New Zealand Journal of Agriculture abstracts

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Endophyte infection accelerates morpho-physiological responses to water deficit in tall fescue

S. G. Assuero¹
J. A. Tognetti²
M. R. Colabelli¹
M. G. Agnusdei³
E. C. Petroni¹
M. A. Posse¹

¹Facultad de Ciencias Agrarias
Universidad Nacional de Mar del Plata
CC 276
7620 Balcarce
Argentina
sgassuero@balcarce.inta.gov.ar

²Comisión de Investigaciones Científicas de la Provincia de Buenos Aires
Calle 526 entre 10 y 11
La Plata , Buenos Aires , Argentina

³Instituto Nacional de Tecnología Agropecuaria
Rivadavia 1439 (1033)
Buenos Aires , Argentina

Abstract  Endophyte-infected (E+) tall fescue plants are usually more persistent under water deficit than endophyte-free plants (E–). The reason for this is still unclear because of conflicting reports about growth and water status variables. A glasshouse experiment was carried out to compare morpho-physiological responses of E+ and E– tall fescue plants to water deficit during a cycle of water deprivation and recovery. Under non-limiting conditions total dry mass per container was higher in E+ plants than in E– plants. However, no differences were found between endophyte treatments in root:shoot ratio, water status or in reducing sugar content of leaf blades or tiller bases. Under water limiting conditions an accelerated response to water deficit was observed in E+ plants. The relatively steeper growth cessation as well as higher leaf and root senescence in E+ than in E– were linked with a higher accumulation of sugars within the stem base of E+ plants which also tended to show a more pronounced decrease in water potential. Under water limiting conditions relative root:shoot ratio tended to decrease in E+ while remaining unchanged in E–. Following re-irrigation, a general recovery in growth and water status variables was observed. A simple explanation is proposed to reconcile our results with previous reports, although further research is needed.

Keywords  tall fescue; Festuca arundinacea; fungal endophyte; Neotyphodium coenophialum; water deficit

A06008; Online publication date 20 September 2006. Received 20 February 2006 ; accepted 25 July 2006 New Zealand Journal of Agricultural Research, 2006, Vol. 49: 359–370

0028–8233/06/4904–0359  © The Royal Society of New Zealand 2006

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