Blackseed grass (Chloris virgata)

Datasheet

Description

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Common names

Blackseed grass, feather finger grass, blue grass, feather finger grass, feathered chloris, hay grass, old land grass, sweet grass, white grass [English]; blougras, hooigras, katstertgras, klosgras, klossiesgras, kwasgras, oulandegras, paardgras, perdegras, spinnekopgras, witgras, witpluimchloris, witpluimgras, wollerigegras [Afrikaner]; amafusine, umadolwana [isiZulu]; sehabane [Sesotho]; umadolwana [isiXhosa], 虎尾草 [Chinese]; 나도바랭이 [Korean]

Species

Chloris virgata Swartz. [Poaceae]

Related feed(s)

Description

Blackseed grass (Chloris virgata Swartz.) is a tropical and subtropical annual grass. Halophytic, leafy, and hardy, it is a pionnering species that can grow on bare ground and can be used for hay and pasture.

Morphology

Chloris virgata is a leafy, annual, caespitose grass that can be 60- 90 cm high. It can form tufts, and sometimes spreads via stolons. Culms are geniculately ascending, or decumbent; 50-100 cm long. The plant roots from the lower nodes. The leaf-blades are 10-30 cm long x 2-6 mm wide. The inflorescence is digitate, made of 4-12 racemes, 2-10 cm long. The seed-heads are initially greenish brown and spreading or drooping in nature. The seeds are hairy, small caryopses (1.5-2 mm long x 0.5 mm wide), light in weight, with a triangular shape, and are easily shed from the heads making them easily dispersed by wind and water. They can attach on animal fur and can be spread by animals (Barkworth, 2021; Nyeleti et al., 2021; Rojas-Sandoval, 2016).

Uses

While considered a weed in many places, Chloris virgata is used for forage and is a valuable grazing grass in the more arid parts of South Africa, where few palatable perennials occur. It is used for revegetation in highly disturbed areas in arid and semi-arid regions (Rojas-Sandoval, 2016).

Distribution

Chloris virgata is thought to be native to Central and South Americas. It is widely distributed in the tropics and in the sub-tropics with a shorter growing season. It occurs naturally from the United States in North America to Argentina in South America, and it has been introduced elsewhere (Rojas-Sandoval, 2016). Within its native distribution range in the USA and Mexico, this species grows as a weed in grasslands, pastures, rangelands and culture crops like alfalfa in the USA and maize and sorghum plantations in Mexico (Barkworth, 2021; Vibrans, 2009). In South Africa, it is a well known grass (not weed) in the maize-producing area (Nyeleti et al., 2021).

Blackseed grass is a very versatile species that can grow in many habitats, most of which being degraded or disturbed areas with harsh conditions (hot, dry). It can be found from sea level up to 2500 m (- 3700 m altitude in China), in areas where mean annual rainfall ranges from 500 mm to 750 mm and where average annual temperatures are between 25-30°C. It still grows in arid areas where the minimum rainfall is about 375 mm. It does better on heavy soils, but has a wide soil range including saline, alkaline, and dark clay soils (Rojas-Sandoval, 2016). Blackseed grass is an alkali-resistant halophytic grass (Yang et al., 2008). In China, a simulation study showed that it could became dominant on slightly alkalinized-salinized soils after 3 years under 50% above ground biomass grazing removal (Shang et al., 2003).

Forage management

Blackseed grass is a high seed producer and it is able to reseed itself year after year (Hosaka, 1963). When sown, the seeds should not be planted deeper than 1 cm depth as the establishment of the seed is stimulated by light (Nyeleti et al., 2021). Blackseed grass can spread vegetatively (Nyeleti et al., 2021).

