Nitrogen is the main limiting nutrient after carbon, hydrogen and oxygen for photosynthetic process, phyto-hormonal, proteomic changes and growth-development of plants to complete its lifecycle. Excessive and inefficient use of N fertilizer results in enhanced crop production costs and atmospheric pollution. Atmospheric nitrogen (71%) in the molecular form is not available for the plants. For world’s sustainable food production and atmospheric benefits, there is an urgent need to up-grade nitrogen use efficiency in agricultural farming system. The nitrogen use efficiency is the product of nitrogen uptake efficiency and nitrogen utilization efficiency, it varies from 30.2 to 53.2%. Nitrogen losses are too high, due to excess amount, low plant population, poor application methods etc., which can go up to 70% of total available nitrogen. These losses can be minimized up to 15–30% by adopting improved agronomic approaches such as optimal dosage of nitrogen, application of N by using canopy sensors, maintaining plant population, drip fertigation and legume based intercropping. A few transgenic studies have shown improvement in nitrogen uptake and even increase in biomass. Nitrate reductase, nitrite reductase, glutamine synthetase, glutamine oxoglutarate aminotransferase and asparagine synthetase enzyme have a great role in nitrogen metabolism. However, further studies on carbon–nitrogen metabolism and molecular changes at omic levels are required by using “whole genome sequencing technology” to improve nitrogen use efficiency. This review focus on nitrogen use efficiency that is the major concern of modern days to save economic resources without sacrificing farm yield as well as safety of global environment, i.e. greenhouse gas emissions, ammonium volatilization and nitrate leaching.

China is the world's third largest sugar producing country after Brazil and India. During milling years 2004/2005 and 2013/2014, the average yearly sugar production in China was 11.64 MT, 49.86 % more that in the previous decade. However, the major increase came from Guangxi province, which produced 7.21 MT sugar per annum in average in recent decade, increased by 104.25 % compared to the production of 3.53 MT sugar per annum in average during 1994/1994 and 2003/2004. Sugarcane contributed more than 90 % of the total sugar production in recent decade. Chinese sugar industry encompasses 270 operating sugar mills, 233 sugarcane, and 37 sugar beet. In the milling year 2007/2008, the total sugar production in China reached 14.83 MT, which was 24.04 % higher than that in previous milling year; and cane sugar production reached 13.67 MT, which occupied 92.18 % of the total. However, the severe low temperature and drought occurred almost every year since 2008, which caused continuous in cane and sugar productivity in the subsequent years. The sugar production began recovering since 2011/2012, and reached 13.32 MT sugar in 2013/2014, still 10.18 % lower than that in 2007/2008. Guangxi is the largest sugarcane and sugar producer in China, 9.41 MT sugar in 2007, and 8.56 MT sugar in 2013/2014. Besides, many products, such as pulp, paper, alcohol, yeast, xylitol, chemicals, cane juice, bio-manure, feed, and electricity are also produced from sugarcane. The sugar industry is also the major contributor to the socio-economic development of the major cane producing areas especially Guangxi, Yunnan and western Guangdong.