Evaluation of forage yield and quality of cowpea, guar and mung bean under drought stress conditions

Identifying annual forage legumes suitable for summer cultivation in terms of forage yield and quality can be a solution to provide a part of required forage. In order to evaluate the quantitative and qualitative traits of three types of summer legumes, including cowpea (Mashhad cultivar), mung bean (Parto cultivar) and guar (local cultivar of Sistan), an experiment was conducted in the Seed and Plant Research Improvement Institute (SPII), Karaj, Iran for two years in 2019-2020. The study included four irrigation treatments (irrigation after 60, 100 and 140 mm of evaporation pan, Class A cumulative pan evaporation) as the main plot and the three legume species as subplots, was carried out as a split plot experiment in a randomized complete block design with three replications. The combined analysis and comparison of means showed that the highest mean fresh forage yield was obtained for cowpea and mung bean (22.29 and 20.39 ton per hectare, respectively), while 9.37 tons per hectare was obtained for guar, although dry forage yield difference between cowpea and mung bean was not significant (4.58 and 3.77 Tha^-1, respectively). Also, dry forage yield difference between two irrigation levels (60 mm and 100 mm) was not significant (5.03 and 4.71 tons per hectare, respectively). The highest percent of crude protein was observed at normal irrigation level for mung bean (16.97%). Also, the highest levels of insoluble fiber in neutral detergent (NDF) and metabolizable energy (30.90 and 2.30, respectively) were observed for mung bean at severe stress level. Finally, the based on the results, for saving irrigation water in area where water resource is limitation, irrigation after 100 mm evaporation in the three legume species can be recommended.