Overview on Crop Genetic Engineering for Drought-prone Environments

Population growth and climate change present crop researchers and plant breeders with one of the great grand challenges of the 21 century to productively grow nutritious crops in water-scarce environments (Pimentel et al. 2004). Agriculture currently uses 75% of the total global consumption of water (Molden 2007). Some of the crop technologies that were able to feed the growing world in the 20 century were highly dependent on inputs including water resources, whose use in agriculture almost treble from the beginning of the 1940s to the end of the century. About a third of the current global population lives in water-stressed locations and this may increase to two thirds within the next 25 years. Consumptive water use (or transpired water) by all food and fodder crops will, therefore, need to increase from its present estimated level (7,000-12,586 km year) to be capable of feeding adequately the 9.3 billion population of 2050 (Falkenmark and Rockstrom 2004). Water use efficiency varies substantially between crops, for example, to produce 1 kg of grain on average requires 900 liters for wheat (Triticum spp.), 1400 liters for maize (Zea mays) and 1900 liters for rice (Oriza sativa) (Pimentel 1997). In addition, there are great prospects for increasing the water use efficiency of specific genotypes within each crop.