Allelopathic effects of Aristida adscensionis.

Investigations were carried out to study the allelopathic potentialities of Aristida adscensionis Linn.Bacterial culture experiments conducted have revealed that extracts of root, shoot and litter bring about a significant inhibition on the development of bacterial colonies of Azotobacter. When soil samples have been treated with these extracts, the soil nitrogen level has been diminished significantly in the soil samples treated with root extract, whereas with shoot extract the reduction in the soil nitrogen level was not significant. With litter leachate the depletion is found to be statistically significant at the 5% level.Thus it is concluded that Aristida adscensionis inhibits nitrogen fixing bacteria and thus creates a depleted nitrogen content in the soil. It is fairly probable that this may be a mechanism by which the species avoids competition from other species requiring good amounts of soil nitrogen for their metabolism. These results provide a possible explanation for the dominance of this grass species in the abandoned fields at Rajkot.