Trifolium semipilosum


Scientific name

Trifolium semipilosum Fresen.

Subordinate taxa:
Trifolium semipilosum Fresen. var. brunellii Thulin
Trifolium semipilosum Fresen. var. glabrescens J. B. Gillett
Trifolium semipilosum Fresen. var. intermedium Thulin
Trifolium semipilosum Fresen. var. semipilosum

Synonyms

var. semipilosum
Trifolium semipilosum Fresen. var. kilimanjaricum Baker f.
Trifolium semipilosum var. microphyllum Chiov.
var. glabrescens
Trifolium johnstonii
sensu Edwards & Bogdan
Trifolium johnstonii auct., non Oliver
Trifolium repens sensu Baker f.

Family/tribe

Family: Fabaceae (alt. Leguminosae) subfamily: Faboideae tribe: Trifolieae. Also placed in: Papilionaceae.

Common names

kenya clover, kenya white clover (English);  trefle africain, trefle du Kenya (French);  trevo do quenia (Portuguese).

Morphological description

Herbaceous perennial, initially with prostrate, pilose stems to ca. 2 mm diameter radiating from crown and taproot, rooting freely at the nodes and forming dense mats;  stem apices ascend through taller grass to about 45 cm.  Leaves trifoliolate;  leaflets orbicular, elliptical, or oblong to cuneate-obovate 0.4-2.4 cm long and 0.4-2 cm wide;  glabrous above, sometimes with leaf markings of silver splash on the midrib and/or purple or brownish crescent across the leafletpilose at the margins and on the midrib beneath and also on the undersides of the lower (outer) half of the lateral leaflets (except sometimes in var. glabrescens);  petiole pilose, (1-) 12-18 (-26) cm long depending on defoliation pressure.  Inflorescence more or less globose, about 2 cm across, comprising (4-) 20-( 40) flowered, on pilose peduncle, mostly longer than the petiole ;  papilionate flowers white to pale pink, 8-10 mm long.  Pods oblongoid, 5-6 mm long and 2-2.5 mm wide, containing 2-6 seeds.  Seeds irregularly discoid or mango-shaped, about 1.5 mm across, dull yellow, light brown, olive grey or even black in colour, often mottled.  700,000-1,000,000 seeds/kg.  It is readily distinguished from Trifolium repens which has glabrous leaves and stems, yellow to golden seeds, and average of 1-1.7 million seeds/kg.
T. repens competes for light with associated grasses by elongation of the petiole .  Although this also occurs in T. semipilosum , it is primarily achieved by ascending stems.

Distribution

Native to:
var. brunellii:
Africa:  Ethiopia (south).
var. glabrescens:
Africa:  Kenya, Malawi , Tanzania, Uganda.
var. intermedium:
Africa:  Ethiopia (central).
var. semipilosum:
Africa:  Eritrea, Ethiopia, Kenya, Tanzania, Uganda (north).
Arabian Peninsula :  Yemen.
Specimens from Madagascar and Malawi are held at the herbarium of the Missouri Botanical Gardens.
Var. glabrescens occurs in rather moister habitats than var. semipilosum and is more variable, growing in upland grasslands, often associated with Pennisetum clandestinum .  Var. semipilosum occurs in upland grasslands, especially near the drier types of upland evergreen forests at 1,400-3,000 m elevation, usually in places where there is much mist and annual rainfall in the range of 550-1,400 mm.

Uses/applications

Used as an alternative to T. repens in permanent pastures on more acid soils and in warmer environments.  Provides good ground cover under more open tree canopies.

Ecology

Soil requirements

T. semipilosum has been collected in soils with pH ranging from 4.0-8.0 (av. 6.0) in Ethiopia, and from 5.4-7.0 (av. 6.6) in Kenya and Tanzania.  Soil textures at collection sites range from sand through silt, loam and gravely clay loam to clay.  'Safari' is adapted to soils with pH 5.0-7.5.  Available soil P levels should be >20 ppm .  It has a slightly lower Ca requirement than that of T. repens, is more tolerant of soluble Al and Mn, but may be more susceptible to Zn deficiency.

