Drought stress in sorghum: Mitigation strategies, breeding methods and technologies—A review.

Agriculture accounts for 70% of the global use of available freshwater. Projections show that demand for water will increase significantly due to climate change, population growth and development of agricultural enterprises globally. There is a need to develop water‐use efficient crop cultivars for sustainable agricultural production. Sorghum [Sorghum bicolor (L.) Moench.] is a powerhouse crop in drier regions supporting more than 500 million people. It is a relatively drought‐tolerant crop adapted to grow and yield in marginal environments where other dominant crops such as maize and wheat fail to survive. However, the mean yield of sorghum in the semi‐arid regions has stagnated around 1.0 ton/ha compared with the global average of 2.5 ton/ha, mainly due to recurrent droughts and heat stress. Breeding for drought‐tolerant cultivars is an economic and sustainable mitigation strategy against the current and projected drought stress. Therefore, the objectives of this review were to document the impact of drought stress and the key mitigation strategies under drought‐prone semi‐arid sorghum production systems. The first section of the review highlighted the impact of drought and its mitigation strategies emphasizing on the use of drought‐tolerant cultivars as the best strategy. This is followed by perspectives on aspects of drought‐response mechanisms, breeding methods and complementary technologies for drought tolerance. Integration of the conventional and molecular breeding technologies with rapid generation advancement methods could reduce the breeding cycle and increase the efficiency of deploying new varieties. Information presented in this review will guide agronomists and breeders to develop and deploy drought‐tolerant sorghum cultivars that are adapted to the changing production environments in the semi‐arid regions. [ABSTRACT FROM AUTHOR]