Yahalom, E., Department of Plant Pathology and Microbiology, Faculty of Agriculture, P.O. Box 12, Rehovot, 76100, Israel
Kapulnik, Y., Department of Plant Pathology and Microbiology, Faculty of Agriculture, P.O. Box 12, Rehovot, 76100, Israel
Okon, Y., Department of Plant Pathology and Microbiology, Faculty of Agriculture, P.O. Box 12, Rehovot, 76100, Israel

Under controlled conditions in pots filled with sand, vermiculite and field soil, inoculation with A. brasilense-Cd ATCC 29729 or with Azotobacter chroococcum caused increases above controls in the weight and N content of panicles of Setaria italica. In no case, however, did N increases in test plants exceed the initial total N content. High acetylene reduction activities (1,000-2,000 nmole/h/pot) could be found only in plants inoculated with Azospirillum. Inoculation with Azospirillum (strain-Cd) in the field caused a significant increase above noninoculated controls of 18.5% in shoot dry weight, of Setaria italica. Azotobacter caused a non significant increase of 8%. No significant differences were found between yields of Setaria italica grown in soil inoculated with A. chroococcum, and those of plants grown in the presence of A. vinelandii. A. brasilense-Cd was more effective in the field than A. brasilense Sp-7 ATCC 29145. The results suggest that Azospirillum may increase yields of S. italica more efficiently than Azotobacter under local field conditions. © 1984 Martinus Nijhoff/Dr W. Junk Publishers.