Stylosanthes hamata


Scientific name

Synonyms

Hedysarum hamatum L.
Stylosanthes eriocarpa Blake
Stylosanthes procumbens Sw.

Family/tribe

Family: Fabaceae (alt. Leguminosae) subfamily: Faboideae tribe: Aeschynomeneae subtribe: Stylosanthinae. Also placed in: Papilionaceae .

Common names

Caribbean stylo (English);  pencil flower, mother segal (West Indies);  tebeneque (Venezuela);  cheesytoes (USA);  Verano (Spanish);  thua-hamata (Thailand);  lucy Julia (Cayman Islands).

Morphological description

Annual to short-lived much-branched herbaceous perennial;  semi-erect, mostly 30-75 cm (rarely -1.4 m), sometimes prostrate .  Stems fine, green, differing from S. humilis in having only fine white hairs down one side, but no bristles as in S. humilis .  Leaves trifoliolate, the central leaflet from 16-26 mm long and 3-6 mm wide, acuteInflorescence an axillary or terminal oblong spike, to 20 mm long, with 8-14 yellow papilionaceous flowers with standard 4-5 mm wide.  2-segmented pod, both segments usually fertile;  the upper segment 6-7 mm long (including recurved beak or hook 3-4 mm long), and the lower segment 3.5 mm long.  A distinct type (a tetraploid) with shorter beak on the pod occurs in southern Florida.  Seeds tan to dark maroon, mottled, 2-2.5 mm long, unsymmetrically kidney-shaped.  270,000 seeds-in-pod and 450,000 dehulled seeds/kg.

Distribution

Native to:
North America:  USA (southern Florida) - (only tetraploids).
Central America:  Guatemala, Nicaragua (native - mostly diploids).
Caribbean:  Anguilla, Antigua and Barbuda, Bahamas, Barbados, Cuba, Dominican Republic, Guadeloupe, Haiti, Jamaica, Martinique, Puerto Rico, St. Kitts and Nevis (St. Kitts), St. Lucia, St. Vincent and Grenadines (North Grenadines), Virgin Islands (British), Virgin Islands (U.S.) (mostly diploids).
South America:  Venezuela, Colombia, Brazil (Bahia, Ceara, Maranhao, Pernambuco).  Some of the Brazilian material is more strongly perennial .

Uses/applications

Mostly used for permanent pastures.  Good for cut and carry as green feed, or for hay if cut before dry season leaf fall when plants become increasingly stemmy.  Can also be used as a ley in cropping systems with nitrogen benefits up to 90 kg/ha recorded in West Africa and northern Australia under experimental conditions.  It is used for feeding cattle, goats, sheep, pigs and poultry.  Growing use of S. hamata in silvipasture systems in India where it is used in undersowing Eucalytus and Dalbergia forests as well as a component in watershed and soil conservation programs.

Ecology

Soil requirements

Two types of plant - diploids and tetraploids.  The diploids are not well adapted to acid soil conditions, originating from predominantly alkaline soils, from coarse coral beach sands to relatively heavy clays, where pH is not less than 6.2.  The tetraploids from Venezuela that provide the common cultivars, grow on acid to alkaline soils (pH 5.4-8.0, usually acid to slightly acid) of various textures, but not on heavy clays.  They are tolerant of low P, but may respond to applied S.  They extend the range originally set by S. humilis , which was largely restricted to infertile, acid, sandy surfaced soils, onto more alkaline soils.  While there are no general comments on salinity tolerance, it appears 'Verano' is more tolerant of moderate salinity levels than S. humilis .  Tetraploids from Florida are very different to those from Venezuela.

Moisture

Top

Annual rainfall in the regions where diploids are found ranges from 1,000-2,000 mm in Florida, from 980-1,500 mm in the Caribbean and from 350-1,000 mm in northern South America.  The tetraploids mainly occur in low to very low rainfall areas with a pronounced dry season.  However, the cultivars, both of which originate from an area of ca. 500 mm annual rainfall , are successfully planted in situations receiving 500-2,000 mm with 700-900 mm considered ideal.  S. hamata is more drought tolerant than S. humilis .  In areas with a very long dry season, S. hamata behaves as an annual .  Some forms have quite good flood tolerance.

Temperature

Diploid races occur over most of the distribution between 3ºS in Brazil and 28ºN in Florida, but tetraploids are restricted to Colombia and Venezuela between 9º and 11.5ºN.  A distinct type of tetraploid occurs in southern Florida at about 26ºN.  Tetraploids are mainly found below 500 m asl in the tropics, and are less common than the diploids from 500-1,500 m asl.  This equates to a range in average annual temperatures of about 23-27ºC.  Aerial growth of the cultivars is cut even by light frosts, although the crowns can survive moderate frosts.  They are best adapted to low elevation between the tropics where average annual temperatures are in excess of 22ºC.  Plant growth is limited when night temperatures decline to about 15ºC, even with warmer day temperatures.

