The Abiu
Patricia Chay-Prove
Fruit of the abiu
(Pouteria caimito)(Photo courtesy of
R.Goebel)
Introduction
The abiu (Pouteria caimito) is a native fruit crop to the warm and moist lowlands of South America. Although introduced to many other locations throughout the world, the abiu is still relatively rare in Australia. It has been described recently along with four other tropical fruits (durian, mangosteen, rambutan and longan) to have good potential for commercial development in north Queensland.
The abiu tree is a precocious and heavy producer and is relatively free from pests and diseases. It is a densely foliaged light green-leaved evergreen with a dense pyramidal crown like the mangosteen. The tree produces shiny dark green lanceolate leaves.
Economics/market
The fresh fruit have to be marketed soon after harvest as it takes only up to 5 days to full ripeness under ambient temperatures. Abiu is eaten slightly chilled or in a fruit salad. The fruit is domestically sold. Due to insufficient production data and a firm idea of market prices, the economics for abiu production is not established.
Abiu have generally received prices ranging between $12-24/tray, averaging $18/single layer tray at the Brisbane Markets. The average weight of each tray is around 5 kg.
General botanical description
The abiu tree is a medium sized evergreen tree, which can grow up to 15 metres in height under ideal conditions. The fruit is oval- to spherical-shaped and ranging from 6 to 12 cm in length. The fruit weighs between 400 to 700 g, and is pointed at the stigma end. When ripe, the skin turns a yellow colour. The skin can be leathery in texture, 3-5 mm thick and produce a sticky latex. The translucent and white flesh inside has a caramel flavour surrounding 1-5 seeds.
The flowers are born along the branches between the outer canopy or leafy tip and the main trunk. Each flowering branch can produce between 20-280 flowers. The hermaphrodite flowers are small and white in colour and found singly or in clusters at the axil of the leaf. The flowers generally open in the morning and last for up to 2 days. First fruiting begins anytime from 2 years onwards for seedlings and grafted trees can flower in the first year. The crop flowers three times a year in north Queensland. Fruit set however is more bountiful during the warmer months.
Fruit development and enlargement proceeds at a constant rate, taking between 100 to 130 days from flowering to fruit maturity depending on the temperature and orchard management. Fruit development is slower during the cooler months of the year than from flowers produced during the November - January period.
Fruiting and bearing patterns
The abiu is a relatively fast growing tropical fruit tree and the bearing age seems to be determined by growth rate. Seedlings take about 2 to 5 years to bear while grafted trees take only 1-2 years.
Several selections currently grown in north Queensland are precocious and highly productive and also have good fruit quality. Propagation is predominantly by seed.
There are three main flowering periods in north Queensland and these may overlap fruit setting. There are no known specific requirements for floral iniation (photoperiod or period of moisture stress) of flowering in abiu. Harvesting is just over three months from flowering. Fruit from any one crop mature over a 3-4 week period.
Good fruit have a distinctive caramel flavour and is rich in vitamins A, B3 and C. It is also a rich source of energy and fibre.
Table 1. Nutritional information for abiu (Anon., 1961)
|
Components |
per 100 g edible portion |
|
Energy (cal.) |
140 |
|
Protein (g) |
1.8 |
|
Fat (g) |
0.4 |
|
Carbohydrate (g) |
36.3 |
|
Fibre (g) |
0.9 |
|
Ash (g) |
0.9 |
|
Calcium (mg) |
22 |
|
Phosphorus (mg) |
41 |
|
Iron (mg) |
1 |
|
Vit A (m g) |
130 |
|
Thiamine (mg) |
0.02 |
|
Riboflavin (mg) |
0.02 |
|
Niacin (mg) |
34 |
|
Ascorbic acid (Vit C) (m g) |
49 |
Production of abiu
Soils and climate
Abiu is a lowland humid tropical or subtropical tree which thrives well in an environment with a high even temperature and high humidity. A temperature range from 20o to 35oC is desirable. The north Queensland environment is suitable for abiu production however, unusually cool temperatures (<-2oC) experienced during the July/August months in north Queensland can limit the areas where abiu is grown. An evenly distributed rainfall of between 1 000-3 000 mm per annum is also desirable. Abiu can be grown at altitudes up to 500 m and the 20oS latitude being the southern limit.
