Panicum maximum Jacq.

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Graminae

Common names

Guinea grass (Australia, United States), zaina, pasto Guinea (Peru), gramalote (Puerto Rico).

Description

A tufted perennial, often with a shortly creeping rhizome, variable 60-200 cm high, leaf-blades up to 35 mm wide tapering to fine point; panicle 12- 40 cm long, open spikelets 3-3.5 mm long, obtuse, mostly purple red, glumes unequal, the lower one being one-third to one-fourth as long as the spikelet, lower floret usually male (Chippendall, 1955). Upper floret (seed) distinctly transversely wrinkled.

Distribution

From tropical Africa, but introduced in many countries.

Season of growth

Summer.

Altitude range

Sea-level to 2 500 m.

Rainfall requirements

It requires a rainfall usually in excess of 1 000 mm per year. With a summer dominance, cv. Gatton and creeping Guinea do not tolerate very wet conditions. Range 780-1 797 mm (Russell & Webb, 1976).

Drought tolerance

It does not tolerate severe drought. On an oxisol at Carimagua, Colombia, it dried the profile to a depth of 60 cm in the dry season, where Andropogon gayanus dried it to over 120 cm depth (CIAT, 1978).

Soil requirements

It will grow on a large range of soils, but produces poor stands on infertile types. It is well adapted to sloping, cleared land in rain forest areas where it will support heavy stocking. It will tolerate acid conditions if drainage is good. On an ultisol at Quilichaco, Colombia, P. maximum gave its maximum yield at 70 kg P2O5/ha per year and on an oxisol at Carimagua, Colombia, maximum yields were obtained at 100 kg P2O5/ha (CIAT, 1978).

Ability to spread naturally

It spreads slowly by seed, but needs fertile soil.

Land preparation for establishment

Full seed-bed preparation is generally required for Guinea grass establishment.

Sowing methods

Drilling on the contour in small drill furrows and pressing in with press wheels (Wilson, 1978) gives an excellent stand. Sowing sods at intervals of 0.6 m in rows 1.25 m apart is successful but laborious. In Sri Lanka, it has been found that close planting of P. maximum cuttings (with a spacing of 15 x 45 cm) increases yield. Transplanting of P. maximum seedlings is more reliable than that of root cuttings, especially if they have recently started to show new growth after rain. In Puerto Rico it is also generally sown by clumps of roots (Vicente-Chandler et al., 1953). One hectare will provide material for five hectares of planting.

Sowing depth and cover

Sowing depth should be no more than 1.5 cm. Rickert (1970) has shown better germination by using a straw mulch at 8 00010 000 kg/ha to cover the surface-sown seed.

Sowing time and rate

Sow in spring or early summer, so the pasture is established before the extreme heat of summer, at 3-6 kg/ha (1-2 kg for 'Hamil', 3.5-4.5 for 'Common').

Number of seeds per kg.

1 750 000; 1 030 000 ('Hamil'); 2 200 000 (United States).

Seed treatment before planting

It does not require any special treatment except ageing.

Tolerance to herbicides

To control weeds in Panicum maximum, atrazine (2- chloro-6-ethylamino-4-isopropylamino-1,3,5-triazine) can be used. Gatton panic survived over 4.5 kg AI/ha on the Atherton Tableland, Queensland, whereas most of the associated weeds Nicandra physaloides, Raphanus raphanistrum, Argemone ochraleuca, Ageratum conyzoides, Sida cordifolia and Eleusine indica were killed with the low concentration of 0.9 kg AI/ha (Hawton, 1976). Panicum maximum is a major weed itself in sugar-cane fields, due to its ability to grow under poor conditions. It can be killed by a pre-emergent spray of 2,4-D sodium salt at 4.5 kg/ha of an 840 g AI/kg product (e.g. Hormicide). No wetting agent is required when used as a pre-emergent spray. Use a minimum of 340 litres of water per hectare. For seedlings in the five-leaf stage, use Diuron at 2.5 kg/ha of an 800 g AI/kg product (Karmex, Diuron) applied in a minimum of 340 litres of water per hectare. For mature plants use 2,2-DPA at 2.3 kg of a 740 g AI/kg product (Shirpon, Dowpon) plus paraquat at 85 ml of a 200 g AI/litre product (e.g. Gramoxone) plus wetting agent at 250 ml per 200 litres of water. Spray to the point of runoff (Tilley, 1977).

Seedling vigour

It has good seedling vigour.

Response to defoliation

Guinea grass stands a good deal of defoliation but should not be grazed or cut below about 30 cm for permanence (McLeod, 1972).

