ABSTRACT
Water deficit, often referred to as “drought’’, is the most prominent abiotic stress, severely limiting crop yields and opportunities to improve livelihoods of poor farmers in the semi-arid tropics. For example, it is estimated that annually, drought causes US$ 520M losses in the case of groundnut alone. One of the major research objectives is then to exploit modern science techniques to develop crops that are more resilient to low and erratic rainfall patterns. Conventional breeding of early maturing varieties, capable of escaping drought and maturing before water deficit becomes too severe, has been a common approach. However, substantial variation for drought tolerance, beyond earliness has neither been identified nor utilized extensively. However, conventional, yield-based selection for drought tolerance is difficult due to the large genotype by environment (GxE) interactions for yield under stress. In view of this, the application of molecular biology technologies holds great promise not only to improve, but also speed up the breeding of drought tolerant genotypes (Ribaut et al., 1996).
