Enhancing the salt tolerance of commercial Eucalyptus hybrid seedlings in preparation for reclamation of inland salinity areas

Salinity is one of the primary issues causing a gradual reduction of fertile lands, especially in the arid and semiarid regions. With an increasing human population and demand for raw materials derived from tree species, it poses a threat for sustainability of such agricultural practices. Deep-rooted species like Eucalyptus can be used to reclaim such lands but seedling establishment in extremely saline conditions can be a challenge and an enhancement of salt tolerance is necessary through chemical treatment. This study attempts to quantify the effect of treating two commercially available Eucalyptus hybrid (H4 and H28) seedlings with chemicals, to increase their chances of survival in highly saline (40 dS m(-1) of NaCl solution) inland environments of Thailand. This is most likely the first investigation of using chemicals to enhance the salt tolerance of Eucalyptus seedlings. After a month, no H28 seedlings could survive, while an average of 40% H4 seedlings survived. H4 seedlings treated with 30 mu M selenium had the highest survival percentage (60%) along with the highest relative weight and lowest electrical leakage, suggesting a higher growth and low cell damage, or an increased salt tolerance under this chemical treatment. Prior to planting in salt-affected areas, application of selenium through root uptake is recommended, to increase the chances for seedling growth in the field.