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Graminae
Common names
Purple pigeon grass.
Description
A tufted perennial on a short rhizome, 60-150 cm high. Culms
geniculate, ascending; somewhat stout below; round, smooth and glabrous
with a ring of short, silvery hairs at the insertion of the sheaths and
the top of the peduncle. Leaf-sheaths light, striate and glabrous, ligule
a narrow, densely and long ciliate rim; leaf-blade linear, up to 50 cm
long and 49 mm wide. Inflorescence a dense, continuous false spike 6-18
cm long, 8 mm wide. Bristles six to nine to a cluster, tinged with purple,
or dull purple all over. Glumes membranous, one-third to one-half the length
of the spikelet, five- to seven-nerved. Lower floret male, upper floret
perfect. Seed elliptical, 1 mm in diameter, 2 mm long, olive-green to yellow
in colour (Setaria, Setaria porphyrantha, 1977).
Distribution
Native to Zimbabwe, where it is a minor forage species; introduced
to Australia as CPI 124582.
Season of growth
Summer.
Rainfall requirements
In Zimbabwe, 500-700 mm.
Drought tolerance
Good, better than makarikari grass.
Soil requirements
It tolerates black soils.
Ability to spread naturally
It spreads readily from shattered seed.
Land preparation for establishment
A fine, well-prepared seed-bed is required.
Sowing methods
It is drilled into a good seed-bed.
Number of seeds per kg.
500 000 seeds with lemma and palea intact but glumes removed.
Seedling vigour
It establishes very quickly, much better than Panicum coloratum
var. makarikariense cv. Bambatsi, P. maximum var. trichoglume and Chloris
gayana.
Vigour of growth and growth
rhythm
Midsummer growth is rapid, but growth in spring and autumn
and overall production is slightly inferior to cv. Bambatsi. It flowers
in six weeks (Truong, personal communication).
Seed yield
Up to 300 kg/ha has been recorded.
Main deficiencies
It becomes a weed.
Optimum temperature for
growth
It does better than most species in hot weather.
Frost tolerance
Very susceptible to frost but recovers in spring (Watt, 1976).
Ability to compete with
weeds
It may invade other grasses itself.
Palatability
Palatable to cattle and sheep.
Response to photoperiod
It is day neutral, flowering through summer and autumn.
Chemical analysis and
digestibility
No figures have been cited.
Natural habitat
Common on cracking black earths.
Seed production and harvesting
It seeds prolifically, but the seed shatters readily.
Further reading
Setaria, Setaria porphyrantha, 1977; Stent, 1931; Watt, 1976.
Value for erosion control
Its potential on black self-mulching clays is impressive, because
of its ease of establishment. It is too tall for waterways, but good for
strip cropping.
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