ABSTRACT
Crop species, grown throughout the world, experience environmental stresses that limit their growth, development, and the full expression of their genetic potential for agronomic yield (Burker et al., 2004). A comparison of average crop yields with reported record yields has shown that the major crops grown in the United States exhibit annual average yields three-to sevenfold lower than record yields due to unfavorable environmental conditions (Boyer, 1982). An analysis of yields from corn (Zea mays L.), wheat (Triticum aestivum L.), soybean (Glycine max L. Merr.), sorghum (Sorghum vulgare L.), potato (Solanum tuberosum L.), sugarbeet (Beta vulgaris L.), oat (Avena sativa L.), and barley (Hordeum vulgare L.) revealed that the average yield represented only 22% of the mean record yield (Burke et al., 2004). Mineral nutrition is one of the most important single factors affecting the yield of annual crops (Fageria, 2009). In most agricultural situations, several factors interact with mineral nutrition over the course of the cropping cycle to limit the growth and the economic yield of crops (Fageria, 2009). Some factors, such as water, cultivar characteristics, nutrients, insects, and diseases, can be controlled to some degree by the farmers, and most crop management practices are directed at balancing the levels of control to obtain maximum economic returns. When such controls are successful, and these factors are not limiting to the growth of plants suitably adapted to the prevailing climate, maximum productivity depends principally on the rates of light interception and carbon dioxide assimilation by the crop surface (Loomis and Williams, 1963; Sinclair and Muchow, 1999; Fageria et al., 2006). This chapter is meant to serve as a brief review of the many factors that can limit the production of ˜eld crops. A subsequent chapter will deal in much greater detail with the limitations of mineral nutrition on the growth and economic yields of the world’s major ˜eld crops.
