2131

8: Vegetables

Abelmoschus manihot (L.) Medikus

Malvenfam.: 46 (1787).

MALVACEAE

2n = 60—68

Hibiscus manihot L. (1753), Abelmoschus manihot (L.) Medikus ssp. manihot.

Aibika (Pidgin), sunset hibiscus (En). Indonesia: gedi (Minahasa), degi (Ternate). Papua New Guinea: aibika. Philippines: lagikuway (Tagalog), barakue (Batanes), glikway (Subanon). Thailand: po-fai (northern).

The genus Abelmoschus Medikus has its origin in continental South-East Asia. Its species are distributed mainly in South Asia, East Asia, South-East Asia and northern Australia. Abelmoschus manihot is a cultigen with a wide distribution. It is a popular traditional vegetable in Melanesia, but has also been introduced into other continents, either as a vegetable or as an ornamental (sunset 'hibiscus'). In South-East Asia it is cultivated particularly in the eastern parts of Indonesia and in Papua New Guinea.

Aibika is grown for its young leaves and stem tips which are used as a cooked green vegetable. Leaves become slimy upon cooking. Even in areas where the vegetable use is not popular (e.g. West Java), Abelmoschus manihot is commonly planted in home gardens, either as an ornamental or for traditional medicinal use. It is often described by Javanese villagers as 'cassava without tubers' because its aerial parts resemble cassava.

Aibika is the most important leafy vegetable in Papua New Guinea and Irian Jaya. In other parts of South-East Asia it is only of local or regional importance. It is grown in compounds for home consumption and constitutes a popular market vegetable. No production statistics are available.

Per 100 g edible portion, aibika leaves and stem tips contain: water 90 g, protein 4.1 g, fat 0.4 g, carbohydrates 4 g, fibre 1 g. The energy value is 150 kJ/100 g. It is a rich source of vitamins and minerals: vitamin A 900 IU, vitamin C 118 mg, Ca 580 mg, Fe 3 mg. Aibika has been recommended by the World Health Organization as a good baby-food, because young leaves are almost fibreless and are easy to mash after boiling.

Perennial shrub, 1—3(—7) m tall. Root system usually adventitious and fairly shallow with most of the roots in the top 30—40 cm of the soil. Stem erect, woody, branching, glabrous or pubescent (without prickly hairs unlike related wild forms). Leaves simple, alternate, extremely variable in shape, size, colour and pigmentation (or marking); petiole 3—25 cm long, stipules filiform or lanceolate, 5—12 mm long; leaf-blade linear, lanceolate, cordate or deeply lobed or parted with 3—7 segments, colour varying from light to dark green through red to purple. Flowers large, bell-shaped, 7—15 cm in diameter, axillary, solitary or in racemes by the reduction or abortion of the upper leaves; pedicel 1—5(—7) cm long; epicalyx segments 4—6(—8), free, ovate to oblong, 1—3 cm x 0.5—1 cm; calyx spathaceous, 2—3 cm long, splitting on one side during the expansion of the corolla, adnate to and falling with the corolla; corolla consisting of 5 large, obovate to orbicular petals, 3—8 cm in diameter, pale yellow with a dark brown or reddish central spot; ovary superior, 5-celled; style surrounded by the staminal column from which it emerges and divides into 5 lobes, each ending in a flattened, disk-shaped, dark brown stigma; staminal column up to 3 cm long, white, bearing numerous filaments and anthers. Fruit an oblong-ovoid capsule, 3.5—6 cm x 2—2.5 cm, hairy, usually 5-angled and splitting into 5 segments. Seeds numerous, spherical to reniform, 2—4 mm in diameter, black.

Aibika propagated from cuttings grows rather slowly during the first 2—3 months and does not cover the ground adequately. After harvesting has started, the regular removal of the growing tips encourages branching and compact bushy growth, and delays flowering.

Abelmoschus manihot is a polymorphic species and its delimitation has been subject to much debate. In a wide sense, it comprises 2 subspecies: ssp. manihot (2n = 60—68, stems without prickly hairs, cultigen) and ssp. tetraphyllus (Roxb. ex Hornem.) Borss. (2n = 130—138, stems with prickly hairs, wild). The present-day tendency followed here is to use Abelmoschus manihot in a narrow sense (restricted to ssp. manihot) and to recognize ssp. tetraphyllus as a distinct species: Abelmoschus tetraphyllus (Roxb. ex Hornem.) R. Graham.
In the literature the great variability of Abelmoschus manihot has been described in many botanical forms, differing mainly in leaf shape, size and colour. Distinction of cultivar groups would be more appropriate, but has not yet been done formally.

Aibika grows over a wide range of climates but in the tropics mainly occurs from the lowlands to 1200 m altitude. However, at high elevations, growth is slower. It requires well-distributed rainfall of at least 1200 mm/year for good production. Abelmoschus manihot is sensitive to waterlogging and prefers well-drained loams with a pH of 5.5—7, but grows on a wide range of soils. Little is known about the eco-physiology of Abelmoschus manihot, but there are indications that it behaves as a qualitative short-day plant. In Port Moresby (9°S), aibika flowers between July and November.

