Placing plants in extreme environmental conditions such as salt stress has a negative effect on the production and development of crops. Various biological stimulants have been used to increase plant tolerance to salt stress, and cyanobacteria extract has provided significant effects on plant performance. It is important to investigate the effects of salinity stress on agricultural products and especially on rice. Therefore, in the present study, the effects of Nostoc commune extract on rice growth parameters under salt stress were investigated. Salt stress was created for rice plants with concentrations of 100 and 150 mM of sodium chloride. Then, 25, 50 and 100% concentrations of 0.5 g/l cyanobacterial extract were used to evaluate the growth indicators. The results showed that the salinity treatment decreased the height of the hypocotyl, the length of the radicle and the weight of the seedling compared to the control. The hypocotyl height increased by 10% only in the 100 mM salinity which was treated with 100% extract. The length of the radicle in the 100 mM salinity, which was treated with 25% and 100% extracts, increased by 31% and 30%, respectively. While the hypocotyl height and radicle length decreased in the simultaneous treatment of 150 mM salinity and different concentrations of the extract. Seedling weight in 100 and 150 mM salinity, which was treated with 100% extract, increased by 25% and 8%, respectively. The results indicate that Nostoc commune extract can be effective in improving rice plant growth under salt stress.
