Datasheet

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18 December 2024

Alocasia macrorrhizos (giant taro)

Author: Mary Taylor [email protected]Authors Info & Affiliations

Publication: CABI Compendium

4220

https://doi.org/10.1079/cabicompendium.4220

Datasheet Types: Invasive species, Host plant, Crop

PDF/EPUB

Abstract

This datasheet on Alocasia macrorrhizos covers Impact, Identity, Overview, Associated Diseases, Pests or Pathogens, Distribution, Dispersal, Biology & Ecology, Environmental Requirements, Natural Enemies, Impacts, Uses, Prevention/Control, Management, Genetics and Breeding, Food Quality, Food Safety, Economics and Further Information.

Identity

Preferred Scientific Name: Alocasia macrorrhizos (L.) G. Don
Preferred Common Name: giant taro
Other Scientific Names: Alocasia cordifolia (Bory) Cordem.; Alocasia indica (Lour.) Spach; Alocasia indica var. diversifolia Engl.; Alocasia indica var. heterophylla Engl.; Alocasia indica var. metallica (Schott) Schott; Alocasia indica var. rubra (Hassk.) Engl; Alocasia indica var. typica Engl.; Alocasia indica var. variegata (K.Koch & C.D.Bouché) Engl.; Alocasia macrorrhiza (L.) Schott; Alocasia macrorrhizos var. rubra (Hassk.) Furtado; Alocasia macrorrhizos var. variegata (K.Koch & C.D.Bouché) Furtado; Alocasia marginata N.E.Br.; Alocasia metallica Schott; Alocasia montana (Roxb.) Schott; Alocasia pallida K.Koch & C.D.Bouché; Alocasia rapiformis (Roxb.) Schott; Alocasia uhinkii Engl. & K.Krause; Alocasia variegata K.Koch & C.D.Bouché; Arum cordifolium Bory; Arum indicum Lour; Arum macrorrhizon L.; Arum montanum Roxb.; Arum mucronatum Lam.; Arum peregrinum L.; Arum rapiforme Roxb.; Caladium macrorrhizon (L.) R.Br.; Caladium metallicum Engl.; Caladium odoratum Lodd.; Calla badian Blanco; Calla maxima Blanco; Colocasia boryi Kunth; Colocasia indica (Lour.) Kunth; Colocasia indica var. rubra Hassk.; Colocasia macrorrhizos (L.) Schott; Colocasia montana (Roxb.) Kunth; Colocasia mucronata (Lam.) Kunth; Colocasia peregrina (L.) Raf.; Colocasia rapiformis (Roxb.) Kunth; Philodendron peregrinum (L.) Kunth; Philodendron punctatum Kunth
International Common Names: Chinese
re ya hai yu; English
Egyptian lily
elephant's ear
giant alocasia
western yam
wild taro; French
alocasie
songe blanc
songe sauvage; Spanish
camacho
malanga
yautía
Local Common Names: Brazil
inhame-açú
orelha de elefante
taioba
taioba-branco; Cook Islands
kape; Costa Rica
hoja de pato
pato; Cuba
malanga de jardín; Fiji
via nganga
viadidi
viamila
viandini
viandranu
viasori; Germany
Tropenwurz
Indische; India
mankachu; Indonesia
bira
mael
sente; Laos
kaph’uk; Lesser Antilles
giant tayo; Malaysia
birah negeri
keladi sebaring; Myanmar
pein-mohawaya; New Caledonia
aware
ica
kape
kaxete
koe
kowe
moerere
peka
pia
pidu
poaere
twowe
wave; Papua New Guinea
paragum; Philippines
aba
aba-aba
badiang
bagiang
biga; Puerto Rico
yautía cimarrona; Samoa
ta'amu; Thailand
hora
kradatdam; Tonga
kape; USA/Hawaii
‘ape; Vietnam
khoais
EPPO code: ALDMA (Alocasia macrorrhiza)

Pictures

Habit of Alocasia macrorrhizos (giant taro). Puerto Rico. — Habit
Alocasia macrorrhizos (giant taro); habit. Puerto Rico.
©Smithsonian Institution/Pedro Acevedo-Rodriguez

Habit of Alocasia macrorrhizos (giant taro)- note person on right for scale. Kahanu Garden NTBG Hana, Maui, Hawaii, USA. June, 2012 — Habit
Alocasia macrorrhizos (giant taro); habit - note person on right for scale. Kahanu Garden NTBG Hana, Maui, Hawaii, USA. June, 2012
©Forest & Kim Starr-2012 CC BY 4.0

Close view of large leaf of Alocasia macrorrhizos (giant taro). Kahanu Garden NTBG Hana, Maui, Hawaii, USA. June, 2012 — Leaf
Alocasia macrorrhizos (giant taro); close view of large leaf. Kahanu Garden NTBG Hana, Maui, Hawaii, USA. June, 2012
©Forest & Kim Starr-2012 - CC BY 3.0

Flowering habit of Alocasia macrorrhizos (giant taro). — Habit
Alocasia macrorrhizos (giant taro); flowering habit.
©Fanghong/Wikipedia - CC BY-SA 3.0

Fruit of Alocasia macrorrhizos (giant taro) at Kahanu Garden NTBG Hana, Maui, Hawaii, USA. June, 2012 — Fruit
Alocasia macrorrhizos (giant taro); fruit at Kahanu Garden NTBG Hana, Maui, Hawaii, USA. June, 2012
©Forest & Kim Starr-2012 - CC BY 3.0

Tubers (roots) of Alocasia macrorrhizos (giant taro) being sold near Khanapur, Uttara Kanara, India. November 2012. — Tubers (roots)
Alocasia macrorrhizos (giant taro); tubers (roots) being sold near Khanapur, Uttara Kanara, India. November 2012.
©L. Shyamal/via wikipedia - CC BY-SA 2.5

Diseases Table

Overview

Alocasia macrorrhizos is a large, succulent perennial herb, 1-1.5 m tall (up to 5 m), with large, elongated stems with several broadly sagittate leaves. Propagation is normally vegetative from suckers. It is common and widely distributed in cultivated lands, waste places, old gardens, mesic valleys, low moist disturbed and secondary forests, and along riverbanks and streams from sea level to 600-800 m in tropical and subtropical warm climates. It is widely cultivated, mainly in tropical and subtropical regions around the world. The crop life is usually 12-18 months, but harvesting can be delayed for up to 4 years. It is grown for its starchy corms which are roasted, baked or boiled. The underground tubers are also cooked as a vegetable and the leaves can be fried with onions or garlic. In some countries, it has been used as animal feed, particularly for chickens. It is resistant to most diseases and pests and is generally cultivated in mixed cropping with taro, yams and banana in South and Southeast Asia, and the Pacific region. It is also important in traditional medicine. It has a wide range of medicinal and pharmacological properties, including anti-cancer and anti-inflammatory. Leaf extracts contain ﬂavonoids, cyanogenic glycosides, citric acid, ascorbic acid and polyphenolic compounds. There are some food safety concerns; wild genotypes are characterized by an extremely high concentration of calcium oxalate. In addition, hydrogen cyanide has been identified in young leaves, and there has been a single reported case of a saponin in a root tuber which acted as a neurotoxin. However, the crop has value as a famine food, a function that could be increasingly important with climate change due to the crop’s relative tolerance of changing rainfall.

