Nitrogen nutrient index and leaf function affect rice yield and nitrogen efficiency

To investigate the ability of higher nitrogen (N) use efficiency (NUE) in rice production to achieve higher grain yields by optimal N management (OPT). In 2012 and 2013, four field experiments were conducted in Liyang and Rugao counties, Jiangsu Province, China to investigate the ability of the N-nutrient index (NNI) to mediate the effects of N-free control (CK), farmers’ fertilizer practice (FFP), and OPT N management methods on grain yield and...