Browsing by Author "Muraya M. M."

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    Evaluation of Tomato Early Blight Pathogens’ Characteristics and Susceptibility of Locally Grown Tomato Varieties to Early Blight Infection in Kirinyaga County, Kenya
    (Chuka University, 2023) Ogolla O. F.; Muraya M. M.; Onyango O. B.
    Tomato (Lycopersicon esculentum Mill) is a highly consumed and produced vegetable crop with an annual global production of over 185 million tonnes, due to its nutritional and health benefits. However, tomato production is characterized by inconsistent quality and yields partly emanating from biotic constraints attributed to fungal foliar diseases. In Kirinyaga County, where tomato production is a significant source of livelihoods, there exists knowledge gap on the identity of pathogens causing early blight in different Agro-ecological zones (AEZs) and on the susceptibility of locally grown tomato varieties to the infection. The objective of this study was to determine the characteristics of early blight pathogen isolated from tomato leaves collected from different AEZs and assess the susceptibility level of some tomato varieties grown in Kirinyaga County to the early blight pathogens isolates. Pathogen characterization was carried out using morphological and molecular approaches while susceptibility of tomato varieties to fungal pathogens was evaluated by artificial inoculation. Molecular characterization for fungal pathogen involved BLASTIN analysis of DNA amplicon Sanger sequenced nucleotides and use of NCBI databases. The susceptibility assay was carried out in the greenhouse using a completely randomised design (CRD). Data on the fungal conidia lengths (µm) were subjected to Analysis of Variance (ANOVA) and significant means separated by Least Significance Difference (LSD) at α = 0.05. Data on the susceptibility (%) of tomato varieties to fungal pathogens isolates was subjected to ANOVA and significance means separated using LSD at α = 0.05. Morphologies of early blight pathogen pathogens differed significantly (p < 0.05) with conidia lengths from 52.8 and 204.20µm. Molecular characterization of some selected culture implicated Alternaria solani and A. alternate involvement in causing early blight. Tomato varieties differed in their susceptibility to early blight pathogens (p < 0.05). Kilele F1 was the most susceptible variety (73.84%) while Terminator F1 was least susceptible (56.48%) to early blight pathogens. It can be concluded that Terminator F1 was the least susceptible among tomato variety cultivated by farmers in Kirinyaga County and can serve as source for genetic improvement of tomato varieties for Kirinyaga pathosystem.
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    MANAGEMENT OF PARASITIC ROOTKNOT NEMATODES IN SWEETPOTATO: REVIEW
    (Chuka University, 2021) Onchari, N. M.; Githae.E. W.; Franklin N.; Muraya M. M.
    Agriculture is the mainstay in Kenyan economy, it currently contributes to 29% in gross domestic product (GDP) and creates employment of over 80% in the rural population. There are four major sub sectors in the agricultural sector which are food crops, industrial crops, livestock, fisheries and horticulture. Sweet potatoes are based under horticultural crops production which are now constrained by many biotic factors including root knot nematodes (RKN).Root knot nematodes pose a significant threat to a wide range of agricultural crops. The effect of RKNs in sweet potatoes are seen through the formation of galls, which reduce water and nutrient uptake, stunted vines and discoloured cracks in root tubers. These effects cause poor quality of tubers hence yield loss and high costs of production leading to poor income. Root knot nematodes diversity depends on ecological conditions and change of environmental conditions with time. Management strategies to control RKN have been practiced over time; cultural methods including fallowing of fields, intercropping and crop rotation have been used however root knot nematodes have ability to infect a wide host range; use of resistant varieties against RKN were adopted however some resistant genes tend to be silent in soil temperatures above 30ᵒC rendering the crop susceptible; use of synthetic nematocides were then found effective against RKN species however they leave residues on plants which are harmful to human consumption and are environmentally unfriendly hence they were banned. With these challenges scientists are focusing on discovery of nematocides from medicinal plants. The use of medicinal plants especially Canavalia ensiformis has shown 87% mortality rate on juveniles at stage two. Due to limited exploration of medicinal plants, more studies are encouraged on the same for RKN management and increase food security