Crotalaria pallida (PROSEA)

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Plant Resources of South-East Asia
Introduction
List of species


Crotalaria pallida Aiton


Protologue: Hort. kew. 3: 20 (1789).
Family: Leguminosae - Papilionoideae
Chromosome number: 2n= 16

Synonyms

Crotalaria mucronata Desv. (1814), C. striata DC. (1825), C. siamica Williams (1905).

Vernacular names

  • Smooth rattlebox, salts rattlebox (Am)
  • Indonesia: kekecrekan (Sundanese), orok-orok (Javanese), telpok (Madurese)
  • Malaysia: giring-giring, rang-rang
  • Philippines: gorung-gorung, kolong-kolong, tambarisa
  • Cambodia: chângrô:ng sva:, dâng höt khmaôch, sandaèk kû:öy
  • Laos: hingx ha:y
  • Thailand: hinghai, honghai
  • Vietnam: lục lạc ba lá tròn, cây muỗng trà, cà phê rưng.

Origin and geographic distribution

C. pallida is probably a native of tropical Africa, but its natural distribution is obscured by widespread cultivation and subsequent pantropical naturalization. In Asia it is common in India and Sri Lanka and throughout South-East Asia.

Uses

C. pallida is used as a ground cover and a green manure crop throughout the humid tropics, though on a limited scale. In tea, rubber and coconut plantations in Sri Lanka and South-East Asia, and in cocoa plantations in West Africa, it is used as a green manure and planted in the inter-rows to reduce erosion. It is one of the oldest green manure crops in Indonesia, but lost popularity because of its susceptibility to diseases and pests. C. pallida replaced the more toxic Crotalaria spectabilis Roth in the south-eastern United States and was grown extensively for soil sanitation and as a green manure crop until the 1960s. It also has some value as a forage crop. However, its use is no longer recommended as the seed occasionally gets mixed into fodder grains, causing poisoning.

In West Java, a fermented product ("dage"), was formerly made from the seeds. Seeds were boiled for two hours, wrapped in banana leaves and left to ferment for several days to remove poisonous components. In Cambodia the flowers are used as a vegetable. In Indo-China a kind of coffee is prepared from roasted seed. In Vietnam, the roots are sometimes chewed with betel-nut.

In traditional medicine, C. pallida is used to treat urinary problems. A poultice made of the roots is applied to painful swelling of joints, and an extract of the leaves is taken as a vermifuge. In Laos the plant is used to reduce fever.

Properties

Tests in Java and Sri Lanka indicated 4.2 g N in above-ground parts per 100 g dry matter; in Florida 2.8 g N was found.

Seeds of many Crotalaria spp., including C. pallida , contain a number of pyrrolizidine alkaloids, such as mucronatine and monocrotaline which affect the liver and may kill birds and mammals. They are particularly insidious toxins, as their effects may only become apparent weeks or months after the animal has stopped eating the seeds. In C. pallida the concentrations are low and toxic effects have only been observed when chicks were fed the seeds for several weeks. Leaves contain an alkaloid poisonous to goats; dried leaves are not toxic. A lectin from C. pallida , which specifically agglutinates type A erythrocytes, is used in cytochemical research. The flavonoids apigenin and vitexin have been isolated from the bark and the leaves. The weight of 1000 seeds is about 5 g.

Botany

An erect, well-branched annual or short-lived perennial herb, up to 1.5(-3) m tall. Stem stout, puberulent, with slender longitudinal grooves; branches densely appressed hairy. Leaves trifoliolate; stipules filiform, up to 3 mm long, caducous or absent; petiole 2-8.5 cm long; leaflets variable, elliptical to obovate, 3-13 cm × 2-5(-7) cm, obtuse, often emarginate, sometimes apiculate, glabrous above, thinly appressed puberulous beneath. Inflorescence a terminal, shortly pedunculate raceme, 15-40 cm long, 20-30-flowered; bracts linear, up to 5 mm long, caducous; bracteoles inserted at the base of the calyx, filiform, 1-3 mm long; pedicel 4 mm long; calyx deflexed, tubular, 6-8 mm long, appressed puberulous, with 5 unequal lobes; corolla about 1.5 cm long, yellow, often reddish-brown veined; standard elliptical, 11 mm × 8 mm; wings oblong-lanceolate, 8 mm × 3 mm; keel shallowly rounded, 11 mm × 4 mm, with narrow, slightly projecting beak. Pod shortly stipitate, subcylindrical, 3-5 cm × 6-8 mm, 30-40-seeded, glabrescent, yellowish when mature. Seed heart-shaped, 3 mm × 2 mm, shiny, mottled ochre and dark grey-green or brown.

C. pallida is cleistogamous and the percentage of outcrossing is usually small. Germination is quick, but initial growth is slow. After one month, 3 leaves and a well branched and nodulated root system have developed. In subtropical southern Brazil flowering starts about 160 days after sowing and the first mature seeds are released from the pods two months later.

