INHIBITION OF SEEDLINGS BY TALL FESCUE: SEASON PATTERNS, INTERSPECIFIC DIFFERENCES AND EFFECTS OF MANURE

Authors: Halvorson, Jonathan; Belesky, David; Godwin, Harry

Submitted to: Ecological Society of America Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 4/15/2005
Publication Date: 8/7/2005
Citation: Halvorson, J.J., Belesky, D.P., Godwin, H.W. 2005. Inhibition of seedlings by tall fescue: Season patterns, interspecific differences and effects of manure. Ecological Society of America Abstracts CD-ROM. Poster presentation at the 2005 Annual Meeting of the Ecological Society of American, August 7-12, 2005, Montreal, Canada.

Interpretive Summary:

Technical Abstract: Tall fescue (Festuca arundinacea) is an important cool-season forage grass typically infected with an endophytic fungus (Neotyphodium coenophialum). While conferring ecological advantages upon the plant, the association produces toxic alkaloids that restrict animal gains and impair reproductive performance. The alkaloids have been associated with lower soil microbial activity and increased soil organic matter accumulation. We hypothesize that the association influences the rhizosphere of endophyte-infected fescue swards to inhibit legume establishment. We used a soil-on-agar method to determine influence of soil from live (L) and killed (K) fescue sods on legume seed germination and development, on the performance of tall fescue cultivars infected with a toxic, non-toxic, or no endophyte; and the possible remediative affects of manure application. Contrary to our expectations legume seedlings proved less successful in K-soil than L-soil especially near the surface. After 30 days of incubation, more and larger seedlings developed in L-soil than in K-soil. Seedling inhibition was greatest in late summer or fall compared to spring. All fescue cultivars produced similar amounts of shoot biomass in L-soil but cultivars performed differently in K-soil and were affected by soil depth. Similar numbers of fescue seedlings were observed for 0-5 cm samples of L- and K-soil but the cultivar infected with the non-toxic endophyte produced most seedlings in 5-10 cm soil. Manure application did not affect the biomass of seedlings grown in 0-5 cm soil but those in K-soil were smaller than in L-soil. For 5-10 cm, manure had no effect on seedlings in K-soil but increased biomass of seedlings in L-soil. Our data indicate that legumes may not be inhibited by live fescue sods as much as they are by conditions associated with killed fescue such as herbicide residue, decomposition products or increased disease organisms.