Summary of Invasiveness

Alocasia macrorrhizos is a fast-growing herbaceous plant, growing up to 5 m in height, which has been intentionally introduced in many tropical and subtropical regions to be used as an ornamental, food crop and animal feed. It can reproduce sexually by seeds, and vegetatively by corms, tubers and root suckers. It can grow in various substrates and habitats ranging from full sun to deep shaded areas.

The massive plants can crown out native species, making them an invasive flora. It is listed as invasive in Cuba, New Zealand, and several islands in the Pacific including Hawaii, Fiji, French Polynesia, New Caledonia and Palau, and it is considered a weed in Vietnam. In Spain, it is on the ‘Attention’ list; a list of species that are climatically suitable for Spain, non-regulated and invasive or potentially invasive. Alocasia sp., including A. macrorrhizos, is a common weed at oil palm plantation in Borneo, Malaysia, competing with immature to young oil palm plants for nutrients.

Taxonomic Tree

Notes on Taxonomy and Nomenclature

Araceae is a family of monocotyledonous flowering plants comprising about 107 genera with over 3700 species distributed mostly in tropical areas in the New World, but also in Australia, Africa-Madagascar, and north temperate regions (Stevens, 2012; Müller and Guzzon, 2024). The genus Alocasia (Schott) G.Don comprises more than 110 species, and is generally found in the understorey of perhumid, subtropical and tropical lowland forests (Arbain et al., 2022; Müller and Guzzon, 2024). A. macrorrhizos is also known as giant taro, mankachu, giant alocasia, metallic taro or giant elephant ear taro; different common names are used by communities across the different cultivation areas (Srivastava et al., 2012; Karim et al., 2014). A. macrorrhizos can be distinguished from A. odora, as A. odora has peltate leaves and a shorter spadix appendix while A. macrorrhizos does not produce stolons from stem bases (Lim, 2015).

Plant Type

Perennial

Seed / spore propagated

Vegetatively propagated

Broadleaved

Herbaceous

Description

Sweet (1839) first described A. macrorrhizos. It is a large succulent perennial herb with large and elongated stems. It is normally 1-1.5 m tall but can grow up to 5 m (Manner, 2011). Factors such as plant age, genotype and environmental conditions influence the height of the plant (Lebot, 2020). Individual plants can become too heavy for the stem to hold upright in which case the stem falls to the ground, but the plant continues to grow from the tip or lateral buds. Adventitious roots can develop from the stem. Inflorescences are relatively large and usually appear in clusters. Fully mature plants develop up to 8 to 16 inflorescence clusters (Garcia et al., 2008). Two or more inflorescences subtended by bracts. Peduncles 20-45 cm long; spathe a whitish to yellowish green, oblong tube; spadix 11-32 cm, pistil 3-4 cm long and about 1.5 cm thick. The upper part of the spathe falls soon after anthesis, and is pale yellow, membranous, oblong and hood-forming (Hay, 1999). Fruit is a fleshy berry, red when mature, globose or ovoid; possibly containing several seeds, (10-50 per fruit). Leaves are arranged in a rosette, ascending; blades flattened, ascending, with basal sinus projecting downward, 25-50 (-100) × 20-36 (-100) cm, green (although white-variegated in some cultivars), slightly lustrous, lance-ovate, coriaceous, wavy or slightly plicate along secondary veins, the apex acute or obtuse and apiculate, the base hastate, the sinuses non-overlapping, up to 30 cm long, the margins wavy, with a sub-marginal vein within 2 mm from the margin; mid-vein broad and conspicuous with 4-7 primary lateral veins per side; lower surface with dark spots on secondary vein angles; petioles 60-100 cm long (Flach and Rumawas, 1996; Wagner et al., 1999; Acevedo-Rodríguez and Strong, 2005; Lebot, 2020; Müller and Guzzon, 2024).The midrib and petiole have laticifers with raphide bundles attached to their inner walls. The laticifers secrete a milky sap reported to contain calcium oxalate crystals (Osuji and Ihenko, 2023). It is suggested that raphide bundles are storage facilities in which calcium is stored in the form of calcium oxalate (Okoli and Green, 1987). Raphides have become an important indicator of aroids in the archaeological record. A. macrorrhizos raphides may be distinguished from other aroid species studied by their bridge, which is visible with light microscopy and relatively short compared to overall crystal length, as well as the shape of the short, wedge-shaped termination (Crowther, 2009).

Corms are long, thick, woody-appearing cylinders or trunks, sometimes reaching a length of more than 2 m, depending primarily on the length of the growth period, which can be over several years. Cultivars are distinguished by their corm characteristics (flesh pigmentation, quality traits, yield, size and shape of corm), leaf pigmentation, variegation and leaf size (Lebot, 2020). Wild genotypes are characterized by an extremely high concentration of calcium oxalate (García et al., 2008).

Species Vectored

Distribution

Alocasia macrorrhizos is native to Bismarck Archipelago, Borneo, Maluku, New Guinea, Philippines, Queensland, Solomon Islands and Sulawesi (Govaerts, 2012). It is currently widely distributed and naturalized in many tropical and subtropical regions. In many tropical parts of Australia, Asia, Africa, the Caribbean and South America, it is valued as an ornamental species or as a minor starch crop. In the Philippines, South Asia and many Pacific Island countries and territories (e.g. Samoa, Fiji, Tokelau, Tonga, Tuvalu, Wallis and Futuna, Papua New Guinea, the Solomon Islands and parts of Vanuatu), it is often cultivated for its starch, as part of traditional agroforestry systems (Wilson and Cable, 1984; García et al., 2008; Manner, 2011; Müller and Guzzon, 2024). It is grown extensively in Samoa, Tonga, the Wallis and Futuna Lau group of Fiji, and parts of Vanuatu (Lebot, 2020).

According to analysis of plastid and nuclear DNA sequences from 71 species of the genus, Nauheimer et al. (2012) showed that Alocasia is monophyletic and sister to Colocasia gigantea from the Southeast Asian mainland. Their findings suggest that the ancestor of Alocasia diverged from its mainland sister group about 24 million years ago; Borneo played a central role in the expansion of Alocasia with the Philippines being reached in the Late Miocene and Early Pliocene, and the Asian mainland 6-7 times in the Pliocene. Domesticated giant taro originated from the Philippines (Nauheimer et al., 2012).