Grazing management

In the wet tropics it is necessary to let this pasture become well-established before grazing so that it can compete with weeds. Guinea usually seeds in autumn; do not graze a new pasture until after this seeding period. Guinea cannot be grazed below 35 cm, or it will recover slowly. Adjust the stocking rate to maintain this height. Rotational grazing will give better control of pasture growth. Mowing or slashing is useful to control excess growth and weeds, but do not mow below 35 cm, and not after mid-autumn, as it will give slow regrowth and encourage winter weeds. Do not graze under extremely wet conditions, as trampling damages pastures growing in boggy ground.

Response to fire

It is tolerant of fire.

Dry-matter and green-matter yields

In the year 1973/74 at South Johnstone, Queensland, cv. Makueni produced more than 60 000 kg DM/ha when 300 kg/ha of nitrogen was applied (Middleton & McCosker, 1975). Vicente-Chandler, Silva and Figarella (1959) obtained 26 846 kg DM/ha with 440 kg N/ha, cut at 40-day intervals, in Puerto Rico.

Suitability for hay and silage

It has been used successfully for silage at Mpwapwa, Tanzania (Semple, 1970). Silage was also made in Brazil (Cezar et al., 1976), Nigeria (Miller, Clifton & Cameron, 1963) and Australia (Teitzel, 1969). It also makes useful hay in Thailand (Ghl, 1975).

Value as a standover or deferred feed

'Hamil' and 'Coloniao' Guinea grasses are reasonably palatable when mature, and provide good roughage to use in conjunction with urea molasses licks.

Toxicity

No clear-cut evidence of toxicity with this grass is recorded by Everist (1974). Ndyanabo (1974) recorded 0.28 percent of total oxalic acid in the dry matter but no toxicity.

Seed yield

Javier (1970) recorded 48-156 kg/ha; Paretas et al. (1972), 395 kg/ha from three cuts in Cuba; Fernando (1958),100 kg/ha in Sri Lanka.

Cultivars

  • 'Hamil Panic' 

seed obtained from Jack Hamil of Daintree, north Queensland, its source unknown. A tall, tufted perennial to 2.5-3 m, more robust and coarser then 'Common Guinea' and more like 'Coloniao'. Dense, stiff hairs on the basal leaf-sheath distinguish it from 'Coloniao'. Leaves blue-green, less hairy than 'Common Guinea'. Adapted to frost-free, warm conditions and fertile scrub soils. Grows vigorously during the wet season, when it is very palatable but is less so as it hays off. Seed set is poor. Probably apomictic.

  • 'Coloniao' 

a giant robust type with thick, fleshy stems growing to 3 m. The leaves are a distinct blue-green, 80-90 cm long and 25-30 mm broad, glabrous, the sheath is glabrous, except for short hairs on the sheath margin toward the junction of sheath and blade. The seed-head is 20-50 cm long, 1540 cm wide, dark green, and the spikelet (seed) outer glume is glabrous (Middleton & McCosker, 1975).

  • 'Embu' (creeping Guinea) 

has a semi-erect, rambling habit, rooting freely from the nodes, producing aerial roots from the lower nodes. It grows to 1-1.5 m. The leaves are light green to green, the leaf-blades have a few short surface hairs, and are 20-30 cm long and 12-16 mm wide. There are occasional short hairs on the leaf surface, and sparse short hairs on the lower outside of the sheath near the node junction; occasional hairs on the lower stem internodes. The panicle is 15-20 cm long, 12-15 cm wide, green, and the spikelet outer glume is glabrous (Middleton & McCosker, 1975). Has good winter growth and is a leafy, light-seeded cultivar.

  • 'Common Guinea' (common Guinea grass) 

medium height 1.8-2 m, erect canopy, fine stems, green leaves 70-80 cm long, 15-18 mm wide, sparsely hairy upper surface, few on lower surface, sheaths moderately hairy on outside surface, density increasing toward node. Stems hairless, panicle 15-40 cm long, 12-30 cm wide, green. Spikelet outer glume hairless. It is the most widely used cultivar, but variable, and cv. Riversdale was selected to replace it.

  • 'Coarse Guinea' 

giant, robust, with thick woody stems, 2.5-3 m high, dark green leaves, 80-90 cm long, 25-30 mm wide, sparse to moderately dense, short hairs giving rough feel to the leaf. Moderately dense, long, stiff bristle hairs on outside surface, increasing in density toward the junction of blade and leaf. Sheath painful to handle. Sow 'Hamil' together with 'Coarse Guinea' to make it easier for stock to penetrate (Walsh, 1959).

