Physiological Responses of Endophytic Turf-type Tall Fescue to Mowing Height and Nitrogen Fertility.

The benefits of  tall fescue (Schedonorus phoenix (Scop.) Holub; formally know as Festuca arundinacea Schreb.) containing endophytes (Neotyphodium coenophialum [Morgan-Jones and Gams] Glenn, Bacon, and Hanlin) are well documented and include resistance to surface feeding insects, increased disease resistance, and increased environmental stress tolerance.  It is uncertain, however, how endophytes and cultural practices like mowing height and nitrogen (N) fertility affect turfgrass physiology. The objective of this field study was to determine how two mowing heights (5 and 9 cm) and three N fertility regimes (0, 98, 196 kg N ha^-1 yr^-1) affect ‘Da Vinci’ turf-type fescue physiological characteristics. Endophyte infection was increased by N treatment, 196 kg ha^-1 yr^-1, in July 2006 (53%) and May 2007 (56%) mowed at 5 cm and in Sept. 2007 (61%) mowed at 9 cm compared to the unfertilized control (29, 26, 50 %, respectively). Alkaloid concentrations, toxins produced by the endophyte, were not affected by N treatment or mowing height. The high, 196 kg N ha^-1 yr^-1, treatment had lower total sugar concentrations in July 2006 (52 mg g^-1), Apr. and Aug. 2007 (139 and 49 mg g^-1) mowed at 5 cm and in Apr. and May 2007 (178 and 78 mg g^-1) mowed at 9 cm than the unfertilized control (80, 165, 57 mg g^-1; 192 and 89 mg g^-1). Protein concentrations increased in Sept., Oct. 2006 (35 and 49 mg g^-1), and June 2007 (24 mg g^-1) for the high, 196 kg N ha^-1 yr^-1, treatment mowed at 5 cm and in May, Oct. 2006 (30 and 42 mg g^-1) and Sept., Nov. 2007 (33 and 30 mg g^-1) mowed at 9 cm as compared to the unfertilized control (21, 33, 12 mg g^-1; 20, 25, 25, 24 mg g^-1). As expected, N treatment affected leaf tissue N content except in Aug. 2007 for the 5 cm mowing height and in May 2006, June, Aug., and Nov. 2007 for the 9 cm mowing height.