Field assessment of plant density effect on biological nitrogen fixation by faba beans [vicia faba]

ABSTRACT

Field experiments were conducted to study the effects of increasing plant density on symbiotic nitrogen fixation by the faba bean /Rhizobium leguminosarum system. Increasing plant density increased the dry matter content of plants. The well nodulated plants had a greater N-uptake, than those plants fertilized with nitrogen. Plant densities up to 160,000 plants/feddan increased pod and seed yields. The results also showed that biological N2-fixation by faba beans was sufficient to supply all the N needed for the plants. However, the limiting factor for yield response, with increasing plant density, is likely to be due to a reduced photosynthetic capacity of the plant population within the limited area