Tuesday, November 14, 2006

Nitrogen Source and Timing Effect on Carbohydrate Status of Bermudagrass and Tall Fescue.

Anthony L. Goldsby and Steven J. Keeley. Kansas State University, 2021 Throckmorton Hall, Manhattan, KS 66506

Non-structural carbohydrates (NSC) are important for physiological plant health and for a plant’s ability to recover from stress. This study, initiated in August 2005, was conducted to determine the effect of various nitrogen source/timing combinations on NSC levels in tall fescue and bermudagrass. Nitrogen sources included two polymer-coated ureas, sulfur-coated urea, urea formaldehyde, and urea. Application timing was fall-only, or fall plus spring. Control treatments consisted of urea applied in May, September, and November for tall fescue, and urea applied in May, June, July and August for bermudagrass. The experimental design was completely randomized with four replications. NSC were measured bi-monthly by extracting two 10-cm diameter plugs from each plot and measuring re-growth in darkness in a growth chamber. Plugs were completely defoliated before being placed in the growth chamber. Each week thereafter shoot growth was removed, the clippings were dried at 80o C for 48 hours, and dry weights were recorded. Results from the first few re-growth periods showed no significant difference in NSC among treatments. We hypothesize differences among treatments will emerge as the study progresses. Complete, first-year results will be presented. This research will continue through August 2007.