Water Use Efficiency in Maize Production – the Challenge and Improvement Strategies

As one of the three most important cereal species, maize is grown in a range of environments, and is a basic food grain in many areas and several cultures. This paper examines water use efficiency (WUE) in maize through a review of literatures on the topic. It then examines strategies to improve WUE, through plant breeding, biotechnology and changes to agronomic practice. In breeding for improved water use and WUE, it specifically examines modification of plant morphology, the use of droughtadaptive secondary traits in breeding, and drought-adaptive improvement through conventional breeding and biotechnology. A successful program in conventional breeding should involve the integration of several criteria into one selection index; and also successful breeding programs for improved tolerance to drought stress frequently combine two or more of the breeding strategies. Combining physiological and genetic information can provide a more complete model of gene-to-phenotype relationships and genotype-by-environment interactions. From an agronomic viewpoint, it examines planting date and planting geometry, tillage and residue retention, weed control, fertilizer use and modified irrigation practices as strategies to improve WUE, and includes comment on use of plastic mulch as means of improving WUE in maize.