Stylosanthes guianensis (Aubl.) Sw.
Var. guianensis

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Leguminosae

Synonyms

Trifolium guianense Aubl.; Stylosanthes hispida Rich.; S. guyanensis var. subviscosa Benth.; S. gracilis H.B.K. var. subviscosa (Benth.) Burkart; S. pohliana Taub.

Common names

Common stylo, stylo (Australia, Malaysia); alfalfa do nordeste, trifolio, mangericão do compo, saca-estrepe (Brazil); alfalfa del Brazil (Colombia); Brazilian lucerne, tarbardillo (Venezuela); tropical lucerne (Malaysia).

Description

Erect summer-growing herbaceous perennial with branching upright stems up to 1 m tall, which may become more prostrate under grazing. Stems hairy, becoming woody at the base with age; leaves pinnately trifoliate with elliptic leaflets 15 to 55 mm long and 7 to 13 mm wide; sticky in some ecotypes; petiole 6 to 15 mm long. Inflorescence of several spikes of a few flowers crowded into terminal heads; spikes sessile in unifoliate bracts and hairy; no axis rudiment; flowers yellow; pod hairy with one fertile joint and a very small beak. Seeds yellowish brown, averaging 1.75 mm long (Barnard, 1967), flat sided, tightly enclosed in a brown hull which can be removed by light threshing. Main taproot extends to 1 m. Runners root downwards but are ineffective (Gilchrist, 1967). At three months, 83.7 percent of the roots were in the top 20 cm of profile, 11 percent from 20 to 40 cm, 3.4 percent from 40 to 60 cm, 1.3 percent from 60 to 80 cm, and 0.4 percent had reached from 80 to 100 cm (Blouard and Thuriaux, 1962).

Distribution

Native to Latin America (Mohlenbrock, 1963), occurring mainly in the northern states of Brazil, from São Paulo and Rio de Janeiro northwards. Now widespread in the tropics and naturalized in many countries.

Altitude range

In Brazil it occurs from 200 to 1 000 m; in Colombia from sea level to 2 000 m (Crowder, 1960). At Mareeba in north Queensland it grows at 450 m. It is not found below 650 m in Costa Rica, but occurs from 650 to 1 000 m (Kretschmer, unpublished).

Rainfall requirements

In Queensland, it is adapted to a rainfall range from 900 to 4 000 mm (Davies and Hutton, 1970); in Uganda above 500 mm (Stobbs, personal communication); in Brazil in the 1 000 to 1 700 mm range; in Chad at 1 100 mm.

Soil requirements

Does well on the coarser textured soils, but not so well on heavy clays. It grows on tropical latosols, gleys, loams and sandy podzolic soils. Does not do well on fine-textured montmorillonitic clays; prefers well-drained open-textured soils. Can tolerate highly acid soils (Davies and Hutton, 1970), and nodulates at pH 4.0. It is not very tolerant of salinity.

Rhizobium relationships

Inoculates freely with native rhizobia in the soil, although it nodulates better in the second year. On new land it is advisable to inoculate the seed. At Pitanguerias, Brazil, plants inoculated with the Australian strain of cowpea type, CB756, grew better than those inoculated with a local strain. Nodules are abundant, of small to medium size on the taproots and laterals, 30 per 5 cm on the taproot, and 15 per 5 cm on the laterals (van Rensburg, 1967).

Land preparation for establishment

For drill-sowing on a prepared seed bed, the soil should be ploughed in early spring and worked down to a fine tilth with disc harrows, finishing with a peg-tooth harrow. Allow weeds to germinate and then apply a preplant 2,4-D amine spray at 0.55 kg. acid equivalent per hectare (280 ml of 50 percent 2,4-D/ha) on old cultivation and sow one week later with a minimum of soil disturbance (Gilchrist, 1967). For cheaper introduction, it can be sown without land preparation or with only one cultivation.