Two varieties of C. pallida are sometimes recognized: var. pallida with elliptical leaflets, widest in the middle, about 6-13 cm long, acute or rounded at the apex, and var. obovata (G. Don) Polhill with elliptical-obovate to obovate leaflets, widest at a point 0.6-0.8 of the length from the base to the apex, about 3-7 cm long, rounded or retuse at the apex. Var. obovata tends to occur in wetter locations. Intermediate forms are reported from Thailand.

Ecology

C. pallida occurs naturally on river banks, edges of lakes, extending into woodland, grassland and waste places from 0-1000 m altitude and may be planted to 1800 m. It is light-demanding and shade strongly retards development. It grows in a wide range of annual rainfall conditions, from 850 mm to over 3000 mm and occurs occasionally in rather dry locations. The average annual temperature varies from 16-26 °C. Tests in Florida showed satisfactory growth on a wide range of soils, except on peat soils that developed under coarse grass. In West Africa it is considered well suited to sandy soils. In Thailand it is found in the tidal zone, growing in association with Avicennia sphaerocarpa Stapf ex Ridley and Ipomoea pes-caprae (L.) R. Br. ex Tuckey. It also occurs in open, secondary thickets with Bambusa bambos (L.) Voss, Chromolaena odorata (L.) R.M. King & Robinson and Lantana camara L.

Agronomy

Fresh seed of C. pallida has a higher germination rate than stored seed. In India germination was found to be improved by treatment with hot water. However, other reports indicate less favourable results and even damage of seed. A seed rate of 10-20(-30) kg/ha is required. In Bogor, Indonesia, C. pallida sown in rows 50 cm apart covered the soil after three months. A few weedings were required. Plants have to be topped when about 30 cm tall to promote branching. C. pallida should be cut at least 20-25 cm above the ground to ensure good regrowth. It can be cut 3-4 times before it dies out, generally after 1.5-2 years.

In Sri Lanka yields of 13.5 t/ha of above-ground green material have been obtained in 6 months, and 23 t/ha in 4 cuts in a little over a year, while annual yields of up to 5.2 t/ha and 10.2 t/ha above-ground air-dry matter are reported from Florida and southern Brazil respectively.

C. pallida is susceptible to the root-knot nematodes Meloidogyne incognita and M. javanica . It is one of the alternative hosts of Maruca testulalis , which is a pest in cowpea ( Vigna unguiculata (L.) Walp.). It also acts as a vector for the "kette" virus affecting cardamom ( Elettaria cardamomum (L.) Maton). During dry periods, flea-beetles may cause severe defoliation. The bug Ragmus importunatas causes leaf fall at the beginning of the rainy season in Java. Other insects causing damage are the beetle Longitarsus sp. and the caterpillar Utetheisa lotrix .

Genetic resources and breeding

The Southern Regional Plant Introduction Station of the United States Department of Agriculture, Griffin, Georgia holds 26 accessions of C. pallida from 19 countries. Around 1960 cv. Giant Striata was the most popular cultivar in the south-eastern United States. About 90% of the seed sold in North Carolina was of this cultivar.

Prospects

C. pallida retains some importance as a cover, green manure and fodder crop in the south-eastern United States. In South-East Asia it will probably remain of minor importance only, as species more resistant to diseases and pests are available.

Literature

  • Dagar, J.C., Jeyamurthy, A. & Sharma, A.K., 1988. An endeavour towards the utility of a common wasteland weed Crotalaria mucronata Desv. from Andaman (India). Journal of Economic and Taxonomic Botany 12(2): 489-490.
  • Duke, J.A., 1981. Handbook of legumes of world economic importance. Plenum Press, New York, United States. pp. 67-68.
  • Jackai, L.E.N. & Singh, S.R., 1981. Studies on some behavioral aspects of Maruca testulalis on selected species of Crotalaria and Vigna unguiculata. Tropical Grain Legume Bulletin 22: 3-6.
  • Polhill, R.M., 1982. Crotalaria in Africa and Madagascar. Balkema, Rotterdam, the Netherlands. pp. 184-186.
  • Rao, D.G. & Naidin, R., 1973. Studies on "kette" or mosaic disease of small cardamom. Journal of Plantation Crops 6 (Suppl.): 129-136.
  • Sandanan, S. & Rajasinghham, C.C., 1982. Effect of mulching and cover crops on soil erosion and yield of young tea. Tea Quarterly 51(1): 21-26.
  • Sikdar, S., Ahmed, H. & Chatterjee, B.P., 1990. A pH dependent, low molecular weight, blood group-A-specific lectin from Crotalaria striata seeds: purification and carbohydrate specificity. Biochemical Archives 6(2): 207-216.
  • Stokes, W.E., 1927. Crotalaria as a soil building crop. Journal of the American Society of Agronomy 19: 944-948.

Authors

N.O. Aguilar