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Graminae
Common names
Red vlei grass, rooikweek (southern Africa), swamp couch (Zimbabwe),
limpo grass (Florida), halt grass (Panama).
Description
A perennial with a creeping, branched rhizome; culms 30-100
cm high, compressed, usually decumbent and rooting from the lower nodes,
generally branched; leaves smooth, glabrous, the blades up to 6 mm wide,
usually folded; inflorescence a solitary raceme terminating the culm and
its branches, these often in clusters, so there are several racemes from
each node; racemes 5-12 cm long, 2-3 mm wide, spikelike, tapering toward
the apex. Sessile spikelets 5-7 mm long, the pedicelled ones 6-9 mm long
(Bor, 1960). During the greater part of the year the whole plant has a
distinctive rust-red colour and it has a mat-forming habit (Chippendall
& Crook, 1976). The leaf-blades, when dry, twist in corkscrew fashion.
Distribution
Tropical Africa, India, Burma. Introduced to the United States.
Altitude range
1 500-2 000 m, 1 200 m in Panama (Rattray, 1973).
Rainfall requirements
It requires a high rainfall.
Drought tolerance
It does not tolerate long droughts but can withstand short,
seasonal droughts. In the dry months the plant assumes a distinct rust-red
colour, hence the name of "rooikweek".
Soil requirements
It tolerates acid soils (CIAT, 1978) and prefers moist, humid
soils (Rattray, 1973).
Ability to spread naturally
It spreads rapidly by creeping rhizomes and culms rooting at
the lower nodes.
Sowing methods
It can be propagated by cuttings placed in wet soil.
Response to defoliation
At CIAT, Quilichao, Colombia, it was found to be most susceptible
to clipping to ground level or 5 cm (CIAT, 1978).
Suitability for hay and
silage
Medling (1972) in Panama made satisfactory silage in plastic
bags, adding 10 percent molasses to the material.
Toxicity
In Zambia, scouring occurs when cattle move from the fibrous
forest grazing to the rich plains grasses consisting of Echinochloa pyramidalis,
E. scabra, Acroceras macrum, Hemarthria altissima, Leersia hexandra and
Vossia cuspidata and it may be two to four months before they regain condition
(Veerboom & Brunt, 1970).
Cultivars
No cultivars have been released. CIAT in Colombia has a selection,
663, under test.
Diseases
It has good disease resistance.
Optimum temperature for
growth
31-35°C (Boyd & Perry, 1972). It was seriously affected
by temperatures above 38°C.H
Pests
Sting nematodes (Belonolaimus longicaudatus) affected growth
of H. altissima at soil temperatures of 18°C (Boyd, Schroder and Perry,
1972). The yellow sugar-cane aphid (Sipha flava) attacks some accessions,
but other accessions exhibit a degree of resistance (Oakes, 1978).
Palatability
It is highly palatable and is valued as a fodder grass.
Response to photoperiod
Grown at 30-25°C in growth chambers at Florida University.
H. altissima did not grow at nine hours; yielded slightly more dry matter
at 15 hours than at 9.5 hours and did not respond to eight hours (Gaskins
& Sleper, 1974).
Chemical analysis and
digestibility
It is of good nutritional value. The OM digestibility of six
pure and hybrid lines of H. altissima ranged from 38.5 percent in mature
plants of a diploid line to 68.4 percent in five-week- old regrowth of
a tetraploid line. Digestibility was inversely related to the percentage
of cross-sectional area of stems occupied by vascular bundles.
Natural habitat
Flooded areas, swamps and lakes, vleis.
Tolerance to flooding
It tolerates flooding well.
Fertilizer requirements
It gave high yields in Venezuela when cut at 5 cm every 20
days and at 20 cm every 80 days, when fertilized with 840 kg N + 200 kg
P + 100- 200 kg K + 3 000-6 000 kg lime + Zn, Cu, B and Mo (Parra &
Bryan, 1974).
Genetics and reproduction
The basic chromosome number of H. altissima is nine. Of 11
introductions, nine were diploid and two tetraploid (Schank, 1972) 2n=18,
20 (Fedorov, 1974) 36, 40.
Seed production and harvesting
It is not a good seed producer.
Economics
Hemarthria germ plasm is undergoing agronomic, entomological
and pathological evaluation by government and private research groups,
and certain accessions have been distributed to Central and South America,
West Indies and Hawaii and are undergoing field trials. Pasture is the
primary use but it has been used successfully for hay and silage. In 1979,
production in Florida from an area exceeding 6 000 ha was valued at over
US$ 1 million. In Lesotho, children eat the raw rhizomes.
Further reading
CIAT, 1978.
Tolerance to fire
It will not tolerate burning.
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