Nitrogen fixation and yield of lucerne (Medicago sativa L.), as affected by co-inoculation with Sinorhizobium meliloti and arbuscular mycorrhiza under dry organic farming conditions

Summary

This study evaluated the effects of co-inoculation with Sinorhizobium meliloti and arbuscular mycorrhizal fungi on the growth, yield and biological nitrogen fixation (BNF) of lucerne (Medicago sativa L.) under organic farming and dry weather conditions. The trial was laid out as a factorial experiment in the fields of the University of Natural Resources and Applied Life Sciences, Vienna-Austria at Raasdorf in 2007. The experimental factors of S. meliloti and arbuscular mycorrhiza (AM) including Glomus etunicatum, G. intraradices and G. claroideum and irrigation levels were tested. Co-inoculation of lucerne with S. meliloti and AM increased shoot dry weight as well as BNF at the first and second harvest but for BNF it was not significant. Irrigation resulted in the enhanced growth of some growth parameters. Microbial activities in this organically managed field were high enough for establishing an effective symbiosis with lucerne without any necessity for inoculation. Hence, it can be suggested that the tripartite symbiosis of S. meliloti, AM and lucerne can improve the performance of lucerne in organic farming and under dry conditions.