Dioscorea cayenensis

Cultivation Details

A plant of the moist, lowland tropics. It grows best in areas where annual daytime temperatures are within the range 20 - 32°c, but can tolerate 12 - 40°c^[2]. Plants can be killed at temperatures of 9°c^[2]. It prefers a mean annual rainfall in the range 1,200 - 1,900mm, but tolerates 900 - 3,000mm^[2]. It prefers a dry season of 2 months or less^[3]. Succeeds in full sun and in moderate shade^[2]. For best yields, this species requires a deep, well-drained, sandy loam that is not liable to water-logging^[3]. Succeeds in relatively light sandy soils^[3], though the soil needs to be very fertile otherwise yields can be low^[1]. Prefers a pH in the range 6 - 6.7, tolerating 5.3 - 8^[2]. Daylengths of more than 12 hours are preferred during the early growing season since this encourages vegetative growth; daylengths of less than 12 hours towards the end of the growing season will encourage tuber formation and development^[3]. Requiring a longer growing season than other yams, mature roots are formed in 9 - 12 months from planting^[3]. The tuber has a very brief resting period and does not store well^[4]. It is in fact best stored, if necessary, in the earth^[4]. The tubers are formed near the surface of the soil^[4] and can be carefully removed from the growing plant without disturbing it, allowing the plant to continue cropping for up to three years^[3]. The tubers can be dug up as required and a common practice is to expose one side of the tuber and to cut away the distal part for consumption leaving the upper part to regenerate; hence the name 'cut-and-come-again'^[4]. This practice may be repeated for upward of three years^[4]. Yields of 30 tonnes per hectare have been obtained in the Caribbean^[3]. There are some named varieties^[3]. Although occasionally monoecious, the plant is usually dioecious, therefore both male and female forms need to be grown if seed is required^[1].