Arachis pintoi

Cultivation Details

A plant of the moist tropics, also succeeding in humid subtropical areas. It is found at elevations up to 1,400 metres. It grows best in areas where annual daytime temperatures are within the range 22 - 28°c, but can tolerate 12 - 30°c^[1]. Top growth is killed by frost, but plants can regrow from the taproot if the frost was only light^[2]. It prefers a mean annual rainfall in the range 1,500 - 2,000mm, but tolerates 900 - 3,000mm, and can tolerate a dry period of up to 4 months^{[3, 1]}. The plant grows best in light shade, but is also tolerant of full sun and heavy shade^[4]. It grows well in most soil types, preferring a fertile soil but succeeding in soils of low fertility^[1]. It cannot reproduce in heavy clay soils, or in any soils that form a hard cap after rain, because the developing seedpod is unable to penetrate the soil and dies^[2]. It can tolerate low levels of salt in the soil^[1]. It prefers a well-drained soil, but can tolerate some water logging^[1]. Prefers a pH in the range 5.4 - 6, tolerating 4.5 - 7.5^[1]. There are no reports about this species becoming a weed. However, once established it is very difficult to eradicate, spreading by stolons for up to 2 metres a year in the wet tropics and about 1 metres a year in the subtropics. Since the seed develops underground any natural dissemination can only be by water erosion. The seeds are soft and digestible and are not spread through animals^[2]. Seedlings develop quickly following germination, and with good growing conditions and several plants per square metre, a complete ground cover can be achieved by a network of stolons in less than six months^[4]. Flowering commences three to four weeks after emergence and continues through the growing season, appearing to intensify following rain or irrigation^[4]. The develping seedpod is borne on a gynophore or peg, which elongates to up to 27cm after pollination and pushes the seedpod up to 7cm deep into the soil^[4]. Plants are rarely subjected to fire in their native habitat. However, high levels of seed in the soil, plus the capacity to re-establish new crowns at depth if the surface crown is destroyed, ensure a good recovery after fire^[2]. This species has a symbiotic relationship with certain soil bacteria; these bacteria form nodules on the roots and fix atmospheric nitrogen. Some of this nitrogen is utilized by the growing plant but some can also be used by other plants growing nearby^[5].