Effect of salt and drought on growth, physiological and biochemical responses of two Tamarix species

Tamarix trees are considered of particular interest for afforestation and reforestation of degraded areas prone to salinity and drought. In this study, a comparison of the performance and physiological responses of two species of Tamarix grown in saline and dried soils was carried out. Stem cuttings of T. aphylla and T. jordanis were collected from a location in the Negev desert and the plantlets obtained were subjected to four different soil treatments under semi-controlled conditions for 14 days. The treatments were: fresh water (C); salt (S: 150 mM of NaCl); drought (D: 50% field capacity); and a combined stress (DS: 150 mM of NaCl + 50% FC). Results showed a higher tolerance to salt stress of T. jordanis as compared with T. aphylla. The maintenance of high amount of cell carbohydrates, the high capacity of carbon assimilation and the active growth were considered as markers of salt tolerance in Tamarix spp. T. aphylla showed better performances in terms of growth and biomass production than T. jordanis in dry conditions. The high accumulation of sugars found in the leaves of T. aphylla under mild drought is considered a mechanism of acclimatization. The combined stress (salt+drought) lowered the performance of plants as compared to salt and drought stress applied alone. The possible role of the accumulation of proline observed in the leaves of both species under stressful conditions is discussed.