Tall Fescue Rooting Mass on a Calcareous Sub-Soil as Affected by Endophyte Infection.

Sufficient soil phosphorus (P) is critical for rapid seedling establishment because P-deficient seedlings lack vigor and form low density turf areas which are more susceptible to soil erosion and nutrient loss.  Endophytes have been shown to exhibit an ecological advantage over non-endophytic grasses under abiotic stressful conditions.  A greenhouse study was conducted to determine the effects of endophytes on tall fescue  (Lolium arundinaceum Schreb.) establishment on a low-P, sub-soil typical of many urban soils in the midwest.  The soil was highly alkaline (8.3) and classified as a clay loam (38 g kg^-1 Sand, 34 g kg^-1 Silt, 28 g kg^-1 Clay).  The subsoil was amended with (0, 3, 9, 25 and 75 mg kg^-1) mono-calcium phosphate to generate a range of soil concentrations. Endophytic tall fescue (TFE+) and non-endophytic tall fescue (TFE-) were planted in 15 cm diam. x 10 cm deep pots.  Nitrogen and moisture were not limited throughout establishment (10 weeks).  Turfgrass cover was measured quantitatively using digital image analysis taken weekly starting 21 days after seeding (DAS).  Visual assessment of turf density was taken at the beginning and conclusion of study.  Root dry weight (RDW) was measured using the dry ashing method.  Endophytic tall fescue resulted in higher visual turf density at the beginning of the study at the 0, 9, 25 and 75 mg P kg ^-1 but at the end of the study no visual differences between P levels or endophyte infection were observed.  Higher P levels resulted in higher turfgrass cover using digital image analysis at the 21, 35 and 42 DAS, however no significant differences between P levels were recorded after 42 DAS.  A significant increase of RDW for TF+ (2.28 g) versus TF- (2.08 g) may explain why TFE+ resulted in improved turf cover, perhaps due to greater nutrient absorption.