Light

Not considered very shade tolerant - comparable with S. guianensis and Macroptilium atropurpureum .

Reproductive development

The diploids are primarily long day plants, while the tetraploids have an indeterminate flowering response to short days.  The cultivars normally flower 9-10 weeks after germination, but perennating plants can flower within 6 weeks of the start of the season and continue throughout the growing season .  Seed takes 15-16 days to ripen from flowering.

Defoliation

Tolerates heavy grazing.  Stocking rate should be adjusted to suppress associated grass if it appears too competitive, especially early in the growing season .  Grazed S. hamata plants tend to perennate better than ungrazed plants.  Higher yields can be obtained from commencing grazing at early flowering and then at 4-week intervals, over starting later and grazing less frequently.  Can become dominant at the expense of perennial grasses through heavy grazing.  Grass and 'Verano' mixtures can be maintained by strategic fire and grazing management with appropriate phosphorus fertiliser use on infertile acid tropical soils.

Fire

Top

Tetraploid cultivars do not tolerate dry season fire, and plants fail to recover following fire.  However, fire improves the germinability of hard seed in the soil, leading to recruitment of stand with the onset of the following wet season.

Agronomy

Establishment

Hard seed levels and embryo dormancy are high in fresh seed.  Level of hard seed can be reduced by dry heat treatment of the seed e.g. heated for 48 hours at 80ºC, or heated for 15-20 seconds at 155ºC in a rotating drum, each followed by rapid cooling.  High soil surface temperatures of the order of 50-65ºC have a similar effect on breakdown of hard seed.  Seed can also be scarified using hot water treatment or dehulling.  Use of more germinable seed leads to more rapid establishment and markedly higher early yields.  Seed is best sown at the end of the dry season.  Sowing rates of 1-4 kg/ha of seed are used.  The tetraploids are promiscuous in their rhizobial requirements, nodulating freely with a wide spectrum of native rhizobia.  It may still be advantageous to inoculate with effective commercial strains such as CB 756 or CB 1650.  The diploid types are highly specific and should be inoculated with CB 2126, a strain isolated from alkaline soils in their native environment.

Fertiliser

Can extract phosphorus from soils low in available soil P.  Respond strongly to applied P.  Application of 10-20 kg/ha P at planting and every 2 or 3 years after establishment (to maintain available soil P levels at ±8 ppm (mg/kg) improves both plant and animal performance. Molybdenum and sulphur may also be necessary in some situations.

Compatibility (with other species)

Combines well with low-growing species and competes well with weeds.  Not suited to growing under trees because of limited shade tolerance.

Companion species

Top

Pests and diseases

Tetraploid cultivars have good field tolerance to anthracnose disease caused by the fungal pathogens, Colletotrichum gloeosporioides and Colletotrichum dematium.  Botrytis head blight, caused by Botrytis cinerea produces blighting of the inflorescence and apical dieback, and is particularly serious in seed crops during periods of high-rainfall .  Web blight caused by Rhizoctonia solani can also be a problem in wet weather, damaging vegetative growth.  There are no major insect pests.

Ability to spread

Seed is spread through ingestion and defecation by cattle, by water movement, and by stock movement, the hook on the upper pod segment adhering to the coat.  Spread is favoured by rhizobial promiscuity suggesting the tetraploids are more successful in this regard than the diploids away from their native habitat.

Weed potential

Not considered a serious weed.

Feeding value

Nutritive value

Top

CP levels range from 17-24% in green leaf and 6-12% in the stem, depending on age of regrowth and general growing conditions.  IVDMD for whole tops are of the order of 60-65%, comprising 66-72% for green leaf and 33-57% for stems.  P levels of the forage depend on the soil P status and age of regrowth, from as low as 0.08-0.3% (0.16-0.37% of DM in green leaf and 0.06-0.34% in stems).  Nutritive value declines rapidly with the onset of dry season leaf drop.

Palatability/acceptability

Extremely palatable.

Toxicity

None recorded.

Production potential

Dry matter

Under ideal conditions, can yield up to 17 t/ha DM in pure stands, but in mixed pasture, more commonly between 1 and 7 t/ha DM, depending on growing conditions, defoliation pressure and grass competition.  Yield of between 7 and 10 t/ha per annum have been recorded under a range of cutting frequencies, soils and rainfalls in cut-and-carry systems in Thailand.  These yields are comparable to those of S. guianensis CIAT 184.

Animal production

Top

Liveweight gain usually in the range of 140-160 and up to 200 kg/hd/yr depending on stocking rates, growing conditions and mineral limitations, but on low fertility soils annual gains can be reduced to 100 kg/hd.

