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Graminae
Common names
Plicatulum (Australia), brown seed paspalum (United States).
Description
Tufted perennial, with open, tussocky habit, up to 1.2 m high.
Leaves usually about 40 cm long, 10 mm wide, folded at the base, pilose
on the upper surface at base near margins, glabrous toward the top; leaf-sheaths
glabrous, ligule 1.5 mm long. Inflorescence of 10-13 racemes, 2-6 cm long,
1.5-2 mm wide, usually one of a pair not developed at base of raceme; sterile
lemma wrinkled just inside the margins, five-nerved, glabrous; glume pubescent,
five-nerved. Seeds dark brown, shining (Barnard, 1972).
Distribution
Native to subtropical and tropical America. Widespread in Florida,
Venezuela and Brazil, and introduced to Australia.
Season of growth
Summer, early spring growth slower than P. dilatatum and P.
wettsteinii. Reaches a marked summer peak and declines with the onset of
flowering in late March.
Rainfall requirements
At least 760 mm, preferably more than 1 000 mm up to 2 036
mm a year (Russell & Webb, 1976).
Drought tolerance
It has good drought tolerance, especially over short dry spells.
Cultivar Rodd's Bay is the best for low-moisture conditions.
Soil requirements
It is tolerant of a wide range of soils, including soils of
low fertility which are too poor for Paspalum dilatatum. It is also fairly
tolerant of high aluminium in soils (Spain & Andrew, 1977). It grows
well on strongly acid to neutral, poorly drained clay loams and on excessively
drained deep sandy soils (Leithead, Yarlett & Shiflet, 1971).J
Ability to spread naturally
It spreads quickly by seedlings.
Land preparation for establishment
Full land preparation is necessary to give a fine seed-bed,
as the early vigour of the seedlings is not high.
Sowing methods
Seed is drilled into a well-prepared seed-bed. P. plicatulum
will also reproduce from short rhizomes.
Sowing depth and cover
10-15 mm, rolled to cover.
Sowing time and rate
Early summer to flower in autumn at 2-3 kg/ha (Ostrowski, 1978).
Number of seeds per kg.
780 000 for cv. Rodd's Bay and 1 million for cv. Hartley.
Tolerance to herbicides
It will not tolerate atrazine (Hawton, 1976).
Seedling vigour
Not good.
Vigour of growth and growth
rhythm
Plicatulum has a long growing period from October to April
and a short flowering period, April-May (Davies, 1970) in Queensland, after
which its growth declines.
Response to defoliation
P. plicatulum decreases in a pasture under continuous grazing;
it responds to rests from grazing of about 30 days (Leithead, Yarlett &
Shiflet, 1971).
Grazing management
Plicatulum is best grazed when it is leafy in spring and summer
rather than saved for autumn grazing or haymaking. Mature growth is poorly
accepted by cattle.
Response to fire
It will survive burning.
Dry-matter and green-matter
yields
Over a three-year period, the mean annual dry-matter yields
per hectare were 11 340 kg/ha for cv. Bryan, 9 470 kg/ha for cv. Rodd's
Bay and 10 560 kg/ha for cv. Hartley, when the yield for P. dilatatum over
the same period was 5 670 kg/ha (Bisset, 1975).
Suitability for hay and
silage
Plicatulum makes good silage but the fermentation is very slow.
The pH level does not fall below 5.96, lactic acid concentration is less
than 0.5 percent of the dry matter and NH3 content is less than 15 percent
of the nitrogen (Catchpoole & Henzell, 1971).
Value as a standover or
deferred feed
Although the mature growth is unpalatable, it provides useful
low-quality roughage to supplement with urea- molasses mixtures.
Toxicity
No toxicity has been reported by Everist (1974), and in Puerto
Rico a low figure of 0.02 percent of the dry weight for oxalates was recorded
(García- Rivera & Morris, 1955). In Taiwan some phytotoxicity
from roots has affected lettuce seedlings (Chou, 1977).
Seed yield
50-150 kg/ha according to variety and treatment; 920-2 620
kg/ha (Chadokar, 1978; Chadokar & Humphreys, 1970). Seed remains viable
for two years (Jones, 1973).
Cultivars
introduced from Guatemala into Australia and developed at
Rodd's Bay near Gladstone, Queensland. It grows faster than naturalized
Paspalum dilatatum in autumn and summer and gives high yields compared
with other types of paspalum at high levels of fertility and moisture.
It flowers two to three weeks earlier than cv. Hartley, over a short period
in late summer. Due to its erect habit, with the seed-heads well above
the leaves, seed harvesting is easy. It differs from cv. Hartley in having
slightly narrower leaves, and hairs on the leaf-blade when the plants are
past the seedling stage (Barnard, 1972).
(Paspalum plicatulum Mich. x var. glabrum Arech.). Introduced
to Australia from Brazil by W. Hartley and J.R. Stephens in 1948. Tends
to give slightly lower yields than cv. Rodd's Bay, but is of higher nutritive
value. It grows on poorer soils than P. dilatatum and is tolerant of low,
wet land. It flowers two to three weeks later than Rodd's Bay. The leaf-blade
and sheath are both glabrous. Its seeding capacity is not as good as Rodd's
Bay, and seed is not available now in Australia.
has long hairs (to 5 mm) near the margins for the bottom
8 cm of the leaf-blade's adaxial surface, and a dense collar of hairs (about
2 mm long) at the junction of sheath and blade; below this, there is a
fairly dense zone of short hairs for 2 cm down the sheath (Loch, 1976).
