Panicum maximum (PROSEA)
Panicum maximum Jacq.
- Protologue: Ic. pl. rar. 1: 2, t. 13 (1781).
- Family: Gramineae
- Chromosome number: 2n= 18, 32, 36, 48
Panicum polygamum Swartz (1788), non Forsskal (1775).
- Guinea grass, buffalo grass, green panic grass (En). Herbe de Guinée, panic élevé (Fr)
- Indonesia: rumput banggala (Indonesian), suket londo (Javanese), rebha luh-buluhan (Madura)
- Malaysia: rumput kuda, rumput benggala
- Thailand: ya-kinni (central)
- Vietnam: co' kê to.
Origin and geographic distribution
Guinea grass is East African in origin, but is now widely cultivated throughout the tropics and subtropics as a forage. It was introduced from Africa into the West Indies before 1756, but for production of bird seed rather than forage. It reached Singapore in 1876 and the Philippines in 1907 and is now widely distributed throughout South-East Asia.
Guinea grass is a palatable and good quality tropical grass used as forage for ruminants in grazed pastures or in cut-and-carry systems. Guinea grass forage is also dried and ground for use in mixtures with legumes as leaf meal, mainly for non-ruminants such as chickens and pigs. It can be conserved as hay or ensiled. It is also used as medicine for heartburn by the Malays under the name "berita".
In vitro digestibilities of 64%, 58%, 54% and 50% have been measured in regrowth of ages 2, 4, 6 and 8 weeks. Comparing young leafy with older stemmy herbage, similar trends occur in N concentrations which can fall from over 2% to below 1%, and in metabolizable energy which declines from 11-7 MJ/kg.
There are 1000-2000 seeds/g.
An erect or ascending perennial tussock grass, rhizomatous at base or rooting at the lower nodes, glabrous to hairy. Low/medium height forms 1-1.5 m tall, tall forms 2.5-3.0 m or more. Leaf-sheath glabrous; ligule membranous, 4-6 mm long, fringed; leaf-blade linear to narrowly lanceolate, up to 60 cm × 2 cm, usually glabrous except in hairy forms (e.g. cultivar "Makueni"); midrib pale, vanishing near the tip, other nerves distinct. Inflorescence usually a large, well extended pyramidal panicle up to 40 cm long by 25 cm across with lower primary branches about 20 cm long and arranged in a whorl; spikelets solitary, numerous, narrowly ellipsoidal, 3-4.5 mm long, green or tinged with purple, acute; lower glume 1-2 mm long, thin, clasping, obtuse, 3-nerved; upper glume 3-4.5 mm long, thin, narrowly boat-shaped, 5-nerved, acute; lower florets male, lemma similar to upper glume; upper florets hermaphrodite, lemma tranversely rugose, boat-shaped, pointed, palea fitting inside lemma, both ca. 2 mm long, anthers and stigma purple. Seed production apomictic.
Growth and development
Poor seed production, as low as 50 kg/ha in the wet tropics, has discouraged the commercial production of guinea grass seed. Environments with longer daylengths and dry seasons are more conducive to successful seed set. Stems of guinea grass root freely from nodes when in contact with moist soil but, as a result of its erect growth habit, such rooted creeping stolons are rarely seen in the field.
Other botanical information
There are many guinea grass cultivars commercially available. Australia is the main producer of guinea grass seed; the forms available include common guinea and colonião and cultivars "Hamil", "Riversdale", "Gatton" and "Makueni". Although the selection of these cultivars was primarily done within Australia, they are adapted to the different environments in South-East Asia. The colonião form was selected in Brazil. Variety trichoglume Robijns is treated separately in this volume.
Guinea grass is indigenous to the more fertile soils in Africa where it is often found growing close to the trunks of thorny Acacia spp. The grass benefits from the trees because of the N they fix and the shade they provide. Guinea grass thrives best under high rainfall conditions and a minimum annual rainfall of 1100-1300 mm has been suggested. Cultivar "Hamil" is more tolerant of waterlogged conditions than other cultivars. Guinea grass is adapted to fertile soils or where appropriate fertilizer is applied. Generally it does not thrive on oxisols or ultisols unless they have been heavily limed. Extensive natural areas of vigorous guinea grass in the tropics are usually only found on fertile dark clay soils with a high Ca content, which are rare in South-East Asia.
Guinea grass responds to moderate shading. At about 30% shade its yield exceeds that obtained in full sunlight. Even in 50% shade, it can still maintain about 50% of its normal production. Because of this shade tolerance, it is well suited to agroforestry situations as in rubber and coconut plantations, or to growing with leguminous forage trees such as leucaena ( Leucaena leucocephala (Lamk) de Wit) which provide partial shade and the essential N.
