Influence of soil water status on arbuscular mycorrhizas in three perennial grasses in central Argentina.

BUSSO, C.A., BOLLETTA, A.I., FLEMMER, A.C., MONTANI, T.

Annales Botanici Fennici

Finnish Zoological and Botanical Publishing Board 2008

Lugar: Helsinki; Año: 2008 vol. 45 p. 435 - 447

1797-2442

In this field study, we determined the effects of water stress, rainfed or irrigated conditions on arbuscular mycorrhizal fungal (AMF) root colonization in the late-seral Stipa clarazii, the earlier-seral S. tenuis and the early-seral S. gynerioides at different developmental stages and sampling dates during 1996 and 1997. Plants grew in a uniform matrix such that each plant of S. clarazii and S. tenuis was surrounded by four plants of S. gynerioides. We had two goals for this study: 1) document levels of AMF root colonization, and 2) examine plant stress responses during imposed water stress in three Stipa species.  We used these data to test the hypothesis that the effects of water stress in Stipa grasslands depend upon the interactions between plant AMF status and plant species identity. No consistent patterns in AMF root colonization frequency were observed among soil water contents. This suggests that AMF root colonization is highly plastic and respond to environmental pressures that we do not yet understand. Mycorrhiza colonization was greater in the late-seral than in the earlier-seral species. Higher AMF root colonization levels in S. clarazii may contribute to explain its higher competitive ability in comparison to the earlier-seral species.