Neonotonia wightii (PROSEA)
Neonotonia wightii (Wight & Arnott) Lackey
- Protologue: Phytologia 37: 210 (1977).
- Family: Leguminoseae
- Chromosome number: 2n= 22 (diploid), 44.
Notonia wightii Wight & Arnott (1834), Glycine javanica auct. mult., non L. (1753), G. wightii (Wight & Arnott) Verdc. (1966).
- Glycine (En). Brazil: soja perene
- Thailand: thua peelenian soibean.
Origin and geographic distribution
The natural distribution of glycine ranges from Africa to Asia. It occurs as far south as the wetter parts of southern Africa, in East Africa, Ethiopia, India and mainland Asia and Indonesia. It can currently be found in many humid tropical and subtropical regions of the world since its widespread introduction for use as forage.
Glycine is used as a grazed pasture legume in Australia in the subtropical and tropical high-altitude regions, and for grazing and hay in Brazil. It is used in small areas of Papua New Guinea where it volunteers as a fallow crop in abandoned gardens and is used as a cover crop and for woody weed control in overgrazed pastures.
Nitrogen concentrations ranging from 2-4.2% have been measured in the leaves, with DM digestibilities of between 55-61%. Although oestrogenic substances are present, no toxicity problems have been recorded.
Perennial twining or climbing herb with a woody base, 0.5-4.5 m long. Taproot long, nodulating, rootstock thick and woody. Stems slender and well branched; a dense crown may develop under grazing; stolons in contact with moist soil often root at the nodes. Leaves pinnately trifoliolate; petiole 2-12 cm long; leaflets ovate or elliptical, 1-15 cm × 1-12.5 cm, glabrous to densely velvety on both sides. Racemes axillary, 2-60 cm long, 20-150-flowered; peduncle 2-10 cm long; flower white or violet, 4.5-11 mm long. Pod cylindrical, 1.5-5 cm × 2.5-5 mm, straight or slightly falcate, thinly septate, glabrous to densely hairy, 3-8-seeded. Seed cylindrical, compressed, 2-4 mm × 1.5-3 mm × 1-1.5 mm, reddish-brown.
Three subspecies are recognized: ssp. wightii (pod densely hairy, flower 4.5-7.5 mm long), ssp. pseudojavanica (Taubert) Lackey (pod glabrous, flower 4.5-7.5 mm long), and ssp. petitiana (A. Rich.) Lackey (pod densely hairy, flower 7.5-11 mm long), and within these a number of varieties; the species as a whole is extremely variable, but due to the occurrence of intermediates, the practical value of the botanical subclassifications can be questioned.
Several cultivars have been developed throughout the world, their selection being based on such factors as cold tolerance, maturity, drought tolerance and tolerance to high Mn levels. The cultivars released in Australia are "Tinaroo", a diploid late-flowering variety with high cold tolerance, "Cooper", a diploid early-flowering type which tolerates excess moisture and drought stress, "Clarence", the earliest flowering cultivar and the first variety to start spring growth, and "Malawi", a tetraploid which is less branched than the other cultivars but adapted to more acid and less fertile soils.
Glycine is a short-day plant. Optimum day/night temperatures for growth and seed production of glycine are in the range 22-27/16 °C with a base temperature for growth of 13 °C, lower than for most tropical legumes. It has limited frost tolerance, but leaf damage occurs in all cultivars.
It is adapted to dry to humid (800-1800 mm) subtropical or high altitude (up to 3000 m) tropical regions with relatively deep, well drained, usually basalt-derived soils, and prefers a pH above 6.0. It is not adapted to very wet or waterlogged conditions. It is not as drought tolerant as siratro ( Macroptilium atropurpureum (DC.) Urban), but more so than centro ( Centrosema pubescens Benth.).
Propagation is by seed which, especially if hand harvested, often has a high proportion of hard seed. Mechanical or acid scarification (concentrated sulphuric acid for 25 minutes and then washed) is usually required for successful establishment. Because seedling growth and nodulation are slow, a weed-free seed-bed is favoured for establishment. Sowing rates of 2-6 kg/ha are recommended with the seed inoculated with a suitable strain of Bradyrhizobium. Seed should be sown at a depth of less than 2 cm. Where weeds become a problem, high slashing is the best control.
To allow build-up of a soil seed reserve and to enable re-establishment, the pasture should be allowed to seed down in its first year. As with other twining legumes, glycine is susceptible to heavy grazing so it should be leniently grazed and rest periods should be allowed at flowering time if under continuous grazing. Because of its ability to climb, glycine has the potential to become a weed among tree crops, although this is unlikely where it would be regularly cut or grazed.
Glycine combines well with a number of grasses and has been particularly successful with a range of Panicum cultivars and with setaria ( Setaria sphacelata (Schumacher) Stapf & Hubbard ex M.B. Moss).
Under wet conditions, the leaves can be damaged by leaf blight ( Rhizoctonia ), leaf-spot ( Cercospora ) and sclerotinea ( Sclerotinea sclerotioru m). On the Atherton tableland in Queensland, the webworm ( Oncopera sp.) can severely damage tops. Control is seldom attempted. Glycine may yield up to 4-5 t/ha of DM per year when sown with a grass and up to 10 t/ha per year if grown alone. Forage is usually grazed directly by animals but where mown for hay, care should be taken not to cut too low as this could damage the crown or low stolons.
Genetic resources and breeding
Germplasm is available from ATFGRC (CSIRO, Australia).
Because glycine plants have a short-day photoperiod response, seed production in tropical regions will be limited for some accessions and cultivars. However, material with origins in the high altitudes of tropical Africa should be reproductive in similar environments in Asia and it is this material which would need to be developed for the region.
In South-East Asia, glycine will be limited to deep, fertile and well-drained soils in tropical high-altitude areas. Such areas are limited and this species is unlikely to be widely used. Currently no selection, breeding or development studies are being carried out.
- Bogdan, A.V., 1977. Tropical pasture and fodder plants. Longman, London. pp. 357-364.
- Cameron, D.G., 1984. Tropical and sub-tropical pasture legumes 4. Glycine (Neonotonia wightii): an outstanding but soil specific legume. Queensland Agricultural Journal 110: 311-316.
- Duke, J.A., 1981. Handbook of legumes of world economic importance. Plenum Press, New York. pp. 88-90.
- Oram, R.N., 1990. Register of Australian herbage plant cultivars. CSIRO, Australia. pp. 179-182.
- Verdcourt, B., 1971. Phaseoleae. In: Milne-Redhead, E. & Polhill, R.M. (Editors): Flora of tropical East Africa. Leguminosae 4 - Papilionoideae 2. Crown Agents for Oversea Governments and Administrations, London. pp. 528-533.
B.C. Pengelly & A.K. Benjamin