Azospirillum inoculation on maize ( Zea mays): effect on yield in a field experiment in central argentina

A field experiment was performed on a Hapludol soil in central Argentina. Maize plants inoculated with a mixture of three Azospirillum spp strains showed a significant increase in shoot and root dry weights over the controls. The number of seeds per ear was increased ca. 2-fold in the inoculated plants. The dry weight of seeds (kg ha −1) was also increased by 59%. A significant stimulation in root development and a large number of Azospirillum cells (10 8 g −1 washed roots) were recorded at harvest of the inoculated plants. Fertilization with 60 kg N-urea ha −1 stimulated yield components above controls to levels similar to inoculation with Azospirillum.