Moisture

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Annual rainfall at collection sites in Ethiopia ranged from 700-1,800 mm (av. 1,070 mm), and 450-2,000 mm (av. 1,070 mm) in Kenya and Tanzania.  'Safari' has been useful in areas with between 800 and 1,600 mm mean annual rainfall.  Although not as drought tolerant as many deeper rooted tropical legumes, T. semipilosum can survive lengthy dry periods and is largely more drought tolerant than T. repens.  However, 'Safari' is less tolerant of waterlogging than T. repens.  Flood tolerance is only moderate, being similar to that of Lotononis bainesii and Desmodium heterophyllum .

Temperature

The species occurs naturally in the high altitude tropics, from about 1,000 m asl to >3,000 m asl, with average annual temperatures from about 16-21ºC.  In the low altitude subtropics, it has been grown from 25-31º latitude.  T. semipilosum has a long growing season , providing moisture is adequate.  In the subtropics where there is seasonal demarcation, the main growing seasons are spring/early summer and autumn, with minimal growth in mid-summer and winter.  It is less tolerant of frost than T. repens but shows more vigorous summer growth.  It is discoloured by moderate frosts and cut by heavy frosts, resuming slow growth once frosts cease.

Light

There are no data, but observations suggest 'Safari' has moderate shade tolerance, but less than that of T. repens.

Reproductive development

T. semipilosum has a quantitative, short-day flowering response, which is enhanced by low night temperatures.  In the southern hemisphere lowland subtropics, 'Safari' commences flowering at low density in April, continuing until October, with a peak in August.

Defoliation

T. semipilosum requires periods of heavy grazing, especially in summer, for persistence.  This ensures that stolons stay close to the ground, giving rise to more nodal rooting.  Under lenient grazing, growing tips ascend through taller grasses, and with constant stolon turnover, ultimately lose contact with the soil, leading to a decline in stand.  Under intensive defoliation, it can form a low, dense swardT. semipilosum , which occurs naturally with Pennisetum clandestinum , is not as readily overtopped by taller companion species as T. repens.  In the humid subtropics or upland tropics, pastures can be grazed at 5-6 beasts/ha during the warm season to utilise the companion grass and reduce grass competition to the legume, and at 2-3 beasts/ha during the cool season to maintain sward structure and optimise production.

Fire

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Burning in spring usually does little or no harm.  It can improve the stand by softening hard seed and increasing seedling regeneration.  Soil seed reserves in established stands are often of the order of 5,000-10,000 seeds/m² (~ 40-80 kg/ha), which gives significant potential for stand replenishment.

Agronomy

Establishment

Hard seed levels, which are usually high in hand-harvested seed, are usually broken down sufficiently in the harvesting and threshing process to achieve the ideal of 25-75% germination needed for sowing.  It is highly specific in its rhizobial association, requiring strain CB 782 (Australia), CC 2408A (Malawi) or the equivalent of Rhizobium leguminosarum bv. trifolii for effective nodulation.  It is best sown in autumn into a well-prepared, fine, firm, weed-free seedbed, either onto the surface or with minimal soil cover, followed by rolling.  This late-season planting results in less competition from warm season grass during establishment.  In the upland tropics, sowing immediately after the start of the wet season is best, minimising grass competition by heavy grazing or mowing once the ground is covered.  Sowing rates of 2-3 kg/ha of seed are used.  Seedlings are fairly vigorous, but sometimes suffer setback often attributed to rugose leaf curl disease.  Establishment is slower and less reliable than in T. repens.

Fertiliser

T. semipilosum can survive in soils of low to moderate fertility, but only thrives in more fertile soils.  Annual applications of 10-20 kg/ha P are usually adequate to maintain appropriate levels of available soil P.

