Yield Enhancement By Short-Term Imposition of Severe Water Deficit in the Vegetative Growth Stage of Grain Sorghum.

Water deficit is generally thought to negatively impact crop yields, though this view may be limited, resulting in excess irrigation. A small body of literature reports physiological enhancements in plants, including in sorghum (Sorghum bicolor L. Moench), with short-term imposition of water deficit during vegetative growth and some report maintenance of sorghum yield in these conditions. With proper management, we hypothesized that yield enhancement was possible. Here we report on a fully replicated and repeated pot experiment in which water deficit was imposed for two 10-day periods in the vegetative growth stage of grain sorghum plants that were otherwise well-watered. The results showed that short-term, though severe (~30% of control ET), water deficit imposed during vegetative growth could enhance grain yield compared to continuously well-watered plants by 21% (P = 0.0356). The enhancement was associated with a substantial shift in shoot resource partitioning, as the harvest index increased by 60% (P = 0.0005) relative to the control. Imposing short-term and severe water deficit in the vegetative growth stage of sorghum as a strategy to improve yield may be viable in environments where agriculture relies on irrigation, in conditions of high evapotranspiration, and in coarser textured soils, which are common conditions in sorghum producing areas.