Grain Sorghum Water Requirement and Responses to Drought Stress: A Review

Abstract

Because sorghum is a drought‐tolerant crop, it is often preferred by producers in cases of expected water stress. The objectives of this review were to summarize the water requirements, effect of water stress, and hybrid variation in drought tolerance of grain sorghum, and to suggest possible solutions that could help narrow the gap between potential and actual dryland sorghum yield. We reviewed more than 70 reports in peer‐reviewed journals, extension publications, books, and websites. Grain sorghum tolerates and avoids drought more than many other cereal crops, but the drought response of sorghum does not come without a yield loss. Water stress at the vegetative stage alone can reduce yield more than 36%, and water stress at the reproductive stage can reduce yield more than 55%. Eighty percent of sorghum production in the world is under dryland conditions. We deduced that by focusing on techniques that can improve water availability in sorghum growing season alone, we can double the current dryland sorghum yield with the existing genetic potential. Results of this review suggest the existence of genotypic variation in drought tolerance among sorghum hybrids due to possible physiological differences or vice versa. We concluded by presenting possible management options to reduce the effects of water stress in dryland conditions and suggesting possible areas of research.

Drought Stress Responses in Plants, Oxidative Stress, and Antioxidant Defense

“…Among the four treatments of the experiment, the first one was the control or non-stress condition, the second one was early stress (when the first truss has set the fruits), the third one was the middle stress (when fruits in the first truss were fully matured and started changing color), and the forth one was late stress (when fruits on the first truss were ripened fully). Water stress at the vegetative stage alone can reduce yield more than 36% and water stress at the reproductive stage can reduce yield more than 55% [176]. Plants were more affected from middle stress than early stress, although both these stresses have less effect.…”

Daily rainfall data to identify trends in rainfall amount and rainfall-induced agricultural events in the Nuba Mountains of Sudan

“…However, described differences between percentages for this period and values for the entire dataset of 60 years were negligible. Dry spells at sensitive crop development stages can strongly affect plant growth and final yield (Barron et al, 2003;Assefa et al, 2010). For this reason, information about the probability of occurring dry spells lengths related to specific dates and crop growth stages, respectively, should guide management decisions.…”

Genotypic variation in sorghum [Sorghum bicolor (L.) Moench] exotic germplasm collections for drought and disease tolerance

“…Although sorghum has a wide range of adaptability and can be grown in a wide series of environments, including heat, drought, salinity and flooding (Ejeta and Knoll, 2007), this crop is usually affected by water stress at both pre- and post-flowering stages of development and has the most adverse effect on yield during and after anthesis (Tuinstra et al 1997; Kebede et al 2001; Blum 2004). Post-flowering drought stress reduces the number and size of the seeds per plant (Rosenow and Clark 1995) by 36 and 55%, respectively, which are the main causes for lower grain yield in sorghum (Assefa et al 2010). …”