Paspalum dilatatum


Scientific name

Paspalum dilatatum Poir.

Subordinate taxa:
Paspalum dilatatum Poir. var. pauciciliatum Parodi
Paspalum dilatatum Poir. subsp. dilatatum
Paspalum dilatatum Poir. subsp. flavescens Roseng. et al.

Synonyms

Digitaria dilatata (Poir.) H.J. Coste
Paspalum dilatatum fo. paucispica Hack.
Paspalum dilatatum var. decumbens Vasey
Paspalum pauciciliatum (Parodi) Herter
Paspalum dilatatum var. sacchariferum Arechav.
Paspalum eriophorum Schult.
Paspalum lanatum Spreng.
Paspalum ovatum Nees ex Trin.
Paspalum ovatum var. grandiflorum Nees
Paspalum pedunculare J. Presl
Paspalum platense Spreng. 
Paspalum selloi Spreng. ex Nees
Paspalum velutinum Trin. ex Nees

Family/tribe

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

Common names

paspalum, dallis grass, water grass (English);  mao hua que bai (China);  hirse (Danish);  paspale dilaté, herbe sirop, herbe de miel, herbe de dallis, millet bātard (French);  Dallisgras(German);  rumput australi (Indonesia);  paspalo dilatato (Italian);  shima suzume no hie (Japan);  herbe codaya (Mauritius);  pasto dallis, zacate dallis (Mexico);  hiku nua (Niue);  lawa-lawa, halanaw, sakata (Philippines);  grama de agua, hierba dallis, hierba de australia pasto chato, pasto dallies, pasto miel (Spanish);  ya-daenlit (Thailand);  co san dep (Vietnam).
prostrate dallis grass (var. pauciciliatum).

Morphological description

Leafy, tufted, sod-forming perennial, with clustered shoots arising from short rhizomes 4-8 mm diameter, bearing thick fibrous roots to >1 m deep.  Foliage largely basal (10-) 20-50 (-90) cm tall;  leaf blades 3-13 (-20) mm wide, (6-) 12-25 (-45) cm long, largely glabrous except for a few long hairs near the collar;  ligule membranous, bluntly triangular to 6 mm long;  leaf sheaths glabrous (sometimes lower ones shortly pilose).  Fertile culms ascending to erect, unbranched or rarely branched, 50-90 (-180) cm tall.  Inflorescence a panicle comprising 2-5 (-11) widely separated, alternate racemes, the lowest 3-10 (-13) cm long, the upper ones shorter.  Spikelets broadly ovate, green or purplish, 2.5-4 mm long, borne in pairs along one side of a flattened rachis, 2 mm long, reddish-brown, elliptic .  500,000-750,000 seeds/kg.
P.dilatatum bears a superficial resemblance to the less palatable P. urvillei (also group Dilatata), which can be distinguished by virtue of its more robust habit , dense, long radiating hairs on the lower leaf sheaths, and smaller, hairier spikelets.

Distribution

Native to:
South America:  Argentina, Bolivia, Brazil, Chile, Paraguay, Uruguay.
Found in moist grassland, occupying different topographic positions, which are subject to various regimes of flooding and drought, both of which may occur in the same growing season .

Naturalised in:
Subtropics of USA, Australia, and Africa and in Portugal, Spain, Azores, Italy, Austria, Germany, Iran, Turkey and India.

Uses/applications

One of the earliest species adopted for permanent sown pastures.  Also suitable for hay and silage, but should be cut before flowering to avoid hay being spoiled by presence of ergot- infected seedheads.  Once established, provides good stable ground cover to combat erosion, particularly that caused by water movement.

Ecology

Soil requirements

Grows best on deep, moist, fertile, sandy loams and clays usually of alluvial or basaltic origin.  Such soils are subject to compaction under intensive grazing.  As the sward ages it often becomes sod-bound.  Periodic renovation by ploughing, disc harrowing or deep ripping helps to overcome both conditions.  The prostrate var. pauciciliatum has been successful on lighter soils.  If fertility is allowed to decline, P. dilatatum is gradually dominated by inferior species such as Axonopus fissifolius P. dilatatum   prefers a pH of 5.5-7, but will grow down to pH 4.5 and up to about 8.  It has little tolerance of salinity, but is very tolerant of poor drainage.