Abiu will grow on a wide range of soils provided it has reasonable water holding capacity and very good drainage. It will not tolerate waterlogged areas or saline soils. It can grow on sandy to clay loams. A slightly acid to alkaline soil in the range of pH 5.5 to 7.5, with high organic matter is preferred.
Abiu need full sun from an early stage. Providing abundant soil moisture is available the above ground conditions do not significantly impact on abiu growth. Supplementary irrigation will be necessary during the dry season for good growth and high yields to be obtained. The abiu plant will tolerate very short periods of moisture stress and moisture stressed trees may still crop well initially, but the size of the fruit will decrease and subsequent cropping reduced until the trees recover. Constant water is required during fruit filling otherwise fruit splitting will occur during this period of rapid maturation.
Windbreaks
Flowering, pollination and subsequent fruit set can be severely limited by exposure to wind and low humidity. Planting of windbreaks is necessary in the Wet Tropics because of the cold south-easterlies during the cool dry period. The windbreaks however, will provide little protection from strong cyclonic winds. Consult your local DPI for suitable windbreak species for your area.
Cultivars
There are several identified varieties. These include Gray, Inca Gold, Cape Oasis, Gray, Z1, Z2, Z3 and Z4, developed in Queensland and T25 and T31 in the Northern Territory. The varieties Z2, Z4, T25 and T31 produce large and good quality fruit. Z1, Z2 and Z3 are good to heavy producers with good fruit flavour. Both Z2 and Z3 have excellent flesh to fruit recovery. Z3 produces small fruit. Planting material of new varieties are becoming available.
Propagation and land preparation
Agronomic practices for this species are largely based on field observations and growers' experience and should only act as a guide.
Plant seed as soon as possible after extraction as seed viability lasts only 1-2 days in dry conditions. Plant seeds near the soil surface. Seeds will germinate readily within 10 days. Germinate in pots or polybags. Seedlings will need regular fertilising, probably with a complete foliar nutrient spray. Field plant when the seedlings are 30-40 cm high and about 9 months old. Field planting can be done at any time in the wet tropical coast of north Queensland so long as irrigation is available.
Deep ripping is recommended if the soil is compacted and also to improve soil drainage and root penetration. In areas where waterlogging or ponding may occur, mounding or installation of undersurface drainage such as agricultural pipes is recommended. Bird manure, compost, straw, etc. may be incorporated into the planting sites 6-9 months prior to planting.
Tree density depends on the soil depth and quality, and irrigation system. Planting distances of 4-8 m in a row and 10 m between rows are used. Full sun is required for healthy growth and development of abiu.
Seedling trees mainly are used for commercial plantings. Grafted trees are not generally used in north Queensland although earlier production can be achieved from grafted trees. Grafting has been shown in other tree species to provide precocity, desirable dwarfness and economy for picking and pruning.
Fertilising
There is little information on fertilising abiu. A preplant application of 15 g is generally given in and around the planting hole followed by split (August, December and April) annual dressings of 10 g N, 2 g P, 17g K per tree per year of age, up to 10 years (Rare Fruits Council of Australia, 1986).
The Department of Primary Industries and Fisheries in the Northern Territory recommend a preplant application of 200 g single superphosphate, 200 g dolomite and 2-3 kg well cured animal manure (1991).
For non-bearing trees split applications of a 10N:10P:10K fertiliser is given in the following amounts:
Year 1 500 g
Year 2 1 250 g
Year
3 2 000 g
Bearing trees need Mg and other trace elements. A fertiliser comprising 12N:12P:17K:2Mg+TE is recommended. Four year old trees require a total application of 2.75 kg per annum. An extra 750 g is needed per year of age, up to 11 years. The applications generally coincide with developmental stages i.e. following each harvest.
