Several species of the genus Urochloa are cultivated as forage and some species of were probably first introduced unintentionally to the Americas in the colonial period, from slave ships. Urochloa eminii was introduced to Brazil in 1952. Urochloa is the most widely used tropical grass in Central and South America, with about 40 million hectares planted in Brazil alone.[12]
Biology
This genus was described in 1812. It is similar to the genus Panicum, and some authors believe Panicum is ancestral to it.[12] A phylogenetic analysis concluded that species of the former genus Brachiaria formed a monophyletic group with those of Urochloa, along with the genera Eriochloa and Melinis, and that further molecular and morphological work is needed to establish clear relationships.[13]
Urochloa species are annual or perennial grasses, most lacking rhizomes. The inflorescence is a branching panicle, and the plant reaches about a meter in height.[14] The plants are bisexual[14] and the flowers are fleshy, with 3 anthers.[15] Some species have a prominent vein in the center of the leaf.[14]Brachiaria are C4 species and can tolerate drier conditions and more light exposure than some other plants.[14]
Ecology and conservation
Cultivated Brachiaria
Urochloa species can grow in many environments, from swamps to shady forest to semidesert, but generally do best in savannas and other open tropical ecosystems such as in East Africa.[13] In Angola, Urochloa brizantha grows on termite mounds and in the ecotone between grassland and woodland habitat.[16] In the Kora National Reserve in Kenya, Urochloa species dominate the ground layer along with those of the genus Aristida.[17] In India, the native Urochloaramosa is an important food source for the Eurasian collared dove and Urochloa species are forage for other local herbivores.[18]
In North America, the native Urochloa platyphylla (broadleaf signalgrass), grows after heavy rains and then reproduces prodigiously and quickly, sometimes becoming a weed.[19]
Wide expanses of the tropics, especially the Neotropics, have been converted to pastures of Urochloa species to support livestock. In Brazil, 80 million hectares of native habitat have been planted with African grasses, mostly Urochloa.[20]
Introduced species such as Urochloa grasses can degrade habitat and compete with native species. In Northern Australia, the exotic Urochloa eminii competes with the native tree Alphitonia petriei by inhibiting the growth of seedlings, slowing the conversion of abandoned pastureland to natural forest.[21] In the Paragominas area of Brazil, however, native forest outcompetes cultivated stands of Urochloa and other exotic forage grasses, and ranchers struggle to maintain pasture cover.[22] Native species may also utilize exotic Urochloa as a food resource, such as the rock cavy, a native rodent of the caatinga.[23]
Cultivation
Brachiaria cultivation in Colombia
Urochloa is the single most important genus of forage grass for pastures in the tropics.[23]Urochloa cultivars can grow in infertile and acidic soils.[23] Brazil is the leading user and producer of Urochloa seeds in the Americas.[23]
Mexico has put effort into improving its trade in Urochloa cultivars, and the grass is thought to have made a positive impact on its milk and beef industries.[24]Central American countries have also increased seed sales and area planted in the grass.[24] The annual growth rate of seed sales in 2009 was 32% in Mexico, 62% in Honduras, 45% in Nicaragua, 39% in Costa Rica, and 54% in Panama. The area planted with Urochloa during this period was about 6.5% of the total surface of permanent grasses in Mexico, 12.5% in Honduras, 1% in Nicaragua, 18.7% in Costa Rica, and 0.1% in Panama.[24]
Agrostis is a large and very nearly cosmopolitan genus of plants in the grass family, found in nearly all the countries in the world. It has been bred as a GMO creeping bent grass.
Panicum (panicgrass) is a large genus of about 450 species of Poaceae grasses native throughout the tropical regions of the world, with a few species extending into the northern temperate zone. They are often large, annual or perennial grasses, growing to 1–3 m (3–10 ft) tall.
Echinochloa is a very widespread genus of plants in the grass family and tribe Paniceae. Some of the species are known by the common names barnyard grass or cockspur grass.
Cenchrus is a widespread genus of plants in the grass family. Its species are native to many countries in Asia, Africa, Australia, the Americas, and various oceanic islands.