Moisture

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It is most prominent in areas with rainfall between 900 and 1,300 mm/yr, but also grows in lower areas with rainfall down to 750 mm, and extends at least to the lower slopes in higher rainfall (to about 1,700 mm) areas.  It commonly invades irrigated pastures.  The deep root system confers significant drought tolerance once it is established.  It occurs in areas that are subject to flooding, tolerating inundation of up to one week.

Temperature

In its native environment, P. dilatatum occurs from sea level to 2,000 m and from about 20-35°S.  It has become naturalised, in areas up to 2,300 m asl (Lesotho, 28ºS) and beyond 40ºN in Europe and USA.  This is probably equivalent to an average annual temperature range of (10-) 15-20 (-23)ºC.  Mean temperature of coldest month is about 0-15°C, and frost, sometimes snow, is encountered in parts of this distribution.  Various optimum temperatures have been cited for development:  30°C for leaf growth, 27°C for tillering and 22.5°C for flowering.  Seed production is inhibited at temperatures below 13°C.  P. dilatatum is moderately frost tolerant (comparable with Pennisetum clandestinum and frost tolerant cultivars of Setaria sphacelata ).  While tops are killed by temperatures below -3 to -4°C, plants survive lower extremes and regrow rapidly with the onset of warmer, moist conditions.

Light

Grows in light shade, but is not as shade tolerant as Axonopus compressus or Paspalum notatum .

Reproductive development

It is a long day plant with a critical photoperiod 14-16 hours, although considered by others to be independent of day length.  Flowering commences in early to mid summer, at which time vegetative growth slows markedly.  Flowering continues through autumn, with little more foliage produced until the following spring.

Defoliation

Defoliation management largely needs to focus on suppression of inflorescence emergence.  Seedhead development alone reduces leaf production, but the presence of ergot-infected seedheads poses a threat to animal health (see "Toxicity").  It is best, therefore, to maintain high grazing pressure during the flowering period in summer.  Slashing or mulching may also be necessary to remove seedheads.  The stand is most productive if maintained at 5-8 cm;  lower grazing can reduce yields by up to two-thirds.  P. dilatatum can tolerate heavy grazing, so sward density is unaffected.

Fire

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Paspalum pastures are seldom subject to fire, but, if burnt, they quickly recover from the rootstock when conditions are again favourable.

Agronomy

Establishment

It can be sown at any time from spring to late summer, although best sown just before the expected rainy season since germination and establishment can be slow.  There is some post-harvest dormancy .  While seed is generally drilled or broadcast into a well-prepared, fine, weed-free seedbed, it can also be sown directly into rice stubble without further seedbed preparation.  It is normally sown at 5-10 kg/ha, and preferably placed less than 1.5 cm deep.

Fertiliser

P. dilatatum can persist in a weak state on infertile soils, but is usually dominated by inferior species such as Axonopus fissifolius in these situations.  The trend towards Axonopus dominance can be easily reversed with the application of 100-150 kg/ha of fertiliser nitrogen.  The use of strategic applications of nitrogen to paspalum can thus play an important role in extending the grazing season of this grass .  Levels of other nutrients, particularly phosphorus, should be monitored and maintained.

Compatibility (with other species)

Although P. dilatatum is not overly competitive in its own right, the only legumes that are compatible with it are those that can tolerate the same grazing regime.  Because of its slow establishment, other more rapidly establishing, but possibly shorter-lived grasses such as Chloris gayana and Setaria sphacelata are sometimes sown with it.  Cool season legumes can be established into it by oversowing or sod-seeding during winter dormancy .

