Seed Germination and Seedling Establishment in Pistacia atlantica Desf. and Pistacia lentiscus L. under Drought

The rehabilitation of degraded Mediterranean areas requires reintroduction of key-stone woody species. However, seed germination and seedling establishment for native species are poor. Germination behavior of Pistacia atlantica Desf. and Pistacia lentiscus L. in response to temperature (15, 20, 25 and 30 degrees C), salinity (0, 10, 25 and 50 mM NaCl) and scarification (seeds with/without pulp) were analyzed. The response of seedling establishment to water deficit was related to soil moisture at 100 and 50% of the field capacity. Scarification facilitated germination while salinity should not exceed 50 mM NaCl and temperature must be between 20 and 25 degrees C for P. lentiscus and 25 degrees C for P. atlantica. In P. atlantica, seedling establishment was susceptible to water deficit and it showed high-water requirement. The survival of stressed P. atlantica seedlings are attributed to the reduction in stomatal conductance, carbon assimilation and shoot growth, and acceleration of old leaf senescence and root growth. The divergence within both species in seed germination, carbon assimilation, growth and biomass allocation are interpreted as a plasticity response, indicating a specialization to either original or resource habitats. For this reason, in reforestation programs, poor performance of planted seedlings is also associated with soil water deficit.