Differential Responses of Anabaena Variabilis and Nostoc Linckia to Salt Stress and Their Role in Improvement the Growth Conditions of Some Salt Stressed Plant Seedlings

Two Species of cyanobacteria: namely, Anabaena variabilis and Nostoc linckia were isolated from Baltem and Sedi-Salem (saline-sodic soils), respectively (Kafr El-Sheikh Governorate, Egypt). A. variabilis was able to grow in salinity level between 4-6 g L -1 NaCl; above 6 g L -1 NaCl the growth rate was relatively constant till 10 g L -1 NaCl. Over 10 g L -1 NaCl, the growth rate declined. Results indicated that A. variabilis was able to utilize NaCl between 1-10 g L-1. On the other hand, N. linckia had a wide range of salinity tolerance. Whereas, the growth rate increased gradually from 1- 4 g L -1 NaCl and more than 4 till 20 g L-1 NaCl the pattern of growth was nearly stable. N. linckia was able to withstand a wide range of salinity but it had no good ability to utilize NaCl. The results indicated that the addition of A. variabilis led to significant increase of shoot and root length as well as, significant decrease of proline content of bean, zea and barley seedlings grown in saline environment, respectively. Also, the presence of alga caused a significant increase in chlorophyll a content of zea seedlings as well as, the germination percentage of barley seedlings in as compared to control ones. N.linckia caused a significant decreasing in proline content of bean, zea and barley seedlings, while, it caused an increasing of both chlorophyll a content of zea and shoot length of barley seedlings as compared with control.