BASIL IONIC RESPONSES TO SEAWATER STRESS AND THE IDENTIFICATION OF GLAND SALT SECRETION

Basil (Ocimum Basilicum) seedlings were subjected to 0,5%,10%,20% and 40% seawater for 10 days under shade house conditions. Increasing seawater concentration led to considerable reduction in plant dry matter accumulation. However, root growth was not affected till treated with 40% seawater. Accumulations of Na + and Cl - were correlated with decline of Ca 2+ and K + in stems, roots or both. Contents of Ca 2+ and K + in leaves increased or remained relatively unchanged with increasing salt levels. In salinity -stressed plants, Na + were partitioned mainly in roots and more than 50% of the K + and Ca 2+ were stored in leaves. Higher K + /Na + and Ca 2+ /Na + ratios in leaves rather than in roots and stems were observed in Basil plants. Scanning electron microscopy coupled with X-ray microanalysis showed that Basil leaf gland secretions contained Na + and Ca 2+ . The Na + secretion increased while Ca 2+ secretion decreased with the increasing seawater concentration. These results suggested that Basil salt tolerance is associated with the compartmentation of Na + in roots and the balance of K + , Na + and Ca 2+ in leaves as well as the salt secretion by the leaf glands.