Study of soil blue-green algae and their effect on seed germination and plant growth of vegetable crops

Nitrogen fixation blue-green algae make a major contribution to the fertility of soil. it has been suggested that blue-green algae (bga) assist higher plant growth by supplying growth substances. there are numerous works about roles of blue-green algae in paddy soils and rice growth but little on other plants. in this research, 19 morphospecies belonging to three families of heterocystous and non-heterocystous blue-green algae from several paddy fields in the north of iran were identified out of which seven species are new to iran. among these taxa, three species were used as inoculum in pot culture of cucumber, tomato and squash. the result revealed that addition of all algal extracts can enhance seed germination and plant growth in all treated plants. statistical analysis showed that there are significant differences in plant height, root length, number of leaves, fresh and dry weight of root, leaf and stem as compared to control.