Effect of regulated deficit irrigation on productivity, evapotranspiration and quality of grain sorghum

The aim of this study was to determine the effect of deficit irrigation on evapotranspiration, crop water productivity, irrigation water productivity, yield response, yield components and quality characteristics of grain sorghum ( Sorghum bicolor L.) grown in Antalya, Turkey. The experiment was carried out in a randomized block design with three replications at four different irrigation water levels (I 100 , I 70 , I 35 and I 0 ) in two growing seasons (2019 and 2020). Deficit irrigation levels significantly decreased plant height, chlorophyll content (SPAD), stomatal conductivity, average leaf area, leaf area index, leaf weight, stem weight, panicle weight, grains per panicle and grain yield in both growing seasons. Except for the ash content in the first year, quality components such as water, oil and protein content were not significantly affected by different irrigation levels. Also, fatty acid contents were not affected by irrigation levels in both growing seasons. The correlation test revealed a strong positive relationship between leaf weight, panicle weight, plant weight and sorghum grain yield in different irrigation applications. On the other hand, there was no correlation between grain yield and different fatty acid contents. When water is not limited, it is suggested that sorghum can be irrigated by bringing soil water to the field capacity when 40–45% of the water at the effective root depth of the sorghum plant is depleted. When water is limited, timing the irrigations when 40–45% depletion in the root zone has occurred, but refilling the profile to only 70% of available water capacity is recommended to limit significant yield loss.