Abstract
Upland rice (Oryza sativa L.) production systems in sub-Saharan Africa are faced with challenges of water stress and nitrogen (N) deficiency, which reduce grain yield, water use efficiency (WUE), and nitrogen use efficiency (NUE). The objective of the study was to determine the response of upland rice to N fertilizer rates under well-watered conditions and to clarify the relationships between WUE and NUE. Upland rice variety Nerica 10 was grown under well-watered conditions and varying N rates in 2014/2015 (Y1) and 2015/2016 (Y2) on the same field at the University of Pretoria’s Hatfield Experimental Farm, South Africa. Yields at harvest increased with increasing N rates, linearly in Y1, and following a quadratic trend in Y2. Mean grain yield was highest (4.5 t ha−1) at 120 kg N ha−1 and lowest (2.4 t ha−1) at 0 kg N ha−1. Agronomic NUE was lowest for 160 kg N ha−1 (11.7 kg kg−1 N), while WUE was highest for the 120 kg N ha−1 (7.58 ± 1.7 kg mm−1) and lowest for 0 kg N ha−1 (4.1 ± 0.9 kg mm−1). Findings revealed that at high N levels, compensative N uptake during tillering can reduce harvest index, WUE, and to a lesser extent, grain N concentration.
Highlights
Rice (Oryza sativa L.) is an important food crop and source of income worldwide
Frequent rainfall events during growth treatments, including 160 kg N ha−1 (2.24 ± 0.08%). These findings suggest that the more N is applied, (Figure 1) may have caused anaerobic conditions that were detrimental to root growth and promoted the more the crop takes up beyond what it needs for growth and grain production
The present study identified compensative uptake of N, increased rooting depth, and delayed senescence as specific physiological traits, which can be attributed to high nitrogen use efficiency (NUE) and sink capacity for this upland rice variety
Summary
Rice (Oryza sativa L.) is an important food crop and source of income worldwide. In Africa, the rate of consumption of rice is increasing faster than most other staple food crops. Between 2000 and 2010, the increase was estimated at 5.5% per year [1] This increased demand for rice has been accompanied by a rapid expansion in cultivated rice area of between 0.4–7.7% per year across sub-Saharan Africa (SSA) [1]. Many rice-growing countries in Africa remain heavily reliant on imports to meet domestic rice demand [1] and will need to increase the area under cultivation and more importantly, the production per unit area, to become more self-sufficient. Upland rice yield potential is not realized worldwide because production is often limited to less fertile and drought-prone lands [3]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
