http://repository.must.ac.ke/handle/123456789/1444 2026-04-13T11:30:32Z http://repository.must.ac.ke/handle/123456789/1447 Bioprotection of Tomatoes against Phytophthora Infestants and Alternaria Using Warburgia Ugandensis Extract and Trichodema Asperellium Kamau, Waithira Esther Phytophthora infestans belongs to Kingdom Chromista and is the causal agent of late blight in tomatoes while Alternaria solani is a fungal pathogen causing early blight in tomatoes. Blight is controlled using chemicals leading to safety challenges. Trichoderma is a soil borne fungi which has been shown to have broad-spectrum antimicrobial activity and is used as a biocontrol agent. Warburgia ugandensis is an indigenous tree of East and South Africa whose extracts have been found to have antimicrobial properties especially in the medical field. The main objective of this research was to evaluate the effectiveness of Warburgia ugandensis in the control of blight pathogens affecting tomatoes and also the effectiveness of the synergy from Trichoderma asperellum in controlling blight pathogens. The blight pathogens were isolated from infected tomatoes in Nchiru, Meru County. Warburgia stem bark sample were processed to obtain crude extracts using different organic solvents in multiple extraction method. Lyophilization was also carried out to obtain crude extracts using water. Phytochemical analysis was carried out on the extracts and minimum inhibitory concentration (MIC) was determined. Screening of the extracts and Trichoderma for antimicrobial properties was carried out and the zones of inhibition were observed and recorded. In vivo studies were carried out in the screen house using lyophilized crude extract and the disease incidence observed and recorded. Percentage severity index and disease reduction were calculated. Gradient column chromatography was carried out on the organic crude extract and the fractions with similar thin layer profiles were pooled together before being subjected to gas chromatography interfaced with mass spectrometry (GC-MS), from which the profiles of the compounds in the extracts were determined. The quantitative data collected and recorded was analyzed using ANOVA by Statistical Analysis Software (SAS) s and the means separated using Tukey's tests. All statistical results with P<0.05 were considered to be statistically significant. Warburgia ugandensis hexane crude extract had the highest mean inhibition zone in A. solani while methanol crude extract gave the highest mean inhibition zone against P. infestans. The MIC for A. solani was 1.25mg/ml while for P. infestans was 2.5mg/ml with Warburgia stem bark lyophilized crude extract. Results of in vivo studies trial 2, showed least disease severity in the combined treatment with Warburgia and Trichoderma at 27.81% for P. infestans and A. solani. This was closely comparable with the commercial fungicide which had disease severity of 33.21%. Warburgia stem bark was found to have different compounds which include terpenes, sesquiterpenoids, fatty acids derivatives, and phytosterols among others. The results from this research showed that Warburgia extracts and Trichoderma were effective in the control of blight pathogens. Further investigation can be carried out on effects of specific Warburgia phytochemicals in the control of blight pathogens and other phytopathogens 2023-01-01T00:00:00Z http://repository.must.ac.ke/handle/123456789/1099 Growth, Yield and Quality of Transplanted Baby Corn (Zea Mays L.) Under Varying Agronomic Conditions in Meru County-Kenya Kirigiah, Richard Corn (Zea mays L.) is one of the most significant cereal crops worldwide. Babycorn is currently farmed in Kenya mostly for export markets, with a very limited quantity being grown for local use, mostly in urban areas. Insufficient evidence-based research prevents baby corn, which is a relatively new crop, from being transplanted at a large scale. Two experimental studies were conducted to establish the performance of transplanted baby corn under varying growth conditions in Meru County. The first experiment was to determine the best baby corn transplanting stage under farmer conditions (Field and Greenhouse conditions). The experiment was setup in a split plot randomized complete block design (RCBD) with three replications. Two baby corn varieties (PAN 14 and Thai Gold) were grown under 4 transplanting stages (0,200, 300 and 400 Growing degree days (GDD)) under green house and field conditions. To determine interaction between different treatments (plastic mulch colours and phased transplanting stages) on the performance of baby corn plant varieties a field experiment was setup in a split-split plot RCBD design with three replications. PAN 14 and Thai Gold were transplanted at four transplanting stages (0,200, 300 and 400 GDD) under four different plastic mulch colour (yellow, clear, black and control). Data was collected on growth (maturity GDD and flowering height) and yield parameters (cob length, diameter and weight). Collected data were analyzed using SAS 2007, and means were separated by LSD test (P≤0.05). There were statistically significant interactions (P≤0.05) observed between the transplanting stage and baby corn varieties and mulch colour on maturity GDD, flowering height under various growing conditions. There were no significant interactions (P>0.05) among plastic mulch colour, transplanting stages, and varieties on cob length, cob diameter, and cob weight. However, significant interactions were found between plastic mulch colour and baby corn varieties on cob length and cob weight. Transplanting baby corn at 200 GDD resulted in significantly(P≤0.05) higher growth and yield performance. Additionally, PAN 14 variety exhibited greater resilience to dynamic growth conditions compared to Thai Gold, suggesting its suitability for field conditions. Black plastic mulches showed significantly (P≤0.05) higher soil temperatures, followed by transparent films, yellow films and non-mulched. Transparent plastic mulches showed the best yield and vegetative growth for both varieties but could not effectively control weeds. Black plastic mulches produced significantly (P≤0.05) higher yield and vegetative performance than non-mulched, but were lower than the transparent film performance. Additionally, black plastic mulches showed better performance. The temperature differences between the mulch treatments were attributed to variations in solar energy reflection, absorption, and transmission. The choice of plastic mulch colour, transplanting stages, and varieties had significant effects(P≤0.05) on factors such as maturity height, maturity days, and soil GDD. Yellow plastic mulch had the longest maturity period, while the control had the longest maturity period in all transplanting stages. The study recommends that transplanting baby corn at 200 GDD under black mulch leads to the best growth performance, while transplanting PAN 14 baby corn variety at 200 GDD under transparent mulch was the best in cob yields in both green house and field conditions. 2023-01-01T00:00:00Z