Companion species

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Pests and diseases

The main disease is ergot, caused by the fungus, Claviceps paspali.  The disease first appears in the form of a dark, sticky exudate from the spikelets or "seed".  A sclerotium replaces the caryopsis , and secondary fungi grow on the exudate.  Anthracnose (Colletotrichum graminicola) and leaf blight (Helminthosporium micropus) also attack the plant but have little effect - similarly paspalum striate mosaic virus transmitted by a leafhopper ( Nesoclutha pallida (obscura); Cicadellidae).
Roots are attacked by the larvae of a number of scarab beetles, caudata canegrub (Lepidiota caudata), white grub (Rhopaea paspali), and the african black beetle (Heteronychus arator) which reduce pasture productivity and open swards.  Argentine stem weevil, (Listronotus bonariensis: Coleoptera: Curculionidae) is also recorded as a pest, but damages softer species more severely.  The sugar cane borer (Diatraea saccharalis: Lepidoptera: Pyralidae) sometimes attacks it.

Ability to spread

It spreads readily by seed where conditions are suitable for germination.  Vegetative spread is extremely slow.  Although a slow establisher and with the impediment of disease of the inflorescence , it has been a remarkably successful coloniser.

Weed potential

It is considered a serious weed of turf.

Feeding value

Nutritive value

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It declines markedly in feeding value as it matures.  Digestibility ranges from 57-63% and crude protein (CP ) can range from 4-23%.

Palatability/acceptability

In the pre-flowering stage, it is very palatable.  Mature growth, particularly when associated with ergot-infected inflorescences, is less attractive to stock.

Toxicity

The grass itself is not known to be toxic, but seedheads parasitised by the ergot fungus, Claviceps paspali, whether in pasture or in hay , can be toxic due to production of tremorgenic pyridine alkaloids in the sclerotia, which appear in late summer or autumn.  The yellow-grey sclerotia are round, roughened, and 2-4 mm in diameter.  Various alkaloids are identified in the literature as being isolated from C paspali sclerotia, although not all may have clinical effect:  agroclavine, chanoclavine, elymoclavine ergine, ergovaline, ergonovine, isoergine, lysergic acid N-1-hydroxyethylamide, paspaline, paspalicine, paspalinine, paspalitrem A and B, and two unidentified ergoline alkaloids.  Rations containing >0.6% of ergot are potentially toxic.  Affected animals (all classes of livestock) at first show excitement, distrust of people and a tendency to attack.  Later they tremble, appear to lack muscular control, stagger and may fall.  They recover in a few days if removed from infected areas in the early stages of excitement.  Recovery follows removal of the animals to feed not contaminated with sclerotia of C paspali.  Topping of the pasture to remove affected seed heads has been effective in control.

Production potential

Dry matter

Total productivity varies with genotype, and growing conditions, including temperature, soil fertility , moisture etc., and pattern of production relates to flowering time.  P. dilatatum is one of the most productive of the warm season grasses in the early spring, but productivity declines with the onset of flowering.  Annual yields of 15 t/ha DM have been achieved, but can be as low as 3 t/ha.  Well-fertilised grass can produce 50-60 kg/ha/day DM when growing actively.

Animal production

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Can support 25 sheep per hectare during the growing season .  At 34ºS, an irrigated, fertilised system, with P. dilatatum constituting 70% of the feed in spring and summer, and sod-seeded temperate species providing the bulk of feed in the cool season, can consistently produce more than 10,000 litres of milk per hectare per year (Friesian cows at 2.5 per hectare in winter, and 5 per hectare in spring and summer).

Genetics/breeding

Various polyploid biotypes, including:
apomictic tetraploids (2n = 4x = 40), var. pauciciliatum
sexual tetraploids (2n = 4x = 40) include var. flavescens, and 'Virasoro' and 'Vacarķa' biotypes.  The group comprises both yellow- and purple-anthered type.
apomictic allopentaploids (2n = 5x = 50) or 'Common' type;  considered to have originated from a hybridisation event between a var. flavescens type and a hexaploid biotype such as Uruguayan;  has purple anthers;  reproduces by apospory and pseudogamy ;  little variation among the various phenotypes.
apomictic allohexaploids (2n = 6x = 60) e.g. 'Uruguaiana', 'Uruguayan' and 'Torres' biotypes.
septaploid (2n = 7x = 70):  a recent discovery at Villa Serrana, Lavalleja, Uruguay.
Breeding is focussing on the use of the possible diploid progenitors, P. intermedium, P. juergensii, P. paniculatum, and P. urvillei to improve ergot resistance.

