Setaria sphacelata (Schumach.) M.B. Moss var. sericea (Stapf) W.D. Clayton

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Graminae

Synonyms

Setaria anceps Stapf.

Common names

Setaria (Australia), golden timothy (Zimbabwe), golden bristle grass (southern Africa).

Description

Tufted perennial 45-180 cm high with the lower culm nodes compressed. Basal leaf-sheaths often nearly flabellate in arrangement. False spike dense with orange bristles and subacute spikelets, 2.5-3 mm long (Napper, 1966).

Distribution

Naturally confined to the African continent, now introduced into several tropical countries.

Season of growth

Early spring and summer.

Altitude range

Sea-level to 3 300 m (Hacker & Jones, 1969), more common at 660-2 660 m.

Rainfall requirements

Mean 900-1 825 mm (Russell & Webb, 1976).

Drought tolerance

Only fairly drought tolerant. Cultivar Kazungula is the most tolerant of dry conditions.

Soil requirements

'Kazungula' is the most tolerant of poor sandy and stony soils. 'Nandi' and 'Narok' prefer medium-textured, fertile soils. It is not common on alkaline or very acid soils, the majority of collections being made from soils in a pH range of 5.5-6.5.

Ability to spread naturally

'Kazungula', if allowed to seed, will spread well and form large crowns.

Land preparation for establishment

A well-prepared seed-bed is preferred for establishment by seed.

Sowing methods

In the Philippines, propagation of new material by rooted cuttings or divided root-stocks has been successful, but drilling seed into a well- prepared seed-bed is better.

Sowing depth and cover

As the seed is small, it should be sown no deeper than 1.8 cm for cv. Kazungula and 2.5 cm for cv. Nandi, then lightly covered and rolled.

Sowing time and rate

Early to midsummer, at 1.5 kg/ha in conjunction with a legume such as Desmodium intortum at 1.15 kg/ha, or Neonotonia wightii at 4 kg/ha.

Number of seeds per kg.

About 1.7 million for cv. Kazungula and 1.4 million for cv. Nandi.

Seed treatment before planting

To control seed-harvesting ants, a seed- dressing of dieldrin at 10 g AI/kg seed can be given.

Tolerance to herbicides

For seed production on the Atherton Tableland, Queensland (lat. 1713'S, altitude 715 m, rainfall 1 420 mm) the weeds Nicandra physaloides and Eleusine indica are troublesome. Competition with E. indica can be reduced by choosing a sowing time favourable to Setaria and unfavourable to Eleusine, that is, when the mean temperatures are less than 23C (Hawton, personal communication). For cv. Narok planted at 5.5 kg/ha in rows 1 m apart, activated charcoal slurry sprayed at 675 litres/ha (168 kg charcoal) in a 2.5 cm band over the seed row, and diuron at 6.25-7.5 kg/ha sprayed at 350 litres/ha over the row eliminated both weeds (Hawton, 1979).K

Seedling vigour

'Nandi' is slow to establish but catches up later.

Vigour of growth and growth rhythm

Growth commences in early spring and continues at low autumn temperatures (Luck, 1979).

Response to defoliation

It withstands heavy grazing and forms a robust crown. The highest yield in a cutting trial at Redland Bay, Queensland, was obtained by cutting every three weeks at a height of 15 cm (Riveros & Wilson, 1970).

Grazing management

It should be lightly grazed until established, then heavily grazed to prevent it becoming stemmy. Early grazing may cause plants to be pulled up by the roots when the soil is moist. Undergrazing causes the plants to become coarse and to shade companion legumes, a real problem with cv. Kazungula. Heavy grazing in winter can clean up a pasture ready for early spring growth.

Response to fire

When established, setaria will survive an occasional fire quite well.

Dry-matter and green-matter yields

At Redland Bay, Queensland, Riveros and Wilson (1970) recorded dry-matter yields from 23 500-28 200 kg/ha over a six- month growing season. The grass was irrigated and supplied with 225 kg N/ha per year. The soil was a basaltic red loam (latosol).

Suitability for hay and silage

The setarias, especially cv. Kazungula, are rather tall and coarse for good quality hay at the flowering period, but cv. Nandi is satisfactory (Catchpoole, 1969). In association with Desmodium intortum, a very good acetic acid-type silage was made by Catchpoole (1970). The good quality was due to the marked ability of the two plants to resist degradation to volatile bases during ensilage. Cultivar Kazungula is used widely for silage in southern Africa.

Value as a standover or deferred feed

Setaria is usually too coarse to be of much value as deferred feed, but it has a place as low-quality roughage, as a supplement to urea-molasses feeding. It is used for this purpose in Kenya and Uganda, but losses of crude protein and dry matter may reach 33 percent.

