BIOLOGICAL NITROGEN-FIXATION IN NON-LEGUMINOUS FIELD CROPS - RECENT ADVANCES

There is strong evidence that non-leguminous field crops sometimes benefit from associations with diazotrophs. Significantly, the potential benefit from N2 fixation is usually gained from spontaneous associations that can rarely be managed as part of agricultural practice. Particularly for dryland systems, these associations appear to be verv unreliable as a means of raising the nitrogen status of plants. However, recent technical advances involving the induction of nodular structures on the roots of cereal crops, such as wheat and rice. offer the prospect that dependable symbioses with free-living diazotrophs, such as the azospirilla, or with rhizobia may eventually be achieved.