An increase in nitrogen content of Setaria italica and Zea mays inoculated with Azospirillum

Abstract

Bacteria belonging to the genus Azospirillum isolated from Cynodon dactylon roots in Israel were compared with Azospirillum brasilense from Brazil and California for their ability to fix nitrogen in association with grasses under greenhouse conditions. The plants were grown in a system which avoided cross inoculation from the inoculated soil to the control, while maintaining the natural soil microflora and humidity level in the soil close to field capacity. The organisms tested significantly increased the dry weight of Zea mays and Setaria italica leaves, the total nitrogen content of these leaves (as measured by the Kjeldahl method), and supported acetylene reduction in intact nonsterile systems as compared with the noninoculated controls. Ethylene production in intact systems could be detected after 6 h and was linear for 72 h, providing a constant soil temperature (28–32 °C) was maintained.