Echinochloa polystachya


Scientific name

Echinochloa polystachya (Kunth) Hitchc.

Subordinate taxa:
Echinochloa polystachya (Kunth) Hitchc. var. spectabilis (Nees ex Trin.) Mart. Crov.

Synonyms

Echinochloa spectabilis (Nees ex Trin.) Link
Panicum spectabile Nees ex Trin.
Psuedechinolaena polystachya (H.B.K.) Stpf.
Iplismenus polystachyusKunth.

Family/tribe

Family: Poaceae (alt. Gramineae) subfamily: Panicoideae tribe: Paniceae.

Common names

aleman, German grass (Australia, Panama);  creeping river grass (North America);  pasto alemain (Venezuela);  pardegrao, prasigrasi (Surinam).

Morphological description

Echinochloa polystachya is an aquatic or sub-aquatic perennial with course culms 1–2.5 m high, thick in the lower parts, from long rhizomes, internodes glabrous, nodes glabrous or obscurely pubescentLigule a rim of stiff, yellow hairs to 4 mm long.  Leaf blades 20–60 cm long 10–25 mm wide, scabrous on the margin.  Panicles mostly 15–25 mm long, dense, the short, thick branches ascending.  Spikelets 5–7 mm long, lanceolate.  Upper floret hermaphrodite, 5–6 mm long, with awn 5–7 mm long, or mucronate;  lower floret staminate with awn on lemma 7–17 mm long.
‘Amity’ differs from the species norm in having flowering culms 100–200 cm long, 7–10-noded, nodes glabrousLigule hairs 1–1.5 mm long.  Leaf blades 30–36 cm long, 10–12 mm wide.  Panicle axis 20–30 cm long.  Spikelets 4.5–5.5 mm long, 1.7–2.0 mm wide.  The most distinctive differences are the much shorter mucros of the lemmas of ‘Amity’;  the lemmas of E. polystachya are normally awned rather than mucronate .
‘Amity’ has flat linear, glabrous leaves, tapering to a narrow apex, rounded or auriculate at the base.  Panicle axis scabrous;  primary branches with spikelets appressed to the rachis, 2.5–9.0 cm long.  Pedicels 0.2–2.0 mm long, scabrous, disarticulation at the base of the spikelet.  Spikelets plano-convex, lanceolate.  Lower glume 2.5–3.0 mm long, ovate-lanceolate.  Upper glume 4.5–5.5 mm long, lanceolate 6–7-nerved, chartaceous, glabrous, strigose on the nerves apically, acuminate, 5.0–5.5 mm long.  Lemma of lower floret 5.0–5.5 mm x 1.0–1.5 mm, lanceolate, chartaceous, 7–9-nerved, the surface glabrous, acuminate, with mucro 1.0–1.5 mm long;  lower palea linear, acute.  Upper floret lemma 4.5 mm long, white, cartilaginous, smooth, ovate-lanceolate, acuminate, with mucro 0.5 mm long;  upper palea cartilaginous, smooth, enclosed at its apex by the lemma .

Distribution

Native to:
North America:  Mexico, USA - Florida, Louisiana, Texas.
Mesoamerica:  Belize, Costa Rica, Honduras, Nicaragua, Panama.
Caribbean:  Antigua and Barbuda, Cuba, Dominican Republic, Haiti, Jamaica, Martinique, Puerto Rico, St. Lucia, Trinidad and Tobago.
South America:  Argentina, Bolivia, Brazil, Ecuador, French Guiana, Guyana, Paraguay, Peru, Suriname, Uruguay.
Native to swamps, lake shores and wet-lands.

Naturalized in:
Tropical and southern Africa, tropical Asia, southern South America and Hawaii.  Introduced to northern Australia but not widespread.

Uses/applications

Permanent grazing in natural wetlands or ponded pastures producing large yields of palatable fodder.  Used for grazing, silage and hay in Central America.
Grown in ponded pasture systems in subtropical Australia, in water up 2 m deep for short periods but normally to 1 m, to complement para grass (Brachiaria mutica ) which will grow in water to 30 cm depth.

Ecology

Soil requirements

Tolerates a wide range of soil fertility, but best on soils of medium to high fertility.  In Colombia, found on clay soils.  It is adapted to soil pH 4.0–8.0 and has some resistance to sodicity .  Very tolerant of poor drainage.

Moisture

Top

Natural habitat is seasonally flooded wetlands, but can grow under very high rainfall (>1,900 mm) conditions.  Generally no growth under dry conditions unless there is a high water table, but re-establishes from stems and stolons with subsequent flooding.  Normally grown in water to 1 m depth but can persist for short periods in deeper water to 3 m.  Grows best in wet or seasonally flooded areas, where flooding can occur for 7–12 months of the year.

