120 tomato farmers using structured questionnaires. A chi square test was used to determine association between different variables using SAS version 9.4. There was no significant (p>0.05) association between source of tomato planting material and agroecological zones. There was significant (p<0.05) association between tomato varieties and the reasons for choice. Irrigation system used in tomato farms was significantly (p<0.05) associated with agroecological zones. Farmers’ knowledge of causative agent of early blight, late blight and septoria leaf spot was significantly (p<0.05) associated with agroecological zones. Farmers able of identifying causative agent of early blight, later blight and septoria spot were 51.7%, 40%and 17%, respectively. Up to 55% of farmers gained knowledge of tomato diseases through farming experience. Observation of the chemical withdrawal period in tomatoes was not significantly (p>0.05) associated with the level of pesticide dose applied. Over 46% farmers use wrong pesticide doses and only 48.33% of farmers use legal pesticides. The knowledge of use of biological control agents among farmers was not significantly (p>0.05)associated with agro ecological zones. Inability of some farmers to identify tomato diseases, use of illegal pesticides and use of improper doses of pesticides are challenges in tomato production in Kirinyaga. Therefore, measures such coordinated education on crop diseases, proper use of pesticide and surveillance to limit access to illegal pesticides should be considered
Dynamic quantitative trait loci and copy number variation: the missing heritability of complex agronomic traits
(Chuka University, 2016) Muraya, M.M
Genetic studies have identified thousands of loci controlling various agronomic traits, revealing important biological pathways and providing valuable insights into genetic basis of trait variation. However, genome-wide association studies (GWAS) have explained relatively small heritability of most complex traits, leading to the question of ‘missing’ heritability of complex traits. This study examined the ‘missing’ heritability and offered clues on the underlying genetic architecture of complex traits, such as biomass accumulation in maize. Twelve main effect and 6-pair of epistasis quantitative trait loci (QTL), displaying different patterns of expression at different developmental time points in 261 maize genotypes were used. Copy number variation (CNV) and presence absence variation (PAV) was used to study the genetic architecture in 34 maize genotypes. The identified QTL and CNV were mapped on maize B73 reference genome. A total of 182 genes were found harboured in the detected QTL regions. A complex CNV architecture, such as smaller CNV nested within larger CNV or overlapping CNV regions was detected throughout the maize genome, which may explain the extraordinary traits variation observed in maize. The complex CNV genetic architecture may partly explain the missing heritability. The differential gene expression and their interactions at different developmental time points may also explain the missing heritability. Consequently, the genetic model from final trait values cannot reflect the real gene action during the entire growth and development of a plant. It is necessary to understand the CNV and the dynamics of gene expression for complex traits at different developmental stages as a basis for quantitative trait manipulation.
PREVALENCE AND DISTRIBUTION OF EARLY BLIGHT, LATE BLIGHT AND SEPTORIA SPOT IN DIFFERENT AGRO-ECOLOGICAL ZONES OF KIRINYAGA COUNTY, KENYA
(Chuka university, 2022) Ogolla, O.F; Muraya, M.M; Onyango, O.B
Tomato production is characterized by inconsistence quality and yields that result from biotic constraints such as foliar fungal diseases that include septoria spot, early and late blights. Despite of disease constraints, information on prevalence of tomato foliar fungal diseases in different agro-ecological zones in Kenya is scanty. Therefore, this study assessed prevalence and distribution of early blight, late blight and septorial spot fungal diseases of tomatofive different agro ecological zones (UM2, UM3, UM4, LM3 and LM4) of Kirinyaga County in Kenya. Study was carried out using cross sectional survey method. At the farm, transects were laid diagonally from where micro plot was established for assessment of foliar fungal diseases of tomato. Percentage incidences and severity data were subjected to analysis of variance using Generalized Linear Model (GLM) and significant means separated using Least Significant Difference (LSD) at α = 0.05. Statistical Analysis Software (SAS) version 9.4 was used for the analysis. Incidences and severity of early blight, late blight and septoria spot in tomato farms in different agro- ecological zones were significantly different (p < 0.05). Incidence of early blight was high 72.09 % in zone UM3and lower in zones LM4 52.32 %. Incidence of late blight was high 51.77% in zone UM3 and lower in zones LM4 40.25 %. Incidence of Septoria spot was high 80.22% in zone LM4 and lower in zones UM4 44.81 %. Severity of Early blight was high 38.21 % in zone UM3 and lower in zones LM4 21.86 %. Severity of late blight was high 31.12% in zone UM3 and lower in zones LM4 19.27 %. Severity of septoria spot was high 39.76% in zone LM4 andlower in zones UM2 at 24.93 %. Incidences and severity of the three foliar fungal diseases of tomato differed in different agro ecological zones of Kirinyaga County. Future studies should consider evaluation of cost benefit analysis to determine economic impact of foliar fungal diseases of tomatoes in Kirinyaga County.