Compatibility (with other species)

In the short term, T. semipilosum is better able to coexist with taller tropical grasses than is T. repens, but both are susceptible to prolonged periods of the lenient management that is more appropriate for tall grass persistence.  It can form stable mixtures with sward-forming species, providing defoliation pressure is maintained.

Companion species

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Pests and diseases

While T. semipilosum is susceptible to rugose leaf curl (r.l.c.) disease caused by a phytoplasma, the symptoms frequently ascribed to r.l.c., mostly in establishing stands, are not typical of the disease, and may well be due to another cause.  It is susceptible to a number of viruses although these are not common in the field - alfalfa mosaic virus, and a host oriented strain of pea mosaic/bean yellow mosaic potyvirus.  Root and stolon rots caused by Pythium spp. are often present, but largely only become a problem in leniently grazed stands when shoots grow upwards, and degree of stolon rooting declines.  It is also susceptible to a Colletotrichum sp., but appears to be resistant to clover rust caused by Uromyces trifolii-repentis and to clover burn or pepper spot caused by Leptosphaerulina trifolii (Sphaerulina trifolii).  Botrytis head blight (Botrytis cinerea) can infect developing pod clusters, particularly during showery weather in spring.
Slugs (Gastropoda) can eat a significant proportion of leaf material, especially after prolonged wet weather.  Pygmy crickets also cause leaf damage, while amnemus weevils (Amnemus quadrituberculatus: Curculionidae) and root knot nematodes (Meloidogyne spp.) attack the roots.

Ability to spread

Despite setting large amounts of seed, 'Safari' has shown little tendency to spread beyond the planted area, possibly due to the lack of spread of the specific rhizobium.  Once established, stolon spread can be significant.

Weed potential

Although it has sometimes become naturalised in favourable situations in the subtropics and upland tropics, it has shown little tendency to weediness.

Feeding value

Nutritive value

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The chemical composition of 'Safari' resembles that of T. repens, except that the sodium content is lower (0.05% vs 0.15%).  Crude protein levels in the DM are around 25%.  The critical value for phosphorus is 0.23% P for dry matter yield, but may be as high as 0.3% P for protein yield.  In vitro dry matter digestibility of 1-2 month regrowth is up to 75% with little change throughout the year.

Palatability/acceptability

  Extremely palatable.

Toxicity

There is no evidence of oestrogenic activity.  While bloat can occur in cattle grazing T. semipilosum , the risks appear to be less than with T. repens.

Production potential

Dry matter

While annual dry matter yields up to 8.5 t/ha have been recorded, yields are more commonly in the 2-5 t/ha range.

Animal production

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T. semipilosum can produce over 470 kg liveweight gain/ha/yr at a stocking rate of about 2.5 beasts/ha, and has produced higher summer and autumn milk yields in the lowland subtropics than T. repens.

Genetics/breeding

'Safari' is cross-pollinating and self-sterile but does not cross with T. repens.  The common chromosome number is 2n = 16, although a tetraploid type has been identified (see 'Promising Accessions').

Seed production

T. semipilosum requires the presence of honey bees (Apis mellifera) for successful pollination and seed production.  Crops should be managed to maximise inflorescence density and stolon health.  In the southern hemisphere, this can be achieved by keeping the area grazed or mowed until about April (subtropics) or July (the upland tropics).  Harvest time is not critical since pods do not shatter readily, except under extremely dry conditions.  Harvesting methods vary from collection of material with a forage harvester for threshing through a stationary header, to prior windrowing and pick-up threshing with the header, to direct heading of the standing crop.  Harvested seed needs drying before final cleaning. Yields of up to 400 kg/ha have been recorded from small areas, but commercial yields rarely exceed 200 kg/ha. Two harvests per year are possible under some circumstances.

