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Graminae
Description
Numerous hybrids between Sorghum spp. have been produced by
plant breeders, and in recent years several fodder and forage types have
been produced and released as cultivars. Some of these are listed here.
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'SS6' (Sweet Sudan grass)
this is a selection from the American variety 'Sweet', obtained
by crossing S. sudanense and S. bicolor cv. Leoti. It has been further
selected for low prussic acid content and uniformity. It is an annual or
short-lived perennial, shorter than Sudan grass; the leaves have cloudy
instead of white midribs. The glumes are glassy and reddish brown or tan
in colour, totally enclosing the seeds. Seeds smaller, longer and narrower
than sweet sorghum, rich red or sienna in colour; 99 000 per kilogram.
The stems are juicy and sweet. Adapted to rainfalls of 460-750 mm per year
with summer incidence; rust and leaf spot diseases affect it at higher
rainfalls. Relatively drought resistant. Flowers in 75 days at Tamworth,
New South Wales (lat. 31.1°S). It is more vigorous and gives higher
yields than Sudan grass, and retains its palatability longer after maturity.
It makes good hay (Barnard, 1972).
originated at Texas Agricultural Experiment Station from
a cross between Sorghum sudanense and S. bicolor cv. Leoti; introduced
to New South Wales. It has large, wide, yellow-green leaves; it tillers
freely. Seed colour ranges from apricot to sienna. It is relatively drought
tolerant. Late-maturing, it produces high yields of palatable forage over
a long period, and gives high seed yields. It recovers quickly after grazing.
More resistant to leaf diseases than sweet Sudan.
an F1 cross between Sorghum sudanense and S. bicolor in
the United States. Requires annual purchase of seed, as the hybrid does
not breed true. Annual, or short-lived perennial, 3-3.6 m high at maturity,
usually 30-60 cm taller than 'Greenleaf' sweet Sudan and generally of à
purple colour. Stem thicker than Sudan grass, juicy and reasonably sweet.
Leaves eight to nine per stem, with cloudy midribs. The grain is red and
ovoid, and threshes free of the glumes. Killed by frost, but stalks remain
juicy for some time. It yields considerably higher than 'Lahoma' and sweet
Sudan; not very suitable for hay but makes excellent silage. For summer
grazing and autumn forage it is equal to 'Zulu'. In the Darwin area of
Australia, its dry-matter production is almost as high as bulrush or pearl
millet in the wet season, and its crude protein higher. It is superior
to S. almum in yield and disease resistance, and to bulrush millet in its
yield under irrigation.
a cross between the male 'Redlan' grain sorghum and 'Greenleaf'
Sudan grass, made by the Queensland Department of Primary Industries. The
stem is erect, soft when young, sweet and juicy; taller than 'Greenleaf'
Sudan. Grain is brown with a dark brown subcoat; black glumes enclose the
grain. It is capable of rapid early growth, of producing a large bulk of
green material quickly and of good recovery after mowing or grazing. It
is one of the best sorghums for summer, autumn and winter grazing, and
under irrigation.
an F1 hybrid between grain sorghum and sweet sorghum, bred
in Texas, United States. It grows to a height of 3-3.6 m at maturity with
stout, juicy, sweet stems and many tillers. Leaves 12-14 per stem, with
cloudy midribs. Stigmas yellow at flowering; glumes black; grain red, ovoid.
This cultivar has an adaptation similar to cv. Sugardrip, and matures earlier
than 'Tracy'. It does not lodge as early as 'Sugardrip'.
A cross between the male-sterile 'Redlan' grain sorghum
and 'Piper' Sudan grass by the Queensland Department of Primary Industries.
Similar to 'Zulu' in appearance, but has a dry or pithy stem and white
midrib. It is agronomically similar to 'Zulu', 'Sudan SX-11A', 'Bonanza'
and 'Sordan'. It is resistant to the prevalent races of head smut (Sphacelotheca
reiliana), whereas 'Zulu' is susceptible. This is the main reason for its
development and release.
a hybrid between Sorghum halepense and S. roxburghii, developed
by CSIRO, Australia. An erect perennial with numerous tillers and a solid,
pithy stem about 3.8 cm thick; reaches 4 m in height. Rhizomes almost entirely
absent. Glumes straw coloured, enclosing the seed. Seeds 160 000 per kilogram,
caryopses 187 000 per kilogram. Requires a soil of high fertility. Growth
from seed is slow and seedling vigour poor. The first defoliation should
not occur before ten weeks; thereafter it will yield well till late in
the season, but becomes coarse at maturity. It is more frost tolerant than
S. almum. It matures late, but seed yield is low. It is resistant to common
leaf diseases and sugar-cane mosaic (Pritchard, 1964).
a selection from a cross between cv. Krish and S. arundinaceum.
Flowers later than S. almum and has a longer vegetative stage, shows better
tolerance to frost and leaf diseases, and grows more vigorously (Silvey,
1977b).
an F2 selection from S. almum crossed with perennial sweet
Sudan grass. It exhibits tolerance to frost and leaf diseases, has a higher
soluble carbohydrate content in the cell sap of the leaves and stems, and
has brown-coloured glumes making the "seed" easily distinguishable from
Johnson grass (Silvey, 1977b).
a hybrid between a grain sorghum and a sweet sorghum. Tall,
free- tillering plant, reaching a height of around 3 m under favourable
conditions. The stems are sweet and juicy and provide excellent standover
feed. Sugar content reaches 20 percent. It is quick growing, has a large
number of stems, excellent regrowth after the first cut, and high yields
(Stevens, 1975).
Animal production
Irrigated 'Sudax' grazed rotationally at one-week intervals
resulted in excess stem. Green lot feeding of 'Sudax' gave low gains of
3.1 kg per head per day for six-week- old fodder and 2.5 kg per head per
day on eight-week old fodder in the Northern Territory, Australia (Blunt,
1969).
In the Macquarie Valley, New South Wales, Australia, 'Sudax SX11A'
stocked at an average rate per hectare of 6.0, 6.0, 9.3 and 10.4 Angus
yearlings (of approximately 200 kg/beast) gave dry-matter production of
18.95, 16.60, 19.41, and 31.10 t/ha respectively, and 274, 219, 249 and
334 kg beef per hectare. At no stage did HCN concentration of 'Sudax' reach
lethal levels nor was the concentration correlated with animal performance.
Archer and Wheeler (1978) found that sodium and sulphur both help stock
grazing sorghum. At Glen Innes, New South Wales, addition of NaCl to the
diet of sheep or steers grazing S. bicolor x S. sudanense cv. Sudax SX6
increased their live-weight gain; the addition of sulphur produced a further
small gain. For steers, average weight gains were 480 g per day with no
dietary supplement, 610 g per day with NaCl, and 710 g per day with NaCl
+ S.
Links for the genus:
- Poisonous
plants: Short description of S. bicolor, S. halepense
and S. sudanese; photographs
Further reading
Archer & Wheeler, 1978; Upton, 1978.
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