Sowing methods

Where necessary (e.g. on erosion terraces or ridges on slopes), it can be planted by stem cuttings (Schofield, 1941; Vivian, 1959; Nwosu, 1960).
Stylo has been proved to be the best legume to establish in Imperata cylindrica (blady, lalang or sword grass) grassland. Vivian (1959) stated that stylo cuttings can be established in this grass by digging individual holes 1 to 2 m apart, adding 50 g rock phosphate per hole and planting three to five stylo cuttings per hole with at least three nodes buried under the damp soil. Risopoulos (1966) established it in Zaire in Imperata grassland by broadcasting at the rate of 3 kg. seed/ha after a single passage of a "Rome plough", after a light scarification of the soil with a disc harrow or after passage of a brush cutter. He found that it was essential that the newly sown area be fenced off from cattle for eight to nine months and that fire be excluded, to allow for good establishment. Other successful methods are to burn the Imperata and scatter seed and superphosphate over the area (Blouard and Thuriaux, 1962), or to feed the seed to cattle and give the cattle access to young Imperata regrowth when it is palatable after a burn. The grazing of the Imperata reduces the competition for the stylo. Stobbs (1969k) found that seed collected from faeces and fistula samples were viable and in fact had an even higher germination rate. Much seed is spread in this way by the grazing animal (Stobbs, 1969k; Foster, 1961).
For seed production and for silage in combination with sorghum or other forage, it can be drill-sown in alternate rows spaced at 0.6 m (Risopoulos, 1966). For general pasture purposes, seed is sown by aerial or ground broadcasting or drilling into seed beds prepared by a single preliminary cultivation, or into ashes or natural pasture.
In Laos, Shelton and Humphreys (personal communication) have successfully established stylo in the rice crop up to day 35 from rice seeding. If left later than this, the rice shades out the developing stylo. The stylo may need hand weeding. When the rice crop is harvested, the stylo becomes a useful nitrogen-fixing pasture ley in a shifting system of rice cultivation.
Oversowing into natural pastures is quite successful, particularly on sandy soils in areas of adequate rainfall, as it the case of Imperata grassland. Van Rensburg (1967) succeeded in oversowing it into Hyparrhenia, Rhodes and star grass pastures in Zambia; Wendt et al. (1970) into Hyparrhenia rufa pastures in Uganda by broadcasting seed and superphosphate just before the rains. It can also be sod-seeded into pasture (Miller and Rains, 1963).

Number of seeds per kg.

264 000 to 352 000. Percentage of hard seeds, 30 to 75 (Risopoulos, 1966).

Seed treatment before planting

Mechanically harvested seed does not require scarification to break dormancy (Rijkebusch, 1967; Gilchrist, 1967). Otherwise: (a) soak for 25 min. in water at 55°C (Risopoulos, 1966) or 85°C for 2 min. (Gilchrist, 1967); (b) scarify mechanically with scarifier or rice polisher (Blouard and Thuriaux, 1962); or (c) treat with concentrated sulphuric acid for 10 min. (Gilchrist, 1967). Pelleting is not necessary unless to protect rhizobia, when it should be pelleted with rock phosphate (Norris, 1967). For insect and disease control, dust with Fernasan D (Wendt et al., 1970).

Nutrient requirements

Stylo is efficient in extracting phosphorus from the soil and is often not fertilized, but it responds to dressings of 125 to 250 kg./ha of superphosphate. At high levels of P, stylo responds to additions of copper (Grof, 1966), and heavy dressings of muriate of potash can cause chlorine toxicity. Horrell and Newhouse (1966) at Serere, Uganda, on a low fertility soil improved the yield of a stylo/Hyparrhenia pasture by 153 percent with added P, 197 percent with added S, and 243 percent with added P and S. Risopoulos (1966) in Zaire established it with 200 kg./ha dicalcic phosphate, 100 kg./ha ammonium nitrate and 50 kg./ha potassium sulphate, with good results for at least two years.

  • Boron: 

Deficiency shows up as yellowing of the leaf tip, little-leaf and unthrifty growth (Stobbs, personal communication).

