, Volume 33, Issue 2, pp 313–319

Inheritance of conditional dormancy in over-summering buds of Phalaris aquatica L.

  • R. N. Oram


The relative ability of the underground buds of a Mediterranean perennial grass species to break dormancy in response to summer rain was compared between individual plants and between half-sib families in two experiments with broadly-based breeding populations under different environmental conditions. Significant genetic variation was found in summer regrowth activity in both experiments. The narrow-sense heritability of the ratio of new to old, dead tillers after summer rain under spaced plant conditions at a relatively cool site was 0.40±0.16. Under sward conditions at a warm site, the narrow-sense heritability of an index of summer regrowth potential on a half-sib family mean basis was 0.36±0.08. Summer regrowth activity was negatively but weakly correlated with flowering time (rg=−0.22), and strongly positively correlated with early autumn herbage yield (rg=0.79). Summer regrowth activity was not genetically correlated with seedling size or herbage yield in the second or third growing seasons. These correlations are different in sign or magnitude from those observed in collections of Mediterranean ecotypes from which the breeding populations were derived by crossing to Australian cultivars and recurrent selection for vigour and persistence. The correlations in Mediterranean populations therefore are not due to pleiotropic effects; they can be altered by recombination. Phenotypic variance relative to the population mean was considerable in both experiments, and hence the level of the responsiveness of dormant buds to summer rainfall should be manipulable readily by selection. The possible effects of altered responsiveness on long term survival and productivity in several different environments are discussed.

Index words

Phalaris aquatica phalaris pasture grass over-summering buds dormancy half-sib analysis heritability selection drought survival 


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Barnard C., 1972. Register of Australian herbage plant cultivars. Div. of Plant Industry, CSIRO, Canberra Australia.Google Scholar
  2. Falconer D. S., 1981. Introduction to quantitative genetics. 2nd ed., Longman, London.Google Scholar
  3. Hoen K., 1968. Summer dormancy in Phalaris tuberosa L. Aust. J. Agric. Res. 19: 227–239.Google Scholar
  4. Hoveland C. S., 1970. Dormancy and seasonal growth of Phalaris species in Alabama. In: M.J.T. Norman (Ed.), Proc. Eleventh International Grassland Congress, p. 608–611. Univ. Queensland Press, Brisbane.Google Scholar
  5. Laude H. M., 1953. The nature of summer dormancy in perennial grasses. Bot. Gaz. 114: 284–292.CrossRefGoogle Scholar
  6. McWilliam J. R. & P. J. Kramer, 1968. The nature of the perennial response in Mediterranean grasses. I. Water relations and summer survival in Phalaris. Aust. J. Agric. Res. 19: 381–395.Google Scholar
  7. McWilliam J. R. & B. D. H. Latter, 1970. Quantitative genetic analysis in Phalaris and its breeding implications. Theor. Appl. Genet. 40: 63–72.CrossRefGoogle Scholar
  8. Nguyen H. T. & D. A. Sleper, 1983. Theory and application of half-sib matings in forage grass breeding. Theor. Appl. Genet. 64: 187–196.CrossRefGoogle Scholar
  9. Oram, R. N., 1974. Breeding Phalaris tuberosa cultivars for dry marginal environments in Australia. In: Proc. Twelfth International Grassland Congress Vol. III, Pt. II, p. 929–936.Google Scholar
  10. Oram, R. N. & R. D. Freebairn, 1984. Genetic improvement of drought tolerance in Phalaris aquatica L. Aust. J. Expl. Agric. Anim. Husb. 24: (accepted).Google Scholar
  11. Oram, R. N., 1983. Ecotypic differentiation for summer dormancy in Phalaris aquatica L. Bot. Gaz. 144: (in press).Google Scholar
  12. Oram R. N. & K. Hoen, 1967. Perennial grass cultivars for long leys in the wheat belt of southern New South Wales. Aust. J. Expl. Agric. Anim. Husb. 7: 249–254.Google Scholar
  13. Sankary M. N., H. M. Laude, R. M. Love & R. E. Fox, 1969. Variation in summer dormancy among collections of Phalaris tuberosa at Davis, California. J. British Grassland Soc. 24: 134–137.Google Scholar
  14. Vegis A., 1964. Dormancy in higher plants. Ann. Rev. Plant Phys. 15: 185–224.CrossRefGoogle Scholar

Copyright information

© Veenman B.V., Wageningen 1984

Authors and Affiliations

  • R. N. Oram
    • 1
  1. 1.CSIRO Division of Plant IndustryCanberra CityAustralia

Personalised recommendations