Abstract:
A survey of blue-green algae from agriculture fields of Sind, belonging to different soil series was carried out.
The results indicate that out of 92 species belonging to 11genera, more than 32 species contain heterocysts and are potential nitrogen fixers. They belong to the genera Nostoc (6 sp.) ,Anabaena(6 sp.) Nodularia (1 sp.), Aulosira (1 sp.), Tolypothrix(4 sp.) Calothrix(1 sp.) Rivularia (1 sp.), Gloeotrichia (1 sp.), Hapalosiphon (1 sp.) and Cylindrospermum(2 sp.).
IT was observed that oscillatoria (31 sp.) and phormidium (11 sp.) Lyngbya(12 sp.), Chroococcus (3 sp.) Merismopedia (2 sp.) Aphanocapsa (1sp.) were amongst non-heterocystous tyoe, whie Anabaena (6 sp.) and Nostoc (6 sp.) Gloeotrichia (5 sp.) amongst the heterocystous type were the most frequently observed in these soils. Amongst the nitrogen fixers Anabaena circinalis was the most commonly occurring alga in these soils.It was aslo noed that Nostoc, Anabaena, Aulosira, Toypothrix and Hapalosiphon and Riviluria amongst heterocystous genera were common Cyanophyceae of the rice fields of Sind.
