Tuesday, November 6, 2007
171-6
Physiological Reponses of Endophytic Turf-type Tall Fescue to Mowing Height and Nitrogen Fertility.
Kristina Walker1, Cale Bigelow1, Douglas Richmond1, Yiwei Jiang2, Jeffrey Volenec1, and George Van Scoyoc1. (1) Purdue University-Agronomy Dept., 3164 Stratus Drive, West Lafayette, IN 47906, (2) Agronomy Dept, Purdue University-Agronomy Dept., Purdue University, 915 W. State Street, West Lafayette, IN 47907
The benefits of endophytic tall fescue 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 turf physiological characteristics, specifically; alkaloids, total sugars, starch, proteins, and leaf tissue N. Mature ‘Da Vinci’ turf-type fescue with a high (> 60%) endophyte infection rate was maintained in the field using a randomized complete block design of the aforementioned mowing and N variables. Twenty tillers were taken bimonthly from May-Nov. in 2006 and monthly from Apr.-Nov. in 2007. Two, 2 mm cross sections of each stem was analyzed for endophyte infection by a tissue print-immunoblot technique to determine seasonal variations in endophyte stem infection rates. Additionally, clippings were taken June, Sept., and Oct. in 2006 and every month from Apr.-Nov. in 2007 to determine ergot alkaloids, total sugars, starch, proteins, and leaf tissue N concentrations. Additionally, visual characteristics like turfgrass quality and canopy greenness were recorded. Thus far, seasonal variations in stem infection rates were observed and in general higher infection rates (53-56%) were associated with the high, 196 kg ha-1 yr-1, compared to the unfertilized control, 29-36%. These variations may have an influence on the physiological properties which are currently being analyzed and this data will be presented.