Response to salt stress of two wetland grasses of forage potentialities

The growth of two wetland forage grasses Leptochloa fusca (L.) Kunth. and Echinochloa stagnina (L.) P. Beauv. was investigated under NaCl salinity regarding the morphological traits, plant chemical composition, photosynthesis and the antioxidant enzymes POD and CAT. Plants of both species were irrigated with 0, 50, 100, 200, 300 and 400 mM NaCl in a sand/perlite mixture of 1:1 (v/v). Salinity negatively affected morphological traits and plant biomass of both species, particularly E. stagnina. Soluble sugars and proline within limits, protein contents of the foliage were increased to different extents by increasing salinity, but insoluble sugar decreased. K+/Na+ ratio of shoot and root of both species was decreased as a consequence of Na+ accumulation and restricted K+ uptake. NaCl salinity adversely affected photosynthetic rate, transpiration rate, stomatal conductance and water use efficiency of both species particularly E. stagnina. Tolerance of L. fusca and E. stagnina to salinity stress can be based on stomatal closure and reduction in leaf area, in order to minimize water loss via transpiration and increase the activity of some antioxidant enzymes to detoxifying ROS generated during stress.