Propagation and planting
Sowing, usually at 2-3 kg/ha of seed into a well-prepared seed-bed, is the best way to establish large areas of guinea grass. A fine soil surface and rolling encourage germination and establishment. Vegetative planting of 2-3 rooted tillers per clump in a triangular planting pattern at 40 cm spacing can expedite establishment, and is suitable for small-scale pasture development, especially when seed is not available. Fertilization immediately before or after planting or sowing can be important because of the slow growth of seedlings in the first month, when they can be easily overwhelmed by agressive weeds, and it is essential in soils which are poor.
After establishment, a guinea grass pasture should be allowed to flower and set seed and then be given a light grazing before the seed drops. Guinea grass combines well with herbaceous legumes, but it is not suited to sustained frequent and close grazing. Guinea grass is very responsive to chemical fertilizers, especially N. Dry matter yield responses under cutting are obtained with N applications up to 800 kg/ha per year. However, a more efficient use of N is obtained with 100-300 kg/ha N per year.
Diseases and pests
Ergot can be a problem in seed production during wet periods. No major diseases or pests of guinea grass have been documented.
Fresh foliage can be grazed directly by animals or can be cut for stall feeding. The N concentration of grazed guinea grass can be 30% higher than in cut material. Although usually fed fresh, guinea grass can be conserved as hay or silage. However, chopping, wilting and the addition of 4% molasses are recommended before silage making.
In Malaysia, annual DM yields range from 16-30 t/ha per year on sedimentary soils, 19-30 t/ha per year on peat soils and 1.5-9 t/ha per year on bris (coastal marine sand) soils when cut at 6-8 weekly intervals. Well managed guinea grass-legume pastures can support cattle at 1000 kg/ha liveweight, gaining 450 kg/ha per year. When fertilized with 300 kg/ha N per year, the animal biomass can be increased to 1400 kg/ha liveweight with an annual gain of 800 kg/ha. Similar liveweight gains to N fertilized guinea grass pastures can be achieved with guinea grass-leucaena pastures. Milk production of 8500 kg/ha milk per year has been recorded on guinea grass with N fertilizer using 2.5 Holstein-Friesian cows per ha yielding 11.3 kg/cow per day. Guinea grass-glycine ( Neonotonia wightii (Wight & Arnott) Lackey) pastures produced 8220 kg/ha per year using Friesian cows producing 12.7 kg/day, at a slightly lower stocking rate.
Large collections of guinea grass have been assembled by ATFGRC (CSIRO, Australia) and CIAT (Colombia). These have provided a wide range of morphological forms and edaphic adaptations.
Selection and breeding of guinea grass for specific ecological conditions has been carried out by a number of research organizations, including CIAT (Colombia) and EMBRAPA (Brazil). Japanese scientists have shown increasing interest in breeding guinea grass for the more difficult climatic conditions prevailing in that country. As a result, cultivar "Natsukaze" has been registered.
The discovery of a few sexual types of guinea grass in very large populations of this usually apomictic grass has made it possible for plant breeders to develop cultivars suited to different environments. Apomicts like guinea grass have a considerable reservoir of "fixed" variability which can be released by crossing with sexual types now available. Using crosses between these sexual types and other vigorous lines, a breeding programme to develop guinea grass cultivars tolerant of acid soils was carried out in Colombia and Brazil. This programme has led to the release of cultivar "Vencedor" by EMBRAPA in 1990. This cultivar thrives in soils with pH < 5, but has also been shown to have better than usual shade and cold tolerance. At the Rubber Research Institute in Malaysia, "Vencedor" was found to be one of the highest yielding tropical grasses at 55-80% light transmission.
Guinea grass is unquestionably one of the best tropical grasses and will be increasingly used in South-East Asian pastures. With the trend towards agroforestry, guinea grass will become more important in associations with trees as diverse as rubber and leucaena. More use could be made of it, particularly when mixed with leucaena, for feeding as leaf meal to non-ruminants.
- Bogdan, K.V., 1977. Tropical pastures and fodder plants. Longman, London & New York. pp. 181-191.
- Eng, P.K., Chen, C.P. & 't Mannetje, L., 1978. Effects of phosphorus and stocking rate on pasture and animal production from a guinea grass legume pasture in Jahore, Malaysia. 2: Animal live weight change. Tropical Grasslands 12: 198-207.
- Gilliland, H.B., Holttum, R.E. & Bor, N.L., 1971. Grasses of Malaya. In: Burkill, H.M. (Editor): Flora of Malaya. Vol. 3. Government Printing Office, Singapore. pp. 132-134.
- Sato, H., Shimizu, N., Nakagawa, H. & Nakajima, K., 1990. A new registered cultivar "Natsukaze" of Guinea grass. Japanese Agricultural Research Quarterly 23: 196-201.
C.P. Chen & E.M. Hutton