Distribution Map

Distribution Table

History of Introduction and Spread

Alocasia macrorrhizos has been intentionally introduced as an ornamental, food crop and for animal feed in tropical and subtropical regions of the world (León, 1987; Manner, 2011). It has been suggested that A. macrorrhizos was introduced into America through Brazil at the beginning of the 20th century to feed pigs (León, 1987; Gómez, 2001). In the Caribbean, the oldest records of this species are from herbarium collections made in 1925 in Haiti, 1930 in the Dominican Republic, and 1938 in Puerto Rico (Smithsonian Herbarium Collection). From Asia, its seeds probably were spread eastwards naturally to Melanesia, where wild forms were also found in natural habitats (Lebot, 2020). Starch grains of A. macrorrhizos have been found on Solomon Island stone tools dated to 27,000 years before present (Loy et al., 1992). It is suggested that the routes of its spread are similar to those of taro with pre-historic colonizers of the Pacific taking plants with them on their migration eastwards. The year of introduction to these regions is very difficult to determine. In many cases, it was introduced into new areas by aboriginal groups (without written records), complicating the possibilities of tracking the introduction path (Ahmed, 2020).

Risk of Introduction

The risk of introduction of A. macrorrhizos is moderate to high. Its attraction as an ornamental plant increases the risk of introduction. It is a fast-growing herb widely cultivated in tropical and subtropical regions of the world, and it has the potential to become invasive (PIER, 2012; Randall, 2012) near to cultivated areas. It has escaped from gardens and cultivated lands and has been reported as naturalized in natural forests.

Means of Movement and Dispersal

Alocasia macrorrhizos reproduces sexually by seeds, and also vegetatively by corms, tubers and root suckers (Wagner et al., 1999; Manner, 2011). However, the most common form of propagation (mostly outside its native distribution range) is vegetatively. Tubers, corms and root suckers easily re-spread producing new plants which in less than 1 year are complete developed. In addition, tubers and corm can remain on the ground for several months, waiting for suitable environmental conditions to sprout (Manner, 2011). Corms and tubers can be propagated by movement of soil by vehicles and farming machinery.

Pathway Causes

Pathway cause	Notes	Long distance	Local	References
Crop production	Planted for human consumption	Yes	Yes	Manner (2011)
Escape from confinement or garden escape	Occasionally planted as ornamental	Yes	Yes	Manner (2011)
Forage	Used to feed farm animals	Yes	Yes	León (1987), Hammel et al. (2003)
Ornamental purposes		Yes	Yes	Manner (2011)
People foraging			Yes	Manner (2011)

Pathway Vectors

Pathway vector	Notes	Long distance	Local	References
Debris and waste associated with human activities	Easily propagated by tubers or suckers	Yes	Yes	Manner (2011)
Soil, sand and gravel	Corms and tubers	Yes	Yes

Habitat

Alocasia macrorrhizos is common and widely distributed in cultivated lands, waste places, old gardens, mesic valleys, low moist disturbed and secondary forests, and along riverbanks and streams from sea level to 600-800 m in tropical and subtropical warm climates (Smith, 1979; Wagner et al., 1999; Manner, 2011). In Puerto Rico, this species is a common herb along roads bordered by moist secondary forests, abandoned farms, and along streams and riverbanks (Acevedo-Rodríguez and Strong, 2005).

Habitat List

Category	Sub-Category	Habitat	Presence	Status
Terrestrial	Terrestrial - Terrestrial – Managed	Cultivated / agricultural land	Present, no further details	Natural
Terrestrial	Terrestrial - Terrestrial – Managed	Cultivated / agricultural land	Present, no further details	Productive/non-natural
Terrestrial	Terrestrial - Terrestrial – Managed	Managed forests, plantations and orchards	Present, no further details	Natural
Terrestrial	Terrestrial - Terrestrial – Managed	Managed forests, plantations and orchards	Present, no further details	Productive/non-natural
Terrestrial	Terrestrial - Terrestrial – Managed	Disturbed areas	Present, no further details	Harmful (pest or invasive)
Terrestrial	Terrestrial - Terrestrial – Managed	Disturbed areas	Present, no further details	Natural
Terrestrial	Terrestrial - Terrestrial – Managed	Urban / peri-urban areas	Present, no further details	Natural
Terrestrial	Terrestrial - Terrestrial – Managed	Urban / peri-urban areas	Present, no further details	Productive/non-natural
Terrestrial	Terrestrial - Terrestrial ‑ Natural / Semi-natural	Riverbanks	Present, no further details	Harmful (pest or invasive)
Terrestrial	Terrestrial - Terrestrial ‑ Natural / Semi-natural	Riverbanks	Present, no further details	Natural

Biology and Ecology

Genetics

Karyotype analysis revealed complex chromocenter type of interphase nuclei and gradient type of prophase chromosomes. Chromosome number was 2n=28. Total length of the 2n chromosome complement was recorded as 98.83±1.39 μm. Chromosomal length range was 2.50±0.10-4.70±0.10 μm. Total form (TF%) value was found to be 43.58%, karyotype symmetry index (Syi %) was 77.00 % and karyotype asymmetry index (AsK %) was 56.66%. The centromeric formula was 18m+4sm+2ac, representing asymmetric karyotype. In DAPI banding, the 1.48% positive banded region indicates the lower amount of AT rich repeats in this material (Warasy, 2021).

Alocasia macrorrhizos showed more symmetric karyotype consisting of maximum metacentric chromosomes compared to A. fornicata and A. longiloba (Das, 2018). The complete chloroplast sequence of A. macrorrhizos is 154 995 bp in length, containing a pair of inverted repeats of 25 944 bp separated by a large single-copy (LSC) region and a small single-copy (SSC) region of 87 366 bp and 15 741 bp, respectively. The chloroplast genome encodes 132 predicted functional genes, including 87 protein-coding genes, four ribosomal RNA genes and 37 transfer RNA genes, 18 of which are duplicated in the inverted repeat regions. In these genes, 16 genes contained single intron and two genes double introns (Wang and Han, 2016).

The genotypes of A. macrorrhizos are divided into wild (non-edible) and cultivated. Wild plants are not used as food because of an extremely high concentration of calcium oxalate crystals. There is a degree of doubt whether truly wild populations exist; there is some speculation that A. macrorrhizos is a cultigen only (Hay, 1999; Boyce, 2008). Escapees from cultivation can be found among wild plants feral genotypes; they look like wild plants but are edible (Garcia et al., 2008).