Environmental impact

Invasiveness

Chloris virgata is an invasive weed of bare areas and degraded or disturbed native vegetation because it can out-compete native vegetation. It is prone to spread from cultivation, pastures, gardens, roadsides, creeks and riversides, coastal forest and sand dunes (Rojas-Sandoval, 2016). It is considered an invasive and environmental weed in Northern Australia (i.e., Queensland and the Northern Territory) and an invasive grass in Cuba, Palau, New Caledonia, the Galapagos Islands, and Hawaii (Rojas-Sandoval, 2016). Blackseed grass is considered a noxious weed in cultivated systems (e.g. sorghum) because of its high seed production and its resistance to glyphosate (Mahajan et al., 2020; Mobli et al., 2020; Davidson et al., 2019; Ngo et al., 2018; Ngo et al., 2017).

Nutritional aspects

Nutritional attributes

Chloris virgata has a medium crude protein concentration, with values ranging from lower than 5 to > 15% DM (when young), often in the same range or with greater protein value than the other local wild grasses, in Swaziland; Kenya, Mexico or US (Cuchillo et al., 2013; Tefera et al., 2009; Dougall et al., 1965; Fudge et al., 1945). Fibre concentration is high, as other similar grasses (NDF 67% DM, ADF 39%, crude fibre 33% DM). Ash content is in the typical range for grasses.

Potential constraints

Tremorgenic syndrome

In Brazil, the presence of invasive Chloris virgata and Chloris barbata in pasture has been presumed to be the main cause of outbreaks of tremorgenic syndrome, an all-inclusive term for a group of nervous system disorders caused by indole-diterpenoid mycotoxins produced by various types of fungi on forages. Clinical signs are staggering, hypermetria, ataxia, wide-based stance and alertness. These outbreaks occurred in cattle in the semiarid region of Pernambuco (Brazil) in 1956 and 1962, and in cattle, sheep and horses in the semiarid region of Paraíba in 2007-2008. The outbreaks reported high morbidity rates but low mortality. When removed from the invaded pasture the animals recovered generally from 3-4 days to two weeks until complete recovery (Pessoa, 2010; Riet-Correa et al., 2017).

Ruminants

Chloris virgata is referred to as a traditional forage for domestic ruminants in Africa (Mgheni et al., 2013). It is a well known grass in the maize producing area of South Africa (Nyeleti et al., 2021). It may represent 10% of pasture biomass in semiarid savannas of Swaziland. It can be grazed or cut for hay at early stages of growth, as it quickly loses nutritive value with maturity (Yu et al., 2014; Göhl, 1982). It is considered a desirable species in natural savannas or rangelands because of its general nutritional profile compared to other available wild species (Tefera et al., 2009). It is grazed by wild African antelopes (Van Zyl, 1965). However, as of 2021, information about the nutritional value of Chloris virgata for ruminants remains limited. Its in vitro organic matter degradability (IVOMD) estimated from gas production is low (448 g/kg DM)(Tefera et al., 2009).

Rabbits

No information seems available in the international literature (as of 2021) on the use of Chloris virgata in domestic rabbit feeding. This grass is claimed to be a source of forage for antelope jackrabbits (Lepus alleni) in the South of the USA (Brown et al., 2014). In the small Hawaiian islet of Lehua (117 ha) introduced blackseed grass is now frequent in some parts of the islet simultaneously with introduced European rabbits (Oryctolagus cuniculus) that are also locally numerous, demonstrating that this poaceae is not hardly browsed by rabbits even if well represented in the local flora (Wood et al., 2004). As mentioned in the Ruminants section, blackseed grass is a common forage for domestic and wild ruminants in Africa, and it could thus be considered as a potential forage for rabbits, mainly as a low-protein source of fibre.

As mentioned in Potential constraints, there have been accidents in Brazil with ruminants and horses grazing mycotoxin-contaminated pastures invaded by Chloris virgata. Fungal quality of the forage should be thus carefully assessed since rabbits are known to be very sensitive to mycotoxins in general (Mézes et al., 2009).

Nutritional tables

Tables of chemical composition and nutritional value

Blackseed grass (Chloris virgata), aerial part, fresh

Avg: average or predicted value; SD: standard deviation; Min: minimum value; Max: maximum value; Nb: number of values (samples) used