  • 'Gatton Panic' 

derived from seed introduced from Zimbabwe. Less robust and not as coarse as cv. Hamil, but more robust than 'Petrie' (green panic, P. maximum var. trichoglume). It has broader and longer leaves, with a more prominent midrib and more scabrid margins than green panic, and its spikelets are glabrous. Adapted to 760-1 000 mm rainfall. A little more vigorous, drought resistant, and persistent and more palatable than green panic, flowers later and responds better to nitrogen. Apomictic. The seed takes on a silver sheen when mature. Harvest when 80 percent has silver sheen and 510 percent seed has shattered. 1 401 000 seeds per kilogram.

  • 'Makueni' 

introduced from Kenya in 1965, it has given better cool- season growth than other Guinea grasses. It is easily distinguished from other Guinea grasses because the whole plant is covered with dense, whitish, soft hairs, giving it a furry feel. The outer seed coat is also hairy and can be so distinguished under magnification. It is very like the seed of green panic and can only be identified after germination. 'Makueni' is erect, tufted, with the leaf canopy slightly drooping, and is not so tall es 'Hamil', 'Coloniao' end 'Coarse Guinea'. It is readily grazed and gives good live-weight gains (Middleton & McCosker, 1975). Not as productive as cv. Riversdale, and is difficult to establish in the presence of weed competition (Teitzel & Middleton, 1979). 1 143 000 seeds per kilogram.i

  • 'Likoni Guinea' 

recommended for the high-rainfall areas (1 0001 270 mm) on the Kenya coastal strip in association with Macroptilium atropurpureum and Neonotonia wightii.

  • 'Ntchisi' 

used in Zambia and propagated by vegetative planting material (Thorp, 1979). Stems hairless, panicle 20-60 cm long, 15-40 cm wide, distinctive dark brown colour, spikelet outer glume hairless (Middleton & McCosker, 1975).

  • 'Riversdale' 

a selection from 'Common Guinea' to be continued as a certified seed line (Middleton, 1977).

  • 'Local' or 'Common' 

resistant to drought and heavy grazing. Suitable for drier areas.

  • 'Gramalote' 

a robust form in more humid areas, but always infested with leaf spot.

  • 'Borinquen', 'Broad-leaf' and 'Fine-leaf' 

under test.

  • 'Silky Guinea' 

a very leafy type for drier areas.

  • 'St Mary's Cowgrass' 

more robust and stemmy, grown in more humid parts. In Mauritius, cv. Sigor was highly productive, nutritious and drought resistant (Wright, 1961). In Brazil, 'Common' is the ordinary robust form; and 'Sempre-verde' (P. maximum var. gongylodes) is a fine-leaved, drought-resistant type with the base of the culms expanded.

Diseases

Bunt has interfered with Guinea grass seed production in Kenya in the Rift Valley (Semple, 1970). In Puerto Rico a leaf spot is caused by Cercospora fusimaculosus. In Colombia the inflorescence has been attacked by Fusarium spp. and a smut (Ustilago sp.) (CIAT, 1978).

Main attributes

Its wide adaptation, quick growth and palatability, ease of establishment from seed and good response to fertilizers (Harding, 1972).

Main deficiencies

'Common Guinea' has two main weaknesses: the bulk of its growth occurs in summer and, in recent years, commercial Guinea grass seed has been contaminated with less desirable types, such as 'Coarse Guinea'. Rapid summer growth and quick subsequent deterioration result in management difficulties (Hartley, 1950).

Optimum temperature for growth

The mean range is 19.1-22.9C (Russell & Webb, 1976). 

Minimum temperature for growth

Mean temperature for the coldest month ranges from 5.4-14.2C (Russell & Webb, 1976).

Frost tolerance

It will not tolerate heavy frosts, but recovers from light frosts with the return of warm weather.

Latitudinal limits

16.3-28.7N and S (Russell & Webb, 1976).,

Response to light

It is fairly tolerant of shading, and in its natural habitat inhabits woodlands throughout subhumid Africa.

Ability to compete with weeds

In the wet tropics, weed competition is severe. However, a well-established Guinea grass pasture, well-fertilized, will suppress weeds.

Maximum germination and quality required for sale

25 percent germinable seed; 40 percent purity in Queensland. Germinate at 20-35C, moistened in water. Germination is promoted by light (Ballard, 1964).

Palatability

It is very palatable.

Response to photoperiod

It is a short-day plant (Wang, 1961).

Chemical analysis and digestibility

In Costa Rica, analysis of flowering material revealed 7.81 percent crude protein, 30.62 percent crude fibre, 40.88 percent nitrogen-free extract, 2.33 percent ether extract and 8.36 percent ash in the dry matter on a 10 percent moisture basis (Gonzalez & Pacheco, 1970). Ghl (1975) has records from Tanzania, Malaysia and Thailand with crude protein varying from 5.3 to 25 percent of the dry matter.s

Natural habitat

Grassland and open woodland and shady places.

