Forage Yield and Quality and Water Productivity of Kochia, Millet, Sorghum and Maize Under Water Deficit Stress Conditions

To evaluate forage yield and quality as well as water productivity of kochia (Kochia scoparia L. Schrad), millet (Pennisetum glaucum L.), sorghum (Sorghum bicolor L. Moench) and maize (Zea mays L.) under water deficit stress conditions, a field experiment was carried-out as split plot arrangements in randomized complete block design with four replications in two years (2016-2017) in Kerman, Iran. Three irrigation regimes including; optimal irrigation, mild and severe stress levels based on 80, 130 and 180 mm cumulative pan evaporation, respectively, were assigned to main plots and four plant species; kochia, millet, sorghum and maize were randomized in subplots. Sorghum had the highest forage yield in all irrigation regimes. Sorghum in optimal irrigation had 101241 kg ha-1 of fresh forage and 30181 kg ha-1 dry forage. With increasing drought stress severity, yield reduction was lower in kochia than other plant species. The highest water productivity obtained under mild drought stress. The highest water productivity in optimal, mild and severe drought stress levels belonged to sorghum with 3.17, 2.97 and 2.8 kg m-3, respectively. Millet had the highest (11.8%) and sorghum the lowest (8.9%) crude protein in dry forage. Based on the results of this research, sorghum had the highest forage yield and water productivity, and kochia was the most tolerant plant for drought stress conditions. Considering the importance of quantity and quality of forage for livestocks, it is suggested that intercropping of sorghum and millet will be considered as a research priority in future.