Association of N2-fixing cyanobacteria with wheat (Triticum vulgare L.) roots

Two locally prevailing hetyerocystous cyanobacterial isolates, collected from alluvial clay soil and identified as Nostoc muscorum and Anabaena variabilis, were tested (either singly or mixed) for their potency to colonize the roots of wheat seedlings. N. muscorum formed close association with root hairs, whereas A. variabilis showed loose binding. The mixture of both cyanobacterial strains formed weak association with the roots of wheat seedlings. The tight colonization of N. muscorum led to accumulation of Chl "a" in the roots, as well as showed a beneficial influence on stimulating nitrogenase activity. Such tight association by N. muscorum significantly increased the growth parameters of wheat seedlings. Dry weight of the inoculated plant seedlings roots augmented by more than 3-fold of the control, wherever the shoots were promoted by more than 36% as compared to the control has no inoculation. However, the loose attachment shown by A. variabilis contributed to the weak association of the mixture of both cyanobacterial agents. Key words: Nostoc muscorum, Anabaena variabilis, Triticum variabilis, cyanobacterial isolates.