| Brachiaria | |
|---|---|
| Scientific classification | |
| Kingdom: | Plantae |
| (unranked): | Angiosperms |
| (unranked): | Monocots |
| (unranked): | Commelinids |
| Order: | Poales |
| Family: | Poaceae |
| Genus: | Brachiaria (Trin.) Griseb. |
''Brachiaria'' is a genus of grasses originating from savannas of eastern Africa. These grasses are widely used as livestock forage. This genus includes 97 species, which can be found in tropical and subtropical climates, mostly in Africa and the Americas1.[1] These grasses are monocots in the family Poaceae.
Some species of Brachiaria were probably first introduced unintentionally to the Americas in the colonial period, from slave ships. More recently B. decumbens was introduced in 1952 into Brazil and B. ruziziensis in the 1960’s also in Brazil. Brachiaria is the most widely used tropical grass in Central and South America, about 40 million ha in Brazil alone[2]
The most problematic pest the Brachiaria faces is the spittlebug[1] , which is a known pest of the tropics. Brachiaria also are prey to leaf-cutter ants and mound-building termites there are also a few fungal and viral diseases that Brachiaria face as well. Disease-resistant cultivars should to be developed as a low-cost alternative to chemical control.[3]
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This genus was recognized over a hundred years ago. Surprising, this large genus has has not been divided further. This could be due to the great similarity with Panicum, leading different authors to exchange species between the two genera, supporting a growing idea that Brachiaria evolved from Panicum.[4] There has also been some taxonomic confusion with this genera and Urochloa.[5] A recent phylogenetic analysis concluded that Brachiaria and Urochloa are a monophyletic group (along with Eriochloa and Melinis) and that further molecular and morphological work is needed to establish clear relationships.[5]
Brachiaria are annual or perennial grasses, most lacking rhizomes. The inflorescence has paniclebranches composed of racemes and the entire plant usually gets no higher than 1 m.[6] The flowers are fleshy with 3 anthers[3] and the plants are bisexual.[6] Some members of the genus have a prominent vein in the center of the leaf whereas others do not.[6] Brachiaria are C4 plants which allows them to tolerate drier conditions and more light exposure than many other plants.[6]
To date, there are very limited studies about Brachiaria'sgeographical range. Brachiaria can grow in environments from swamps to light forest shade to semi desert, but generally do best in savannas and other open tropical ecosystems such as in East Africa1.[5] In Angola, Brachiaria brizantha does especially well on termite mounds and along the ecotone between grasslands and woodlands.[7] In the [[Kora National Reserve]] in Kenya, Brachiaria dominates the ground layer along with Aristida.[8] In India, the native Brachiaria ramosa is an important food source for the Indian Ring Dove, Streptopelia decaocto and Brachiaria species serve as forage for other herbivores within its native range.[9]
In North America, the native Brachiaria platyphylla (broadleaf signalgrass, an important agricultural pest) grows after heavy rains and then reproduces prodigiously and quickly.[10]
Wide expanses of the tropics have been converted to Brachiaria pasture in order to support livestock, especially in the Neotropics. In Brazil 80 million hectares of native habitat have been converted to Brachiaria pasture, using exotic species from Africa[11].
Besides direct loss of habitat through land conversion, introduced Brachiaria can degrade habitat my competing with native species. In North Australia, the exotic Brachiaria decumbens competes with the native tree Alphitonia petriei by inhibiting the growth of seedlings, frustrating the conversion of old pastureland to natural forest.[12] In the Paragominas region of Brazil, however, where much of the native forest has been replaced with Brachiaria and other exotic forage grasses, native forest naturally outcompetes the exotc pastureland and ranchers struggle to maintain pasture cover.[13] Native species may also utilize exotic Brachiaria as a food resource. In the caatinga of Brazil the native rodent Kerodon rupestris uses the exotic Brachiaria mutica as a food resource[14].
There has also been research done showing that Brachiaria could inhibits nitrification of soils.[15] This could be an amazing find since this it’s the most widely grown grass in South America on the same land as cattle. The cattle can eat this highly nutritious grass and it helps to keep down nitrous oxide (a greenhouse grass) levels in the atmosphere.[15]
Brachiaria is the single most important foraging grass for pastures in the tropics.[14]. Brachiaria cultivars have impacted the economy of various countries found in the tropics because of its ability to grow in infertile soil with high acidity[14]. One of the best attributes to Brachiaria is that it can grow so well in low-fertility acid soils and still be able to produce highly nutritious forage for many ruminants. In the past 25-30 years Brachiaria cultivation and export has become a major component of sown pastures[14]. In the America’s, Brazil represents the leading user and producer of Brachiaria seeds[14].
In Central America, Mexico has in the recent decades made great strides to improve their Brachiaria cultivar economy[16] Mexico has the highest volume of marketed seed, which has greatly improved their milk and beef industry[16]. Other Central American countries have also reached high volumes of seeds sold and area planted[16]. The annual growth rate of seeds sales was very high in 2009, reaching 32% in Mexico, 62% in Honduras, 45% in Nicaragua, 39% in Costa Rica, and 54% in Panama. The area planted with Brachiaria species during this period totaled 6.5% of the total surface of permanent grasses in Mexico, 12.5% in Honduras, 1.0% in Nicaragua, 18.7% in Costa Rica, and 0.1% in Panama[16].
Common name: Signalgrass