Regulation of summer dormancy by water deficit and ABA in Poa bulbosa ecotypes

Micha Ofir*, Jaime Kigel

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

24 Scopus citations

Abstract

• Background and Aims: Survival of many herbaceous species in Mediterranean habitats during the dry, hot summer depends on the induction of summer dormancy by changes in environmental conditions during the transition between the winter (growth) season to the summer (resting) season, i.e. longer days, increasing temperature and drought. In Poa bulbosa, a perennial geophytic grass, summer dormancy is induced by long days, and the induction is enhanced by high temperature. Here the induction of summer dormancy in a Mediterranean perennial grass by water deficit under non-inductive photoperiodic conditions is reported for the first time. • Methods: Plants grown under 22/16°C and non-inductive short-day (9 h, SD) were subjected to water deficit (WD), applied as cycles of reduced irrigation, or sprayed with ABA solutions. They were compared with plants in which dormancy was induced by transfer from SD to inductive long-day (16 h, LD). Responses of two contrasting ecotypes, from arid and mesic habitats were compared. Dormancy relaxation in bulbs from these ecotypes and treatments was studied by comparing sprouting capacity in a wet substrate at 10°C of freshly harvested bulbs to that of dry-stored bulbs at 40°C. Endogenous ABA in the bulbs was determined by monoclonal immunoassay analysis. • Key Results: Dormancy was induced by WD and by ABA application in plants growing under non-inductive SD. Dormancy induction by WD was associated with increased levels of ABA. Bulbs were initially deeply dormant and their sprouting capacity was very low, as in plants in which dormancy was induced by LD. Dormancy was released after 2 months dry storage at 40°C in all treatments. ABA levels were not affected by dormancy relaxation. • Conclusions: Summer dormancy in P. bulbosa can be induced by two alternative and probably additive pathways: (1) photoperiodic induction by long-days, and (2) water deficit. Increased levels of endogenous ABA are involved in both pathways.

Original languageEnglish
Pages (from-to)293-299
Number of pages7
JournalAnnals of Botany
Volume99
Issue number2
DOIs
StatePublished - Feb 2007

Keywords

  • Abscisic acid
  • Ecotype
  • Geophyte
  • Perennial grass
  • Poa bulbosa
  • Summer dormancy
  • Water deficit

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