Ficus elastica

Cultivation Details

A plant of the dry to moist tropics, where it is found at elevations up to 1,650 metres. It grows best in areas where annual daytime temperatures are within the range 20 - 30°c, but can tolerate 10 - 36°c^[1]. It can be killed by temperatures of -1°c or lower^[1]. It prefers a mean annual rainfall in the range 600 - 1,000mm, but tolerates 300 - 2,800mm^[1]. Prefers a sunny position^{[2, 1]}. Succeeds in most well-drained soils of moderate fertility^{[2, 1]}. Prefers a pH in the range 5.5 - 7.5, tolerating 5 - 8.3^[1]. Ficus elastica seedlings develop root nodules containing 95% water, which act as a water reservoir^[3]. This most probably helps the seedlings to survive the initial epiphytic phase^[3]. During this phase the plant sends down thin aerial roots which only thicken after they have reached the ground^[3]. Young specimens in Java are reported to be epiphytic. The root system of Ficus elastica is shallow and dense, making mixed plantation or intercropping systems impossible. Roots may spread over a distance of 40 metres, as reported for India^[3]. The yield of individual trees in plantations of Ficus elastica can vary very widely, the highest attains 30 times more than the lowest^[4]. The yield of the first harvest is directly influenced by the circumference of the tree and the horizontal length of the incision. A tree of 1.8 metres in diameter yielded 15 kg rubber; the average yields in three consecutive years of 50 wild trees measuring 34 metres tall and 5.7 m in diameter (aerial roots included) were 4, 1.9 and 0.4 kg/tree respectively^[3]. The average annual yield of 55 trees in Bogor Botanical Gardens tapped four times at the age of 8 to 17 years is only 41 g/tree^[3]. It has been reported that the first yield of a tapped aerial root with a diameter of 15 cm yielded 9.3 kg of rubber, but this exceptionally high yield was never confirmed by other measurements^[3]. The symbiotic relation of Ficus spp. With specialized wasps is well-known. Figs can only be pollinated by female agaonid wasps (Hymenoptera, Chalcidoidea, Agaonidae). These wasps are highly species-specific; the fig-wasp associated with Ficus elastica is Blastophaga clavigera, known from India. In Ficus elastica the wasps arrive when female flowers are receptive. They enter the fig via the osteole, a bract-covered apical pore. Once inside they pollinate the female flowers and deposit their eggs in the ovaries. As style length varies greatly within these figs and because the wasp can only reach the ovary of short-styled flowers, only some of the flowers obtain an egg, while in others the seed develops. Male and female wasps emerge after a few weeks, and mate within the fig. The females then emerge from the fig and, in so doing pick up pollen from the newly mature anthers of male flowers. Figs on a single tree mature at the same time, while different trees of the same species flower out of synchrony, thus inducing cross- pollination. The symbiotic relation of Ficus spp. With specialized wasps is well-known. Figs can only be pollinated by female agaonid wasps (Hymenoptera, Chalcidoidea, Agaonidae). These wasps are highly species-specific; the fig-wasp associated with Ficus elastica is Blastophaga clavigera, known from India. In Ficus elastica the wasps arrive when female flowers are receptive. They enter the fig via the osteole, a bract-covered apical pore. Once inside they pollinate the female flowers and deposit their eggs in the ovaries. As style length varies greatly within these figs and because the wasp can only reach the ovary of short-styled flowers, only some of the flowers obtain an egg, while in others the seed develops. Male and female wasps emerge after a few weeks, and mate within the fig. The females then emerge from the fig and, in so doing pick up pollen from the newly mature anthers of male flowers. Figs on a single tree mature at the same time, while different trees of the same species flower out of synchrony, thus inducing cross- pollination^[3].