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Trifolium fragiferum L. |
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Leguminosae Common names Strawberry clover. |
Author:
Dr. John Frame
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Description Subglabrous perennial with slender, pointed trifoliate leaves. Leaflet venation distinctive with veins meeting edge of leaf at right angles. Hairs present on petioles and underside of leaflets. Stipules relatively conspicuous and becoming gradually narrowed to apex. Stolons initiated from leaf axils form a prostrate branched network radiating from an initially tap-rooted seedling; overall growth habit similar to that of white clover with perennation dependant on adventitious-rooted plantlets developing from stolon nodes though the tap root of strawberry clover persists for longer than that of white clover. Inflorescences globular and compact, 10-12 mm in diameter, with pink or purplish red florets and when ripe, become reddish and resemble strawberry fruits. Mediterranean types tend to be self-incompatible while types from northern latitudes tend to be self-compatible (Townsend, l985). After pollination in summer by bumble bees (not present in mainland Australia) and honey bees, the pubescent fruiting calyces contain1-2 seeds each. Seeds are heart-shaped and coloured light brown with dark brown flecks. Distribution Moderately distributed in mild, temperate areas, e.g. western USA, New Zealand, southern Australia. Characteristics Adapted to poorly drained soils with high water table though plants become shallow-rooted; also suited to wet saline or alkaline soils (Townsend, l985). Useful forage legume for soils too saline for white clover. Suited to moist climate with 750-1500 mm rainfall annually (PLANTS database 2000) and summer moist areas with 600 mm average annual rainfall. Useful component of seed mixtures for irrigated pastures, e.g. in western USA. Tolerant of close continuous grazing on account of its stoloniferous growth habit (Pederson, l995). Has cool-season growth in mild temperate areas, e.g. New Zealand. Intolerant of shade. Season of growth Highest yielding in spring and summer. Drought tolerance Moderate, better than white clover. Tolerance of flooding High tolerance due to a tropic response which elevates stolon tips above surface of water (Townsend, l985). Soil requirements Has established well on a range of soils from acid sands (pH 5.5) to alkaline peats and clays (pH 9.0) and in badly drained swampy and occasionally flooded areas (Smetham, l973); however, it thrives best at pH 6.0-8.4 (PLANTS database, 2000). Responsive to P application. Strawberry clover gave a greater yield response from liming an acid soil than red, white or subterranean clovers, and common or hairy vetch (and five forage grasses) while it was also the most Al tolerant (Pires et al., l992). Rhizobium relationships The correct strain of Rhizobium leguminosarum bv. trifolii should be used for seed inoculation prior to sowing. Ability to spread naturally Some spread may occur due to shed seed in open sward canopies, but main spread in pastures is by stolon proliferation. Land preparation for establishment Well-cultivated, uniform and firm seed bed required for good results. Sowing methods Seed can be drilled or broadcast after conventional seed-bed cultivation. Direct sowing, i.e. without a cover crop, is best. If undersown on saline soils, barley is the most suitable cereal cover crop (Townsend, l985). Sowing depth and soil cover The maximum sowing depth is 10-15 mm with a light but firm soil cover. Sowing time and rate Spring is a suitable time though late-summer sowing is a practical alternative provided there is adequate moisture and sufficient time for the clover seedlings to develop well before winter. It can also be oversown into swards, using circa 9 kg/ha. Sown at 3-6 kg/ha in grass/legume mixtures. In Australia, most dryland swards are established in late winter and early winter with strawberry clover typically sown at 1-2 kg/ha in grass/legume mixtures. Number of seeds per kg Circa 660 000. Percentage hard seed Harvest seed can contain up to 70% hard seed. Seed treatment before sowing All the seed may be scarified to ensure a good initial germination or alternatively, part of the seed lot may be left unscarified to act as a reservoir for later germination should the early-germinating scarified seed be adversely affected – by drought, for example. Compatibility with grasses and other legumes In general, non-aggressive grass species are the most compatible. Ability to compete with weeds Poor during early establishment but improves with time. Seedling vigour Initially poor on account of small seed size. Seedlings may be killed if winter flooding prolonged. Vigour of growth and growth rhythm Once established, capable of vigorous growth, especially in warm, wet conditions. Growth slow in winter and early spring, but peaks in late spring/early summer. Capable of cool-season growth in mild winters. Nitrogen-fixing ability Reported to have a moderate to high N-fixing ability. Response to defoliation Growth characteristics make it adapted to close and severe defoliation, e.g. to continuous sheep grazing. Grazing management In general, prostrate types are suited to continuous stocking, for example by sheep, and the more upright types to rotational grazing or conservation. Breeding system Cross-fertilized by bumble bees and honey bees. Chromosome number 2n = 2x = 16. Breeding objectives Improved yield and persistency under sheep grazing. Improved erect, larger-leaved type for cattle grazing and conservation. Dry matter yields When grown with dallis grass (Paspalum dilatatum) total herbage DM yields up to l8 t/ha have been noted (Townsend, l985). Suitability for hay and silage Mixed swards are highly suitable for conservation as hay or silage. In hay making it is important to avoid the loss of the nutritious leaf fraction during the curing process by judicious crop handling. Feeding value Typical of clovers, the herbage is richer in protein and poorer in water-soluble carbohydrate contents than grasses. Acceptability Highly acceptable to livestock whether at leafy grazing stage, or as conserved hay or silage. Anti-quality factors Has propensity to cause bloat in ruminant livestock. Seed harvesting methods Seed crops may be directly combined or else cut, swathed and threshed. Ripe seedheads may be prone to shattering and so harvesting is best done when they are slightly damp. Seed yield Yields in the USA range from 40 to 300 kg/ha with an average of l00 kg/ha (Townsend, l985). Cultivars In the USA, Salina was developed from the large-leaved, salt-tolerant Australian cultivar, Palestine, which originated near the Dead Sea. Another USA cultivar, Fresa, has been released for ground cover and amenity turf purposes. Australasian releases are Grasslands Upward, a large-leaved, prostrate type from New Zealand and O’Connors, a small-leaved type from Australia. Diseases More susceptible to clover rot (Sclerotinia trifoliorum) than white clover. Clover rust (Uromyces spp.) can adversely affect seed crops. Pests Susceptible to root-knot nematodes (Meloidogyne spp.) (Quesenberry et al., l986). Main attributes N-fixing, protein-rich species particularly adapted to waterlogged and/or saline soils and to heavy irrigation. Growth habit makes it suitable for close grazing but some cultivars have been developed for laxer grazing and/or conservation. Main shortcomings Persistence and yield variable from year to year. Slow winter and early spring growth. Can cause bloat. Performance In Australian work, weaned lamb liveweight gains were less from strawberry clover than from red clover (Reed et al., l980). Links
Main references Pederson G.A. (1995); Plants Database 2000; Smetham M.L. (l973); Townsend C.E. (l985) Other references Pires A.L.et al.(l991); Quesenberry K.H. et al.(l986); Reed K.F.M. et al.(l980) |