Effects of Seawater Salinity on Seedling Growth Nodulation and Tissue Nitrogen in Acacia nilotica (L.) Delile

A pot experiment was conducted to determine the effect of sea water salinity on growth, nodulation and nitrogen content of Acacia nilotica (L.) Delile seedlings. Eight weeks old seedlings were irrigated with 40, 50, 60, 70 and 80% sea water for one month. After 12 weeks the plants were uprooted and the nodules were observed for their frequency, shapes and sizes. Nodules showed morphological alterations in size and shape in different salinity levels. The root-shoot ratio, nitrogen contents in the leaf, stem and root were analyzed. In general salt stress resulted in a decrease of plant growth, nodulation and percent tissue nitrogen in A. nilotica plants. Root-shoot ratio showed gradual increase with increasing sea water concentrations. Nitrogen contents decreased in leaf and stem, whereas it increased in roots. Nodules showed morphological alterations in size and shape with increasing salinity. A. nilotica accumulated NaCl in the xylem of the roots that may be considered as a preliminary salt tolerant mechanism adopted by the plant.