Effect of Salinity on Growth and Gas Exchanges in Seedlings of Pinus nigra Subsp. Pallasiana

Aims Salinity, due to its remarkable effects on physiology and performance of plant is considered as a world major problem in arid zone ecosystems. Pinus nigra subspecies pallasiana is known as a nurse and pioneer species. The aims of this study were to determine growth responses and gas exchanges of the seedlings of Pinus nigra subspecies under different salinity stress in the greenhouse environment. Materials & Methods In this experimental Study, Seedlings of Pinus nigra was investigated under salinity stress in 6 NaCl levels including 0, 50, 100, 150, 200 and 250mM as completely randomized design in greenhouse conditions. Height and diameter growth and gas exchanges parameters were determined in day 90 (August) and biomass allocations in day 150 (November). For data analysis One-Way ANOVA, Duncan’s test and SPSS 19 software were used. Findings The highest survival appeared in zero and 50mM with 100 and 93.33%, respectively. Salinity stress decreased survival, height and diameter growth and also biomass of root, shoot, root:shoot and total of seedling. With increasing salinity, photosynthesis, stomatal conductance, transpiration reduced. Higher survival, better growth and gas exchanges were detected below 50mM NaCl salinity. Conclusion Salinity has adverse effects on growth and gas exchanges of P. nigra seedlings during the studied period. Survival in 50mM NaCl has a high percentage, but in higher salt concentrations (200 and 250mM NaCl) it drastically reduce. Similarly, decrease in seedling performance was found in severe salinity levels. This species has a relatively good resistance to 50mM NaCl.