Toxicity

The setarias contain oxalates which can poison cattle. The amount of oxalate varies with the cultivar and stage of growth. Young plants contain more than older plants and strains highest in nitrogen are also highest in oxalate. Amounts of oxalates ranging from 3.7 percent in cv. Nandi to 7.8 percent in cv. Kazungula have been reported. Lactating cows and horses have been affected. Affected cattle have a staggering gait and diarrhoea, and then collapse and lie on their briskets. Rectal temperatures vary from 37.7 to 38.5C. The muzzles are dry and rumination ceases. In eight days there is extensive subcutaneous oedema of the brisket and dewlap, and the animals die within three weeks of eating the grass. Death results from a build-up of calcium oxalate crystals in the kidney, which brings on acute hypocalcaemia. Poisoning rarely happens, but animals, especially lactating cows, should not be placed on young, luscious setaria pastures after a period of starvation (Everist, 1974). Horses, also, should be kept away from setaria pastures, as they can contract big-head disease (Cook, 1978). Feeding a calcium supplement, such as ground limestone or lucerne hay (containing calcium), can help control the disease.

Seed yield

In Kenya, seed yields seldom exceed 330 kg/ha of 25 percent pure germinating seed (Hacker & Jones, 1969). Cultivar Nandi yields about 112 kg/ha.

Cultivars

  • 'Nandi'

originated in the highland Nandi district in Kenya, and introduced to Australia in 1961 and 1964 after selection at Kitale, Kenya. It is more sensitive to frost than cv. Kazungula, and top growth can be killed by heavy frosts, but its roots survive. It tolerates waterlogging; flowers earlier than cv. Kazungula (one to two months after commencement of rain in spring) and, if ungrazed, flowers through the season and becomes stemmy. It is cross-pollinated and seeds well. It establishes less readily than cv. Narok and cv. Kazungula. It has a high oxalate content, 3.22 percent (Ndyanabo, 1974).

  • 'Kazungula' 

native to Zambia, developed for grazing and hay. It is coarser and more robust than 'Nandi', and is tetraploid. The seed-heads are lighter than 'Nandi', and tend to bend. The coloration of the sheaths of the basal leaves is blue-green, and the stigmas are purple. Seed is slightly smaller than that of 'Nandi'. It flowers a month later than 'Nandi', in spring. It is hardier and more adaptable; more frost- tolerant under waterlogged conditions and a little more drought resistant, growing on as little as 575 mm annual rainfall. It has considerable tolerance to waterlogging and is suitable for areas frequently inundated with flood water, and for areas under irrigation. It has a high sodium content and far higher oxalate content than 'Nandi'. Cattle accept stubble grazing with 'Kazungula' more readily than with 'Nandi'. 'Kazungula' is fairly resistant to Piricularia leaf spot.

  • 'Narok' 

collected on the Aberdare Mountains, Kenya, and introduced to Australia in 1963. More robust then 'Nandi' but less so then 'Kazungula', it is greener in colour than both; some plants lack the red pigmentation at the base common to 'Nandi' and 'Kazungula'. Inflorescence rust-coloured, seed larger than 'Nandi'. Leaves broad, soft and hairless. It is a tetraploid. Its principal feature is its frost resistance. Negligible leaf damage occurs at temperatures of -3.3 to -2.8C but heavier frosting results in leaf kill. Grazing in winter should not be heavy. It is more nutritious than either 'Nandi' or 'Kazungula'. It is low in sodium and intermediate in oxalate content. Like 'Nandi', it is susceptible to leaf spot fungus (Piricularia trisa) under hot humid conditions (Barnard, 1972). 'Narok' gives low seed yields with consequent scarcity and high prices (Cook, 1978).

  • Gomoto-Mogolelo River ecotype 

very tall, densely tufted with narrow, dark green leaves and fine stems; suitable for hay and silage.

  • Du Toits or Middleveld ecotype

short, rhizomatous, with purplish leaves producing little seed; best suited to grazing (Whyte, Moir & Cooper, 1959).

  • 'Bua River' 

collected in Malawi, it is used for silage, hay or green chop.

  • 'Du Toits Kraal' 

from Zimbabwe, and not used outside South Africa, where it has been recommended for areas with 500-700 mm rainfall. It is drought resistant and retains some greenness and palatability into winter (Hacker & Jones, 1969).
In the Philippines several selections are under test (Farinas, 1970): 'Hairy K' and 'CRHS', selections from S. sphacelata; 'Decolores' and 'Mabolo', probably S. sphacelata var. sericea x S. sphacelata var. splendida; end 'Greencross A- X', probably a S. sphacelata cross.

Diseases

The leaf spot caused by Piricularia trisa attacks cv. Nandi and cv. Narok (but usually not cv. Kazungula) under hot, humid conditions. In Kenya a bunt disease caused by Tilletia echinosperma can devastate seed crops.

Main attributes

Setaria sphacelata var. sericea is palatable, establishes easily from seed, persists under grazing on a wide range of soils, gives high yields of digestible energy, has some cold tolerance, gives early spring growth, responds to fertilizer and will cross-pollinate.

Main deficiencies

Heavy summer seeding of cv. Nandi and cv. Kazungula is a disadvantage (Quinlan & Edgley, 1975); susceptibility to frost in low-lying areas, and its oxalate content.

Optimum temperature for growth

Mean 18-22C (Russell & Webb, 1976).#

Minimum temperature for growth

At temperatures below -4C cv. Nandi dies. Mean temperature of the coldest month 8.6 + 3.4 (Russell & Webb, 1976).

