Sorghum spp. hybrids

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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.
  • '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).
  • 'Lahoma' 
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.
  • 'Sudax SX-11A' 
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.
  • 'Zulu' 
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.
  • 'FS-22A' 
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'.
  • 'Bantu' 
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.
  • 'Krish' 
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).
  • 'Silk' 
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).
  • 'Sucro' 
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).
  • 'FS-26' 
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.