However, annual leaf tissue analysis and soil analysis will allow more accurate recommendations to be given. Deficiencies in the trace elements zinc, iron and boron can be corrected. These trace elements are generally applied during flushing, zinc at a rate of 1-2 g/L, iron at 1 g/L and solubor at 1 g/L.
Maintenance
A general maintenance program such as slashing and/or use of contact herbicides to remove competition from surrounding weeds is recommended. During early growth, weeds around the tree trunk should also be controlled, taking care not to damage the young trees.
Pruning is undertaken when the tree is young to develop a good tree shape. Pruning of the growing trees is necessary to remove dead and diseased or broken and misshapen limbs. Strong pruning is essential, selecting strong and fewer branches to hold the fruit crop. A single trunk to at least 3 m height and branches not lower than 1 m from ground level is desirable as this will make harvesting easier. Following harvesting of fruit, any suckers and dry panicles are removed to promote healthy and vigorous regeneration.
The tree and fruits are relatively free from insect pests and diseases. The main insect pests are fruit spotting bugs,fruit piercing moth, peach moth larvae, thrips and fruit flies. Apart from the damage to young foliage, flowers and fruit by these insects, thrips can cause russet scarring of fruit. Scale insects are minor and where they occur, sooty mould can be present.
The flesh is also susceptible to a brown discolouration and produces a watery and bland taste which is unsuitable to market.
Harvesting and postharvest storage
Fruit colour change from green to light and then bright yellow is an indication that the fruit is ready to be picked. The fruit is also quite edible at this stage, but will continue to colour after harvesting. Fully colured, deep gold yellow fruit is over ripe and undesirable as they will damage during packing and transport. Fruit is hand picked. In north Queensland harvesting begins in December and ends in June, with the main pick between January through to March.
Pick at the bright yellow stage. Always handle the fruit with carefully and gently as the skin is susceptible to mechanical damage during handling. At the same time the fruit develops the desirable rich yellow colour. Full ripeness occurs 1-5 days after harvest.
Generally fruit can be harvested just after 3 months after fruit set. Yields are variable, from 10 kg for young (~3 years) trees and 200 kg fruit can be expected annually from mature and large fruited varieties. Fruit picked at the appropriate stage and stored at 10oC have a shelf life of 7 to 14 days.
Fruits are often cleaned following picking and graded according to the size of each fruit. Pack only uniform quality sound yellow fruit. Fruit is often packed in a single layer in polystyrene or cardboard trays, lined with shredded paper to prevent movement during transport and bruising. Coloured tissue wrapping may also be used to improve general appearance.
Further information
- Contact the DPI&F Business Information Centre on 13 25 23 - local call 8 am to 6 pm Monday to Friday (non-Queensland residents phone 07 3404 6999). E-mail: callweb@dpi.qld.gov.au
- Contact the DPI&F bookshop on 07 3239 3772 or DPI&F Shop-Online or at some DPI&F offices throughout Queensland for the DPI publications
- Infopest CD-ROM contains current national information on registered agricultural chemicals and is available from Infopest, DPI&F, GPO Box 46, Brisbane Qld 4001 or by email from infopest@dpi.qld.gov.au
- Recommended Reading:
Parker, G.H. (1986). Rare Fruits Council of Australia. Fact Sheet No.13 Abiu.
Lim, T.K. (1991). Abiu. An old/new fruit. Northern Territory Department of Primary Industries and Fisheries Agnote 446.
Lim, T.K. (1991). Abiu. A botanical and agronomic review. Northern Territory Department of Primary Industries and Fisheries Technical Bulletin No. 169
Anon. (1961) Food composition table for use in Latin America. The Institute of Nutrition of Central America and Panama, Guatemala City and National Institute of Health, Bethesda, Maryland U.S.A.
Information contained in this publication is provided as general advice only. For application to specific circumstances, professional advice should be sought. The Department of Primary Industries and Fisheries, Queensland has taken all reasonable steps to ensure the information in this publication is accurate at the time of publication. Readers should ensure that they make appropriate inquiries to determine whether new information is available on the particular subject matter.
Last reviewed 15 December 2005
