Biochemical responses to an imposed water deficit in mature leaf tissue of Festuca arundinacea

Plants of a single genotype of Festuca arundinacea cv. Grasslands Roa were grown in 24-1 capacity pots in a temperature-controlled glasshouse and a water-deficit stress imposed through water deprivation. Five responses, changes in leaf elongation rate (LER) and leaf water potential (LWP), and the accumulation of abscisic acid (ABA), proline and glycinebetaine, were measured in mature leaf tissue at specific time points during the course of the water-deprivation treatment. In plants subjected to water deficit, the LER declined as the soil water content (SWC) decreased until zero values were observed. Concomitant with the decline in LER was the accumulation of ABA, proline and glycinebetaine. Leaf ABA levels increased from a range of 5-30 ng g(-1) FW in leaf tissue from water sufficient giants to up to 200 ng g(-1) FW in leaf tissue that had ceased to elongate in response to the water deficit. In the same tissues, proline levels increased from a range of 20-70 to 2.3 mg g(-1) FW, and glycinebetaine from a range of 6-11 to over 24 mu mol g(-1) FW. These observations are discussed with respect to the significance of metabolite accumulation in response to a water deficit. (C) 1998 Published by Elsevier Science B.V. All rights reserved.