|
Graminae
Common names
Water couch (Australia), gramilla blanca, pate de gallina,
salaillo (Peru), knot grass (Hawaii), groffe doeba (Suriname), eternity
grass (United States), gharib (Iraq).
Description
A creeping, perennial grass often growing in water. Leaves
4 cm long and 3 mm wide. The seed-head, which is carried on a stalk 5-30
cm long, consists of spikes with the seeds arranged in two rows along the
axis. The "seeds" are elliptical, about 3 mm long and do not have hairs.
Distribution
Widely distributed over tropical regions.
Season of growth
Summer.
Rainfall requirements
It grows in a rainfall regime of 500-1 500 mm, and in swamps
where water accumulates.
Drought tolerance
It endures drought because of its moist environment.
Soil requirements
It usually grows in clay bottoms.
Ability to spread naturally
It spreads quickly by rhizomes and stolons, and by seed under
suitable conditions.
Sowing methods
It is propagated by roots and sods (Breakwell, 1923).
Tolerance to herbicides
To kill P. paspaloides, spray with diuron at 10 kg per hectare
in 1 350 litres of water with 1 percent non-ionic wetting agent (Kleinschmidt
& Johnson, 1977).
Response to defoliation
It stands heavy grazing.
Grazing management
For maximum production, no more than half of the current season's
growth (by weight) should be grazed off. Grazing deferments of 60-90 days
every two to three years during the growing season increase seed production
and improve plant vigour (Leithead, Yarlett & Shiflet, 1971).
Response to fire
Controlled burning is not recommended. It withstands accidental
burning if there is water above the soil level.
Suitability for hay and
silage
It makes useful hay where soil conditions become dry enough
for it to be harvested.
Cultivars
In Queensland there are two varieties: var. normale, a broad-leaved
creeping grass which was introduced and has become naturalized; and var.
littorale, with shorter-running underground stems, narrower leaves and
erect stems, occurring only in coastal swamps.
Diseases
It is occasionally attacked by ergot of P. dilatatum and can
then be toxic (Everist, 1974).
Main attributes
Its palatability, its ability to grow in swampy places and
tolerate flooding, its availability during the dry months.
Frost tolerance
It is affected by frost, but not usually killed.
Palatability
It is readily grazed by cattle and horses in Australia.
Natural habitat
Freshwater swamps.
Tolerance to flooding
It tolerates standing water and is a good soil binder but does
not thrive in brackish water (Colman & Wilson, 1960).
Fertilizer requirements
It is usually not fertilized, the accumulation of organic matter
in its environment yielding sufficient sustenance.
Genetics and reproduction
2n=40, 48, 60 (Fedorov, 1974).
Seed production and harvesting
It produces seed two to three times a year.
Economics
The seed is choice food for wild ducks on fresh water marshes.
It is an important forage species for the swamp buffaloes of Iraq.
Animal production
No quantitative figures have been cited, but it is a valuable
forage grass, especially as it is available when other grasses have dried
off in the low-rainfall months.
Further reading
Leithead, Yarlett & Shiflet, 1971.
Tolerance to salinity
It tolerates moderate salinity (Leithead, Yarlett & Shiflet,
1971).
|
