ABSTRACT
Producing 70% more food for an additional 2.3 billion people by 2050 is one of the main challenges world agriculture will face in the coming decades (FAO 2009). Considering the escalating scarcity of natural resources, increasing water and nutrient use eciency in crop plants is a key component of the strategy to sustainably enhance agricultural productivity and food production (Vlek et al. 1997; Tilman et al. 2002; Lynch 2007; Fageria et al. 2008; Falkenmark et al. 2009; Passioura and Angus 2010). e global average water use eciency (grain yield per unit of seasonal evapotranspiration) of rain-fed wheat (Triticum aestivum L.), for instance, is currently only 32%–44% of attainable eciency, as a result of deciencies in soil mineral nutrients and inadequate crop/soil management practices (Sadras and Angus 2006). e nutrient use eciencies are currently only 30%–50% of applied nitrogen (N) and around 45% of phosphorus (P) fertilizers (Raun and Johnson 1999; Tilman et al. 2002). is means that a signicant amount of applied N and P is lost from agricultural elds due to surface runo, leaching, microbial denitrication, and volatilization. Such nutrient losses harm neighboring ecosystems and diminish water quality through over-enrichment, eutrophication, hypoxia, and decline in biodiversity (Tilman et al. 2002). Phosphorus fertilizers are produced from nonrenewable resources, and the global P reserves are being rapidly depleted. e existing rock phosphate reserves could be exhausted in the next 50-100 years (Steen 1998; Cordell
et al. 2009). Furthermore, ineciencies in nutrient use are associated with substantial economic losses. Nitrogen fertilizers, for instance, represent about one-third of the costs of cereal production (Le Gouis et al. 2000; Fageria and Baligar 2005). Improving crop/soil management practices and developing more ecient crop cultivars can make a signicant contribution to meet the challenges of increasing food production while reducing the adverse environmental impacts of agriculture and reducing farmers’ costs.
