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Graminae
Synonyms
Andropogon hirtus L.
Common names
Tambookie grass (Australia), coolatai grass (New South Wales),
South African bluestem (United States), common thatching grass (southern
Africa).
Description
Tufted perennial up to 90 cm high. Panicle loose, rather scanty;
spatheoles 5 cm long with terminally exserted white or grey villous racemes,
upper raceme base glabrous, fine, 4 mm long; pedicelled hairy spikelets
5-6 cm long. There are ten to 14 awns per raceme pair compared with two
to six for H. filipendula (Napper, 1965).
Distribution
Mediterranean region, Near East, Iran, Iraq to north-west India,
tropical eastern and southern Africa.
Season of growth
Summer-growing, with good autumn growth and some winter greenness.
Altitude range
1 200-2 500 m.
Rainfall requirements
It grows satisfactorily with a rainfall of 500 mm or more,
with a general range of 750-1 000 mm in Africa (Robinson & Potts, 1950).
Drought tolerance
Extremely drought tolerant and persistent.
Soil requirements
It has wide soil tolerance, including dry, hard, rocky soils
and deep dry sands (Barnard, 1969).
Ability to spread naturally
It does not spread well by seed (Robinson & Potts, 1950).
Number of seeds per kg.
1 320 000.
Vigour of growth and growth
rhythm
A vigorous grass, making good summer growth.
Response to defoliation
It stands heavy grazing and in fact requires it to prevent
its running to seed and becoming inedible.
Grazing management
Graze heavily to prevent seeding and top-dress with 50 kg N/ha
in midsummer.
Response to fire
It is usually burnt to destroy old growth and makes a good
recovery after a burn.
Dry-matter and green-matter
yields
Under irrigation in south-west Australia it produced from 24
000-30 000 kg DM/ha with six fertilizer dressings totalling 168, 66 and
180 kg/ha of nitrogen, phosphorus and potassium respectively, plus lime
and the trace elements calcium and zinc (Roberts & Carbon, 1969).
Suitability for hay and
silage
It provides only fair hay and silage.
Value as a standover or
deferred feed
It becomes coarse and inedible if stood over.
Cultivars
No cultivars have yet been established, but Humphries (1959)
recorded 150 distinct forms in the introductions into Australia.
Main attributes
Its ability to establish on hard stony soils and eroded land.
Its drought tolerance and persistence.
Main deficiencies
Its poor and variable seed production and its variety of ecotypes.
Optimum temperature for
growth
The seed germinates well over a range of 10- 40°C.
Minimum temperature for
growth
Germination rates of seed are low below 25°C (McWilliam,
Clements & Dowling, 1970).
Frost tolerance
It is sensitive to frost and is killed in a hard winter in
the United States (Robinson & Potts, 1950) but gives some winter growth
in South and Western Australia (Greenwood, 1966).
Palatability
It is not very palatable, except for the young growth after
burning.
Response to photoperiod
Flowering is accelerated by short days (Evans, Wardlaw &
Williams, 1964).
Chemical analysis and
digestibility
Karue (1974) records 3.2 percent crude protein, 38.1 percent
crude fibre, 45.6 percent nitrogen-free extract, 1.8 percent ether extract
and 49.6 percent total digestible nutrients in the dry matter.
Natural habitat
Grassland, rocky places and open woodland.
Fertilizer requirements
It responds to a spring application of nitrogen. Two strains
introduced to Australia, CPI.5786 and N.72, had low nitrogen requirements
when heavily defoliated (Greenwood, 1966), but responded to summer applications
and were affected by autumn applications in south-western Australia.
Genetics and reproduction
The chromosome numbers are 2n=30, 40, 44, 60 (Fedorov, 1974).
It is apomictic.
Seed production and harvesting
Seed set is quite variable between plants and flowering is
stimulated by decreasing temperature and rising humidity, or by increasing
temperature and decreasing humidity (Robinson & Potts, 1950). It flowers
over an extended period but is a poor and erratic seeder and sheds its
seed readily (Barnard, 1969).
Economics
Besides being used for grazing, it is a useful thatching grass
(Chippendall, 1955).
Animal production
A valuable fodder grass when young. Used for thatching, mat
weaving and baskets. In the Hyparrhenia veld in Africa, cattle increase
in weight and milk production from late November to March when pasture
leaf protein is high (21 percent in late November, falling to 6 percent
in early April). Thereafter, live weight and milk production decline (Smith,
1961).
Further reading
Greenwood, 1966; Robinson & Potts, 1950.
Value for erosion control
In southern Africa and the United States it is recognized as
a useful conservation grass on hard stony soils and as a pioneer in vegetating
eroded areas.
Tolerance to salinity
In south-western Australia, Rogers and Bailey (1963) found
clones of CPI.5786 moderately tolerant.
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