ABSTRACT
This investigation aimed to select efficient Azospirillum strains for inoculation of maize and sorghum at Assiut and Sohag Governorates and reach the best method[s] for inocula application under field condition. Different irrigation regimes and different N-fertilization levels were tested with inoculation to secure the highest yields with least input. The results showed that seed inoculation with peat inocula was better than seed soaking in broth cultures. The double inoculation of maize cultivars [seed treatment + soil spray] gave better growth and yield than the single inoculation as seed treatment. Maize and sorghum cultivars showed variations in response to inoculation with azospirilla. The two-week irrigation intervals were the best regime for maize cultivars, whereas the four-week intervals were the optimum for sorghum cultivars. Significant positive interactions found between inoculation and the two-week irrigation regime in case of maize and between the three-week regime and inoculation in case of sorghum reflected a significant increase in grain yields