Endophyte Effects on Growth and Persistence of Tall Fescue along a Water‐Supply Gradient

Abstract

Emphysiology of the endophyte (Acremonium coenophialum Mor· gao-Jones and Gams)-tall fescue (Festuca arundinllcea Schreb.) as· soci~1tion needs to be understood in order to promote environmental fitness traits of the association while reducing its deleterious effects on ruminants. Our objective was to determine the influence of en· dophyte on drought stress tolerance, persistence, and yield components of field-grown tall fescue on a Typic Hapludalfs soil. A water supply gradient was established during 1988 and 1989 with line-source irrigation on established populations ofO and 80o/o endophyte-infected tall fescue. Whole plots consisted of endophyte infection status, across whi<:h a gradient of water was applied in a strip-split fashion with eight replicates. Tiller population density and herbage yield were determined every 28 d and yield components were measured on selected dates. Relative to populations receiving high irrigation (375...{;50 mm applied), tiller density in nonirrigated stands (0-50 mm applied) from July to October 1988 was reduced an average of 42% in infected tall fescue and 55% in noninfected tall fescue. Tiller density of nonirri· gated, infected populations recovered fully to that of high irrigation treatments by 17 November, whereas that ofnonirrigated, endophyte· free populations recovered to only 62% of irrigated treatments. The advantage in population density due to endophyte infection continued throughout 1989, a relatively wet year. A benefit in total forage yield due to endophyte infection was not consistently evident because of greater yield per tiller in endophyte-free stands in 1989. Enhanced tiller density and survival were associated with endophyte infection during severe water deficit, and this advantage continued throughout the subsequent year. Endophyte infection confers population stability in tall fescue during drought stress through improved tiller and whole plant survival.

Grasses and Neotyphodium endophytes: co-adaptation and adaptive breeding

“…While there appears to be a consistent pattern with tall fescue associations (West et al 1993;, no clear picture emerged with perennial ryegrass. Many studies with different species have identified interactions between host plant, endophyte infection and other factors (Cheplick et al 2000;Morse et al 2002;Cheplick and Cho 2003;Hesse et al 2003).…”

“…Early attention focused on water stress (West et al 1993). Mechanisms such as osmotic adjustment, control of leaf rolling and phyto-hormone status have been postulated, but no theory has been supported by sufficient evidence to command a consensus.…”

Benefits of a symbiotic association with endophytic fungi are subject to water and nutrient availability in Achnatherum sibiricum

“…Significant differences (P<0.05) for each variable are indicated by lowercase letters for variables where water treatment, fertilizer treatment and endophyte infection were analyzed together higher net photosynthetic rate than EF plants. The maintenance of a high root:shoot ratio can enhance plant survival (Hesse et al 2005), particularly in areas where water is the primary limiting factor (West et al 1993;Buck et al 1994). The higher photosynthetic rate and higher root:shoot ratio suggest that endophyte infection was beneficial to drought tolerance of the host.…”

Age-specific response of the grass Puccinellia distans to the presence of a fungal endophyte

“…Some fungal endophytes may stimulate growth and reproduction of host plants by the production of auxin-like plant-growth regulators (Siegel et al 1987). Plants infected with endophytes were found to exhibit increased vegetative vigour (West et al 1993;Groppe et al 1999;Malinowski et al 1999), higher production of generative tillers (Clay 1990), increased seed crop or seed germination rate (Clay 1987;Petroski et al 1990) in comparison with uninfected individuals of the same species. Host plants may benefit from fungus-produced alkaloids as some of them provide defence against other fungi (Arnold et al 2003;Clay 2004) and reduce herbivory by vertebrates (Schardl and Phillips 1997;Jones et al 2000), insects (Clay 1988;Clay et al 1993;Brem and Leuchtmann 2001) and nematodes (Kimmons et al 1990).…”