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Graminae
Common names
Broad-leaf paspalum (Australia).
Description
A semi-prostrate, tufted perennial with stoloniferous habit;
grows to 90 cm high, tufts reach 100 cm in diameter. Culms erect, glabrous,
unbranched, concealed by the leaf-sheaths; nodes pubescent. Ligules up
to 2 cm long, membranous, surrounded by long hairs at the back. Leaf-blades
rounded, up to 40 cm long and 3 mm broad, with wavy margins. Inflorescence
a panicle with four to nine spike-like racemes. Spikelets are almost glabrous,
and broadly oval; the upper glumes and lower sterile lemma are about equal,
and equal the fertile floret; they are thinly membranous and three-nerved.
Mature seeds are smaller and browner than those of P. dilatatum; its leaves
are broader and the spikelets are less densely arranged (Barnard, 1969).
Distribution
Native to the humid subtropical areas of southern Brazil, Paraguay
and northern Argentina; introduced to the United States and Australia.
Season of growth
Early spring (September in Australia, ahead of P. dilatatum)
to late summer seeding, after which little vegetative growth occurs.
Rainfall requirements
Best adapted to a subtropical summer rainfall of 1 0001 500
mm.
Drought tolerance
It has a high degree of drought resistance, comparable to Kikuyu
grass (Pennisetum clandestinum).
Soil requirements
It is tolerant of a wide range of soils and, because of its
relatively low nitrogen requirement, has the ability to compete with poorer
grasses, such as mat grass.
Ability to spread naturally
Its spreading stems allow rooting from the nodes.
Land preparation for establishment
A good, fine, firm seed-bed is needed.
Sowing methods
The seed can be broadcast or drilled in, and rolled after seeding.
Apply 250 kg/ha superphosphate at sowing, N and K if needed.
Sowing depth and cover
Do not sow or cover too deeply.
Sowing time and rate
Summer, when soil moisture is good (usually from November to
March in Australia), at 4.5 kg/ha broadcast or 2 kg/ha drilled.
Number of seeds per kg.
775 000 (Queensland).
Seedling vigour
Early growth is slow but, once established, it grows rapidly.
Vigour of growth and growth
rhythm
It produces very early spring growth, better than other paspalums,
Kikuyu and setaria. Seeding commences early in April (south-eastern Queensland),
after which little vegetative growth occurs (Cook, 1978) up to maturity
in May-June (Kemp, 1975).
Response to defoliation
It stands grazing well.
Grazing management
As it matures later than P. dilatatum, it has a greater potential
for summer production; it is easier to manage because it does not need
frequent mowing. With careful selection of a companion legume it can give
year- round grazing. At 8-10 weeks (when 22-30 cm high) graze quickly to
10 cm high, and then remove stock. If grazed intensely, pasture should
be top-dressed with 65- 90 kg N/ha. P. wettsteinii pasture can be top-dressed
with 250 kg superphosphate/ha per year (and with 125 kg/ha of muriate of
potash if potassium is deficient) and oversown with a temperate legume
in autumn to give grazing in late winter and spring if the climate is suitable
(Leggett, 1968).
Response to fire
It recovers well from fire.
Dry-matter and green-matter
yields
Yields of green and dry matter are equal to or better than
other useful grasses grown in a similar environment. At Mt Mee, south-eastern
Queensland, it yielded 4 333 kg DM/ha in autumn and 2 049 DM/ha in spring
(Ostrowski & Fay, 1979).
Cultivars
'Warral' is described above.
Diseases
It is resistant to ergot. (Leggett, 1968).
Main attributes
Its palatability and high production, especially in autumn
and spring; its resistance to ergot.
Optimum temperature for
growth
Growth commences at 13-15°C in spring. At 16-18°C,
it produces 30 kg DM/ha per day (Kemp, 1975).
Minimum temperature for
growth
Growth ceased in autumn at 12-14°C (Kemp, 1975).
Frost tolerance
Less frost tolerant than P. dilatatum, but it is not killed.
The frosted material is readily eaten. It recovers earlier than most other
grasses.
Palatability
It is very palatable and selectively grazed in the presence
of P. dilatatum, Pennisetum clandestinum and Setaria sphacelata.
Chemical analysis and
digestibility
No figures have been cited.
Tolerance to flooding
Good; it survives moderate flooding and poor drainage.
Fertilizer requirements
It needs a basic treatment with nitrogen, phosphorus and potassium
as indicated by soil tests. It responds well to nitrogen, increasing annual
dry-matter yields from 639 kg/ha with no nitrogen to 2 299 kg/ha with 150
kg N/ha, and to 4 333 kg/ha with 300 kg N/ha during the autumn (Ostrowski
& Fay, 1979).
Compatibility with other
grasses and legumes
It competes well with weedy grasses such as Axonopus spp. and
is compatible with the subtropical legumes Neonotonia wightii, Desmodium
uncinatum, D. intortum, D. axillaris, Lotononis bainesii and Macroptilium
atropurpureum and with white clover (Barnard, 1969).
Genetics and reproduction
It is believed to be apomictic.
Seed production and harvesting
It seeds abundantly, its seed-heads resembling those of P.
dilatatum, but there is no seed production before April in Queensland.
Animal production
It has given good milk production in northern New South Wales
and south-eastern Queensland.
Further reading
Leggett, 1968.
Dormancy
There is some post-harvest seed dormancy which, for germination
tests, is broken by treating the seed with 0.2 percent KNO3 solution. Otherwise,
the seed can be stored for a few months before planting.
Minimum germination and
quality for commercial use
40 percent germinable seed, 60 percent purity, in Queensland.
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