Differences in drought responses of seedlings of Prosopis chilensis, P. flexuosa and interspecific hybrids: implications for reforestation in arid zones

Abstract

In the arid Chaco region are severe processes of degradation of ecosystems. The reforestation with adapted species to the main climate limitation (drought) is a technique that can reverse such degradation processes. According to their water requirements, Prosopis flexuosa grows in plain drier environments, while Prosopis chilensis grows next to the mountains, on the banks of temporary rives. Genetic studies have demonstrated the existence of interspecific hybrids in contact areas between these species. The objectives of this study were (1) to determine the differential response in growth and survival of seedlings of P. flexuosa, P. chilensis and interspecific hybrids under controlled water stress conditions, and (2) to determine the influence of an imposed treatment of drought hardening in the nursery on the performance of plants in the field. In controlled water stress conditions, P. flexuosa showed lest growth under control treatment (no stress), however under stress treatment was the least affected by water stress. By contrast, P. chilensis was the most susceptible to drought stress,response that could be enhanced by hardening treatment before planting. The hybrid was similar to P. chilensis (under stress treatment and control treatment), but showed grate survival rate, similar to P. flexuosa. Both P. chilensis and hybrids showed a positive effect of hardening, but in P. flexuosa only this effect was observed at the driest site. The combination of these two characters in general are given as a mutual commitment, and focus highlights the need for ecophysiological studies (mechanisms) and genetic (stability and segregation of characters in the offspring) in this taxon.