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Water deficit and induction of summer dormancy in perennial Mediterranean grasses

Volaire, Florence and Seddaiu, Giovanna and Ledda, Luigi and Lelievre, François (2009) Water deficit and induction of summer dormancy in perennial Mediterranean grasses. Annals of Botany, Vol. 103 (8), p. 1337-1346. eISSN 1095-8290. Article.

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DOI: 10.1093/aob/mcp080


Background and Aims: Summer dormancy is a trait conferring superior drought survival in Mediterranean perennial grasses. As the respective roles of environmental factors and water deficit on induction of summer dormancy are unclear, the effect of intense drought were tested under contrasting day lengths in a range of forage and native grasses.
Methods: Plants of Poa bulbosa, Dactylis glomerata ‘Kasbah’ and Lolium arundinaceum ‘Flecha’ were grown in pots (a) from winter to summer in a glasshouse and subjected to either an early or a late-spring drought period followed by a summer water deficit and (b) in controlled conditions, with long days (LD, 16 h) or short days (SD, 9 h) and either full irrigation or water deficit followed by rehydration. Leaf elongation, senescence of aerial tissues and dehydration of basal tissues were measured to assess dormancy. Endogenous abscisic acid (ABA) in basal tissues was determined by monoclonal immunoassay analysis.
Key Results: Even under irrigation, cessation of leaf elongation, senescence of lamina and relative dehydration of basal tissues were triggered only by a day length longer than 13 h 30 min (late spring and LD) in plants of Poa bulbosa and Dactylis glomerata ‘Kasbah’ which exhibit complete dormancy. Plants of Lolium arundinaceum ‘Flecha’ maintained leaf growth under irrigation irrespective of the day length since its dormancy is incomplete. ABA concentrations were not higher during late-spring drought than early, and could not be associated with spring dormancy induction. In summer, ABA concentration in bulbs of the desiccation-tolerant Poa were greater than in basal tissues of other species.
Conclusions: The results of both experiments tend to invalidate the hypothesis that water deficit has a role in early summer-dormancy induction in the range of tested grasses. However, a late-spring drought tends to increase plant senescence and ABA accumulation in basal tissues of forage grasses which could enhance summer drought survival.

Item Type:Article
ID Code:3807
Uncontrolled Keywords:Poa bulbosa, Dactylis glomerata, Lolium arundinaceum, abscisic acid, water deficit, photoperiod, summer dormancy, perennial grass
Subjects:Area 07 - Scienze agrarie e veterinarie > AGR/02 Agronomia e coltivazioni erbacee
Divisions:001 Università di Sassari > 01 Dipartimenti > Scienze agronomiche e genetica vegetale agraria
Publisher:Oxford University Press on behalf of the Annals of Botany Company
Copyright Holders:© The Author 2009
Deposited On:03 May 2010 13:40

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