STUDY THE INDUCTION EFFECT OF AZOSPIRILLUM INOCULATION ON THE FORMATION OF PARA-NODULES ON GRAMINEAE

In order to study the effect of Azospirillum brasilense inoculation on graminae, two field experiment were conducted at Maruit experimental station, Alex., Desert Research Center. Azospirillum brasilense characterized by its ability to fix atmospheric nitrogen and production of plant hormones like indole- 3- acetic acid (IAA). Also, Azospirillum brasilense has the ability to transform tryptophan into IAA. Azospirillum brasilense was inoculated into wheat and maize to show its effect on growth and development of these plants. The achieved results could be summarized as follows 1- Addition of tryptophan in concentration up to 200 ppm to the growth media of Azospirillum brasilense lead to vigorous increase in the production of indole acetic acid (IAA) by the microorganism. 2- Azospirillum brasilense in presence of tryptophan up to 200 ppm had promoting effects on seedlings of wheat and maize compared to all other treatments, whereas treatment with tryptophan only in concentration of 500 ppm gave an inhibitory effect on treated seedlings, reaching a level lower than control. 3- Inoculation of wheat and maize seedlings with Azospirillum brasilense and tryptophan up to 200 ppm lead to formation of tumor like structures called paranodules on roots of treated seedlings, which enhanced the nitrogen-fixing activity, growth parameters and increased yield in two crops of maize and wheat.