  • Calcium: 

Stylo gave 64 percent of its maximum yield in the absence of added calcium, the maximum yield being at 740 kg./ha. It was depressed at higher levels. The percentage of calcium in stylo tops is higher than in temperate legumes because of its ability to extract Ca from the soil. In the nil treatments, the percentage of Ca was almost double that of other leguminous species (Andrew and Norris, 1961), indicating its high efficiency in extracting its necessary calcium from low calcium soils.

  • Copper:

Stylo gave only 7 percent of its maximum yield in the absence of copper and is sensitive to low copper supply. However, it has a high copper uptake per unit weight of root tissue and the Cu content of seed is 20.1 ppm (Andrew and Thorne, 1962). Eleven kg./ha of copper sulphate should be applied to deficient soils (Gilchrist, 1967). With copper deficiency in stylo, the first symptom is interveinal chlorosis of the younger fully expanded leaves, and a change in habit of growth from semiprostrate to upright. Tip necrosis of the leaflets follows, with subsequent twisting and then abscission of those immediately below the growing shoot. The growing shoot is retarded and shows some chlorosis. The final appearance is a stem devoid of leaves, except for a few old leaves at the base of the plant and one or two young chlorotic leaves at the top. Axillary growth takes place from the base of the plant (Andrew, 1963).

  • Nitrogen: 

Parbery (1967a) obtained a positive response by stylo to 100 kg./ ha N on Cunnunurra clay in northern Australia, but a depression of growth with a similar application to Cockatoo sand. Risopoulos (1966) used 20 kg. N/ ha as ammonium nitrate in Zaire with success.

  • Phosphorus:

Lack of phosphorus causes yellowing of the leaf tips in seedlings, small leaves, generally unthrifty growth and eventual death of young plants (Gilchrist, 1967).

  • Potash:

Andrew and Pieters (1970a) obtained healthy growth in stylo when the potassium concentration was 1.53 g/100 g dry weight, but deficiency symptoms at 0.55 percent. Symptoms commence as dark brown spots on the leaflets of the mid- to lower-positioned leaves; spots are irregular in shape and the pattern of placement and leaflets are not uniformly affected. Initially they are restricted to the upper leaflet surface and are in greatest concentration interveinally near the leaflet tips. This condition is followed by a general chlorosis of the leaflet, particularly the distal half and, subsequently, the brown spots become necrotic, resulting in leaflets having varying degrees of intensity of deficiency. Thus, a leaflet may have a brown necrotic tip, the necrosis merging into severely chlorotic tissue grading to light chlorosis with normal green colouring at the base of the leaflet. As necrosis proceeds further, particularly when half or more of the leaflet is affected, there is a tendency for the distal half to roll upward. With increased severity, all three leaflets become necrotic and may absciss from the petiole, which itself may develop brown necrotic spots and eventually absciss. The stipules of affected petioles may also show necrosis. The end result is a plant with a few fully expanded leaves at the growing tip in varying stages of chlorosis and necrosis, and a bare stem devoid of leaves and petioles. The primary stem of the plant is more affected than the secondary stems (Andrew and Pieters, 1970a). Stylo will respond to potash only in the presence of adequate copper (Teitzel, 1969a).

  • Sulphur:

Horrell and Court (1965) found that S gave the greatest response on the poor sandy soils of Serere, Uganda. Sulphur was used at 33 kg./ha, along with P at 104 kg./ha.

Compatibility with grasses and other legumes

Stylo combines well with colonial guinea grass (P. maximum) in north Queensland (Davies and Hutton, 1970) and in Brazil; molasses grass and Brachiaria ruziziensis in Madagascar (Granier, 1966) and Zaire (Risopoulos, 1966); and Hyparrhenia rufa, Rhodes grass, Panicum maximum and Setaria at Serere, Uganda (Stobbs, personal communication). It grows with pangola grass in Brazil and north Queensland. Schofield (1945) found that stylo was shaded out by Brachiaria decumbens, B. brizantha, P. maximum and P. coloratum, lasted two years with Brachiaria mutica and persisted with Kikuyu (Pennisetum clandestinum) and Paspalum dilatatum. Ordinary guinea grass (P. maximum) offers it intense competition in summer (Gilchrist, 1967). If the pasture is short, it is compatible with puero, centro and siratro.

