Physiological Study of Soil-Born Cyanobacteria of Rice Fields in Guilan and Application of Efficient Strains in Improving Growth and Yield of Rice

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- 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.