Adaptation and seed yield of cool season grain legumes in Mediterranean environments of south-western Australia

A range of cool season grain legume species have shown considerable potential for soils unsuitable for the production of narrow-leafed lupin (Lupinus angustifolius L.) at limited sites in the Mediterranean-type environments of south-western Australia. In this study the adaptation of these grain legume species was compared by measuring crop phenology, growth, and yield in field experiments at a total of 36 sites over 3 seasons, with the aim of identifying species with suitable adaptation and seed yield for specific environments. The grain legumes examined appeared to fall into 3 categories: (i) field pea (Pisum sativum L.), faba bean (Vicia faba L.), common vetch (Vicia sativa L.), and narbon bean (Vicia narbonensis L.) clearly had superior seed yield to the other species over a wide number of sites and years across south-western Australia (mean 1.0-2.3 t/ha); (ii) albus lupin (Lupinus albus L.), desi chickpea (Cicer arietinum L.), and Lathyrus cicera, L. sativus, and L. ochrus produced seed yields of 1-1.3 t/ha; and (iii) red lentil (Lens culinaris L.), bitter vetch (Vicia ervilia), and kabuli chickpea (Cicer arietinum L.) generally produced the lowest yields (0.6-1.0 t/ha). There were clear species x environment interactions. At low-yielding sites (<1.4 t/ha), field pea was the highest yielding species, while faba bean often produced the highest seed yields under more favourable conditions at high yielding sites. Lentil, bitter vetch, Lathyrus spp., and desi chickpea showed average response to increasing mean site yield. Soil pH and clay content and rainfall were the environmental factors identified as the most important in determining seed yields. Soil pH and clay content appeared to be especially important in the adaptation of lentil, narbon bean, bitter vetch, and kabuli chickpea, with these species performing best in soils with pH >6.0 and clay contents >15%. Seed yields were positively correlated with dry matter production at maturity across a number of sites (r(2) = 0.40, P < 0.01). Future improvements in seed yield of these species are likely to come from management practices that increase dry matter production such as increased plant density and early sowing, and through the development of genotypes with greater tolerance to low winter temperatures, and more rapid phenology, canopy development, and dry matter production than existing commercial cultivars.