عنوان مقاله [English]
نویسندگان [English]چکیده [English]
With regard to the crucial role of cyanobacteria in molecular nitrogen fixation, the present
study was aimed to isolate the native strains of cyanobacteria from paddy fields in Guilan province,
and also examined their important physiological characteristics for production of bio-fertilizer.
After isolation, purification and identification of efficient cyanobacterial isolates, chlorophyll
content, phycobiliproteins and nitrogenase activity of isolates were determined, and then efficient
strains for pot cultivation of rice plants were selected. The results showed that the Nostoc sp.
GGuCy-47, Nostoc sp. GGuCy-46, Anabaena sp. GGuCy-21, Cylindrospermum sp. GGuCy-25 and
Anabaena sp. GGuCy-42 had the higher phycobiliproteins content. Thus isolates which had higher
content of phycobiliproteins also had a greater nitrogen fixing capacity, especially the two isolates
Cylindrospermum sp. GGuCy-25 and Anabaena sp. GGuCy-42 possessed the highest nitrogenase
activity. Based on the results obtained, the efficient isolates of cyanobacteria increased grain yield
and improved the growth of the rice (cv. Tarom Hashemi) but the amount of growth varied among
different isolates. Finally, Cylindrospermum sp. GGuCy-25 and Anabaena sp. GGuCy-42, as two
more efficient isolates can be used as biofertilizer in rice paddy fields.