Abstract:
Tomato is the second most important vegetable crop in Kenya after potato whose production is limited due to abiotic and biotic constraints among them water availability and bacterial wilt caused by Ralstonia solanacearum. The study was conducted at KALRO-Kakamega, Kenya. The objectives of the study Were; to determine the effects of different concentrations of bunching onion (Allium fistulosum) cmde extract and irrigation levels on (i) bacterial Wilt inhibition in-vitro (ii) incidence and severity and (m) growth, yield and quality of tomato. The study entailed a laboratory in- vitro antibacterial bioassay and a greenhouse experiment and employed a single factor treatment design with combinations of different levels of Alliumfistulosum crude extract and different levels of irrigation treated as distinct treatments. Data was collected on diameter of Zone of inhibition, disease incidence and severity, growth parameters, yield parameters and quality parameters. Results indicated that the highest inhibition mean diameter of ll.48 mm was obtained under 20% concentration of Allium fistulosum in the in-vitro antibacterial assay while lowest inhibition was under negative control treatment (distilled water). In the greenhouse experiment, use of Allium fistulosum crude extract combined with irrigation levels significantly(P<0.05) reduced disease incidence and severity, improved growth, yield and quality parameters of tomato plant. During all data collection days, the lowest disease incidence and severity was recorded under 20% combined with one litre and half a litre of water while the highest disease incidence was recorded under positive control (Greencop) and negative control combined with two liters of water. Treatments with 20% combined with two liters and one and a half liters of water in both experiments significantly (P<0.05) had the tallest plants, highest number of branches and intemodes. Highest length of intemodes and thickest stems were obtained under 20 % combined with two litres and one and a half litres of water. Early flowering was achieved under 20% combined with one litre of water treatment. Significantly highest number of tomato fruits and fmit Weight were produced under 20% combined with two litres of Water. Shelf-life of fruits was highest under 20% combined with one and a half litres of water while total soluble solids, ascorbic acid content, lycopene content while beta-carotene content under 20% combined with one litres and half a litre of water. To conclude, 20% concentration of Allium fislulosum crude extract combined with one and a half litres of water can be considered for use by tomato growers in order to improve tomato growth and yields while 20% combined with one litres of water for improving quality of tomato fruits