It is the most palatable of the three cultivars, but none are as palatable
as most other sown grasses in similar situations.
Diseases
It is free from ergot and has no other disease problem.
Main attributes
It produces fairly well in poor soils, does not become sodbound
and combines well with legumes. Suited to infertile coastal soils which
are flooded in the wet season and then dry out rapidly (Harding, 1972).
Main deficiencies
Low nutritive value, nitrogen content and palatability compared
with other tropical sown grasses such as Nandi setaria (Setaria sphacelata
var. sericea) and green panic (Panicum maximum var. trichoglume cv. Petrie).
Optimum temperature for
growth
18.9-23.3°C (Russell & Webb, 1976).r
Minimum temperature for
growth
Minimum temperature for coldest month, 6.1°C (Russell &
Webb, 1976)..
Frost tolerance
Susceptible to frost, but maintains nutritive value well after
frosting. The crowns are not killed. Frosts seriously affect nutritive
value of cv. Rodd's Bay.
Latitudinal limits
17-28°S in Guatemala and 20°S to 31°N in the American
tropics.@
Response to light
It does not do well in shade.
Ability to compete with
weeds
Fair, due to its open, tussocky habit.
Maximum germination and
quality required for sale
In Queensland seed must have 60 percent purity and give a germination
of at least 40 percent.
Pests
It has no specific pests.
Palatability
Cultivar Bryan is more palatable than cv. Rodd's Bay, but there
are more palatable summer grasses.
Response to photoperiod
It has a short-day flowering response; floral initiation occurred
at Brisbane (lat. 28°S) at a day length of 13.1 hours (Chadokar &
Humphreys, 1974).1
Chemical analysis and
digestibility
'Hartley' has a high nutritive value even when mature and frosted
(Milford, 1960a & b). The daily intake of plicatulum was 359 g per
sheep with 3.4 percent protein compared with buffer grass (cv. West Australian)
at 740 g and 7.1 percent protein in Queensland, Australia.
Natural habitat
Adapted to marshy or aquatic habitats, usually growing in shallow
water in the United States.
Tolerance to flooding
It is highly tolerant of waterlogging and flooding for short
periods; flooding for 35 days at 7.5 cm did not affect it. Deeper water
at 12.5 cm caused some wilting (Colman & Wilson, 1960).
Fertilizer requirements
A basic fertilizer of 250-650 kg/ha of superphosphate (with
potassium if needed) with 100 kg N/ha at the beginning of the growing season
for seed production is used. Although it responds to nitrogen, it will
produce better than other grasses under low soil nitrogen supply. Calcium
deficiency shows when the distal ends of the young leaves turn brown, twist
and die; seed setting may also be reduced (Humphreys, 1975).
Compatibility with other
grasses and legumes
It combines well with a range of legumes to maintain a stable
pasture. Silverleaf and greenleaf desmodium, siratro, lotononis, stylo
and white clover have each formed a stable pasture with it. It does not
become sod-bound. If sown with Nandi or Narok setarias, these latter will
be selectively grazed but cv. Kazungula setaria will combine with it for
some years before 'Kazungula' becomes dominant. Heavy grazing and slashing
in the wet season will help to give plicatulum dominance (Bisset, 1975).
Genetics and reproduction
It is an aposporous apomict, 2n=40, or sexual 2n=20 (Bashaw,
Hovin & Holt, 1970); 2n=20, 40, 60 (Fedorov, 1974).
Seed production and harvesting
It flowers earlier, yields better and the seed viability is
higher under high nitrogen; about 100 kg N/ha is the best application.
The seed turns brown at maturity, harvest direct with a drum speed of 900-1
100 rpm (Humphreys, 1975) about 18-22 days after peak flowering (Kowithayakorn
& Kannasoot, 1978).
Animal production
In grazing experiments by CSIRO at Beerwah, Queensland, P.
plicatulum cv. Rodd's Bay showed great persistence in combination with
legumes under both rotational and continuous grazing at stocking rates
of one beast to 0.4-0.6 hectares. However, the annual live-weight gain
of 232 kg/ha was less than those from pastures based on P. dilatatum (272
kg) and Digitaria decumbens (290 kg) over an eight-year period. The plicatulum
pasture was as good as the others from September to December (spring and
summer) but inferior from January to August (late summer to late winter).
Over a three-year period (from June 1972 to 1975), a pure cv. Bryan plicatulum
pasture fertilized with 440 kg N/ha gave a mean annual live-weight production
of 740 kg/ha when grazed at 5 steers per hectare (Bisset, 1975).
Further reading
Bisset, 1975; Bryan & Shaw, 1964; Humphreys, 1975; 't Mannetje,
1961; Milford, 1960a.
Dormancy
There is no post-harvest dormancy, but seed remains viable
for two years (Jones, 1973). Seeds germinate at 20-35°C, moistened
with KNO3 solution.
Tolerance to salinity
No record has been found.
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