Reproductive Biology

In the Araceae family, flowers are borne on a type of inflorescence called a ‘spadix’, which is usually accompanied by a spathe or leaf-like bract (Stevens, 2012). The spadix is divided into different zones with a female zone at the bottom of the spadix and a male zone at the top. These two zones are separated by a sterile mid-zone. At the top of the spadix is a sterile appendix, whose main purpose is to release odorous substances. The spadix is covered by a cream-coloured spathe and forms a floral chamber, which narrows around the sterile mid-zone. Soon after pollen is released, the upper spathe and spadix begin to decay, wither and then drop off (Bown, 2000; Takano et al., 2012; Müller and Guzzon, 2024).

The protogynous flowers in Alocasia are pollinated by insects. For example, in Borneo, flowers of A. macrorrhizos are pollinated by Colocasiomyia flies. A syndrome of pollination mutualism has been described by Takano et al. (2012). Within its native range, A. macrorrhizos reproduces sexually by seed, and vegetatively by tubers and root suckers. However, in Puerto Rico, this species is not known to flower and plants mainly spread vegetatively (Acevedo-Rodríguez and Strong, 2012). Garcia et al. (2008) considered sexual reproduction to be rare due to self-incompatibility and lack of effective pollinators. Lebot (2008) noted that it is predominantly a cross-fertilizing species.

The main pollinators are insects, mostly flies and small beetles, which are attracted by a strong odour. Wind may also be a pollinating agent. Rain usually causes self-pollination and self-fertilization of self-compatible genotypes that can produce numerous seeds. Self-fertilization can be prevented by self-incompatibility, protogyny and the constriction of the spathe in the sterile region between the female and male parts of the spadix. In wild populations, flowering is usually synchronized, which enables cross-fertilization.

Insect pollination is assisted by thermogenesis in the inflorescence, first described by Lamarck (1778). Ivancic et al. (2005) showed that the fertile male part and the sterile appendix were thermogenically active, and that the thermogenic period lasted 38-42 h, with the highest temperatures observed during the female phase, in the sterile appendix tissue. A later study suggested that there are probably three independent heating tissues during the female phase, namely, sterile appendix, fertile male part and differentiated sterile area below fertile male part. The main purpose of thermogenesis of this latter area is heating of the floral chamber, thereby optimizing the environment for pollinating insects (Ivancic et al., 2009). Thermogenic activity occurs in cycles and is synchronized with the receptivity of the stigmas, release of odour and pollen, and visits by pollinating insects (Müller and Guzzon, 2024). The fruits of A. macrorrhizos are berries that may contain several, but not many, seeds. The berries are ovoid and 8-10 mm long (Manner, 2011); the colour of ripe berries appears to be controlled genetically and can be red, orange or yellow. The number of seeds per fruit head varies from 10 to 50 (Lebot, 2008).

Longevity

For cultivated A. macrorrhizos, the crop life is usually 12-18 months, but harvesting can be delayed for up to 4 years. Plants can live for several years and flowering occurs sometime during the second year of growth (Manner, 2011).

Environmental Requirements

Alocasia macrorrhizos prefers to grow in humid tropical and subtropical climates with temperatures ranging from 25°C to 35°C and more than 1700 mm of rainfall at elevations from sea level to 600-800 m (Smith, 1979; Wagner et al., 1999). It is the most drought tolerant of the edible aroids, and cold resistant tolerating temperatures down to 10°C. Freezing temperatures damage the leaves, but new ones sprout readily (Kay, 1987). A study investigating the occurrence of cuticular wax (CW) and its role in physiological mechanisms found that, despite having lower CW than Colocasia and Xanthosoma, A. macrorrhizos had higher sun protection which correlated with the thin and glossy appearance of wax crystals (Pieniazek et al., 2022). The species can be found growing in a wide variety of soil types, ranging from freely drained sandy soils to deep, well drained clayey soils. It tolerates shallow flooding, but it does not tolerate waterlogged soils. A. macrorrhizos has the capability to grow in habitats ranging from full sunlight to deep shade and tolerates up to 4 months of drought (Flach and Rumawas, 1996). Consequently, it can be found growing in limestone rocky soils with low water-holding capacity and holes in the exposed limestone substrate (Manner, 2011). It also grows in gaps in the forest understorey, margins of wet fields, and alongside streams or in roadside ditches. It is moderately salt tolerant and occurs on many South Pacific atolls (Lim, 2015). It is not wind tolerant (https://pfaf.org/user/Plant.aspx?LatinName=Alocasia+macrorrhizos).

Climate

Climate type	Status	Description
Af - Tropical rainforest climate	Preferred	> 60mm precipitation per month
Am - Tropical monsoon climate	Preferred	Tropical monsoon climate ( < 60mm precipitation driest month but > (100 - [total annual precipitation(mm}/25]))
As - Tropical savanna climate with dry summer	Preferred	< 60mm precipitation driest month (in summer) and < (100 - [total annual precipitation{mm}/25])
Aw - Tropical wet and dry savanna climate	Preferred	< 60mm precipitation driest month (in winter) and < (100 - [total annual precipitation{mm}/25])
Cs - Warm temperate climate with dry summer	Tolerated	Warm average temp. > 10°C, Cold average temp. > 0°C, dry summers

Latitude/Altitude Ranges

Latitude North (°N)	Latitude South (°S)	Altitude lower (m)	Altitude upper (m)
24	24	0	800

Air Temperature

Parameter	Lower limit (°C)	Upper limit (°C)
Mean annual temperature	23	31

Rainfall

Parameter	Lower limit	Upper limit	Description
Dry season duration	0	4	number of consecutive months with <40 mm rainfall
Mean annual rainfall	1500	5000	mm; lower/upper limits

Rainfall Regime

Bimodal

Uniform

Soil Tolerances

Soil texture > Light (sands, sandy loams)

Soil texture > Medium (loams, sandy clay loams)

Soil drainage > Free

Special soil tolerances > Shallow

Notes on Pests

According to Manner (2011), giant taro is resistant to most diseases and pests. In Tonga, pests include black cutworm (Agrotis ipsilon), taro sphinx moth (Hippotion celerio) and cluster caterpillar (Spodoptera litura). Minor diseases are caused by Cladosporium colocasiae and Mycosphaerella colocasiae. If soils are poor or waterlogged, leaf blotching and tuber rotting may occur. Other diseases include leaf spot (caused by Cercospora spp., Mycosphaerella alocasiae, Pestalotiopsis spp. or Phoma spp.), anthracnose (Glomerella cingulata) and taro leaf blight (Phytophthora colocasiae). Intercropping, good crop sanitation (including the removal of diseased leaves and plants), fallowing and shifting cultivation are carried out across the Pacific to control pests and diseases.

