Pages: 35-42

Abstract

Nitrogen is generally considered one of the major limiting nutrients in plant growth. The ‎biological process responsible for reduction of molecular nitrogen in ammonia called nitrogen ‎fixation. An extensive diversity of nitrogen fixative bacterial species fit to most phyla of the ‎bacteria domain has the ability to settle the rhizosphere and to communicate with plants. ‎Leguminous plants can produce their nitrogen by association with differentiation on their ‎particular host plants from a specialized organ, the root nodule. Other symbiotic relations ‎contain heterocystous cyanobacteria, although a growing numbers of nitrogen fixative species ‎have been identified such as Azobactor, Azospirillium, Endophytes bacteria, Frankia are ‎colonizing on the root surface of cereal crops and in certain conditions, inside the roots of a ‎variety of cereal crops tree, and pasture grasses. The Basic and advanced facets of these ‎associations are discussed in this review‎.