Gas exchange of four woody species under salinity and soil waterlogging

Extensive irrigated areas worldwide have shown reduction in production due to the excess of salts (Leal et al., 2008). Salt-affected areas occur all over the world, especially in regions with arid and semi-arid climate, where irrigation is fundamental for a successful agriculture. It is estimated that 20% of irrigated areas are affected by salinization, resulting from the accumulation of salts caused by irrigation (Aragues et al., 2011). This advancement in irrigation with the use of low-quality water in semi-arid regions and in marginal land areas has increased the accumulation of salts in the soils and, consequently, their degradation (Ribeiro et al., 2016).Another factor that contributes to the increase of salinity is the excess of water, caused by inadequate irrigation management. Waterlogging periods in which the water depth covers the soil at higher levels can cause death of the seedlings and also produce differences in their structure and density (Soares & Oliveira, 2009).It is common knowledge that some forest species, native and/or exotic, are physiologically tolerant to the most varied types of stress. Thus, studies on the physiological responses of plants under stress conditions can generate useful information for the reforestation of degraded areas.Physiological evaluations, such as gas exchanges, can be performed in a direct and non-destructive manner and are related to the excess of salts and saturation or waterlogging of the soil. In this context, this study aimed to evaluate gas exchanges in seedlings of four forest species cultivated in saline soils and under soil waterlogging cycles.