Effect of sowing rate and irrigation on dry biomass and grain yield of bitter vetch (Vicia ervilia) and narbon vetch (Vicia narbonensis)

Genotypes of 2 vetches, ie hitter vetch [Vicia ervilia (L.) Willd.] and nar bon vetch [Vicia narbonensis L.] were evaluated for their performance at 2 sowing rates with low and high irrigation and under 2 harvest management. F ield trials were carried out using a split split plot design with 4 replica tions at the University in Ramtha (northern Jordan) during the 1994-95 and 1995-96. Irrigation increased and stabilized forage and grain production re ducing the consequences of erratic rainfall. Mean dry biomass and grain yie ld increased due to irrigation were 35 and 15% in bitter vetch (Kersenne), 31 and 8% in narbon vetch (Fouileh) respectively. Sowing rate interacted ma inly with irrigation treatment and length of vegetative period. The high so wing rate under irrigation in bitter vetch and narbon vetch increased forag e production more than grain yield. The herbage and grain yield components that responded to the high sowing rate under irrigation were plant height, stems/m(2) for both vetches, pods/stem and grains/pod for narbon vetch and bitter vetch. Adapted varieties and ecotypes identified within each species represent genotypes with superior genetic potential for dry biomass produc tion and grain yield under a semi-arid environment.