Seed production

Paspalum seeds freely, but the seed ripens from the tip of the racemes downwards and shatters as soon as it is ripe.  It is thus hard to harvest, and viability is often low.  Seed production is also affected by ergot infection.  Crop management is similar to that for P. notatum i.e. graze the paddock heavily (to ca. 7 cm) during spring following a dressing of 50-75 kg/ha N (preferably as a mixed fertiliser), and follow up with a further 50-75 kg/ha N in the boot stage in early summer.  Seed ripens progressively over the summer and at no time is all the seed mature.  Because of the asynchronous ripening of seed, one approach with harvesting is to use a mechanical stripper or brush harvester, which non-destructively removes only ripe seed, facilitating up to 10 passes with the machine in a season.  This can yield 30 kg or more of seed each pass.  Header harvesting should begin when 60-80% of the seed-heads are a light brown colour.  Crops are often mixed with Axonopus fissifolius , the seed of which is easily screened from the P. dilatatum seed.  Ergot sclerotia are mostly larger than the seed and can also be largely removed with screening.

Herbicide effects

Triclopyr and picloram, halosulfuron-methyl, imazethapyr and 2-4, D can be used for broadleaf weed control in grass swards.  Young plants of P. dilatatum can be controlled with paraquat, while older stands are best controlled with glyphosate, preferably pre- or early flowering.  Stands can be desiccated with fluazifop-P, glufosinate, and haloxyfop.  Pre-emergent herbicides that can be used to control germinating seed include bensulide, DCPA, dithiopyr napropamide, oryzalin, oxadiazon, pendimethalin, prodiamine, pendimethalin, oryzalin, or combinations of benefin plus oryzalin, or benefin plus trifluralin.

Strengths

  • Palatability when young.
  • Ability to stand heavy grazing and trampling.
  • Legume compatibility.

Limitations

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  • Short grazing season.
  • Early and heavy seeding.
  • Susceptibility to ergot.
  • Tendency to become sod-bound.

Other comments

  

Selected references

Bogdan, A.V. (1977) Tropical Pasture and Fodder Plants. pp. 205-212. (Longman: London and New York).
Burson, B.L., Voigt, P.W. and Evers G.W. (1991) Cytology, reproductive behavior, and forage potential of hexaploid dallisgrass biotypes. Crop Science, 31, 636-640.
Burson, B.L. and Watson, V.H. (1995) Bahiagrass, dallisgrass and other Paspalum species. In: Barnes, R.F et al . (eds) Forages: An introduction to grassland agriculture. pp. 431-440. (Iowa State Univ. Press, Ames, IA).
Casa, A.M., Mitchell, S.E., Lopes, C.R. and Valls, J.F.M. (2002) RAPD analysis reveals genetic variability among sexual and apomictic Paspalum dilatatum Poiret biotypes. Journal of Heredity, 93, 300-302.
Evers, G.W. and Burson, B.L. (2004) 20 Dallisgrass and Other Paspalum Species. In: Moser, L.E., Burson, B.L. and Sollenberger, L.E. (eds) Warm-Season (C4) Grasses . Agron. Monogr. 45 . pp. 681-713. (ASA, CSSA, and SSSA, Madison, WI).
Hacker, J.B., Williams, R.J., Vieritz, A.M., Cook, B.G. and Pengelly, B.C. (1999) An evaluation of a collection of Paspalum species as pasture plants for southeast Queensland.  Genetic Resources Communication No. 32.  (CSIRO Tropical Agriculture, St Lucia, Qld, Australia) ISBN 0 643 05915 6.
Mannetje, L. 't  and Kersten, S.M.M. (1992) Paspalum dilatatum Poiret. In: 't Mannetje, L. and Jones, R.M. (eds) Plant Resources of South-East Asia No. 4. Forages. pp. 178-180. (Pudoc Scientific Publishers, Wageningen, the Netherlands).
Venuto, C., Burson, B.L., Hussey, M.A., Redfearn, D.D., Wyatt, W.E. and Brown, L.P. (2003) Forage Yield, Nutritive Value, and Grazing Tolerance of Dallisgrass Biotypes. Crop Science, 43, 295-301.

