EFFECT OF NITROGEN RATES ON YIELD COMPONENTS AND QUALITY OF LINSEED (Linum usitatissimum L.) VARIETIES UNDER IRRIGATION IN ANGOLELA TERA DISTRICT, CENTRAL HIGHLANDS OF ETHIOPIA

Abstract

Linseed (Linum usitatissimum L.) is one of the most important oilseed crops in the central highlands of Ethiopia. However, its productivity is low mainly due to inappropriate use of nitrogen fertilizer and lack of improved varieties. Hence, a field experiment was conducted during 2021 under irrigation in the demonstration farm of Debre Berhan university, Chacha, Angolela Tera District, to evaluate the effects of four nitrogen rates (0, 11.5, 23, and 34.5 kg ha-1) and three linseed varieties (Kulumsa-1, Tolle and Bekoji-14) on growth, yield and quality of linseed. The experiment was conducted using a randomized complete block design in a factorial arrangement with three replications. The results revealed that linseed varieties significantly influenced all phenological, growth, yield and quality parameters while nitrogen rate affected all parameters except plant population and fatty acid composition. The interaction effects of nitrogen rates and linseed varieties were highly significant (P<0.001) in relation to days to flowering and maturity, plant height, branch height, number of capsules plant-1, thousand seed weight, total dry biomass yield, seed yield, straw yield, harvest index, percent oil content and oil yield. The application of N at a rate of 11.5 kg ha-1 to Bekoji-14 variety increased plant height (89.07 cm), number of capsules per pant (37.87), thousand seed weight (7.16 g) and seed yield (2200.99 kg ha-1) by 30.16%, 9.83%, 40.94% and 40.68% as compared to Bekoji-14 variety with no nitrogen application. According to the results of partial budget analysis, the application of N at a rate of 11.5 kg ha-1 on the Bekoji-14 variety was economically beneficial as compared to the other treatments as it produced the highest net benefit (118,625.70 ETB ha-1) with a MRR value (9591.96). In addition, correlation analysis revealed that seed yield is positively and significantly correlated with plant height, number of capsules per plant, number of seeds per capsule, aboveground dry biomass yield, straw yield, harvest index and oil yield but it is negatively correlated with percent oil content. Hence, it can be concluded that the application of N at a rate of 11.5 kg ha-1 on Bekoji-14 variety could be recommended to enhance seed yield and quality of linseed in the study area and other similar agro-ecologies. However, as this is a one-season experiment at one location, a similar experiment has to be repeated over multiple locations and seasons in the district to reach a conclusive result.