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Leguminosae
Synonyms
S. montevidensis Vog. var. intermedia Vog. and others according to 't
Mannetje (1977) and (1984), but Williams et al. (1984) regard it as S
hippocampoides Moh., and could well be right. Agronomically fine stem
stylo is quite a different plant to the var. guianensis stylos.
Common names
Fine stem stylo.
Description
A semiprostrate perennial with a strong taproot. Differs from common
stylo in having a well-developed crown with buds both below and above
ground level. It also has finer stems and smaller leaflets. The narrow
deep green leaflets are 1.5 to 3.5 cm long, 3 to 5 mm wide and have few
hairs It has 4 to 20 small yellow flowers subtended by leaflike bracts
in small compact spikes. Flowers are mainly terminal but sometimes occur
in the leaf axils. The light brown pods are flattened, single-seeded,
3 mm long and 2 mm wide with a minute coiled beak; conspicuously fine-veined
without hairs. Pods fall as they ripen. Seeds are yellowish brown (Davies
and Hutton, 1970). Very little root development occurs at the nodes of
prostrate stems except under high moisture conditions, and even then rather
poorly (Stonard, 1968). It was introduced to Australia by W. Hartley,
as CPI 11493, from sandy loam at Asunción, Paraguay.
Distribution
It is found in Paraguay, Argentina, northern Uruguay and southern Brazil,
extending to latitude 33°S.
Season of growth
Comes away earlier in the spring than other legumes grows through the
summer with peak growth in November and in the absence of frosts grows
into the winter. It is perennial in habit and has a longer growing season
that S. humilis.
Altitude range
In Queensland, it is grown at 100 to 130 m, in Paraguay it occurs at
about 200 m (Fretes, Samudio and Gay, 1970).
Rainfall requirements
Mediumfrom 625 to 875 mm in Queensland. In Paraguay it occurs in
a rainfall zone of 1 300 to 1 500 mm.
Soil requirements
Prefers sands and sandy loams, but will establish on basalt loams. Does
not establish on heavy self-mulching clays. Has a wider range of adaptability
than common and Townsville stylos. It grows best in soils of pH 6.5 to
6.7. Its tolerance of salinity is unrecorded.
Rhizobium relationships
Although it may nodulate weakly with some local rhizobia and those of
the cowpea type, it requires a specialized Rhizobium for best growth.
The current (1970) Australian recommendation is CB1552. The nodules are
small and irregular in shape and are found mainly on the taproot
seldom on the laterals (Stonard, 1968).
Ability to spread naturally
Quite good in suitable soils. At Brian Pastures, Queensland, it has spread
on granitic sands with the aid of grazing by cattle, hares and wallabies
(Stonard, 1968).
Land preparation for establishment
Does not need elaborate land preparation; burn the pasture in the spring,
then cultivate lightly.
Sowing methods
Seed is broadcast after light cultivation. Oversowing into natural pastures
is successful; the area should be continuously stocked after seeding to
reduce competition from the grass. Do not sow deeper than 1 to 1.5 cm
and lightly cover. Sow in midsummer (during the rainy season) at 2 to
5 kg./ ha.
Number of seeds
per kg.
770 000 (Davies and Hutton, 1970). There is a high percentage of hard
seed in the pod (Stonard, 1968), which is an advantage in perpetuating
the sward under unreliable rainfall conditions.
Seed treatment
before planting
To break dormancy: (a) scarify mechanically; or (b) immerse in hot water
at 80°C and allow to cool for 40 min.; or (c) treat with concentrated
sulphuric acid for 10 min., wash and dry. Inoculation is necessary. Pelleting
is not needed unless to protect the rhizobia, when rock phosphate should
be used (Norris, 1967). If seed-harvesting ants are troublesome, dust
with dieldrin, 13.2 cc of dieldrin 15 percent emulsifiable concentrate
(or 2.2 g acid equivalent per kg. seed).
Nutrient requirements
Grows well even on soils of low fertility, but responds to phosphorus
and molybdenum.
Fine stem stylo, like S. humilis, is very efficient in extracting phosphorus
from the soil and grows quite well on granitic sands at Brian Pastures,
Queensland, with an available P content of 35 ppm. It responded to 250
kg. of molybdenized superphosphate per hectare, which increased total
native grass/fine stem stylo yield by 23 percent and the protein content
of the grass by 0.47 percent, but not that of the legume.