Li et al. (2016) reported leaf blight caused by Ceratocystis fimbriata in Yunnan, China. Irregular yellowing and brown necrotic lesions form on leaf margins or in the centre of leaves, which enlarge into greyish brown lesions with yellowish halos; infected leaves senesce and die. He et al. (2014) noted that severe leaf spot caused by Colletotrichum karsti infected plants in Guangzhou, China. Small water-soaked dark green spots formed on leaves, enlarging into greyish-white lesions with a yellow halo. Dasheen mosaic virus (DsMV) also affects A. macrorrhizos. In China, a leaf spot disease caused by Fusarium asiaticum has been reported (Zheng et al., 2022). Further, there has been reports of Colletotrichum capsici causing anthracnose on A. macrorrhizos (Ben et al., 2021), and A. macrorrhizos being a new host of ‘Candidatus Phytoplasma asteris’-related strains associated with yellows symptoms (Yu et al., 2023). Diseases caused by C. colocasiae and M. colocasiae are reported as ‘minor’ (Manner, 2011).

List of Pests

Non-Infectious Disorders

Nutrient deficiencies are more likely when A. macrorrhizos is being grown as an ornamental, particularly indoors as a houseplant. Pests include spider mites, mealybugs, scale insects and aphids. Diseases include root rot and leaf spot (https://www.gardenia.net).

Notes on Natural Enemies

According to Kay (1987), A. macrorrhizos is resistant to most pests and diseases affecting the aroid family. For islands in the Pacific, where this species is commonly cultivated, pests include the black cutworm (Agrotis ipsilon), taro sphinx moth (Hippotion celerio) and the cluster caterpillar (Spodoptera litura). Taro beetles (Papuana spp. and Eucopidocaulus spp., order: Coleoptera, family: Scarabaeidae) can also cause some damage but this is relatively small compared to the damage on Colocasia esculenta. Wild pigs can cause damage (Walter and Lebot, 2007).

Natural enemies

Natural enemy	Type	Life stages	Specificity	References
Agrotis ipsilon (black cutworm)	Herbivore	All Stages	not specific	Manner (2011)
Cercospora	Pathogen	All Stages	not specific	Manner (2011)
Eucopidocaulus spp.	Herbivore	Plants\|Whole plant	not specific	Manner (2011)
Glomerella cingulata (anthracnose)	Pathogen	All Stages	not specific	Manner (2011)
Hippotion celerio (taro hawkmoth)	Herbivore	All Stages	not specific	Manner (2011)
Macrophoma	Pathogen	All Stages	not specific	Manner (2011)
Papuana spp.	Herbivore	Plants\|Whole plant	not specific	Manner (2011)
Passalora alocasiae	Pathogen	All Stages	not specific	Manner (2011)
Pestalotiopsis	Pathogen	All Stages	not specific	Manner (2011)
Phoma	Pathogen	All Stages	not specific	Manner (2011)
Phytophthora colocasiae (taro leaf blight)	Pathogen	All Stages	not specific	Manner (2011)
Scarabaeidae	Herbivore	Plants\|Whole plant	not specific	Manner (2011)
Spodoptera litura (taro caterpillar)	Herbivore	All Stages	not specific	Manner (2011)
wild pigs	Herbivore	Plants\|Whole plant	not specific	Walter and Lebot (2007)

Impact Summary

Category	Impact
Economic/livelihood	Positive and negative
Environment (generally)	Positive and negative
Crop production	Negative
Human health	Positive and Negative

Economic Impact

No data are available on the economic damage caused by the spread and invasiveness of A. macrorrhizos.

Impact: Environmental

Alocasia macrorrhizos is an invasive fast-growing herbaceous plant with the potential to displace native vegetation (PIER, 2012). This species has become naturalized outside its native distribution range and is listed as invasive species in Cuba, New Zealand, and several islands in the Pacific including Hawaii, Fiji, French Polynesia, New Caledonia and Palau where it is affecting native vegetation mainly in moist secondary forests and along stream and riverbanks (Sykes, 1970; Smith, 1979; Wagner et al., 1999; Space et al., 2009; Florence et al., 2011; Rankin, 2012; PIER, 2012). In Vietnam, this species is listed as a weed and represents a problem in lowland rainforests (Koo et al., 2000). Alocasia sp. (A. sarawakensis, A. robusta and A. macrorrhizos) is a common weed at oil palm plantation in Borneo, Malaysia, competing with immature to young oil palm plants for nutrients (Abas et al., 2021).

Social Impact

Ferreira-Keppler et al. (2017) demonstrated that the axils of A. macrorrhizos, which are commonly used as ornamental plants in urban areas of Manaus, Amazonas, provide breeding sites for Aedes aegypti and Aedes albopictus, which are medically important species.

Risk and Impact Factors

Invasiveness

Proved invasive outside its native range

Has a broad native range

Tolerates, or benefits from, cultivation, browsing pressure, mutilation, fire etc

Tolerant of shade

Benefits from human association (i.e. it is a human commensal)

Long lived

Fast growing

Reproduces asexually

Impact outcomes

Modification of nutrient regime

Monoculture formation

Reduced native biodiversity

Threat to/ loss of native species

Impact mechanisms

Competition - monopolizing resources

Competition - smothering

Pest and disease transmission

Rapid growth

Rooting

Likelihood of entry/control

Highly likely to be transported internationally deliberately

Uses

Alocasia macrorrhizos is mainly cultivated for its starchy stem tubers. In the Pacific islands, the stem tubers are roasted, baked, or boiled, and eaten as a source of starch. In southeastern Asia (i.e. India, Bangladesh and Malaysia), the stem tuber is peeled, cut into pieces and eaten as a vegetable after cooking, usually in curries or stews (Manner, 2011). In Bangladesh, the leaves are sometimes eaten. In Fiji, the leaves are used to cover the lovo (a traditional earth oven). In the Kingdom of Tonga, A. macrorrhizos is the first crop to be planted when land is cleared, intercropped with yams as the main crop (Müller and Guzzon, 2024). In times of scarcity, it is used as a famine food (Wagner et al., 1999). The underground corms and leaves are cooked and used for food. In tropical America, this species has been used to feed pigs and farm animals (León, 1987; Gómez, 2001). Root and leaf meal has also been used in feeding poultry (López et al., 2012; Diarra et al., 2016; Diarra, 2018). Diarra (2020) found that peeling or increasing dietary Ca carbonate level from 40 to 60 g/kg improved the utilization of whole or peeled corm in terms of egg production and egg qualities. Baidiango and Elogsong (2024), studied the impact of substituting A. macrorrhizos meal on the growth performance, feed conversion efficiency and meat quality of hogs, accompanied by an economic and nutritional analysis. They found that despite the potential cost-saving in using A. macrorrhizos, the economic and nutritional trade-offs may restrict its use in large-scale operations. In Hawaii, A. macrorrhizos, namely the varieties Faitama and Laufola, are being evaluated for their use as animal feed (Kularatna et al., 2024).

