Genetic Basis of Sorghum Drought Resilience
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Water availability has a large influence on the selection of crops that can be grown productively in different ecological zones. Analysis of climate indicates that large areas of the world, including portions of Australia, North Africa, Central Asia and the North American Southwest are arid or semi-arid and subject to annual drought. More than 0.5 billion people lived in these regions and as population continues to increase, additional pressure will be placed on these marginal lands creating the need for drought resilient crops that can provide yield and yield stability in these water limited regions of production.Periodic drought also occurs in agricultural regions not considered arid or semi-arid (28). The impact of drought in non-arid regions is often dramatic because the crops grown are not usually drought tolerant. The impact of periodic drought in the U.S. resulted in drought being the largest source of insurance indemnities paid to farmers during the period 1935-1975 (3). Even in years when drought is not widespread, water limits crop productivity. Boyer (3) used the difference between record yields and average yields to estimate the impact of various constraints including drought on crop productivity and found that drought accounted for approximately 40% of the loss of potential yield in several major crops in the U.S. These data indicate that crop plants are not ideally designed to maximize yield in environment subject to intermittent or terminal water limitation. Crops better adapted to water limited environments could be created if there was a more complete understanding of the traits, QTL/genes (alleles) and biochemical mechanisms that contribute to improved plant performance in drought prone regions.