Frost tolerance

Compared with other summer-growing grasses it is fairly frost tolerant. It will make some growth in winter if frosts are not too heavy. 'Nandi' is best adapted to cold (Hacker & Jones, 1969).

Latitudinal limits

25.9N and S + 5.7 (Russell & Webb, 1976).

Response to light

'Nandi' begins flowering in December (summer) in Australia, and flowers over a period of five months with a peak six weeks after head emergence. 'Kazungula' flowers one month later over a short period.

Ability to compete with weeds

When established, it suppresses most weeds. In the first season, cv. Nandi is troubled by weed competition but recovers well after the first grazing or mowing.

Maximum germination and quality required for sale

20 percent germinable seed, 60 percent purity in Queensland.

Pests

General pests such as army-worms and locusts can attack pastures.

Palatability

The various cultivars are very palatable when young but less so as they approach maturity.

Chemical analysis and digestibility

Five-week-old S. sphacelata cv. Nandi contained 1.8 percent total nitrogen and 5.5 percent sugar on a dry-matter basis; at eight weeks, 1.9 percent nitrogen and 11.9 percent protein (Catchpoole, 1970). Dougall, in Kenya, showed a progressive fall in crude protein (from 15 to 5 percent), digestible crude protein (10-2 percent) total digestible nutrients (62-49 percent), while crude fibre increased from 23 to 42 percent over a four-month period (Hacker & Jones, 1969). Digestibility values of 70-72 percent of the dry matter have been recorded.

Natural habitat

Grassland, woodland and swampy places, usually on clay soils.

Tolerance to flooding

S. sphacelata generally tolerates waterlogging over short periods, and cv. Kazungula is particularly tolerant (Hacker & Jones, 1969). Aquatic roots form at the submerged nodes, and leaves appear at these sites (Colman & Wilson, 1960).€

Fertilizer requirements

A basal dressing of NPK is usually required. The critical level of phosphorus as a percentage of the dry matter at the immediate pre-flowering stage is 0.21 (Andrew & Robins, 1971). The rate of potassium uptake is very high and the critical level for potassium in cv. Nandi is about 1 percent of the dry matter. Setaria responds markedly to nitrogen and in Queensland gave an average response over a four-year period of 30 kg dry matter and 3 kg protein for every kilogram of applied nitrogen (Hacker & Jones, 1969).b

Compatibility with other grasses and legumes

The setarias compete successfully with Rhodes grass, green panic, paspalum and blue couch in coastal districts of Queensland, but generally should be the sole grass in mixtures of grass and legumes. This setaria combines well with white clover, Neonotonia wightii, Desmodium intortum, D. uncinatum and siratro. 'Kazungula' has little compatibility with legumes on the Atherton Tableland, Queensland (Quinlan & Edgley, 1975).

Genetics and reproduction

In 18, 36, 54 (Fedorov, 1974) cv. Nandi is a diploid 2n=18; cv. Kazungula and cv. Narok are tetraploids, 2n=36.

Seed production and harvesting

Flowering occurs over a long period, and it is difficult to decide on a best harvesting date. Cutting and curing before threshing gives higher seed yields, but the crop is usually direct-headed. The pasture is well fertilized with 100-150 kg N/ha per harvest, and headed once in midsummer and again in autumn. Head when 10-15 percent of the seed has shattered at medium drum speed. Dry the seed immediately.

Economics

The setarias are important pasture plants in Africa and have been introduced to other tropical areas. They do not contain prussic acid and so can replace Sorghum spp. They are nutritious and, though they contain oxalate, they usually give little trouble.

Animal production

In Kenya, live-weight gains from three pasture species over a three-year trial, without nitrogen fertilizer and without a legume, respectively, were 336 and 192 kg/ha from Nandi setaria, 369 and 220 kg/ha from Nzoia Rhodes grass, and 369 and 131 kg/ha from molasses grass. Hereford steers continuously grazing Nandi setaria and Samford Rhodes grass, fertilized with 330 kg N/ha each at Samford, Queensland, and stocked at 2.5 and 4 steers per hectare, gained a mean of 575 and 522 kg/ha per year on Nandi setaria and 535 kg/ha on the Samford Rhodes grass. In the first two years the animals on Nandi setaria gained significantly more weight at the higher stocking rate than did those on Rhodes grass (Hacker & Jones, 1969).

Further reading

Hacker & Jones, 1969; Luck, 1979.

Dormancy

Fresh seed has a germination inhibitor and should be stored for two months (Hacker & Jones, 1969). Germinate at 25-35C, moistened with water. Exposure to light increases germination.

Value for erosion control

'Kazungula', with its large crowns, gives very good control of erosion when sown in contour strips.

Tolerance to salinity

Two hexaploid collections, CPI 32847 and CPI 32714 from near the Aberdare Mountains in Kenya showed some tolerance in south-eastern Queensland and also tolerated cool conditions (Evans, 1967b), but generally it had low last tolerance (Russell, 1976).