Setaria is a widespread genus of plants in the grass family. The name is derived from the Latin word seta, meaning "bristle" or "hair", which refers to the bristly spikelets.
Axonopus is a genus of plants in the grass family, known generally as carpet grass. They are native primarily to the tropical and subtropical regions of the Americas with one species in tropical Africa and another on Easter Island. They are sometimes rhizomatous and many are tolerant of periodic submersion.
Urochloa eminii, commonly known as Congo grass, is a species of forage crop in the family Poaceae that is grown throughout the humid tropics. With fast growth at the beginning of the wet season due to strong seedling vigour, ease of establishment, good seed production and yield and the ability to suppress weeds it has the ability to become developed into the most important forage crop planted in the tropics. With the aid of genomic tools to research the genotype and gain more information there is the ability to increase breeding programs which are currently rather limited.
Rupichloa is a genus of Brazilian plants in the grass family.
Urochloa fusca, the browntop signalgrass, is a wild grass species with a native range extending from Paraguay in South America to the southern United States, and it is now found as a weed in Australia. The species is diploid, with a base chromosome number of 9, and utilizes the PCK enzymatic subtype of C4 photosynthesis. Based on a molecular phylogeny of the genus Urochloa, the closest relatives of U. fusca are Urochloa arizonica and Urochloa mollis The genome of U. fusca is currently being sequenced by the Joint Genome Institute.
Urochloa ramosa, the browntop millet or Dixie signalgrass, is an annual, millet grass belonging to the grass family (Poaceae). The native range of Urochloa ramosa is from Africa to tropical and subtropical Asia.
References
↑ "Genus: Urochloa P. Beauv". Germplasm Resources Information Network. United States Department of Agriculture. 1999-03-09. Retrieved 2014-10-08.
1 2 Clayton, W. D., et al. (2002 onwards). Brachiaria. GrassBase - The Online World Grass Flora.
↑ Estes, R. D. and R. K. Estes. (1974). The biology and conservation of the giant sable antelope, Hippotragus niger variani Thomas, 1916. Proceedings of the Academy of Natural Sciences of Philadelphia 126, 73-104.
↑ Alibhai, S. K.; Key, G. (2009). "A preliminary investigation of small mammal biology in the Kora National Reserve, Kenya". Journal of Tropical Ecology. 1 (4): 321–7. doi:10.1017/S0266467400000407. JSTOR2559449. S2CID86618426.
↑ Boddey, R.M.; MacEdo, R.; Tarré, R.M.; Ferreira, E.; De Oliveira, O.C.; De p. Rezende, C.; Cantarutti, R.B.; Pereira, J.M.; Alves, B.J.R.; Urquiaga, S. (2004). "Nitrogen cycling in Brachiaria pastures: The key to understanding the process of pasture decline". Agriculture, Ecosystems & Environment. 103 (2): 389–403. Bibcode:2004AgEE..103..389B. doi:10.1016/j.agee.2003.12.010.
↑ Sun, Dan; Dickson, Geoff R. (1996). "The Competition Effect of Brachiaria decumbens on the Early Growth of Direct-Seeded Trees of Alphitonia petriei in Tropical North Australia". Biotropica. 28 (2): 272–6. Bibcode:1996Biotr..28..272S. doi:10.2307/2389082. JSTOR2389082.
↑ Nepstad, D. C.; Uhl, C.; Serrao, E.A.S. (1991). "Recuperation of a degraded Amazonian landscape: Forest recovery and agricultural restoration". Ambio. 20 (6): 248–55.
1 2 3 4 Singh, R. J. (ed.). "Forage Crops". Genetic Resources, Chromosome Engineering, and Crop Improvement. Florida: CRC Press. p.209.
↑ McGregor, John T.; Smith, Roy J.; Talbert, Ronald E. (1988). "Broadleaf Signalgrass (Brachiaria platyphylla) Duration of Interference in Rice (Oryza sativa)". Weed Science. 36 (6): 747–50. doi:10.1017/S0043174500075767. JSTOR4044781. S2CID182717787.
↑ Kalaisekar, A (2017). Insect pests of millets: systematics, bionomics, and management. London: Elsevier. ISBN978-0-12-804243-4. OCLC967265246.
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