Tolerance to herbicides

Bailey (1964, 1965a) has shown that stylo has good tolerance to 2,4-D; from about six weeks of age, 1.65 kg. of acid equivalent per hectare can be used. Because stylo is well adapted to low fertility soils where bush regrowth is often troublesome, it is well to know the effect of 2,4,5-T, used in timber control, on this legume. Between 50 and 75 percent reduction in stylo can be expected 12 to 18 months after spraying with 2,4,5-T at 1.1 kg./ ha acid equivalent, mixed with water. Provided the associated grass is not too dense and stylo has set seed, regeneration occurs from both seed and surviving root stocks. Obviously, 2,4,5-T should be used in stylo pastures only in exceptional circumstances.

Nitrogen-fixing ability

Unfertilized stylo/Hyparrhenia pastures at Serere, Uganda, yielded equivalent to grass receiving 165 kg. N/ha (Horrell and Newhouse, 1966) . In north Queensland, soil nitrogen under a bare fallow was 34.4 ppm, and in soil which had stylo ploughed in after 18 months of growth the nitrogen content was 54.5 ppm (Schofield, 1945). Grass/legume swards containing stylo and centro fertilized with phosphorus and sulphur gave liveweight gains equivalent to animal production from grass swards receiving 157 kg. N/ha/year (Stobbs, 1969). In Nigeria, stylo fixed 4.6 mg N/day, compared with 14.5 mg for Cajanus cajan and 10.3 mg for Centrosema pubescens, and 98 percent of the fixed N was transferred to the plant (Oke, 1967a).

Response to defoliation

Heavy grazing is detrimental. Grof and Harding (1968) found that harvesting at 18-week frequency caused the lower stems and crown to become woody, with an almost complete loss of stand. There are very few growing points on these plants as they mature. Stylo persisted under grazing at eight-week intervals at Sigatoka, Fiji (Payne et al., 1955). Root-stocks die if cut after two years' ungrazed growth, as the base of the plant is very woody then (Risopoulos, 1966). Cutting lower than 20 cm also affects it (Vivian, 1959). Grazing sheep do less damage to stylo as they tend to pluck the leaves (Tuley, 1968).

Grazing management

Stylo should be lightly grazed in the first year after six to eight weeks, to promote tillering and prevent it from becoming woody (Risopoulos, 1966). Long grass should be prevented from shading the stylo. Rotational grazing, one week on and four to eight weeks off, is best. Cattle graze the leafy material first and then move lower down with each successive grazing until the woody parts are consumed and damage results.

Response to fire

It is advisable to exclude fire from common stylo, as dense stands may be weakened. Light fires or fires passing when the ground is wet are less severe and may even stimulate it. Hot fires when the soil is dry will kill it, and two successive fires will virtually eliminate it. Seeds survive, however and fire stimulates new seedling growth by breaking seed dormancy.

Breeding system

Self-fertilized; chromosome number 2n = 20.

Dry-matter and green-matter yields

Otero (1952) recorded yields of 15 to 20 t/ha of green material, in Brazil; Risopoulos (1966), 35 t/ha/year in Zaire; and Granier (1966) 43 t/ha on high ground and 70 t/ha after one year on low ground in Madagascar. At Sigatoka, Fiji, Payne et al. (1955) recorded 4 180 kg./ha/year of dry matter averaged over three years; and van Rensburg (1967) reported 4 600 kg./ha/year in Zambia. Gilchrist (1967) gives yields of 11 000 kg. DM/ha in north Queensland. Blouard and Thuriaux (1962) recorded no significant differences in yield from four cutting regimes over 24 months in Zaire. The average annual yield from four cuts over 24 months was: cut every three months at 15 cm, 7 281 kg./ha/year; at 25 cm, 6 785 kg. Cut every 41/2 months at 15 cm, 6 845 kg.; at 25 cm, 6 529 kg.

