Green Fodder Production and Water Use Efficiency of Some Forage Crops under Hydroponic Conditions

The objectives of this study were to evaluate five forage crops (alfalfa (Medicago sativa), barley (Hordeum vulgare), cowpea (Vigna unguiculata), sorghum (Sorghum bicolor), and wheat (Triticum aestivum)) for green fodder production and water use efficiency under hydroponic conditions. The experiment has been conducted under temperature-controlled conditions (24 ± 1°C) and natural window illumination at growth room of Soilless Culture Laboratory, Arabian Gulf University, Manama, Bahrain. The results showed that green forage can be produced in 8 days from planting to harvest using hydroponic technique. Highest values for green fresh yields were recorded for the crops cowpea, barley, and alfalfa which gave 217, 200, and 194？tons/ha, respectively. However, only cowpea and barley crops gave the highest green dry yield, but not alfalfa. Barely crop used water more efficiently than the other four tested crops when produced about 654？kg fresh matter/m3 water in comparison to 633, 585, 552, and 521？kg fresh matter/m3 water for cowpea, sorghum, wheat, and alfalfa, respectively. No significant differences between barley and cowpea for water use efficiency were noted. It can be concluded from this study that barley crop can be considered the best choice for production of hydroponic green fodder with less water consumption. 1. Introduction Reducing agricultural water use while maintaining or improving economic productivity of the agricultural sector is a major challenge in arid and semiarid regions. Irrigated agriculture is the major consumer of fresh water supplies in many parts of the world, particularly in relatively arid and semiarid regions like Jordan as well as Gulf Cooperation Council (GCC) countries. The demand on scarce water resources in these countries is increasing with time for both agricultural and nonagricultural purposes. Over recent years, severe shortages in food supplies for livestock have been experienced in Jordan and GCC countries as well as many other countries in the region, mainly, due to repeated droughts as well as shortages of water for irrigation. Many projects to produce forages have been established during the last two decades to cover some green and dry forage needs in these countries. However, scarcity of adequate fresh water supplies might pose challenges for sustainability of the field projects especially with utilizing ground water for irrigation, which is consumed in large amounts as these countries are characterized with very high rates of evapotranspiration and soils of low capacity to retain water. Therefore, methods and