*Present address: Facultad de Ciencias Agrarias, Universidad Nacional de Mar del Plata, CC 276, 7620-Balcarce, Argentina.
Abstract Morphological and physiological responses to water deficit of two tall fescue (Festuca arundinacea) cultivars were compared in a glasshouse experiment and the effect, on those responses, of artificial infection of the tall fescue plants with two fungal endophyte (Neotyphodium coenophialum) strains was evaluated. The cultivars were Maris Kasba (MK), of Mediterranean origin, and El Palenque (EP), an Argentinian cultivar of temperate origin. The endophyte strains AgResearch isolate (AR501) and the Kentucky (KY31) wild type were compared with nil-endophyte controls. Leaf growth rate of EP plants under water deficit was higher and leaf senescence rate lower than for MK plants (P < 0.05). MK plants showed a greater increase in the proportion of dead leaf tissue than EP plants as water deficit increased (P < 0.05). Stomatal conductance and lamina osmotic adjustment at low soil moisture were lower for MK than EP (P < 0.05). Endophyte-infected plants had a lower dry weight and tiller number, but a higher net growth rate during water deficit treatments than endophyte-free plants (P < 0.05). A significant cultivar x endophyte interaction (P < 0.05) was observed for many variables studied. This implies that any new endophyte strain should be evaluated in combination with the plant genotypes with which it is likely to be associated in commercial practice. MK-KY31 and EP-AR501 associations appeared to tolerate short-term water deficit more effectively than other associations studied. There was evidence that the two endophyte strains studied had different physiological effects on their tall fescue host plants.
Keywords fungal endophyte; Neotyphodium coenophialum; Mediterranean; morphology; tall fescue; water deficit; water relations
New Zealand Journal of Agricultural Research, 2000, Vol. 43: 49-61
0028-8233/00/4301-0049 $7.00/0 (c) The Royal Society of New Zealand 2000
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