The use of biofertilizers instead of chemical fertilizers is preferred due to economic and environmental benefits. Sesame is one of the profitable and strategic plants and due to the beneficial effects of Nostoc cyanobacteria as a biofertilizer, in this study the effect of aqueous extract of cyanobacterium N. commune on growth indicators in sesame was investigated. Aqueous extract was prepared at a concentration of 0.1 g l-1 and then at concentrations of 0, 5, 10, 20, 30, 40, 60 and 80% was added to Petri dishes containing 10 sesame seeds and seedlings were harvested after 8 days. The results showed that wet weight, seedling length and root length indicators were significantly different between different concentrations. Concentrations of 60% and 80% showed the lowest fresh weight, seedling length and root length. The highest fresh weight was related to the concentration of 10% and the highest seedling and root length was related to the control group; however, there was no significant difference with 10% concentration. Seedlings grown at 30% concentration showed the highest amount of chlorophyll a and carotenoids and seedlings grown at 10% concentration showed the highest amount of chlorophyll b. The results showed that high concentrations of the extract had a negative effect on growth indicators while low concentrations had positive effects on fresh weight and the photosynthetic pigments content. It seems that with longer treatment period, low concentrations of aqueous extract of N. commune can probably be a good stimulant for growth of sesame.
