Distribution

Although the botanical literature claims that this species can be found south of a line extending from Nigeria to Sudan and Ethiopia (and across to Yemen), the primary diversity is far south of that. The main concentrations are in Botswana, Zimbabwe (in mopane woodland), Malawi, Zambia, Mozambique, Namibia, Swaziland, and South Africa (lowveld and extending south along the coast to just touch the eastern edge of Cape Province). Commercial lines are exported from Kenya.

Beyond Africa, the plant is currently under small-scale commercial cultivation at least in New Zealand, the United States, Israel, the Netherlands, Italy, Spain, Portugal, and France. It has also been introduced many other places.

Environmental Requirements

As a general rule, suitable sites for horned melon are those where cantaloupes can be cultivated (see Chapter 8, Melon).


Daylength Flowering and fructification can be influenced by daylength. Flowering induction seems to require short days; days longer than 14 hours halt flowering. On the other hand, short days can lead to parthenocarpic fruits, in which the fruits grew directly from the ovule (like pineapples and bananas) without the intervention of pollination. Details are currently uncertain but the optimum length is said to be 12-hour days.


Rainfall The plant is not particularly demanding of water and performs well with as little as 350 to 550 mm. However, dry air during the harvest period is a benefit.


Altitude Although current commercial experience suggests that the plant performs best near sea level, it is probably better to say that it grows well at low to medium altitudes, up to perhaps 1,000 m. Near the equator, however, the upper limit may be closer to 1,800 m.


Low Temperature The lower survival temperature is probably 0°C. However, cool temperatures during the growing period can suppress growth. A report from France notes that optimum germination temperatures were found to lie between 20 and 30°C. Germination was delayed at 12°C and totally inhibited at 8°C.


High Temperature The plant’s growth is largely unaffected by temperatures as high as 40°C; however, it seems that temperatures over about 30°C affects flowering. In addition, germination is greatly inhibited at temperatures above 35°C.



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