The phenology and seed yields of a range of commercially-grown grain legume species (Lupinus albus L. cv. Kiev mutant, L. angustifolius L. cv. Yorrel, Cicer arietinum L,. acc. T1587, Lens culinaris Med. acc. ILL6002/cv. Digger, Vicia faba L, cv. Fiord, and P. sativum L. cv. Dundale) were compared with potential new grain legume species (L, atlanticus L. accs P22924/P22927, L. pilosus Murr. acc. P23030, V. narbonensis L. acc. ACT60104, Lathyrus cicera I. acc. 495, L. ochrus (L.) DC acc. 537, L. sativus L. acc. 453, V. benghalensis L. cv. Early purple, and V. sativa L. cv. Languedoc) in low rainfall Mediterranean-type environments of southwestern Australia. Species were compared on fine-textured, neutral to alkaline soils, at two fields sites (Merredin and Mullewa), and in two consecutive growing seasons (1993 and 1994). At Merredin, a section of each trial was irrigated at regular intervals commencing at flowering and ending just before maturity. V. faba and P. sativum were generally the highest yielding grain legume species at both field sites, and in the two years that the species were compared (> 200 g/m(2) at Merredin in 1993 and at Mullewa in both years, and > 100 g/m(2) at Merredin in 1994 which had below-average rainfall). Seed yields of V. faba and P. sativum were comparable with or greater than those of wheat. Both grain legume species yielded well in the water-limited environments because of their early flowering and podding, which allowed pod filling to occur in winter when temperatures were low and soil moisture conditions were most favourable. This early flowering and podding was matched with vigorous early growth, which laid the potential for a large total biomass. Seed yields of the other commercially-grown grain legume species were smaller than those of V. faba and P. sativum. Yields of C. arietinum at Merredin were severely reduced by frost damage in both years, implying that with current cultivars/accessions frosts represent a significant risk to this crop in susceptible areas. None of the potential new Lupinus, Lathyrus, and Vicia species that were tested consistently produced the seed yields of current commercial cultivars of V. faba or P. sativum. Nevertheless, most species produced substantial biomass at maturity at each site, particularly in years of higher rainfall and in irrigated plots (> 425 g/m(2) at Merredin in 1993 and in irrigated plots), confirming their adaptation to fine-textured, neutral to alkaline soils. Low seed yields of species were attributed to later flowering and podding relative to V. faba and P. sativum. Selecting for more rapid crop development in the new grain legume species is likely to increase seed yields of these species in the short-season environments of southwestern Australia. (C) 1997 Elsevier Science B.V.