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Citrullus lanatus (Thunberg) Matsum. & Nakai

Citrullus lanatus (Thunberg) Matsum. & Nakai

Family

Cucurbitaceae

Synonyms

Citrullus vulgaris Schrader ex Ecklon & Zeyher, Colocynthis citrullus (L.) O. Kuntze, Momordica lanata Thunberg.

Vernacular Names

Malaysia

Tembikai, mendikai.

English

Watermelon.

Indonesia

Semangka, cimangko (Minahasa).

Papua New Guinea

Melon.

Philippines

Pakwan (Tagalog), sandiya (Bicol), dagita (Marinduque).

Cambodia

öö’w llök.

Laos

Moo, teeng moo.

Thailand

Taeng-mo (Central), taeng-chin (Peninsular), matao (Northern).

Vietnam

D[uw]a h[aa] [us], d[uw]a d[or].

French

Pasteque.

Geographical Distributions

Citrullus lanatus originated from the drier, open areas of tropical and subtropical Africa. Its cultivation became widespread in the Mediterranean region at least 3000 years ago. Introduction into India must also have occurred in ancient times and there a strong secondary centre of genetic diversity developed. Watermelon reached China around the 10th Century and Japan in the 16th Century. From India and China, it spread to Southeast Asia in the 15th Century. It was introduced to the Americas in post-Columbian times. C. vulgaris is now widespread in all tropical and subtropical regions of the world.

Description

Citrullus lanatus is a monoecious, occasionally andromonoecious, spreading and annual vine. The root system is extensive but shallow, consisting of taproot and many lateral roots growing in the top 50-60 cm of the soil. The stem is thin, angular and grooved, measures 1.5-5 m long, with soft, long and white hairs.

The leaves are simple, alternately arranged, oblong-ovate in outline, heart-shaped at base, measuring 5-20 cm x 2-19 cm and palmately deeply 3-5(-7)-lobed. The lobes are elongated-ovate in outline, pinnately sinuate-lobulate, shallowly sinuate-toothed, rarely subentire and largest at the central lobe. The petiole is 2-14 cm long. The tendrils are simple to 2(-4)-fid.

The flowers are solitary, axillary, with long hairy pedicels, pale yellow in colour, measure 2-3 cm in diametre and usually in cycles of 6 staminate flowers followed by 1 pistillate flower. There are 5-lobed sepal and 5-partite petal. The male flowers are with 3 free anthers on short filaments. The female flowers are with an inferior, ovoid, hairy ovary and a short style terminated by a 3-lobed stigma. The nectaries are present in male and female flowers. The fruit is an indehiscent pepo, globular to oblongoid or ellipsoid, measuring up to 60-70 cm in length and weighing 1.5-30 kg.

The fruit wall is hairless to hairy, thin to thick, brittle to tough and flexible while the color varies from creamy, golden-yellow, light green to dark green and uniform or mottled or striped. The flesh is derived from the placenta, mostly red or yellow but also pink, orange or white. The flesh texture is from finely grained and 'melting' to firm, coarse and fibrous.

The seeds are scattered throughout the flesh, numerous (200-900 per fruit), smooth, flattened, measuring 6-15 mm x 5-7 mm x 2.5 mm, black, brown, red, yellow, rarely white and without endosperm.

Ecology / Cultivation

Citrullus lanatus is day length neutral. A warm (day temperatures 25-30°C, night temperatures > 18°C), sunny and relatively dry climate is required for rapid growth and fruiting. Excessive rainfall and high humidity give excessive vegetative growth, affect flowering, induce leaf diseases and fruit rot. Market garden production is usually concentrated in the dry season, with furrow or drip irrigation. It prefers well-drained, fertile loamy sands with high organic matter content and pH 6-7. At lower pH values, soilborne diseases (Fusarium) may become a serious problem.

Line Drawing / Photograph

Citrullus_lanatus

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References

  1. Plant Resources of South-East Asia No.8: Vegetables.