Effects of Azospirillum inoculation on root infection and nitrogen incorporation in wheat

Abstract

In two field experiments, wheat was inoculated with various strains of Azospirillum spp. The two A. brasilense nir− strains isolated from surface-sterilized wheat roots increased the number of Azospirillum in surface-sterilized roots, plant dry matter, and percent N. The total N accumulated in plant tops at heading stage was increased by 30% in the first experiment (strain Sp 107 st) and by 51 and 89% (strains Sp 107 st and Sp 245, respectively) in the second experiment. The Azospirillum numbers (MPN) in chloramine-t treated roots were correlated with total nitrogen accumulation in plant tops (r = 0.92**). Numbers of Azospirillum in nonsterilized roots did not correlate with total plant N accumulation.