Influence of Endophyte and Water Regime Upon Tall Fescue Accessions. I. Growth Characteristics

Superior growth and persistence has been reported in endophyte-infected grasses; however, findings may have been confounded by experiment conditions including plant genotype. A controUed-environment study was designed to address some growth characteristics of four tall fescue (Festuca arundinacea Schreb.) accessions as influenced by endophyte (Acremonium coenophiahim Morgan-Jones et Gams) and water regime. Endophyte-infected plants were collected, vegetatively propagated and some treated with propiconazole (11 kg a.i. ha−1) to develop non-infected isolines of each accession. The phenotypically diverse accessions, each represented by infected and non-infected isolines, were grown with adequate (−0–03 MPa), or a series of deficit (<−1·5 MPa) and recovery water regimes, replicated three times. Plant growth characteristics were measured during (leaf elongation and tillering) and upon conclusion (phytomass production, tillering, and leaf area) of the study. Leaf elongation, as a function of leaf length, was significantly different among accessions, and generally decreased with water deficit although some non-infected isolines were not affected. Water deficit depressed tiller production in virtually all accessions while endophyte effects depended upon accession. Leaf blade yield was not significantly influenced by endophyte status or interaction of endophyte, with water regime and accession; however, pseudostem (stem base and leaf sheath), root and dead leaf yields were affected in some cases. Non-structural carbohydrate concentration in all plant parts except roots, was decreased by water deficit, whereas root non-structural carbohydrate concentration tended to increase with water deficit. Non-structural carbohydrates of all plant parts was not influenced by endophyte status. Tall fescue-endophyte association responses vary due to genotype, therefore a simple generalization of endophyte impact upon tall fescue productivity and persistence is not possible based upon the results of this study