Across South and Southeast Asia, giant taro has been used in traditional medicine, for example, in the treatment of diabetes, pus in the ears, jaundice, snake bites and constipation (Rahman et al., 2012; Arbain et al., 2022). In Malaysia, the juice is used to treat stings of the giant nettle (Laportea spp.) and sap from the petioles is used to treat coughs. Chopped up roots and leaves are applied to joints to relieve pain and as a rubefacient. Young leaves and their sap are used to treat headaches in Papua New Guinea, while in India the corm is used for scorpion stings, and to treat gout, rheumatism, and spleen and abdominal problems (Lim, 2015). In India, the Konda Reddis and Savaras tribes use A. macrorrhizos to kill worms in domestic animals (Haque et al., 2014). Leaves are used as an astringent, a styptic and an anti-tumour agent, and to treat skin disorders and burns. Cordeiro et al. (2023) reported the potential utility of A. macrorrhizos against vitiligo (skin pigmentation disorder). Leaf poultices are used to relieve joint pain. In Indonesia, the tuber has a range of uses, including the treatment of fevers, influenza, diarrhoea, headaches, malaria, typhoid, rheumatism, tuberculosis, abscesses, ringworm and bites of dogs and insects. In West Java, the leaf stalk of A. macrorrhizos is boiled in water and drank (or eaten) raw by the traditional people of the Cikondang village to treat coughs (Arbain et al., 2022). Leaves, harvested from gardens, are used to wrap food, mainly tape (made by processing cassava or sticky rice with a yeast fermentation process) in central Java (Metananda et al., 2023). Stem juices are used to treat oedema, pain and bleeding from wounds in Bangladesh. Ground petioles are used in the Philippines to treat toothache. In China, it is used widely to treat joint problems, influenza, headaches, bleeding haemorrhoids, pulmonary tuberculosis, bronchitis and appendicitis, and is used as an anti-inflammatory. In Hawaii, tubers are used to treat burns and stomach aches (Lim, 2015).

Medicinal and pharmacological properties were extensively reviewed by Lim (2015). Tuber and leaf extracts have significant antioxidant, anti-hyperglycaemic, anti-cancer, anti-inflammatory, cytotoxic, analgesic, anti-bacterial, hepatoprotective, anti-diarrhoeal, haemagglutinating, thrombolytic, anti-malarial, immunomodulatory, anti-protozoal, anthelminthic, anti-hyperlipidaemic and proteinase inhibitory activities. Significant laxative, diuretic and natriuretic activity was also noted. Lignanamides and monoindoles might be responsible for the anti-inflammatory activity (Huang et al., 2017). Tubers were found to contain the sterols cholesterol, β-sitosterol, stigmasterol, campesterol and fucosterol (Lim, 2015) and piperidine alkaloids (Huang et al., 2017). Piperidine alkaloids isolated from A. macrorrhizos rhizomes have demonstrated significant anti-tumour activity (Gao et al., 2022), as has the sulphated polysaccharide extract of tubers where studies have indicated inhibition of the carcinogenesis initiation phase (Gamal-Eldeen et al., 2023). A. macrorrhizos lectin (AML) suppressed the proliferation of mice Ehrlich ascites carcinoma (EAC) cells by 35% and human lung cancer (A549) cells by 40% at 512 μg/ml concentration (Hridoy et al., 2024). Leaf extracts contain ﬂavonoids, cyanogenic glycosides, citric acid, ascorbic acid and polyphenolic compounds (Lim, 2015). Most plants containing flavonoids also have hypolipidemic properties. However, a study by Ramya et al. (2012) demonstrated that A. macrorrhizos may not be suitable as a lipid-lowering agent as it increased serum LDL-cholesterol.

Alocasia macrorrhizos has been also used as an ornamental for its attractive leaves (Kay, 1987). It has been shown to be useful against termites. High percentage yield, high anti-termite efficacy and high toxicity levels were achieved using ethanol extracts from the stalks of wild A. macrorrhizos (Egloso, 2018). A. macrorrhizos has been studied in China for its ability to stabilize municipal sludge. Results indicate that the sewage sludge could be stabilized at about 5 months and that the E. coli numbers significantly decreased (Samake et al., 2003; Lin et al., 2022). Saim et al. (2018) reported that A. macrorrhizos was a promising plant for degrading cyanide. Its use as a component of a microbial fuel cell in an evapotranspiration reactor demonstrated 60-95% higher electric power potential than Eleusine indica grass in short-term (30-day) operation (Zaman and Wardhana, 2018).

Uses List

General > Botanical garden/zoo

Environmental > Agroforestry

Environmental > Amenity

Medicinal, pharmaceutical > Source of medicine/pharmaceutical

Medicinal, pharmaceutical > Traditional/folklore

Human food and beverage > Emergency (famine) food

Human food and beverage > Flour/starch

Human food and beverage > Food

Human food and beverage > Root crop

Human food and beverage > Vegetable

Animal feed, fodder, forage > Fodder/animal feed

Animal feed, fodder, forage > Forage

Ornamental > Garden plant

Ornamental > Potted plant

Prevention and Control

Due to the variable regulations around (de)registration of pesticides, your national list of registered pesticides or relevant authority should be consulted to determine which products are legally allowed for use in your country when considering chemical control. Pesticides should always be used in a lawful manner, consistent with the product's label.

Mechanical removal of A. macrorrhizos is effective but is labour intensive. All corms and tubers should be removed to prevent spread into new areas. Dense stands should be removed using specialized machinery. In Borneo, trials using different herbicides as ‘cocktail’ treatment showed good bioefficacy compared to single herbicide treatment with a combination of contact and systemic herbicide, demonstrating significant cost-effectiveness compared to others (Abas et al., 2021).

Cultivation

In the Pacific islands, mostly in Samoa, Tonga, Wallis, Futuna and Niue, A. macrorrhizos is grown in mixed cropping with taro (Colocasia esculenta), yams and banana. Cropping time is 18-24 months from planting and tubers are reportedly over 1 m in length and up to 20 cm in diameter (Singh et al., 2017). In Vanuatu, it is considered a neglected crop, but yield potential is considered high and there are no serious pests or diseases (Garcia et al., 2008).

Suckers and cormlets are used as propagules. Suckers are planted in holes, 15-25 cm deep, and cormlets are planted in shallower holes (8-15 cm deep). Humus, ash and decomposed leaves are occasionally mixed into the soil before planting. During sole planting crop spacings of 60 to 1.5 m are used, but when intercropped with yam, plants are spaced at 3.5 m (Manner, 2011). On Fais Island, A. macrorrhizos is often intercropped with C. esculenta. Weeding is undertaken at least every 2 weeks and earthing up is common. In Hawaii, the crop was fertilized (280 kg/ha/crop each of nitrogen, phosphate and potash); nitrogen was used as a pre-plant at 3, 5 and 7 months; phosphate as a banded pre-plant; and potash as a pre-plant at 5 months. Dolomite limestone was added as an amendment at 1120 kg/ha (Foliaki et al., 1990).