Herbicide effects

Trifluralin can be used for pre-emergence broadleaf weed control, and 2, 4-DB post-emergence.  Although adversely affected, it is not killed by low rates of glyphosate, and gradually recovers.

Strengths

  • High quality forage .
  • Tolerant of heavy grazing.
  • Combines well with many tropical perennial grasses.
  • Moderate drought and heat tolerance.

Limitations

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  • Erratic persistence and production.
  • High hard-seed content.
  • Requires specific inoculum .
  • Needs medium to high fertility soils.
  • Slow and unreliable establishment.
  • Poor winter growth.
  • Sensitive to heavy frost.

Other comments

  

Selected references

Bogdan, A.V. (1956) Indigenous clovers of Kenya. East African Agricultural Journal, 22, 40-45.
Bogdan, A.V. (1977) Tropical Pasture and Fodder Plants. pp. 415-417. (Longman: London and New York).
Cook, B.G., Mulder, J.C. and Powell, B. (1985) A survey to assess the influence of environment and management on frequency, vigour and chemical composition of Trifolium semipilosum cv. Safari in south eastern Queensland. Tropical Grasslands, 19, 49-59.
Cook, B.G. and Shaw, K.A. (1985) Rugose leaf curl in Safari Kenya white clover. Letter to the Editor. Tropical Grasslands, 14, 3-4.
Gillet, J.B. (1971) Trifolieae. In: Milne-Redhead, E.E. and Polhill, R.M. (eds) "Flora of Tropical East Africa". (Part 4). pp. 1027-1028. (Crown Agents for Overseas Governments and Administrations: London.).
Ison, R.L., Parson, Anne E.B. and Jacobs, B.C. (1992) Comparative growth and development of Kenya clover (Trifolium semipilosum ) and white clover (T. repens cv. Haifa): I. Seedling and plant growth. Tropical Grasslands, 26, 40-50.
Ison, R.L. and Parson, Anne E.B. (1992) Comparative growth and development of Kenya clover (Trifolium semipilosum ) and white clover (T .repens cv. Haifa): II. Temperature and daylength effects on flowering. Tropical Grasslands, 26, 51-57.
Jones, R.J. (1973) The effect of cutting management on the yield, chemical composition and in vitro digestibility of Trifolium semipilosum grown with Paspalum dilatatum in a subtropical environment. Tropical Grasslands, 7, 277-284.
Jones, R.M. and Benjamin, A.K. (1992) Trifolium semipilosum Fresen. In: 't Mannetje, L. and Jones, R.M. (eds) Plant Resources of South-East Asia No. 4. Forages. pp. 226-228. (Pudoc Scientific Publishers, Wageningen, the Netherlands).
Jones, R.M. and Cook, B.G. (1981) Agronomy of Kenya White Clover - cultivar Safari. CSIRO Division of Tropical Crops and Pasture Information Service, Sheet No. 41-3, December 1981.
Pritchard, A.J. and Mannetje, L. 't (1967) The breeding systems and some interspecific relations of a number of African Trifolium spp. Euphytica, 16, 324-329.
Wilson, G.P.M. and Bowman, A.M. (1993) Trifolium species on the New South Wales north coast: 2. African species. Genetic Resources Communication No. 19. (CSIRO Division of Tropical Crops and Pastures, St Lucia, Queensland, Australia).

Internet links

Cultivars

Cultivars

Country/date released

Details

'Safari'
(CPI 27218)
Australia (1973) From the Kitale Seed Company, Kenya.  Selected to extend warm season production of Trifolium in the subtropics, particularly on acid soils.  Less affected by a virus akin to bean yellow mosaic virus than other introductions.
'Kabete 4' Kenya A mixture of four clones selected for vigour and persistence, was available in Kenya, but it is no longer believed to be available.

Promising accessions

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Promising accessions

Country

Details

CPI 57436
(K 6735)
Australia From Kenya.  A tetraploid .  Morphologically more robust than 'Safari', but agronomically similar.