Salt tolerance of native trees relevant to the restoration of degraded landscapes in the Monte region, Argentina

Abstract

Afforestation with native trees can enhance the conversion of degraded saline lands into productive landscapes with considerable economic and environmental benefits. To identify the native salt-resistant species for restoration, we investigated how salinity affects the growth and water status of sapling from two Neltuma species from the Monte region. We produced Neltuma flexuosa and Neltuma chilensis saplings using seeds harvested from native forests with multiple provenances (Fiambalá, Chilecito, Mogna, Pipanaco, Talampaya, and Andalgalá). We conducted a greenhouse trial in which 810 saplings of different species/provenance combination received one of three saline irrigations, that is, sodium chloride solutions of 0.01 (no stress), 0.10 (moderate stress), and 0.25 M (severe stress). We found that Neltuma saplings exhibited varying degrees of reduction in their growth (plant height and aboveground biomass) and water status (e.g., stomatal conductance and leaf water potential) traits with increasing salt stress. N. flexuosa-Fiambalá and N. flexuosa-Chilecito were the most tolerant and sensitive, respectively, while all provenances of N. chilensis showed intermediate tolerance to salinity. These results suggest that N. flexuosa displays highly variable plasticity to salt stress compared to N. chilensis, emphasizing the need to select appropriate provenances for afforestation in saline-degraded areas.