Njalayao, Anthony Herman2026-03-132026-03-131994https://www.suaire.sua.ac.tz/handle/20.500.14820/7406DissertationA field experiment was conducted (under rainfed conditions with supplimentary irrigation) to evaluate the effects of nitrogen fertilizer, post emergence herbicides and other weed control treatments on itchgrass ( Rottboellia cochinchinensis (Lour) Clayton) control, yield and quality of sugarcane ( Saccharum officinarum L.). The experiment was laid out as split-plot randomized complete block design replicated in a four times. Nitrogen fertilizer rates (0, 50 and 100 kg N/ha) were main plots while herbicides and other weed control treatments were subplots. The herbicides included gramuron (3.2 kg a.i/ha), basta (2.0 kg a.i/ha) and asulam (3.7 kg a.i/ha). Other weed control treatments were cane trash mulch, cane trash mulch plus hand weeding, intercrop plus hand weeding, cowpea intercrop, gesapax combi cowpea (4 kg a.i/ha) plus two hand weedings plus mechanical cultivation, weed free and unweeded checks. Nitrogen fertilization was ineffective in controlling itchgrss. Mulching or intercropping supplemented with hand weeding as well as gesapax combi (4 kg a.i/ha) plus two hand weedings plus mechanical cultivation completely eliminated itchgrass. Asulam (3.7 kg a.i/ha) controlled the weed by an average of 88%. Gramuron (3.2 kg a.i/ha) basta(2.0 kg a.i/ha) and mulching had between 70 and 75% control of the weed. Intercropping was ineffective in itchgrass control. Increasing the rate of nitrogen from 0 to 100 kg N/ha significantly (P<0.05) increased cane yield by 14%. Plots which were mulched and then weeded, hand treated with asulam (3.7 kg a.i/ha) or gesapax combi (4 kg a.i/ha) plus two hand weedings better control plus of mechanical itchgrass cultivation provided higher and cane yields averaging between 85 and 88 tons/ha. Sugarcane yields positively correlated with number of sugarcane tillers (r=0.766), stalk population (r=0.734) and stalk length (r=0.433). Among sugarcane growth parameters, tiller length counts, of number negatively harvestable correlated stalks (r=0.749, and 0.850, stalk 0.886 respectively) with itchgrass count. Analysis of coefficient 9 of determination (r ) influenced (r^=0.60) indicated that cane yield was more by tiller counts than by the other parameters. Application of 100 kg N/ha reduced sucrose content which is significantly (P<0.05) the main parameter sugarcane quality compared to unfertilized cane. ofiv Economic analysis showed that mulching plus hand weeding applied with 100 kg N/ha had the highest marginal rate of return of 192%.enNitrogen fertilizerQuality of sugarcane Cowpea intercropItchgrass controlSaccharum officinarum L.Sugarcane trashThesis