Autecology of Bradyrhizobium japonicum in soybean-rice rotations

摘要: The effect of rice culture on changes in the number a strain soybean root-nodule bacteria, (Bradyrhizobium japonicum CB1809), already established soil by growing inoculated crops, was investigated transitional red-brown earth soils at two sites south-western New South Wales. At first site, 5.5 years elapsed between harvest last four successive crops and sowing next. In this period three one crop triticale were sown intervals these after triticale, land fallowed. Before crop, Bradyrhizobium 1.32×105 g−1 soil. respective numbers bradyrhizobia first, second third 4.52 ×104, 1.26×104 6.40×102 following population remained constant. Thus sufficient survived to nodulate allow N2-fixation succeeding crop. declined during but decline less than when fallowed (400-fold cf. 2200-fold). Multiplication rapid rhizosphere seedlings without inoculation bays. 16 days sowing, their not significantly different (p<0.05) from those plots where had been sown. Nodulation soybeans greatest grown, yield grain nitrogen (p<0.05). Our results indicate that flooding has deleterious survival but, under conditions experiments, B. CB 1809 provide good nodulation covering total soybean.