Intercropping with rubber trees in plantations, a system practiced in Hainan, China, significantly inhibited the growth of A. macrorrhizos by decreasing the soil nutrient content (Li et al., 2019), but the addition of nitrogen fertilizer at 200 kg ha^-1 mitigated the adverse effects of intercropping (Li and Lin, 2021). Plant height, leaf area and the number of leaves produced by the main plants had a strong positive influence on the yields (Kularatna et al., 2024).

Harvesting

Unlike taro, the edible part of the stem is produced above ground which facilitates harvesting. Harvesting may take place 6-11 months after planting across India, Sri Lanka and Bangladesh (Singh et al., 2017).

Postharvest Treatment

Postharvest handling and processing are similar to those used for taro (Colocasia esculenta). The harvest must be used within a month of harvesting to avoid rotting. The storage life can be extended to 3-5 months by keeping the stems in a cool, dry and dark environment (Müller and Guzzon, 2024).

Genetic Resources and Breeding

An online search of the Genesys, the Global Information Portal for Plant Genetic Resources (Genesys, 2024) showed that 15 accessions, of which 11 originate from Samoa (seven accessions), Tonga (three accessions) and Fiji (one accession), are stored in the in vitro collection of the Centre for Pacific Crops and Trees (CePaCT), Fiji; two accessions are conserved at the Tropical Agricultural Research Station, Clonal Repository USDA/ARS; and two accessions are conserved at the National Arboretum-Germplasm Unit, USDA/ARS. The GRIN Global of the U.S. National Plant Germplasm System [NPGS 2024] shows that one accession (a variegated sport) is held at USDA, ARS Tropical Agriculture Research Station in Puerto Rico. 18 accessions are held at the National Plant Resources Centre Vietnam, Hanoi, as field collections. The gene bank of ICAR-RCER, Research Centre for Makhana, holds ten Indian accessions collected from Bengal, Jharkhand and Bihar (Jana, 2019). Guarino (2004) reported 13 local varieties of A. macrorrhizos conserved in a field collection of the National Agriculture Research Institute (NARI) in Papua New Guinea and two local varieties conserved in vitro by the Ministry of Agriculture, Forests, Fisheries and Meteorology of Samoa. The Global Crop Diversity Trust (2006) reported a field collection of ten accessions at the VARTC (Vanuatu Agricultural Research and Technical Centre) in Vanuatu. Rahim et al. (2021) reported five local accessions conserved at BAU-GPC (Bangladesh Agricultural University Germplasm Centre). There are collections of several ornamental (presumed wild) species in botanic gardens and nurseries. The Hortus Botanicus Leiden, in the Netherlands, holds 42 accessions, and the Belgium National Botanic Gardens hold 17 accessions (https://www.genebanks.org/wp-content/uploads/2017/01/Edible-Aroids-Strategy-2010.pdf).

In a study of 20 accessions collected from across Java, Suratman et al. (2016) reported a high level of genetic diversity in morphological characteristics. Isoenzyme polymorphism showed no relationship between genetic diversity and geographical distribution. Paul and Bari (2011) also noted a high level of variation in morphological traits in Bangladesh accessions. Retrotransposon-based molecular markers have been used within X. saggitifolium and C. esculenta to assess intraspecific variability. Using information on the location of oligonucleotide repeats in the chloroplast genome of taro, 30 primer pairs were identified to amplify and sequence polymorphic loci. The primers were tested in a range of intra-specific to intergeneric comparisons, including Alocasia. These primer pairs show suitability for phylogeographic and evolutionary studies of aroids (Lebot, 2020).

With regards to breeding/selection work, the cultivar ‘AU Man Kachu-1’, recently released by BAU-GPC (Bangladesh), is particularly suitable for commercial production in southern districts of Bangladesh (Rahim et al., 2021). There is speculation that A. macrorrhizos has hybridized with A. portei in the Philippines to give a form with slightly wavy leaf margins. In Vanuatu, all attempts to cross A. macrorrhizos and Colocasia esculenta have failed. The focus of any crop improvement programme would be quality of corms, growth cycle (the growth period is extremely long), environmental adaptability and disease resistance (Lebot, 2020).

Correlation and path coefficient analysis found that plant height, leaf area index, corm length and corm diameter had positive correlations with yield both at the genotypic and phenotypic level (Paul et al., 2015). Emasculation and hybridization procedures are detailed by Ivancic (2011).

In wild populations, the most variable traits observed in wild populations are the number of inflorescences, number of infructescence per plant and corm length. These traits are highly variable even within genetically uniform populations and are highly influenced by age differences between plants (Garcia et al., 2008).

Major Cultivars

Wild and non-edible forms have corms with high levels of oxalic acid, but cultivated forms have lower levels of this anti-nutrient. Cultivated genotypes may be distinguished by leaf and tuber characteristics such as length, diameter, smoothness and colour of tuber skin and flesh. Feral forms, that escaped from cultivation, are edible but have the appearance of wild forms (Garcia et al., 2008). Manner (2011) noted that there are four landraces in Tonga. The most cultivated one is 'Kape hina' but similar genotypes, 'Kape 'uli' and 'Fohenga', are more popular in the Vava'u islands where the climate is warmer and wetter. 'Kape fulai' has a high irritant content. On Fais Island (part of the Caroline Islands group), where A. macrorrhizos is preferentially grown, ten landraces are recognized (Manner, 2011). In Samoa, 12 varieties are known (Müller and Guzzon, 2024). Niu Kini and Tonga are the main cultivars in the South Pacific (Foliaki et al., 1990). In Bangladesh, two main varieties are grown, namely ‘Giraman’ and ‘Dheki Man’. Laufola and Faitama are two varieties better suited to be grown in Hilo, Hawai‘I (Kularatna et al., 2024).

Propagation

Propagation is normally vegetative from suckers but shoot tips with a narrow part of the stem and rolled leaves can be used along with stem sections bearing two or three buds (Lim, 2015). Propagation from seed is possible and seeds may be sown on well drained compost at a depth of 5-8 mm. High humidity is essential and the optimum temperature for germination is 24-28°C (Ivancic, 2011).

Bolaños-Portilla and Montes-Rojas (2016) compared the effectiveness of vegetative propagation methods including use of stem discs, stem buds, T3-T4 suckers and buds. Buds were the most effective propagule in terms of plant height achieved. Adelberg and Toler (2004) noted that an agitated thin film liquid system was more effective than using agar as a culture medium for micropropagation. However, modified MS medium was used successfully for in vitro propagation using seeds (Zhang et al., 2012) and dormant buds (Liu et al., 2009) as explants. Mohamed-Yasseen (2002) developed shoots from callus using MS medium supplemented with 2.2 µM BA. Rachmawati et al. (2023) reported on a method utilizing microbulblet explants and MS supplemented with thidiazuron and BAP for Alocasia cuprea which they believe could be used as the basis for propagation of other Alocasia species. Yachya et al. (2023) found that kinetin at a concentration of 10 mgL^-1 is the optimum concentration for the formation and growth of roots of A. macrorrhizos variegata.

