Résumé
Much has been told about transpiration efficiency (TE) and much more is still needed in an agriculture era marked by water scarcity, not only from the standpoint of dry climate but also from competition for water sources in agriculture. Therefore, research is needed to improve the water-use efficiency (WUE) of drought-tolerant sorghum [Sorghum bicolor (L.) Moench]. This paper presents the theory around WUE and TE. It covers the methods used to measure WUE that have been used in sorghum and reports the range of genetic variation found including in genetic material introgressed with stay-green quantitative trait loci (QTL). The last part explores the main avenues currently being investigated to increase WUE in sorghum.