Assessment of strains of Bradyrhizobium sp. (Lupinus) for serradellas (Ornithopus spp.)

Abstract

Several strains of Bradyrhizobium sp. (Lupinus) were compared, in the glasshouse and field, with the Australian commercial inoculant strain, WU42.5, for symbiotic performance on serradella. Strains WSM471 and USDA3709 were more effective in nitrogen fixation (12 and 8% respectively) than WU42.5 across 10 serradella lines, although WU42.5 generally displayed good levels of effectiveness. WSM471 was a more saprophytically competent strain than WU425 in mildly acidic sandy soils, resulting in a 2.8-fold increase in the nodule score of serradella sown 32 cm from a line of bradyrhizobia established the previous year. Although WSM471, when compared with WU42.5, increased the nodulation and early production of an established sward of serradella, it did not improve total annual production of the sward. The possible replacement of WU42.5 with WSM471 in serradella inoculants is discussed.