Influence of nitrogen rate and inter row spacing on seed yield, yield components and oil content of sunflower (Helianthus annus L.) in Bure, North Western Ethiopia
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Abstract
The yields of oilseeds in Ethiopia were extremely low even though, it has a conducive agro-ecology for the production of various oilseed crops such as sunflower. An approach to increase yield and oil content was to optimize the crop management, including fertilization and plant spacing. Hence, a field experiment was conducted in 2021/2022 cropping season at Bure using four rates of nitrogen (0, 15, 25 and 35 kg ha-1) and three inter-row spacing (60, 75 and 90 cm) laid out in a randomized complete block design. Phenological, growth, yield components, yield and oil content parameters were observed under the study. Results indicated that nitrogen rates were significant (P<0.01) on yield, yield components and oil content of sunflower except days to emergence. Interrow spacing treatments were significant (P<0.05) on days to flowering, days to maturity, plant height, stem diameter, head diameter and number of seeds per head. The interaction of nitrogen and inter-row spacing was significant (P<0.05) on stem diameter only. The greatest head diameter (20.1 cm) and seeds number per head (1480.9 cm) were recorded from an inter-row spacing of 90 cm, whereas the maximum plant height (310.17 cm) was obtained from inter-row spacing of 60 cm. The interaction between 35 kg N ha-1 and 90 cm inter-row spacing resulted in the highest stem diameter of (36.13 cm). The maximum oil yield (1758.3 kg ha-1) and seed yield (5763 kg ha-1) were recorded from nitrogen application at a rate of 35 kg ha-1 and inter-row spacing of 90 cm while, application of 15 kg N ha-1 resulted the highest oil content. Based on this study, application of 35 kg N ha-1 on 90 cm inter-spaced plants would be the best for maximizing seed yield of sunflower. However, to produce the highest oil content, it is not recommended to apply nitrogen more than 15 kg ha-1 under Bure conditions, Ethiopia.
Moreover, the study should be conducted over multiple seasons to validate this finding.