Abstract

Soil microorganisms promote growth and generate better response to abiotic stress in plants. Specifically, the arbuscular mycorrhizal fungi (AMF). AMF is one of the most important biotic components in environments subjected to water limitations, it is well known its role enhancing access water in plants under water stress. In this study, mycorrhizal status of representative species high Andean ecosystems of the Region of Tarapaca, were analyzed (3749-4134 m s.n.m.), ecosystems characterized for a low development of soils, as well as presence saline and water stress. For this, samples roots and rhizosphere soil of Parastrephia lucida, Deyeuxia curvula and Festuca crysophylla, were collected. In roots the percentage of AM colonization by the gridline intercept method (Giovannetti & Mosse 1980), after rinsing in a 10% (w/v) KOH solution and staining with 0.05% (w/v) trypan blue in lactic acid, was determined. In rhizospheric soil the spore density, by the wet sieving and decanting method in a 70% sucrose solution (w/v) (Gerdemann & Nicolson 1963), was determined. The measurement of mycelium length in the soil was carried out according to the method described by Borie et al. (2000) and total Glomalin-related soil protein (T-GRSP) was determited according to Wright and Upadhyaya (1998). Additionally, nitrogen (N) and biochemical activity (FDA) in soil were determined. The results showed high rates mycorrhizal plants (from 13.6 to 73.6%), fungal mycelium densities of 0.22 to 7.83 g m-1, spores densities between 101 and 6624 per 100 g soil, and T-GRSP contents varied between 0.2 and 3.48 mg g-1, under natural conditions. The pH values between 7.8 to 9.1 and salinity levels to 6000 dS m-1. These results show high dependence of plant species to produce mycorrhizal symbioses, under the limiting conditions of soil and climate in which these are growing, and suggest the need use in ecological restoration programs under these conditions.