EFFECT OF NITROGEN FERTILIZER RATES ON GROWTH, YIELD AND YIELD COMPONENTS OF OAT (Avena sativa L.) VARIETIES AT ROBA EXPERIMENTAL SITE IN WAMANGYE ALKASO KEBELE, KOFELE DISTRICT, OROMIA REGIONAL STATE, SOUTHERN ETHIOPIA

Abstract

Effect of Nitrogen Fertilizer Rates on Growth, Yield and Yield Components of Oat (Avena sativa L.) Varieties in Wamangye Alkaso Kebele, Kofele District, Oromia Regional State, Southern Ethiopia Hussein Watta Kaliyo (BSc) Hussein Mohammed ((PhD) Demalesh Kefale (PhD) Absence of nitrogen rate studies and lack of well adapted varieties are the major yield limiting factors for Oat growth and production in the study area. Thus, the experiment was conducted at Kofele District in the 2023 growing season (July - December) to evaluate the effect of nitrogen fertilizer rates on the growth, yield and yield components of oat varieties; and to identify economically appropriate combination of variety and nitrogen level that gives maximum forage and seed yield. Factorial combination of three oat varieties (WALQAA, WAS, SRCP) and five levels of nitrogen (0, 25, 50, 75, 100 kg ha -1 ) were studied in three replications of the Randomized Complete Block Design (RCBD). Data were collected and analyzed by using SAS statistical software. Results showed that the variety and Nitrogen main effects were significant for days to heading, days to physiological maturity, total tillers, effective tillers, spikes plant -1 , plant height, seeds plant -1 , forage yield, above ground biomass, thousand seeds weight, straw yield, grain yield and harvest index. The variety main effect was also significant for plant height at 30 day and 60 days after planting. The Variety x N interaction was significant for days to heading, total tillers, effective tillers, plant height at 90 days, days to physiological maturity, number of seeds per plant, forage yield, aboveground biomass, thousand seeds weight, grain yield, straw yield, and harvest index. The highest forage yield (24.46 t ha -1 ), above-ground biomass (22.5 t ha -1 ) and straw yield (20. 03 t ha -1 ) were obtained from variety WLAQAA at nitrogen rate of 75 and 100 kg ha -1 , respectively. The highest thousand seeds weight (39.30 gm) was obtained from variety SRCP at 100 kg of nitrogen ha -1 while the highest grain yield (6.39 t ha -1 ) was obtained from variety WAS at 75 kg of nitrogen ha-1 . The results of the research indicated that the best variety for forage yield was WALQAA while the best variety for grain yield was WAS. The economic analysis for forage yield revealed that the highest net benefit of 146,737.5 ETB ha -1 was obtained from variety WALQAA with 75 kg of nitrogen ha -1 which gave marginal rate of return (MRR) of 1,110.2%. However, the result of the present study needs to be evaluated and reconfirmed under different agro- ecologies in order to reach a conclusive recommendation. Keywords: Nitrogen fertili