Tolerance to herbicides
Herbicide responses of Stylosanthes spp. reported by Stonard (1968) are
given in Table 14.11.
Nitrogen-fixing ability
Evidence of effective nodulation is provided by Stonard (1968): yield
from unfertilized native pasture was raised by 17 percent and from similar
pasture fertilized with 250 kg./ha molybdenized superphosphate by 23 percent
when fine stem stylo was grown with it.
Response to defoliation
Can stand close grazing; a profusion of short leafy shoots develops
from the crown, giving the plant a higher leaf to stem ratio. Grazing
management. Can be grazed throughout the year. Stock it heavily after
burning native pasture and introducing stylo seed, and again in the autumn
to control excessive grass growth.
Response to fire
Survives fire much better than common stylo because of its buried crown,
and its seed-shattering habit and hard-seededness allow it to regenerate
from seed.
Breeding system
Self-fertilized; chromosome number 2n = 20.
Dry-matter and green-matter
yields
In unfertilized natural pasture, Stonard (1968) obtained 637 kg./ha of
fine stem stylo in a total yield of 1 735 kg. of mixed natural pasture/fine
stem stylo pasture, and 950 kg./ha when fertilized with 250 kg./ha molybdenized
superphosphate in a total yield of 2 065 kg./ha. The highest dry-matter
yield of legume in a grass/legume mixture was 5 044 kg./ha/year over two
harvests when fertilized at 23 kg./ha of P; unfertilized legume yielded
a maximum of 2 027 kg./ha (Stonard and Bisset, 1970).
Suitability for
hay and silage
No records of conservation are documented. The plant is quite prostrate
and would be difficult to cut.
Value as a standover
or deferred feed
It is valuable in the absence of frosts.
Feeding value
It is well grazed but no data on live-weight gains are available. Chemical
analyses and digestibility are not available. It is a little unpalatable
when young, but improves as it matures.
Toxicity
None recorded.
Seed harvesting methods
Ripe seed is exserted from the flower head, making harvesting difficult.
The whole plant can be harvested with a rotary lawnmower fitted with a
grass catcher when 30 percent of the seed is ripe. The material is then
dried and threshed (Stonard, 1968). Otherwise, the seed can be allowed
to fall and be sucked from the ground with a vacuum harvester (Bisset,
1968). If the crop is grown for seed production, it can be grown in rows,
and, at flowering, plastic strips are laid under the plants to catch seed
when it falls on ripening. Seed-harvesting ants may take some seed.
Seed yield
The average yields of seed is 300 to 500 kg./ha, but up to 1 000 kg./
ha have been obtained.
Cultivars
The Oxley fine-stem stylo is the only cultivar of Stylosanthes guianensis
var. intermedia in Australia, although unselected material is also available.
Several more ecotypes are under test but have not been released for commercial
planting.
Main attributes
Extreme tolerance to grazing and fire; drought and some frost resistance;
efficiency in extracting calcium and phosphorus from the soil; compatibility
with grasses. Strong ability to naturalize on suitable country.
Main deficiencies
Difficulty of seed harvest; specificity of Rhizobium; lack of bulk.
Performance
Dry-matter yields have been given. Main reference. Stonard (1968).
Latitudinal limits
It is used in latitudes 24 to 30°S; its performance elsewhere is
not known.
Ability to compete with weeds
In its adapted low rainfall environment, it competes successfully with
weeds.
Maximum germination and quality required
for sale
Not available.
Diseases and pests
Only seed-harvesting ants have been recorded.
Temperature for
growth
Optimum approximately 27 to 29°C. It withstands temperatures up to
43°C. Although frosts affect tops, crowns of established plants have
survived temperatures of -10°C. In the absence of frost it grows through
the winter.
Tolerance of drought
and flooding
Has excellent drought-resisting qualities (deep taproot, small leaves);
it is unable to withstand flooding.
Vigour of seedling, growth and growth rhythm
Seedlings quite vigorous, but light should be available to them for quick
establishment. It has a long growing season (September-April in south-eastern
Queensland). Its yield over nearly three years is given by Stonard and
Bisset (1970) in Figure 79.
Compatibility with
grasses
Combines well with Heteropogon contortus and with buffel (Cenchrus ciliaris)
and Rhodes (Chloris gayana) grasses.
Response to photoperiod
and light
Fine stem stylo flowers over a long period; grows best in pasture mixtures
where there is ample light provided by burning or heavy grazing. |