Tolerance to flooding

It does not tolerate waterlogging.

Fertilizer requirements

The optimum content of phosphorus in the dry matter was determined by Falade (1975) as 0.185 percent. Inoculation with Spirillum lipoferum increased yield by 480 kg DM/ha without nitrogen and 1 021, 1 690 and 1 930 kg/ha with 20, 40 and 80 kg N/ha, respectively (Quesenberry et al., 1976). Phosphorus at 24 kg/ha and nitrogen at 137 kg/ha are required in north Queensland, but soil fertilizer experiments are required to diagnose needs on various soils. Hendrick concluded that at nitrogen levels above 45 kg/ha, phosphorus and potassium may become limiting to P. maximum in western Nigeria (Ademosun, 1973). It tolerates high aluminium (Spain, 1979).

Compatibility with other grasses and legumes

Guinea combines well with the legume centro (Centrosema pubescens) and this is a common pasture mixture for the wet tropics. In Brazil, 'Coloniao' Guinea, centro and siratro are used successfully. Guinea and Stylosanthes guianensis is a successful mixture. Puero and glycine also combine well.

Genetics and reproduction

The somatic chromosome numbers are 2n=18, 32, 48 (Fedorov, 1974). It is a facultative apomict in which both apospory and pseudogamy occur (Warmke, 1954, quoted by Javier, 1970). The amount of sexual reproduction varies from 1-5 percent depending on the variety.

Seed production and harvesting

Seed ripens unevenly, and is shed as it matures. Javier (1970), in the Philippines, found the highest seed yield (19 percent recovery) was obtained when the panicle had shed 40-60 percent of its spikelets, which occurred about 12 to 14 days from panicle emergence. Harvesting is usually done by direct heading.

Animal production

Cultivar Makueni and common Guinea grass are capable of giving live-weight gains of up to 0.8 kg per animal per day (Middleton & McCosker, 1975). The selection (cv. Riversdale) from common Guinea grass consistently gave in excess of 600 kg/ha annual live-weight gain in association with legumes in north Queensland (Middleton, 1977). In So Paulo State, south-central Brazil, with an annual rainfall of 1 154 mm, of which 80 percent occurs in summer, an annual live-weight gain from Nellore strain Zebu steers of 241 kg/ha was obtained from unfertilized 'Coloniao' Guinea grass, and a mean of 586 kg/ha from a similar pasture fertilized with 200 kg N/ha annually over a seven-year period. Basic phosphorus and sulphur were applied. Application of nitrogen during the cool season gave earlier marketing to obtain a 15-30 percent higher price, but time of application had no overall advantage in live-weight gain.
Richards (1965) in Jamaica recorded annual live-weight gains ranging from 816-1 262 kg/ha from irrigated Guinea grass fertilized with 158 kg N/ha per year. At Utchee Creek, near South Johnstone in north Queensland, at a stocking rate of 4.2 beasts per hectare, first year annual live-weight gain increased from 377.4 kg/ha on Guinea grass alone, to 464.4 kg/ha with the inclusion of the legume Centrosema pubescens. A further increase to 601.1 kg/ha was obtained by the addition of 169.5 kg/ha of nitrogen. In the second year the corresponding live-weight gains for pure Guinea grass, Guinea grass/ centro and Guinea grass with nitrogen were 315, 481 and 731 kg/ha respectively. Each kilogram of applied nitrogen produced an average of 3.96 kg of live-weight gain (Grof & Harding, 1970). In a comparison of cultivars at South Johnstone, the average annual live-weight gains per hectare were 756 kg for 'Common Guinea', 698 kg for 'Hamil' and 633 kg for 'Coloniao' over three years. Cultivar Embu pastures did not persist (Mellor, Hibberd & Grof, 1973a). An irrigated Guinea grass/centro pasture at Ayr, north Queensland, under 41 weeks' grazing with shorthorn beef cattle gave a daily live-weight gain of 0.68 kg per head. From January to March, gains fell due to high day temperatures and high humidity (Allen & Cowdry, 1961). In the Solomon Islands, Gutteridge and Whiteman (1978) obtained a yield of 11 700 kg/ha per year from a mixture of P. maximum cv. Hamil and Centrosema pubescens, under coconuts.
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Dormancy

The quality of the seed improves for some months after harvest.

Value for erosion control

Its great bulk aids in erosion control, but its generally tussocky growth (except for cv. Embu) makes it less valuable than other species.

Tolerance to salinity

It has little tolerance.

Links:

Links for the genus:

  • Grass genera of the world: Information about botany, ecology etc. of the panicum genus; links to photographs of different species

Further reading

Grof & Harding, 1970; Middleton & McCosker, 1975; Motta, 1953.