Summer dormancy, regeneration and persistence of perennial grasses in south-western Australia

Abstract

Autumn growth and persistence of periodically grazed, spaced plant swards of eleven perennial grasses were measured at two sites registering 750 mm and 1120 mm annual rainfall respectively. The grasses were grown on gravelly podzolic soils of moderate internal drainage and depth of A horizon. After the third summer, autumn regrowth was generally better in Phalaris tuberosa lines than in lines of Dactylis glomerata, Festuca arundinacea and Lolium perenne, Festuca arundinacea cv. Melik and D. glomerata cv. Currie regenerated better than P. tuberosa lines in the first two autumn seasons at the drier site. Capacity for autumn growth appeared to be associated mainly with the level of dormancy achieved by basal buds at mid-summer, though relatively high dormancy of one or two lines at the drier site did not prevent significant plant mortality. Numbers of reproductive tillers per plant in spring and active basal buds per tiller in late summer were less important traits affecting the growth of some lines. We think that rankings for summer dormancy would be useful for screening future introductions for wetter parts (> 750 mm annual rainfall) of the south-western region of Western Australia.

How can forage production in Nordic and Mediterranean Europe adapt to the challenges and opportunities arising from climate change?

“…Cultivars of bulbous canary-grass (Phalaris aquatica L.) and tall fescue that express summer dormancy play an increasing role in eastern Australia and the semi-arid environment of the Southern Great Plains in the USA, and can be used in regions with down to about 550-500 mm precipitation per year (Oram and Lodge, 2003;Malinowski et al, 2005Malinowski et al, , 2009Norton et al, 2016). Such cool season grasses were also found to be quite productive and successful in south-west Australia (Rogers et al, 1976;Biddiscombe et al, 1977) although until recently they have been poorly adopted by the seed industry. The association of summer dormant grasses and Mediterranean type alfalfa, combining the dehydration tolerance of the grass and the dehydration avoidance of the legume provides high functional complementarity for water use in summer and is advocated for drought prone areas .…”

Improving the grazing and drought tolerance of temperate perennial grasses

“…The levels of both summer activity and of dormant buds therefore need to suit the particular environment. In contrast to phalaris, cocksfoot, ryegrass, and tall fescue have an additional mechanism-they show more regeneration in autumn, from the growing points of vegetative and sterile tillers which stop growing over summer (Knight 1965;Biddiscombe et al 1977). This may lessen their need for dormant buds.…”

The place of C4grasses in temperate pastures in Australia

“…However, high rates of growth invariably lead to rapid water use, requiring in turn, a stronger dormancy response to ensure persistence. Thus the more persistent grasses characteristically have shorter growing seasons and stronger dormancy responses (Hoen 1968;Biddiscombe et al 1977;Oram & Freebairn 1984).…”