Suitability for hay and silage

Makes good hay, containing 14 to 16 percent crude protein. Only one cut should be taken annually in north Queensland, in late summer to autumn at a height of at least 20 cm. The stubble after seed threshing has 5 percent crude protein and can be hammer-milled for roughage feeding­the seed left in it is then distributed by the livestock (Gilchrist, 1967). Nwosu (1960) cut it three times a year in Nigeria, taking only the top 45 cm of crop (cut at 45-cm height), dried it in the field for seven days and hammer-milled it into feeding meal containing 17.17 percent crude protein­at a cost of about 19.8 U.S. cents/kg. In well-established stands in Malaysia, cutting has little effect for up to four years, but thereafter yield declines and at six years its economic production is finished (Vivian, 1959). The hay should be handled as little as possible to preserve the more nutritious leafy portion.
Risopoulos (1966) sowed sorghum and stylo in alternate rows 0.6 m apart and with this mixture made excellent silage of 6 to 7 percent crude protein. The first year the proportion of stylo to sorghum is 1:3, the second year the mixture is balanced and from the third year there is a pure stylo crop. Cattle ate stylo silage whether ensiled with 1 percent salt, 1 percent molasses, 1.5 percent molasses, 2 percent molasses or with no additive. One percent molasses gave a pleasant odour to the silage.H

Value as a standover or deferred feed

It is excellent as standover feed as its palatability is high at this stage. Sillar (1969b) showed that cattle could be fattened during the three normal dry months in north Queensland on a pure diet of standing stylo.

Feeding value
  • Chemical analysis and digestibility: 

Chemical analysis figures for stylo are listed in Appendix 1. Crude protein figures range from 12.1 to 18.1 percent for the whole plant. Van Rensburg (1967) recorded 7.9 percent for the stem and 13.6 percent for the leaf. Crude fibre figures range from 21.7 to 37.7 percent. Milford (1967) recorded 11.8 percent crude protein with a digestibility of 52.6 percent, and 37.7 percent crude fibre with a digestibility of 42.2 percent. The digestibility of the dry matter was 48.4 percent and voluntary intake of dry matter 33.9+4.3 g/kg. live weight/day, the lowest of the tropical legumes tested. The plant material tested was green, fairly stemmy, unfrosted and seeding freely, growing at Lawes, Queensland. Risopoulos (1966) in Zaire recorded a range of 15 to 17 percent crude protein, 33 to 40 percent crude fibre, 0.1 to 0.2 percent P, 0.8 to 1 percent Ca, 1.2 to 1.8 percent K, 0.3 to 0.8 percent Mg, a trace 0.02 percent Na and 0.1 to 0.8 percent Cl in the dry matter. Nwosu (1960) in Nigeria prepared a meal with 17.17 percent crude protein and 28.9 percent crude fibre.

  • Palatability: 

It is relatively unpalatable in the early stages of growth. Schofield (1945) found that it was not grazed by cattle which had no experience with the legume but, after confining the stock for two days to pure legume alone, they ate it readily. Nwosu (1960) also observed this lack of early palatability and suggested that it was due to the harsh hairs on the plant. In stall-feeding green stylo, he found that the material had to be wilted before feeding (to remove the turgidity of the hair) to make it palatable to the cattle. In Brazil (Lychatchynsky and Steenmeyer, unpublished), palatability tests showed stylo to be the least palatable of eight tropical legumes early in the summer, but among the most palatable later on. Stobbs (1969k) observed intake of stylo over a period. Over six weeks, 27.8 percent of stylo of a pasture containing 29.1 percent of this legume was consumed. Animals preferred to eat Hyparrhenia rufa when introduced to the mixed pasture, and intake of stylo was significantly lower on the first day of grazing. When herbage was plentiful, mainly the leafy parts of stylo were selected, but as the amount of herbage declined, complete florets, which contained viable seed, were eaten. On the last few days of grazing, a higher proportion of the stemmy parts of the legume was consumed.

