CO-OCCURRENCE OF ARBUSCULAR MYCORRHIZAE AND DARK SEPTATE ENDOPHYTES IN GRAZED GRASSLANDS

GARCÍA, I.*; MENDOZA, R.; MARBÁN, L.; POMAR, M.

Mar del Plata

Congreso; XIX Congreso Latinoamericano y XXIII Congreso Argentino de la Ciencia del Suelo; 2012

Asociación Argentina de la Ciencia del Suelo

ABSTRACT The impact of the mode and intensity of sheep grazing on the co-occurrence of AM fungi and DSE in Poa rigidifolia and Deschampsia flexuosa roots and their associations with N and P in plant tissue was studied in a range of grazed degraded grasslands from Tierra del Fuego (Argentina). Under different grazing modes and/or intensities, AM colonization was always higher in Deschampsia (36.8%) than in Poa (24.5%), whereas DSE colonization was similar in both species (28% in Deschampsia and 27% in Poa). High DSE colonization was associated with soils of low fertility and subjected to grazing associated with an intense grassland disturbance. In contrast, AM colonization was associated with more fertile soils and low intensity of grassland disturbance. Nutrients in the plant tissue were always higher in Deschampsia than in Poa. Nitrogen concentration in both plants was positively correlated with AM and negatively with DSE colonization, whereas P concentration showed no correlation with AM or DSE. The highest AM colonization indexes and nutrients in tissue may explain why Deschampsia is much better adapted to the acid, xeric conditions and low fertility in soils of these grasslands than Poa.