Water productivity, morphological and biochemical responses of Sorghum bicolor (L.) under various levels of drought stress

Sorghum is a potential fodder crop that has high yielding and superior quantity to feed of livestock. In arid and semi-arid areas, both quantity and quality are susceptible to drought. This study assesses the impact of drought stress on morphological characteristics, forage quantity and quality, and water productivity on two sorghum varieties. The experiment was carried out in a split-plot, based on the completely randomized design with three replications in Isfahan, Iran, in 2017, and 2018 crop years. The treatments consisted of irrigation treatments with three levels (control, 80, and 60% full irrigation) and two varieties of sorghum (Speedfeed and Pegah). The results showed that drought stress had no adverse effect on the vegetative traits and forage yield of sorghum, while it improved some traits related to animal nutrition. The results indicate that drought stress up to 60% full irrigation had no significant effect on the qualitative and quantitative yield of sorghum forage and water productivity. Besides, according to Stress Susceptibility Index and Stress Tolerance Index, Also increase wet and dry forage water productivity in 60% irrigation compared to 100%, the Pegah variety is more adapted to water stress conditions. The Speedfeed variety is appropriate as a result of animal nutrition, but depending on the reduction in Neutral detergent fiber and Lignin, the Pegah variety may be more appropriate for forage quality.