Molasses Grass

Molasses grass

Scientific name

Melinis minutiflora P. Beauv.

Synonyms

Melinis tenuinervis Stapf

Panicum melinis Trin.

Panicum minutiflorum (P. Beauv.) Raspail

Family/tribe

Family: Poaceae (alt. Gramineae)

Subfamily: Panicoideae

Tribe:Paniceae.

Morphological description

Tufted perennial with foliage 0.6-0.8 m deep, and slender, loose, straggling or trailing stems (sometimes rooting from lower nodes) to 2 m long; leaves crowded towards ends of sterile shoots; fertile culms erect or geniculately ascending, to 1.5 m tall. Leaf sheaths and blades minutely to densely covered with glandular hairs exuding drops of viscid oil, with characteristic molasses or cumin odour; leaf blades flat, 4-20 cm long, 0.5-1.3 cm wide, usually flushed purple or red-brown, tapering to a fine point. Inflorescence a panicle 10-30 cm long, with racemes initially appressed, spreading to present a pale pink to purple plume effect at anthesis, and becoming appressed again towards maturity; spikelets glabrous, sometimes shortly hairy, purplish, 1.5-2.5 mm long, comprising 2 florets (only the upper one fertile); upper glume often with awn to 9 mm long, and the lower lemma with or without awn 5-15 mm long; caryopsis 1.2-1.4 mm long, spindle-shaped or elliptical; 6-15 million spikelets (“seeds”)/kg. There is wide variation in growth habit , hairiness, leafiness, and vigour.

Uses/applications

A vigorous pasture grass, used as a fast-establishing pioneer to suppress weeds and cover disturbed soil; for grazing, hay (loses odour with drying), and silage. Not favoured for cut-and-carry due to low, dense growth, stickiness, and strong aroma. Value for intercropping to reduce insects and ticks.

Ecology

Soil requirements

Grows on a variety of well-drained soils, with surface textures ranging from sands to medium clays. Tends to grow most vigorously on steep hillsides and road cuttings. Tolerant of low fertility, pH from 4.5-8.4, and high aluminium. Responds to improved fertility. Intolerant of salinity.

Moisture

Native or naturalised in areas with annual rainfall between about 750 mm and 2,500 mm, and mostly from about 1,000-2,000 mm. Relatively drought-hardy over a dry season of four to five months. Does not tolerate waterlogging or flooding.

Temperature

Largely found between 800 and 2,200 m asl in the tropics and subtropics, in areas with average annual temperatures from 18-21 (-25)ºC and mean temperature of the coldest month between 6 and 15ºC. Higher growth rate at 30ºC than at 20ºC. Foliage is “burnt” by frost, and repeated heavy frost kills the plant.

Flowering on a hillside in tropical Austalia

Light

Found in full sunlight and partial shade.

Reproductive development

A short-day plant, flowering between April and June in the southern hemisphere subtropics. Varies with provenance .

Defoliation

Does not withstand grazing below 15-20 cm because crowns are well above ground level. Should be well established before grazing and then grazed sparingly. Stands decline under heavy grazing. Develops quickly and may be harvested 50 days after planting seed.

Fire

Adapted to moderate fire, in which the dense mats are generally only partly consumed, allowing rapid regeneration from remaining portions. Plants are killed by fierce fires, which develop when burning mature growth.

Agronomy

Guidelines for the establishment and management of sown pastures.

Establishment

Land preparation with fire or rough cultivation is usually adequate. Fresh seed has little dormancy but can be hammer-milled to improve germination and seed handling. Seed can contain 2-3 million caryopses/kg. This very fine seed is sown at 0.5-1 kg/ha, either broadcast onto the surface or placed very shallowly, no more than 2.5 cm, sometimes under-sown with cereal crops. It establishes quickly.

Also propagated from cuttings, which strike readily, and cover the ground quickly.

Fertiliser

Establishes and performs well on soils of low to moderate fertility, but responds to additions of nutrient, especially N and P, on very infertile soils.

Compatibility (with other species)

Melinis minutiflora establishes quickly from seed, developing into a competitive mat, and dominating other grasses initially. Combines well with legumes under appropriate management. Can be transient, and should not be the only species sown. Strong ability to suppress annual weeds. Once established, if unmanaged, it forms monospecific stands.

Companion species

Grasses: Chloris gayana , Setaria sphacelata .

Legumes: Centrosema pubescens , Desmodium intortum , D. uncinatum , Macroptilium atropurpureum , Neonotonia wightii , Pueraria phaseoloides , Stylosanthes guianensis , Vigna parkeri .

Pests and diseases

Generally little affected by insects or disease.

Ability to spread

Spreads quickly under favourable conditions, by virtue of stolons and wind-dispersed seed.

Weed potential

Listed as a weed in many countries. Develops considerable fuel load that leads to forest reduction from severe understorey fires.

Feeding value

Palatability/acceptability

Generally not relished on first exposure. Livestock must become accustomed to the grass before they eat it readily.

Toxicity

Calcium oxalate levels in the leaves of 1.1-1.7% have not caused problems.

Production potential

Dry matter

Annual dry matter yields are mostly of the order of 5-10 t/ha, but vary from as low as 2 to nearly 20 t/ha, depending largely on moisture availability and N fertility.

Animal production

Can carry 1 beast/ 0.5-2 ha, gaining 0.4-0.5 kg/day LW.

Maturing seedheads

Seed production

Mechanical harvesting is difficult due to the bulk of viscous foliage. This problem is reduced if the crop is mowed and sweated prior to threshing. The best crops have been taken low when it has been over-ripe and seed is retained in the mat, but such crops are difficult to clean. Cleaning problems are exacerbated by the seed’s small size and the fact that several asteraceous weeds of similar seed size (e.g. Ageratum) are common in the country where it grows. Hammer milling has been used to remove the awns, a job that produced vast amounts of irritating dust. De-awning is now achieved by blowing seed out of a fan and through a rotary (Hannaford) screen before putting the fragmented material over a conventional cleaner. Seed yields mostly range from 100-200 kg/ha, but may be as low as 12 and up to 280 kg/ha depending on conditions, harvest method and provenance .

Strengths

  • Adapted to infertile soils.
  • Tolerant of aluminium.
  • Pioneer species (rapid establishment and ground cover).
  • Weed suppression.

Limitations

  • Susceptible to severe fire.
  • Invasive.
  • Intolerant of heavy grazing.

Cultivars

Cultivars

Country/date released

Details

‘Branco’ Brazil Light green leaves, poorer quality than ‘Roxo’.
‘Cabelo de Negro’ Brazil Smaller than ‘Roxo’, more grazing tolerant.
‘Chania’ Kenya From Chania River, Kenya (0º, 36ºE, 2,000 m asl).  More prostrate growth habit and lower seed production than ‘Kitale Commercial’, but higher field tolerance to molasses grass dwarf disease.
‘Comum’ Brazil Similar to ‘Kitale Commercial’ and ‘Roxo’.  Probably the type introduced to Australia from South America in the early 1900s.
‘Francano’ Brazil Similar to ‘Roxo’, but more vigorous.
‘Kitale Commercial’ Kenya Probably the variety naturalised throughout the tropics and subtropics.  Very susceptible to molasses grass dwarf disease.
‘Mbooni Hills’ From Kenya (1º40′S, 37º28′E, 2,000 m asl).  Creeping stoloniferous variety, forming close sward.  Lower seed production than ‘Kitale Commercial’, but higher field tolerance to molasses grass dwarf disease.
‘Roxo’ Brazil Similar to ‘Kitale Commercial’.