Macroptilium longepedunculatum (PROSEA)
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Introduction |
Macroptilium longepedunculatum (Benth.) Urban
- Protologue: Symb. Antill. 9: 457 (1928).
- Family: Leguminosae
- Chromosome number: 2n= 22
Synonyms
Phaseolus longepedunculatus Bentham (1837), P. campestris Bentham (1837, non Bentham 1859).
Vernacular names
- Llanos macro (En).
Origin and geographic distribution
The natural distribution of llanos macro is from southern Brazil to northern Mexico. It was taken into cultivation outside tropical America only recently, e.g. in Australia.
Uses
M. longepedunculatum is a pasture legume for monsoonal lowland regions. It can be grazed during the growing season, or used as a fodder crop to make hay, as saved standover fodder or as green manure.
Properties
Nitrogen concentrations range from 1.4-3.0% during the growing season but decline to 1-1.4% during the dry season. DM digestibility of plant material during the growing season ranges from 57-67%, falling to 47-53% during the dry season. Phosphorus concentrations range up to 0.23% during the growing season and from 0.06-0.13% during the dry season. Sulphur concentrations range up to 0.21% during the growing season and from 0.06-0.10% during the dry season. There are approximately 300 seeds/g.
Botany
Short-lived perennial twining herb to 60 cm high with trailing stems; vegetative parts shortly pilose, hairs of the stem retrorse to spreading. Leaf pinnately 3-foliolate; petiole, petiolule and rachis grooved above and closely ribbed; petiole 24-45 mm long; lateral leaflets ovate with asymmetrical bases, 2-4 cm × 1-3 cm; terminal leaflet broadly lanceolate to deltoid, 2.5-5 cm × 1-3 cm. Inflorescence an axillary raceme, 20-40 cm long; flowers shortly pedicelled, solitary or in pairs and threes; standard greyed orange, concave, obovate, emarginate, ca. 14 mm long; wings purple, partly adhering to the keel petals, limb orbicular, ca. 15 mm long, apex curved and slightly twisted. Pod linear, 3-7 cm × 2-3 mm, containing 10-18 seeds; valves twisted on drying. Seed small, flattened ovoid, mottled light and dark grey.
Llanos macro has a juvenile phase during which floral initiation will not take place. It flowers and seeds prolifically, producing up to 240 kg/ha of seed. Freshly harvested seed has a very variable (20-80) percentage of hard seed.
M. longepedunculatum is a new species to cultivation and has not been closely studied. It is closely related to M. atropurpureum (DC.) Urban, M. gracile (Poepp.) Urban and M. domingense Urban, but further biotaxonomic studies are needed. There is only one cultivar, "Maldonado", released in the Northern Territory of Australia. "Maldonado" is a late flowering cultivar, flowering from mid-April in northern Australia. It appears to be a short-day plant, but the critical photoperiod has not been determined.
There are a number of lines of M. longepedunculatum, some of which flower earlier than "Maldonado", and some of which are amphicarpic.
Ecology
In its region of origin llanos macro occurs generally at low altitudes (up to 250 m) in areas with rainfall between 950-1300 mm per year. It is adapted to tropical monsoonal regions with strongly seasonal rainfall between 1100-1600 mm. It is not adapted to the humid tropics. It is tolerant of drought, burning, waterlogging and flooding for up to three months.
Agronomy
Llanos macro is propagated by seed using seeding rates of 2-4 kg/ha. A good seed-bed preparation is desirable for establishment. It can be sown as a mixed pasture or a pure stand. It nodulates freely and effectively with natural cowpea type rhizobia and does not need inoculation.
Llanos macro grows best with good soil fertility, but will persist at low soil fertility levels after being established with minimal non-N fertilizer as required.
After periods of wet weather small patches of dead leaves (leaf blight) are caused by Rhizoctonia spp. The areas involved are only small and no control measures are required.
DM yields of llanos macro in well-fertilized pure swards reach 5-7 t/ha. In mixed swards, they can be 3-4 t/ha. It is usually consumed fresh or as a saved standover fodder. Seed formation is essential for long-term persistence, particularly in the year of establishment. It should not be severely defoliated early in the wet season.
Genetic resources and breeding
Llanos macro "Maldonado" is new to cultivation, and seed production is increasing. Small quantities of seed are available for sale. A germplasm collection is held by ATFGRC (CSIRO, Australia). There is scope for further development of cultivars as some lines have different flowering times than "Maldonado" and some lines are amphicarpic.
Prospects
"Maldonado" is recommended for tropical monsoonal areas with annual rainfall between 1100 and 1600 mm. It may grow in wetter monsoonal environments. Other cultivars may be developed for cooler, subtropical regions.
Literature
- Cameron, A.G., 1990. Maldonado - a new legume for the Top End. Department of Primary Industry and Fisheries, Darwin, Australia. Agnote No 429. 2 pp.
- Lackey, J.A. & D'Arcy, W.G., 1980. Macroptilium. In: Dwyer, J.D. et al. (Editors): Flora of Panama 5(5). Leguminosae. Annals of the Missouri Botanical Garden 67: 724-728.
- Maréchal, R., Mascherpa, J.M., Stainier, F., 1978. Etude taxonomique d'un group complex d'espèces des genres Phaseolus et Vigna (Papilionaceae) sur la base de données morphologiques et polliniques, traitées par l'analyse informatique [Taxonomic study of a group-complex of species of the genera Phaseolus and Vigna (Papilionaceae) based on morphological data and on pollen morphology, through computer analysis]. Boissiera 28: 151-157.
- Ross, B.J. & Cameron, A.G., 1991. Pasture legume evaluation on seasonally flooded soils in the Northern Territory. Tropical Grasslands 25: 32-36.
Authors
A.G. Cameron
