Abstract
Modern rice cultivation relies heavily upon inorganic nitrogen fertilization. Effective fertilizer management is key to sustainable agricultural development. Field and pot trials were conducted in 2014–2016, including a 15N-labeled urea pot experiment (2014) to investigate mechanism by which optimized nitrogen fertilizer application (OFA) increases nitrogen utilization efficiency (NUE). Results showed that the applied nitrogen recovery efficiencies with OFA were 71.71%, 110.17%, and 51.38% higher than those obtained with traditional nitrogen fertilizer application (TFA) in 2014, 2015, and 2016, respectively. These improvements are attributed mainly to the high recovery efficiency rates derived from spikelet-developing and spikelet-promoting fertilizer applications at the jointing stage and 15–20 d after jointing. Under OFA, the amount of nitrogen fertilizer applied at the early stages was half that used in TFA, which not only promoted the absorption of soil nitrogen, but also reduced nitrogen loss to the environment, as the NUE of basal and tillering fertilizer was only about 22%. Nitrogen applied during the panicle differentiation stage increased the expression of ATM1;1, a NH4+ transporter in roots. This effect significantly improved the uptake of nitrogen derived from fertilizer from jointing to heading stage. Up-regulation of the expression and activity of GS and GOGAT at the panicle differentiation and grain-filling stages promoted nitrogen translocation from vegetative organs to reproductive organs. The uptake of nitrogen derived from fertilizer increased from 22.51% in TFA to 35.58% in OFA. Nevertheless, rice absorbs most of the nitrogen it requires from the soil. The OFA treatment could effectively utilize the environmental compensation effect, promote the absorption and transport of nitrogen, and ultimately lead to improvement in NUE. Future research should aim to understand the soil nitrogen supply capacity in order to apply nitrogenous fertilizer in such a way that it sustains the nitrogen balance.
Highlights
Rice is the staple food for more than 65% of the Chinese and for 3 billion people worldwide (Zhang et al, 2005; Liu et al, 2016)
The RE of applied nitrogen is an important index of applied paddy nitrogen fertilizer utilization, which was 71.71%, 110.17%, and 51.38% higher in optimized nitrogen fertilizer application (OFA) than that in traditional nitrogen fertilizer application (TFA) in 2014, 2015, and 2016, respectively
Under the OFA conditions, more nitrogen fertilizer was assimilated by the plants and less was lost to the environment than under the TFA condition
Summary
Rice is the staple food for more than 65% of the Chinese and for 3 billion people worldwide (Zhang et al, 2005; Liu et al, 2016). According to the Food and Agriculture Organization of the United Nations, the area under rice production and harvest in China was 19.1% and 28.5% of global production in 2016, respectively. Rice production in China affects food security in the country and even globally. Rice yield per unit area in China was 1.5 times that of the world average (FAOSTAT, 2016), which attributable to a rapid increase in use of chemical nitrogen fertilizer. A close relationship was found between annual food production and utilization of nitrogen fertilizer (Zhu and Chen, 2002). About 15% of total nitrogen fertilizer used in agriculture is applied to rice alone (Heffer, 2009; Patil et al, 2010); it is important in the context of sustainable development to improve nitrogen utilization rate (NUE) while ensuring rice yield
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
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 call