Internet links

Cultivars

Cultivars

Country/date released

Details

'La Estanzulea Chiru' or 'Chiru' Uruguay Selection from 'Uruguayan' biotype.  More erect than 'Common' and produces more forage .  Not widely used.
'Grasslands Raki' New Zealand (1979) Composite of two accessions selected on the basis of productivity from 22 accessions from Uruguay.  At least as productive as best commercial lines available in NZ.  Susceptible to ergot.
'Louisiana B-230' USA (1951) Selected from clones from naturalised stands in southern USA for seed yield and quality as well as forage traits.  Better quality seed and remaining green later in autumn than 'Common'.
'Louisiana 430' USA (1951) Selected from clones from naturalised stands in southern USA for seed yield and quality as well as forage traits.  A higher pure live seed content and less ergot (Claviceps paspali) infection than naturalised 'Common'.
'Natsugumo' Kumamoto, Kyushu, Japan (1980) Selected from naturalised dallisgrass plants from southern Kyushu.  Taller, with longer, narrower leaves than 'Louisiana B-230'.  Flowers later and produces more dry matter than 'B-230'.

Biotype

Country of origin

Details

'Common' Western Uruguay. Semi-erect to erect growth habit, with erect or nodding panicle comprising (2-) 3-5 (-11), ascending to drooping racemes, 3-10 cm long.  The type most commonly planted and naturalised throughout the subtropics and temperate areas.  More cold tolerance than the 'Uruguaiana' and 'Torres' biotypes, but less than that of 'Uruguayan'.
var. flavescens Southern Uruguay, eastern Buenos Aires Province, Argentina. Yellow-anthered dallisgrass.  More upright growth habit than 'Common', with larger, more pubescent spikelets.
var. pauciciliatum Eastern Argentina, southern Brazil, Paraguay, Uruguay. Prostrate dallisgrass.  More decumbent growth habit, and spikelets slightly smaller and less pubescent than those of 'Common'.  Stand persistence and forage production satisfactory, but major limitation is poor seed set.
'Torres' North-eastern Rio Grande do Sul to south-eastern Santa Catarina, Brazil. Semi-prostrate growth habit, with multiple racemes arranged in a spiral, somewhat similar to those of 'Uruguayan'.  Its spikelets are glabrous and smaller than those of common.  Lacks the persistence to be potential forage .
'Uruguaiana' Western Rio Grande do Sul, Brazil. More robust than 'Common'.  Inflorescences normally with more racemes arranged in a spiral on the central axis;  spikelets similar to those of common.  Lacks the persistence to be potential forage .
'Uruguayan' North-western and northern central Uruguay. More robust, and grows more erect than 'Common'.  Inflorescences normally with more racemes arranged in a spiral on the central axis;  spikelets similar to those of 'Common'.  More cold tolerant than 'Uruguaiana' and 'Torres' biotypes.  Persists better and produces more forage on poorly drained clay soils than 'Common'.  Nutritive value equivalent to that of 'Common'.  Could have commercial value.
'Vacaria' North-eastern Rio Grande do Sul to south-eastern Santa Catarina, Brazil. Variable comprising an array of types intermediate between var. flavescens and P. urvillei.
'Virasoro' North-eastern Corrientes Province, Argentina to northern central Rio Grande do Sul, Brazil. Morphologically similar to var. flavescens (including anther colour), but has more racemes (8-12) that tend to ascend or droop downward.  Has some resistance to Claviceps paspali.

Promising accessions

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Promising accessions

Country

Details

None reported.