Genetics/breeding

Most ecotypes are diploids (2n = 20), which occur throughout much of the distributional range.  Most tetraploids (2n = 40) are restricted to Colombia and Venezuela, where they are sympatric with S. humilis (one tetraploid type also found in Florida USA).  Evidence suggests that the Venezualan and Colombian tetraploids are more correctly referred to as S. hamata sensu lato, and are allotetraploids, derived from diploid S. humilis and S. hamata sensu strictoStylosanthes is primarily a genus of self-pollinating species, with low levels of outcrossing.  S. hamata is no exception and has a low level of cross-pollination .

Seed production

Experience relates to the tetraploids.  Seed can be hand-picked or machine harvested by direct heading with or without suction harvest follow-up.  Seed is normally machine-harvested once flowering has ceased or nearly so.   Most seeds should be no longer green but brown.  Although total seed set may be as high as 1,750-2,000 kg/ha, harvest yields are usually of the order of 300-600 kg/ha or 800 kg/ha from suction harvesting.

Herbicide effects

Like many Stylosanthes spp., the tetraploid S. hamata are tolerant of a wide range of herbicides.  For seed production, weeds can be reduced using pre-planting trifluralin and post-planting 2,4-D or 2,4-DB at low rates when plants are 5 cm high, higher rates on established crops.  Also tolerant of bentazone, but susceptible to acifluorfen and fluazifop-butyl.

Strengths

  • Can be oversown into native pasture country or grown with sown grasses.
  • Grows on low fertility soils.
  • Highly persistent under grazing.
  • Field tolerance of anthracnose disease.

Limitations

Top

  • Intolerant of waterlogging .
  • Frost sensitive.
  • Restricted to tropical environments.

Other comments

Has some acaricidal effect on cattle tick, Boophilus microplus.

Selected references

Chaisang Phaikaew, Ramesh, C.R., Kexian, Yi and Stür, W. (2004) Utilisation of Stylosanthes as a forage in Asia. In Chakraborty, S. (ed.) High yielding anthracnose-resistant Stylosanthes for agricultural systems. ACIAR Monograph No. 111 .
Edye, L.A. and Topark-Ngarm, A. (1992) Stylosanthes hamata (L.) Taub. In: 't Mannetje, L. and Jones, R.M. (eds) Plant Resources of South-East Asia No. 4. Forages. pp. 213-216. (Pudoc Scientific Publishers, Wageningen, the Netherlands).
Edye, L.A. and Maass, Brigitte L. (1997) Recent advances in studies of anthracnose of Stylosanthes. I. The biogeography of Stylosanthes hamata , S. scabra and "Stylosanthes seabrana ".  Tropical Grasslands, 31, 417-423.
Hall, T.J. and Glatzle, A (2004) Cattle production from Stylosanthes pastures. In Chakraborty, S. (ed.) High yielding anthracnose-resistant Stylosanthes for agricultural systems. ACIAR Monograph No. 111 .
Pengelly, B.C., Clem, R.L. and Whitbread, A.M. (2004) The role of Stylosanthes spp. in mixed crop-livestock systems in Africa and Australia. In Chakraborty, S. (ed.) High yielding anthracnose-resistant Stylosanthes for agricultural systems. ACIAR Monograph No. 111 .
Stace, H.M. and Edye, L.A. (eds) (1984) The biology and agronomy of Stylosanthes . (Academic Press: Sydney, Australia).

Internet links

Cultivars

Cultivars

Country/date released

Details

'Verano'
(CPI 38842)
Australia (1973) From Maracaibo, Venezuela (10°N, 10 m asl, rainfall 563 mm).  Selected as more productive, less disease-prone alternative to S. humilis in the dry tropics of northern Australia.
'Amiga'
(CPI 55822)
Australia (1988) From Maracaibo, Venezuela (11°N, 30 m asl, rainfall 460 mm).  Morphologically similar to 'Verano'.  Selected for seed and DM yield, and resistance to anthracnose.  Extends S. hamata range into drier and cooler environments (rainfall >500 mm, <23°S) but both cultivars are poorly adapted to subtropical environments.  Similar to 'Verano' in flowering time, nodulation response, palatability , digestibility and nutritive value, but greater longevity of individual plants.

Promising accessions

Top

Promising accessions

Country

Details

CPI 55804, 55811(a) and 55871 Ex Brazil These accessions are Brazilian and more strongly perennial than other germplasm, including 'Verano' and 'Amiga' but have lower productivity.
CPI 61670 Indonesia At Timor, Indonesia, gave higher yields than 'Amiga' and 'Verano' on alkaline clay soil with pH 8.6 and average annual rainfall of 1,200 mm.  Lower DM yield and seed yield than S. seabrana .
ILRI 15876
(CPI 110073)
ILRI 15868
(CPI 110063, CIAT 11769)
Nigeria At Kaduna in the subhumid zone of Nigeria.  Comparable, or superior, to 'Verano', higher biomass yields and remaining greener in the dry season.
CPI 110094, 110159, 110185 Venezuela Very high yielding (up to 17.4 t/ha/yr DM).  Anthracnose in some lines.