Temporal and spatial patterns of soil water following wildfire-induced changes in plant communities in the Great Basin in Nevada,USA

Infection of tall fescue (Festuca arundinacea Schreb.) with its endemicNeotyphodium coenophialum-endophyte (Morgan-Jones and Gams) Glenn, Bacon and Hanlin appears to reduce copper (Cu) concentrations in forage and serum of grazing animals, contributing to a range of immune-related disorders. A greenhouse experiment was conducted to identify effects of novel endophyte strains on Cu acquisition by tall fescue (Festuca arundinacea Schreb.) varieties Grasslands Flecha and Jesup infected with a novel, non ergot producing endophyte strain AR542, and two perennial ryegrass (Lolium perenne L.) varieties Aries and Quartet infected with a novel, non lolitrem B producing strain AR1, and their noninfected (E−) forms. Individual endophyte/grass associations were cultivated in nutrient solutions at 1.0 (P+) and 0.0 mM (P−) phosphorus concentrations. The Cu²⁺-binding activity of extracellular root exudates, and concentrations of Cu and other heavy metals in roots and shoots were measured. Extracellular root exudates of AR542-infected vs. E− tall fescue had higher Cu²⁺-binding activity only in P− nutrient solution as shown by lower concentration of free Cu²⁺ (0.096 vs. 0.188 mmol Cu²⁺ g⁻¹ root DM, respectively). The Cu²⁺-binding activity by root exudates of perennial ryegrass was not affected by endophyte infection, but was higher (i.e., lower concentration of free Cu²⁺) in P− vs. P+ nutrient solution (0.068 vs. 0.114 mmol Cu²⁺ g⁻¹ root DM). In this hydroponic experiment, Cu concentrations in shoots of both grasses were not a function of Cu²⁺-binding activity and endophyte effects on heavy metal concentrations in shoots and roots were specific for each variety. The Cu²⁺-binding activity of extracellular root exudates may affect Cu accumulation by field-grown, endophyte-infected tall fescue under P-limiting growth conditions and warrants verification by more specific methods.