|
Graminae
Synonyms
Panicum tennuissimum Benth.
Common names
Queensland blue couch grass (Australia), seragoon grass (Malaysia).
Description
A small, creeping grass, blades narrow about 2.5 cm long, with
a fine setaceous tip and usually two racemes, conjugate and sessile. It
is close to D. ciliaris, but differs in its perenniality, fine leaf-blades,
small number of racemes and their slender build. It differs from Cynodon
dactylon in its shorter, broader leaf and its distinctive bluish colour.
Distribution
Native to the Mascarene Islands and Madagascar, and now introduced
to many tropical countries, primarily as a lawn grass.
Season of growth
Summer.
Altitude range
Sea-level to 1 500 m.
Rainfall requirements
It generally grows within the rainfall limits of 7001 250 mm.
Drought tolerance
It survives droughts very well.
Soil requirements
It has wide soil tolerance, but grows best on sandy loams and
loams.
Ability to spread naturally
Blue couch spreads rapidly by runners and from seed.
Land preparation for establishment
It requires a very fine, well-prepared and level seed-bed for
seed planting of lawns. When planting turfs a level area is also required,
usually underlying the turfs with sand.
Sowing methods
Lawns are usually laid as turfs. Where a pasture is desired
it can be planted by runners, turfs or seed.
Sowing time and rate
Sow in the wet season as turfs or slips.
Seed treatment before
planting
Dehulling markedly inhibited germination of seed.
Response to defoliation
It can stand heavy defoliation.
Grazing management
It requires little management, apart from preventing seeding,
and fertilizing with nitrogen to keep it productive.
Dry-matter and green-matter
yields
Henzell (1963) recorded dry-matter yields of 11 200 kg/ha with
up to 225 kg N/ha per year with little response above this nitrogen level.
Seed yield
Febles-Perez, Whiteman and Harty (1974) harvested 103 kg/ha
in January 1971, and 98 kg/ha in November 1971, by mechanical harvesting.
Main attributes
Its dense turf, response to nitrogen, suitability for erosion
control and its palatability.
Main deficiencies
Its lack of bulk unless heavily fertilized.
Optimum temperature for
growth
25- 40°C.
Minimum temperature for
growth
15°C.
Frost tolerance
It will become frosted but the frosted material is of good
quality as forage. Frosted lawns recover.
Ability to compete with
weeds
It generally grows vigorously enough to suppress weeds, though
in south-east Queensland the annual Ambrosia artemisifolia is able to germinate
and dominate local patches by strong root competition and shading.
Maximum germination and
quality required for sale
60 percent germinable seed and 97 percent purity in Queensland.
Tolerance to flooding
It will survive temporary flooding.
Fertilizer requirements
Blue couch grass can survive with little fertilizer, but responds
to added fertilizer, especially nitrogen. At 110 kg N/ha it invaded Samford
Rhodes grass pastures at Samford, Queensland (Jones, 1970). Hegarty (1958)
recorded a linear response in yield up to 105 kg N/ha.
Compatibility with other
grasses and legumes
In its natural state it will combine with the legume Desmodium
triflorum in Queensland, but yields are low unless adequate fertilizer
is applied.
Genetics and reproduction
2n=18, 36 (Fedorov, 1974).
Seed production and harvesting
Commercial seed production has not been undertaken in Queensland,
but adequate seed is produced. For seed testing, dormancy is broken by
treating pre-chilled seeds with 0.2 percent KNO3 solution and holding them
at 50°C for seven days.
Economics
One of the most popular lawn grasses in Queensland.
Animal production
No figures have been cited but it is a valuable pasture grass
in south-east Queensland. It does not produce much bulk unless well fertilized
whit nitrogen.
Further reading
Febles-Perez, Whiteman & Harty, 1974.
Dormancy
There is some post-harvest dormancy. Seeds harvested in January,
1971, gave significantly higher germination after 13.5 months' storage
than those from a November, 1971, harvest used after 3.5 months' storage.
Tetrazolium tests showed 84 percent and 65 percent viability respectively.
Value for erosion control
Excellent.
|
