Content area
Full Text
1. Introduction
Drastic climate changes and increased water scarcity challenge global food security, which is further exacerbated due to the need to feed a growing global population [1]. A reviewed estimate states that global agricultural production might need to increase by 60-110% to meet the increasing demands [2] as well as to provide food security to the predicted 870 million people who will be chronically undernourished by 2050 [3]. However, the rates of global crop production are far below the amounts required to meet projected demands by 2050 [4,5]. Crop yield is affected by agronomic factors and various environmental variables such as water availability and temperature [6,7]. There is extensive crop yield variability in many semi-arid regions, which are owed to water limitation and year-to-year fluctuations in meteorological conditions. Although an increase in temperature is beneficial for crop productivity in some cooler regions of the world, drought still significantly reduces national cereal production by 9-10% on a global scale [1] via negative effects on plant growth, physiology, and grain development [8,9,10]. Caused by reduced precipitation and increased temperature [11], drought has been the most important limiting factor for crop productivity and, ultimately, for food security worldwide [12]. Wheat (Triticum aestivum L.) and rice (Oryza sativa L.) are two of the three major global cereals (wheat, rice, and maize (Zea mays L.)) with global annual productions of 713.2 and 745.7 million tons, respectively. Wheat and rice contributed more than 50% to global cereal production in 2013 [13]. Previous studies have revealed that their grain yields have declined in recent years because of drought. These studies have included several meta-analyses, summary studies, and model simulation results with only drought taken into account or an interaction with temperatures (see Table 1). It will be necessary to increase biomass production and economic yield under the conditions constrained by climate and water availability [14]. However, before this can occur, the extent of wheat and rice yield reduction and other agronomic traits that are affected by changes in the climate must be understood.
[ Table omitted. See PDF. ]
Now, more than ever, the effect of drought on agronomic traits of rice and wheat has become more significant. With a changing climate, droughts are predicted to become more intense and frequent...