Although aibika can be propagated from seed, it is easier to use stem cuttings. Traditionally, in Papua New Guinea and Irian Jaya, cuttings of 40—50 cm length are used. If planting material is scarce, they may be shorter but should have at least 3—4 nodes. Cuttings are planted directly in the field, buried about half their length, at a spacing of 25—100 cm in rows 1 m apart (10 000—40 000 plants/ha), preferably at the start of the main rains. Cuttings which have not sprouted in 3 weeks should be replaced. A fairly rough seed-bed, obtained by hoeing or disk ploughing and harrowing is adequate since quite large cuttings are used. Perennial weeds should be removed before planting. Manure at 20—30 t/ha should be incorporated before planting.

Aibika should be clean-weeded; this is best achieved with a thick layer of grass mulch which also controls soil erosion. Although the fertilizer and manure requirements of aibika have not been worked out, observations in Papua New Guinea have shown that it responds to fertilizers by producing bigger leaves and this is likely to lead to higher yields. When aibika starts being harvested, top dressing with 10 kg/ha of nitrogen at monthly intervals (120 kg/ha per year) will maintain active vegetative growth and yield. Aibika can be grown at any stage of the rotation, and can be intercropped with a wide range of annual crops.

No serious diseases have been reported. Collar rot (Phytophthora nicotianae), leaf-spot (Cunninghamella spp.), powdery mildew and green mottle (probably a virus) have been reported from Papua New Guinea. Control measures are not usually economic. Like all malvaceous plants, aibika is very attractive for insects. Important pests include leaf rollers (Sylepta derogata), semi-loopers (Anomis flava), flea beetles (Nisotra sp.), jassids (Amrasca sp.), white scale (Pseudaulacaspis pentagona), red/black scale (Para saisettia nigra), and various other sucking bugs, leaf-eating caterpillars, beetles and grass hoppers.

Tips of shoots, consisting of the growing point and a few young leaves are harvested. New shoots develop from axillary buds and provide another harvest in about 4 weeks. Harvesting starts about 80—90 days after planting and the bush remains productive for at least a year.

Annual yields of 5—15 t/ha can easily be obtained. When well watered and manured, yields of 40—60 t/ha per year are possible.

Aibika is marketed as fresh leaves on the day of harvest. No further processing or preservation is currently practised.

New Guinea is an important centre of diversity for Abelmoschus manihot, but numerous types have also been described from other parts of the region, in particular the eastern parts of Indonesia. Collections have only systematically been made in Papua New Guinea, and they are maintained as living plant collection by the Laloki Research Station, Konedobu.

Little or no breeding work has been done on aibika anywhere. Work has been limited to cultivar trials and compatibility studies. Abelmoschus manihot is self-fertile but from studies of seedling populations it is obvious that there is a high degree of outcrossing.

Aibika makes a substantial contribution to the diet of Melanesians, and could very well do so in other parts of South-East Asia. Very little is known about Abelmoschus manihot in general, and the Melanesian plant material in particular. More research is needed.

Mutthapa, B.N., 1985. Collar rot of aibika. Plant Pathology Note No 27. Harvest 11: 82-83.
Ochse, J.J. & Bakhuizen van den Brink, R.C., 1980. Vegetables of the Dutch East Indies. 3rd English edition (translation of 'Indische Groenten', 1931). Asher & Co., Amsterdam, the Netherlands. pp. 464-473.
Powell, J.M., 1982. Traditional vegetables in Papua New Guinea: retrospect and prospect. In: Proceedings of the Second Papua New Guinea Food Crops Conference, July 14-18, 1980, Goroka. Department of Primary Industry, Port Moresby, Papua New Guinea. pp. 64-77.
Smith, E.S.C. & Thistleton, B.M., 1982. Some common pests of vegetables and fruits in Papua New Guinea and their control. In: Proceedings of the Second Papua New Guinea Food Crops Conference, July 14-18, 1980, Goroka. Department of Primary Industry, Port Moresby, Papua New Guinea. pp. 476-491.
Standal, B.R., Street, J.M. & Warner, R.M., 1974. Tasty, protein rich, and easy to grow - the new edible 'sunset' hibiscus. Hawaii Farm Science 2: 2-3.
Westwood, V. & Kesavan, V., 1982. Traditional leaf vegetables of Papua New Guinea: aibika. In: Proceedings of the Second Papua New Guinea Food Crops Conference, July 14-18, 1980, Goroka. Department of Primary Industry, Port Moresby, Papua New Guinea. pp. 391-395.

A.M. Gurnah

Gurnah, A.M., 1993. Abelmoschus manihot (L.) Medikus. In: Siemonsma, J.S and Piluek, K (Editors): Plant Resources of South-East Asia No 8: Vegetables. PROSEA Foundation, Bogor, Indonesia. Database record: prota4u.org/prosea