Nutritional Value

Aberoumand et al. (2010) reported proximate values of stems: 5.44% crude protein, 9.1% ash, 3.25% crude fats, 22.9% crude fibre and 59.31% carbohydrates with an energy value of 288.25 kcal per 100 g DW. Mineral contents per 100 g DW were 4.63 mg potassium, 1.62 mg sodium, 7.37 mg calcium, 5.04 mg iron and 3.83 mg zinc and presented a good source of the micronutrients, potassium, sodium and zinc.

Raw stem tubers were reported by Dignan et al. (2004) to contain (per 100 g) 70 g water, 2.2 g protein, 0.1 g fat, 22.5 g available carbohydrate, 1.9 g dietary fibre and 4262 kJ/102 kcal energy value. Micronutrient contents were 30 mg sodium, 267 mg potassium, 38 mg calcium, 52 mg magnesium, 0.8 mg iron, 1.6 mg zinc. Vitamin contents were 0.02 mg thiamine, 0.02 mg riboflavin, 0.5 mg niacin, 17 mg ascorbic acid and 2.4 mg vitamin E.

In an analysis of several root crops in Northeast India, high carotenoids (12,466 ± 32.08 μg/100 g) were observed in the A. macrorrhizos leaves (Chyne et al., 2019).

Phytosanitary Issues/Food Safety

Phytosanitary

New Zealand has specific requirements for importing fresh A. macrorrhizos for human consumption (https://www.mpi.govt.nz). Australia requires mandatory pre-shipment methyl bromide fumigation for importing giant taro (https://www.agriculture.gov.au/biosecurity-trade/import/industry-advice/2021/03-2021).

The acrid juice from the leaves causes skin blisters and swelling of the mouth and throat if chewed due to the presence of raphides of calcium oxalate; prolonged boiling or roasting is required to reduce levels of raphides of calcium oxalate before consumption (Quattrocchi, 2012; Lim, 2015). Washing, peeling, dicing, soaking overnight, blanching and drying also reduces calcium oxalate levels. Kumoro et al. (2014) reported that soaking corm chips in 2% w/v sodium bicarbonate solution for 20 min at room temperature reduced levels of calcium oxalate to 67.7 mg/100 g, which is below the safe threshold level of 71 mg/100 g.

Lim (2015) cited other toxicity issues concerned with levels of hydrogen cyanide present in young leaves (up to 0.018%) while ingestion of root tuber caused a single case of poisoning. Severe pain and numbness around the mouth and throat along with nausea, vomiting and abdominal pain was caused by a saponin acting as a neurotoxin. Other cases involving symptoms of salivation, dysphonia, abdominal pain, mouth ulcers, difficulty in swallowing, thoracodynia, chest tightness and swollen lips were thought to be caused by raphides of calcium oxalate. Research in India evaluated the influence of different growth media on calcium oxalate content. It was observed that T4 [Fertile soil (50%) + leaf mould (25%) + ash (25%)] produced healthy and bigger plants with minimum calcium oxalate content of 72.66 mg/100 g edible (Jana, 2018).

Production and Trade

Commercial production is confined to South and Southeast Asia and the Pacific region, with Samoa and Tonga being the two countries with the highest production. Theoretically, yields of up to 80,000 kg/ha are obtainable. In the Piihonua area, near Hilo on the Island of Hawaii, 78,500kg/ha were obtained with cv. Tonga whereas only 16,000 kg/ha was obtained with cv. Niu Kini (Foliaki et al., 1990). Recent research exploring the possibility of A. macrorrhizos as fodder found that the cv. Laufola gave good yields compared to the cv. Faitama (Kularatna et al., 2024). With traditional cultivation in polycropping systems, yields between 15,000 and 30,000 kg/ha are more realistic. Tonga exports 700-1000 t of frozen stems to Australia, New Zealand and West Coast USA, while Samoa exports mainly to American Samoa (Manner, 2011).

Prospects

There is potential for A. macrorrhizos to be utilized as a supplementary fodder feed (Baidiango and Elogsong, 2024). The cultivar ‘AU Man Kachu-1’, recently released by BAU-GPC (Bangladesh), is particularly suitable for commercial production in southern districts of Bangladesh (Rahim et al., 2021).

The advantages of A. macrorrhizos could become more apparent with climate change. In Papua New Guinea, it is grown successfully across locations with rainfall of 2000-4000 mm per year, yet at the same time, it can be quite tolerant to extended periods of drought. Drought results in a reduced leaf area but the plant resumes growth once rainfall resumes. It is susceptible to cyclone damage, but the corms will support new vegetative growth (McGregor et al., 2016). Plants will also grow in periodically flooded areas.

Gaps in Knowledge/Research Needs

There are several areas where future reseach could focus on:

•

Increasing the productivity of this crop through research on better agronomic management, crop breeding and strengthening of local value chains (Müller and Guzzon, 2024).

•

Better understanding the climate resilience of the crop.

•

Better understanding the history of introduction and spread.

•

Evaluating its impact on native plants and natural communities to develop appropriate management and control strategies.

•

Determining recommendations for management and control in natural areas invaded by this species.

•

Establishing the link between traditional uses, active compounds and pharmacological activities of Alocasia species.

•

Optimizing the processing methods for A. macrorrhizos to improve its nutritional value and to reduce the impact of anti-nutritional factors.

•

Investigating the long-term effects of A. macrorrhizos on animal health and the potential for using other locally available feed resources in combination with A. macrorrhizos to improve overall feed efficiency and economic viability (Baidiango and Elogsong, 2024).

Links to Websites

Website	URL	Comment
Angiosperm Phylogeny Website	http://www.mobot.org/mobot/research/apweb/
ASEAN Tropical Plant Database	http://211.114.21.20/tropicalplant/html/introduction01.html
Flora of the West Indies	http://botany.si.edu/antilles/WestIndies/
Specialty Crops for Pacific Island Agroforestry	http://agroforestry.net/scps
Kew Botanic Gardens Plants of the World	https://powo.science.kew.org/
Plants for a Future	https://pfaf.org/user/
Creating gardens	https://www.gardenia.net/
CGIAR genebanks	https://www.genebanks.org/

References

Abas, M.A., Karim, M.F.A., Fitriani, N., Razikin, M.Z.M., Hamzah, Z., 2021. Commercial herbicides trial against Alocasia sp. (wild yam) at oil palm plantation, Borneo, Malaysia.IOP Conference Series : Earth and Environmental Science, 756:012057. https://iopscience.iop.org/article/10.1088/1755-1315/756/1/012057

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