Toxicity

None has been reported, but it has a toxic effect on succeeding cotton crops at Serere, Uganda (Horrell and Newhouse, 1965). Leaf and stem exudate depressed seed germination of Pennisetum typhoides in Petri dishes. At Ngeta, Zambia, van Rensburg (1968) found that it reduced subsequent cotton yields by 30 percent and also cottonseed germination. The toxic effect was confirmed by pot tests in which stylo leaves were incorporated in the soil. Rijkebusch (1967) also observed an adverse effect on subsequent crops of sisal in Tanzania.

Seed harvesting methods

As it matures over an extended period, some loss of seed is unavoidable owing to immaturity or shedding when seed is mechanically harvested. The crop is harvested with an all-crop harvester with a peg drum, a high cylinder speed being employed in combination with a full set of concaves. The comb is set 20 to 25 cm below the top of the sward. A second harvest a few days later, using a lower comb height, recovers more seed. The seed is cured by drying, during which some after-ripening of seed takes place. The seed sample has testa colouring varying from black to yellow; the paler seeds germinate better (Cowdry and Verhoeven, 1961). It is not advisable to let it grow for two years for a seed crop and then cut it to the ground in harvesting, as the woody root-stocks will die (Risopoulos, 1966).

Seed yield

Seed production is heavy, but the small pods shed on ripening so that only a fraction of the seed crop can be mechanically harvested. Risopoulos (1966) recorded 100 to 200 kg./ha in Zaire, and at the IRI Research Institute at Campinas, Brazil, the yield is about 100 kg./ha. In north Queensland, yields average 90 to 100 kg./ha, reaching up to 330 kg./ha (Gilchrist, 1967).

Cultivars

Cv. Schofield was introduced into Australia from Brazil in 1933 and was the major cultivar until it collapsed with anthracnose (Colletotrichum gloeosporioides) in 1978. Cv. Cook, from Colombia in 1965, flowers earlier and gives better cool-season yields; it also currently maintains some fields tolerance of anthracnose. 'Endeavour', from Guatemala in 1965, collapsed to anthracnose just as it was beginning to be widely used in 1974. Cv. Graham was released in 1979 as an earlier flowering, more persistent type. It still retains some field tolerance to anthracnose.
In Brazil, three cultivars­Deodora I, Deodora II and FAO 13821­and in Senegal, one cultivar­N-6399­are available. In addition, in Brazil, EMBRAPA is in the process of releasing a tardio line called cv. Bandeirante.(l 

Diseases

Anthracnose has been reported in Brazil under wet conditions (Otero, 1952). Corticium and Rhizoctonia solani attack it under wet conditions in Zaire (Blouard and Thuriaux, 1962), and Diplodia in Malaysia (Vivian, 1959). Hutton and Grylls (1956) listed it as susceptible to little-leaf. Generally, however, stylo is one of the most disease-free of the tropical legumes. Grazing management can limit damage by pathogens.

Main attributes

Where fertilizer costs are high it offers one of the best opportunities to raise productivity of natural grassland because of its low phosphorus requirement. An adaptable non-climbing legume, it grows in poor soils, is easily established by oversowing, continues to increase in palatability and persists into the dry season, when it is most needed. Its phosphorus requirement is only 0.17 percent, compared with 0.24 percent for siratro (Andrew and Robins, 1969a).

Main deficiencies

It is frost susceptible; will not stand heavy grazing; can reduce the yield of subsequent crops (seed tends to shatter on ripening, thus reducing yields); has a relatively low protein content and tends to become woody.

Performance

The inclusion of the legumes Stylosanthes guianensis and Centrosema pubescens into a Hyparrhenia grassland at Serere, Uganda, increased animal production by 11 to 49 percent (Stobbs, 1969) . Over a three-year period, rotationally grazed oversown Stylosanthes guianensis pasture at Serere produced a mean of 254 kg./ha/year live-weight gain without fertilizer and a mean of 450 kg./ha/year where single superphosphate was applied (Stobbs, 1969). A Hyparrhenia/stylo pasture under low-frequency rotational grazing (i.e. seven days grazing and 28 days resting) and high-frequency rotational grazing (i.e. 3 1/2 days grazing and 14 days resting) gave equally high live-weight gains per hectare­740 kg. 'ha/year at Serere (Stobbs, 1969i) . This pasture showed better animal returns in the dry season than a Hyparrhenia/centro pasture which gave the same yearly live-weight gain. Both swards appeared tolerant of both grazing regimes. As a cover crop, stylo competes with rubber for water in Sri Lanka, but in Malaysia competition is reduced by cutting the stylo periodically for feeding (Vivian, 1959). It grows well under coconuts in Tanzania, though more erectly.
Agronomically quite a different plant to the subtropical fine stem stylo.

