YIELD AND OIL CONTENTS OF LINSEED (Linum usitatissimum L.) VARIETIES AS INFLUENCED BY SOWING DATES SEED AND NPS FERTILIZER RATES IN HORO GUDURU WOLLEGA DISTRICT, WESTERN ETHIOPIA

Abstract

Linseed (Linum usitatissimum L.) is one of the oil crops cultivated in the highlands of Ethiopia. Its average yield is low largely due to several poor agronomic practices, biotic, and a biotic factor, among which non optimum sowing dates, seed rates, inorganic fertilizer, and improved varieties usages are the major ones. Consequently the field experiment was conducted in Horo Guduru district during the 2019 and 2020 with five objectives: (1) to identify the effect of sowing dates and linseed varieties on yield components, and oil contents. (2) to assess the effect of seed rates and linseed varieties on yield attributes, and oil content. (3) to assess the response of NPS blended fertilizer rates and linseed on growth, and yield attributes. (4) to assess the influence of NPS fertilizer rates and linseed varieties on oil contents and fatty acids compositions, and (5) to estimate net benefit values of seed rates and NPS fertilizer rates. Accordingly, the field experiment was laid out in (a factorial) randomized complete block design (4 SD and 4 varieties) and three times replicated. The analysis of variances on growth parameters, yield component, oil contents, and oil yield were significantly (p<0.01) affected by the main effect of sowing dates and varieties at both sites and seasons. Above-ground dry biomass, seed yield, and straw yield had significant (p<0.05) differences due to the interaction effects of sowing dates and varieties. Higher seed yield were recorded from Kuma variety on June 1st and June 10th sowing dates, respectively (1833.3 kg ha-1 to 1857.1 kg ha-1 ), followed by Berene (1856.8 kg ha-1 to 1871.3 kg ha-1 ) and Belay (1843.2 kg ha-1 to 1855.5 kg ha-1 ). But, lowest seed yield (1423.96 kg ha-1 ) was registered from local cultivar sown at 30th June. On average high seed yields of 1833.84 kg ha-1 and 1812.89 kg ha-1 were obtained from June 1st and 10th sowing dates, respectively from Kuma and Berene varieties. Similarly, higher oil contents (41.16% and 40.68%) were obtained from the June 1st and 10th sowing dates, respectively from Kuma variety. Therefore, June 1st sowing of Kuma variety can be recommended for the study sites and similar agro ecologies. xxi The second experiment, which consist of twenty treatments of five seed rates (20, 25, 30, 35, and 40 kg ha-1 ), combined with four linseed varieties (Belay-96, Berene, Kuma, and local cultivar), were laid out in RCBD with factorial arrangements, replicated three times. The analysis of variance revealed that seed yield, straw yield, above-ground dry biomass, capsules per plant, thousand seed weight, oil content, and oil yield were highly significantly (p<0.01) difference due to the main effect of seed rates and varieties. Higher seed yields (1,819 and 1,869 kg ha-1 ) were recorded at 35 and 40 kg ha-1 seed rates, respectively from Kuma, followed by Belay (1812 and 1,854 kg ha-1 ), and Berene (1802 and 1,853 kg ha-1 ). Low seed yield (1343.35 kg ha-1 ) was recorded from seed rate of 20 kg ha-1 by the local cultivar. The seed rate of 35 kg ha-1 has increased the seed yield by 16.16% over the control (25 kg ha-1 seed rate). High net benefit (48,520 Ethio birr) was also obtained from 35 kg ha 1 seed rates for Kuma variety, while the low benefit (33,270 Ethio birr) was recorded at 20 kg ha-1 seed rate from local cultivar. Thus, 35 kg ha- 1 seed rates for Kuma variety advisable for the tested sites and similar agro ecologies. The third experiment was consist of sixteen treatment combinations (4 NPS rates and 4 varieties), was laid out as RCBD with factorial arrangement, replicated three times. Seed yield, oil content, oil yield, and fatty acids were significantly (p<0.01) affected by the main effect of NPS rates and varieties at both sites and seasons. Maximum seed yield and fatty acids were obtained at 150 kg NPS ha-1 for improved varieties, against the low seed yield of 0 kg NPS ha-1 for the local cultivar. Increasing NPS rates were noticed to decrease the oil content, oleic and linoleic fatty acids, but increase the palmitic, stearic, and linolenic acids. Higher net benefit (41,775 Ethio birr and 41,806.5 Ethio birr) were obtained from Berene and Kuma varieties, respectively at 150 kg NPS ha-1 , while the lowest (23,536.5 Ethio birr) was from local cultivar at 0 kg NPS ha-1 .Therefore, application of 150 kg ha-1 NPS with improved varieties of Kuma and Berene were recommended at Harato and Gitilo sites and other areas with similar environments