Temperature

Summer growth only, no frost tolerance but often protected from overnight frosts by surrounding volume of water.  Tropical and marginally subtropical lowlands.

Light

Full sunlight.

Reproductive development

Seed production is poor with few viable seeds developing.  Seed heads are produced throughout the year when plants have stems longer than 1 m.  There has been no evidence of viable seed ever being produced in Northern Territory, Australia.

Defoliation

Very palatable grass but access by livestock may be limited by depth of water.  Cattle get access as seasonal flood levels recede.  Can be grazed, or conserved on dried soil surfaces.  Cutting below 40 cm reduces yield.  Supports high stocking rates with rotational grazing with 45-day rest.

Fire

Top

Not normally applicable due to moist /wet conditions but will recover from mild fires from stems and rhizomes.

Agronomy

Establishment

Seed yields and quality are very low.  Aleman is normally planted from stem or stolon cuttings (1–2 t/ha) at spacings of 1–4 m between rows and plants within the rows.  Stem sections with 2–3 nodes are planted with 1 node above the surface.  They can be planted manually into wet mud or dropped into the surface of shallow water and pushed into the soil by special wheels on a light-weight tractor.  Establishment is most successful where competition from existing vegetation has been removed.

Fertiliser

Not normally fertilised as it relies on nitrogen mineralised by fluctuating soil water, rapid decomposition of organic matter and by the activity of nitrogen-fixing bacteria in the roots of the grass .  However, it can be very responsive to high levels of N fertiliser.

Compatibility (with other species)

Not generally compatable with other species due to flooded conditions.

Companion species

Top

Complements para grass (Brachiaria mutica ) (water to 30 cm deep) and Hymenachne amplexicaulis (water deepr than 1 m).

Pests and diseases

No serious insect pests in Australia but likely to be affected by fungi that infect other native Echinochloa grasses, e.g. smuts (Ustilago tricophora) and leaf spots due to Bipolaris spp., Cercospora spp. and Curvularia lunata.

Ability to spread

Spreads easily in wet places from broken pieces of stem and stolon carried by water.

Weed potential

Like other water grasses, it can spread into wetlands to form mono-specific stands that smother native species.  Although rated as very useful fodder in the native wetlands of tropical America, it is regarded as a potential significant environmental weed in some other countries.
Aleman grass can no longer be recommended for new planting into wetland areas of Queensland, Australia.

Feeding value

Nutritive value

Top

Comparatively high nutritional value (especially during the dry season when dryland grasses have matured into very low quality feed).  Fresh material has yielded 30% DM with 13–18% crude protein (up to 22% CP in fresh leaf).  Digestibility generally 55–63%;  up to 74% has been recorded in fresh growth.

Palatability/acceptability

Very palatable and eagerly sought by cattle.

Toxicity

None recorded.

Production potential

Dry matter

DM yields of 8–12 t/ha in South America, and 10–20 t/ha in northern Australia.

Animal production

Top

Average daily liveweight gains of about 0.5 kg/day at stocking rates of 0.2–1 ha/animal with 700 kg/ha LWG have been recorded off irrigated or rain-fed pasture but little data is available from ponded pasture systems.  However, the critical benefit from ponded systems is the ability to fatten/finish stock into the dry season when dry-land native pastures have matured.

Genetics/breeding

No information available.

Seed production

Produces little viable seed, with no evidence at all of viable seed being produced in northern Australia.

Herbicide effects

No information available.

Strengths

  • Can grow in standing water to 3 m deep, but more generally to 2 m.
  • High quality feed during cool dry season with ponding.
  • Tolerates high stocking rates under rotational grazing.

Limitations

Top

  • No seed but spread from pieces of stem .
  • Cannot tolerate low rainfall or drought .
  • Potential environmental weed in wetlands.

Other comments

  

Selected references

Pittaway, P.A., Wildin J.H. and McDonald, C.K. (eds) (1996) Beef production from ponded pastures. Tropical Grassland Society of Australia Occasional Publication No.7.
Farias, M.L. and Piedade, M.T.F. (2000) Growth and biomass of Echinochloa polystachya (Poaceae) under nitrogen fertilization and different harvest treatments. German-Brazilian Workshop on neotropical ecosystems; Living Resources Management, Hamburg 2000.

Internet links

Cultivars

Cultivars

Country/date released

Details

‘Coapim’    Introduced into N.T., Australia prior to 1900.  Leaves darker green than in ‘Amity’; also with fungal leaf spots (not found on ‘Amity’).
‘Amity’
(CPI 61147)
Australia From Orinoco Delta, Venezuela.  Flowering culms 1–2 m long, much shorter mucros of the lemmas of ‘Amity’ compared to awned lemmas of other E. polystachya .

Promising accessions

Top

Promising accessions

Country

Details

None reported.