Latitudinal limits

About 23°N and S. Grows well at Campinas, Brazil (lat. 22°45'S) and in Laos (lat. 19°N).

Ability to compete with weeds

When it is established, it competes very successfully with weeds and can invade natural grassland. It is aggressive because of its low early palatability and heavy seeding habit (Horrell, 1963).

Pests

A variety of insects attack the plant and reduce seed yields under wet conditions in Panama and Bolivia. The caterpillar of the moth Lamprosema diemenalis Gueen. did some slight damage. Colbran (1963) recorded the nematode Meloidogyne hapla on the roots of stylo. In east Nigeria it is recommended in an arable crop rotation because it is not susceptible to the particular nematode affecting these crops (Tuley, 1968).

Temperature for growth

Prefers high summer temperatures. Adapted to frost-free conditions; continues active growth to 15°C (Allen and Cowdry, 1961b); defoliates at 0°C and plants are killed at -2.5°C (Boelcke, 1964). Tops are cut by heavy frosts. In the subtropics, it will grow on elevated slopes above the frost line (Gilchrist, 1967).

Tolerance of drought and flooding

Has good drought tolerance, even in areas subject to frost. It will tolerate temporary waterlogging (Rijkebusch, 1967), but will not grow in swamps (Gilchrist, 1967).

Vigour of seedling, growth and growth rhythm

Stylo is slow to establish (Risopoulos, 1966). Oke (1967a) explains this in terms of nodulation: he found it slow-growing up to six weeks and then rapid, the increased growth coinciding with the increase in nodule size. The older nodules of stylo were more effective than the young ones. Its growth during the wet season is good. It grows vigorously to a height of 1 to 1.5 m. If uncut, it collapses and new shoots arise from the pendant stems. In this way it has a valuable suppressive effect on weeds.

Response to photoperiod and light

A short-day plant, it requires a day length of less than 12 hours for flowering, with best results at ten hours ('t Mannetje, 1965). Does not flower well in the subtropics. It flowers in June-August (north Queensland), March-May (Kelantan, Malaysia), June-July (Colombia) and January-February (northern Nigeria). Common stylo is only moderately tolerant of shading. It grows under coconuts in Tanzania, though with a more erect habit. Its yield is reduced more than 75 percent when grown under closely planted oil-palms (Fodder crops and fallows in Dahomey, 1965b) . It will grow with the tall Panicum maximum if well managed. Among tall tussock-forming grasses, it often fails to persist because cattle avoid the grass tussock and trample the legume­thus, the trampling factor may be more important than light competition in its disappearance from a mixture (Schofield, 1945).

Minimum germination percentage and quality required for sale

Minimum germination 40 percent, maximum hard-seed content 10 percent, and purity of at least 96.5 percent in Queensland. Seed stored in sacks deteriorates after one year, but in sealed containers retains its viability longer (Risopoulos, 1966). Blouard and Thuriaux (1962) obtained 26 percent germination in three-month-old seed, 73 percent after eight months, 52 percent after 10 months, 12 percent after 36 months and only 7 percent after 41 months . In the field, stylo seeds kept germinating continuously over three years of recording (Tuley, 1968).

Sowing depth, cover, time and rate

Sow into a cultivated seed bed at a depth no greater than 1.5 cm and lightly cover with a "Cambridge"-type roller, harrow, or a bush dragged over the area. Sow at the start of the rains at 0.5 to 2.0 kg./ ha.