Paspalum notatum (PROSEA)
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Introduction |
Paspalum notatum Flueggé
- Protologue: Gram. monogr., Paspalum: 106 (1810).
- Family: Gramineae
- Chromosome number: 2n= 20 (sexual), 30, 40 (apomicts)
Vernacular names
- Bahia grass, Pensacola Bahia grass (En, Am)
- Indonesia: rumput pencasilan (Timor)
- Thailand: ya-bahia
- Vietnam: co san dâú.
Origin and geographic distribution
Bahia grass is indigenous to the Americas, particularly in southern Brazil. It is now widely distributed in the southern United States, Central and South America, and occurs in restricted areas in Australia, Asia, and Africa, extending into and even beyond the subtropics.
Uses
Bahia grass is primarily used as forage for grazing, but also to protect slopes and terraces from soil erosion. It is also used as a lawn grass and provides suitable material for compost or mulch. It is sometimes regarded as a "weed" grass when it invades pastures of preferred species.
Properties
In vitro digestibilities of 65-70% have been measured in young growth, falling to 40-50% in older material. Similar declines have been measured in N concentrations, with old material containing only 0.5% N. Palatability declines markedly once seeding occurs or leaves mature. The digestibility of 6-week-old material in Queensland (Australia), was slightly higher (60%) under 50% shade than it was in full sunlight (55%). There are 300-550 seeds/g.
Botany
A low-growing creeping perennial with stolons and stout rhizomes. The tough stolons close to the ground have short internodes and root freely from the nodes, forming a dense sod. Culms erect or geniculate, up to 75 cm tall. Leaf-blade linear, 5-20(-50) cm × 2-10 mm, sometimes hairy on margins; ligule membraneous, 0.4 mm tall, hairy from behind. Inflorescence composed of 2 (rarely up to 5) terminal racemes, each 4-12 cm long; spikelets solitary in 2 rows on a narrow rachis and broadly ellipsoid, 2-4 mm long; florets 2, the lower reduced to an empty lemma. Caryopsis ovoid, 3 mm long, flattened on one side, yellowish-green, glossy.
Bahia grass is a polymorphic species in which three varieties have been distinguished: var. notatum , 2 n = 40, tetraploid apomict, with short narrow leaves, mainly occurring in southern United States; var. latiflorum Doell., 2 n = 40, tetraploid, usually apomict, vigorous, widespread throughout Central and South America; and var. saureae Parodi, 2 n = 20, sexual diploid, long narrow leaves, endemic to northern Argentina. There are several cultivars, the best known being "Pensacola", selected from var. saureae in the United States. Other selections have been released as cultivars in the United States, Brazil and Australia, and cultivar "Tifthi-1" was bred in the United States.
Several studies have been made into the fixation of atmospheric N by micro-organisms, such as Azotobacter paspali, in association with Bahia grass. Most reports indicate fixation of only small amounts of N, up to 20 kg/ha per year, but one reported fixation of 90 kg/ha per year.
Ecology
Bahia grass is a vigorous aggressive grass that spreads vegetatively and by seed. Viable seed is spread through dissemination in faeces. It prefers sub-humid to humid subtropical climates with annual rainfall ranging from 800 to 2000 mm. The optimum temperature ranges for growth (25-30 °C maximum and 20 °C mean) are slightly lower than those of grasses best suited to the lowland humid tropics. Top growth is killed by frost but established plants can tolerate temperatures down to -10 °C. It is very tolerant of shade and 35% higher yield has been measured under 50% shade than in full sunlight. It is best suited to sandy or light-textured soils but can grow on a wide range of soil types. It has good drought tolerance and has also been known to survive 36 days of flooding, and has some salt tolerance.
Agronomy
Bahia grass can be established from seed or vegetatively, from pieces of rhizomes or stolons planted closely at spacings of 15-25 cm. Hand-harvested seed has a high proportion of hard-seededness so the germination percentage is initially low, but improves progressively with up to 3 years of storage. Hammer milling of seed or treatment with sulphuric acid also improves germination. Sowing rates of 2-5 kg/ha are recommended. For optimum establishment, seed is sown into a fully prepared seed-bed to a depth of less than 1 cm, followed by rolling.
Bahia grass is very persistent and competitive and, given very fertile soil, can be reasonably productive. Frequent defoliation close to ground level is not only tolerated but is desirable to keep the sward leafy and acceptable to animals. It is more difficult to maintain legumes with Bahia grass than with most tropical grasses, partly because it is so competitive and partly because Bahia grass pastures have to be closely and regularly grazed. Good results have been achieved with prostrate legumes, especially with white clover ( Trifolium repens L.) in the subtropics, but also with Vigna parkeri Baker and perennial Arachis spp.
Cultivars differ in their susceptibility to a stinging nematode ( Belonolaimus longicaudatus ), but Bahia grass is resistent to root-knot nematodes and has been used in rotation with crops susceptible to these nematodes to reduce populations. Seed yields can be reduced by Paspalum ergot ( Claviceps paspali ), although "Pensacola" is resistant.
Herbage yields of Bahia grass are not particularly high. Yields of 3-8 t/ha of DM can be expected given moderate fertility and a suitable climate, with extreme yields ranging from 1 to 20 t/ha, the latter from heavily fertilized and irrigated swards. In the United States, Bahia grass pastures fertilized with N, usually 100-200 kg/ha, produce 400-600 kg/ha of liveweight gain per year and can carry about 5 head per hectare. In comparative studies, gains per head are usually slightly lower than recorded from pastures of Cynodon spp. Bahia grass is usually harvested by grazing animals. It is not suited for making hay or silage as yields are low when it is in a young leafy stage and as quality is poor if it is left for a longer growth period to achieve higher yields. It is a heavy seeder and seed yields of 100-350 kg/ha have been reported.
Genetic resources and breeding
A major collection is maintained by the USDA at Tifton, Georgia. Hybrid lines of Bahia grass have been produced in the United States, but there are no current breeding programmes.
Prospects
The potential for Bahia grass is South-East Asia has yet to be assessed. Although not ideally adapted to the lowland tropics, it has potential for use in plantation crops because of its tolerance to moderate shade. Where it is well adapted, the benefits of its persistence and competitiveness must be balanced against its tendency to have lower yield, quality and acceptability.
Literature
- Agata, W., 1985. Studies on dry matter production of Bahia grass (Paspalum notatum) sward. I. Characteristics of dry matter production during the regrowth period. In: Proceedings of the XV International Grassland Congress, August 24-31, 1985, Kyoto, Japan. Science Council of Japan and Japanese Society of Grassland Science, Nishinasuno, Japan. pp. 1235-1236.
- Blue, W.G., 1988. Response of Pensacola Bahia grass on a Florida Spodosol to nitrogen sources and times of application. Proceedings Soil & Crop Sciences Society of Florida 47: 139-142.
- Bogdan, A.V., 1977. Tropical pasture and fodder plants. Longman, London. pp. 205-212.
- Marousky, F.J. & West, S.H., 1988. Germination of Bahia grass in response to temperature and scarification. Journal of the American Society for Horticultural Science 113: 845-849.
- Shaw, N.H., Elich, T.W., Haydock, K.P. & Waite, R.B., 1965. A comparison of seventeen introductions of Paspalum species and naturalized P. dilatatum under cutting at Samford, south-eastern Queensland. Australian Journal of Experimental Agriculture and Animal Husbandry 5: 423-432.
- Skerman, P.J. & Riveros, F., 1990. Tropical grasses. FAO, Rome. pp. 571-575.
Authors
B.B. Baki, I.B. Ipor & C.P. Chen
