Pomegranate

24.05.17

Pomegranate (Punicum granatum) is believed to be the first domesticated tree in the world. Its centre of origin is Persia (modern-day Iran) and its existence has been recorded over several millennia.

Overview

Depending on its environment, pomegranate is a small, deciduous or semi-deciduous shrubby tree, growing 5–8 metres tall. The tree has glossy, narrow, oblong leaves and in spring, bears bright red flowers. The fruit is a rounded hexagonal shape, 5–12cm in diameter, with thick skin that ranges from yellowy red to bright red when ripe. The fruit has many seeds (400–1,200) contained in a juicy, sweet, pulpy structure (aril). The whole fruit is divided by a membranous pith which is bitter. By weight, the average aril is approximately 50% seed and 5% juice, while the entire fruit may be about 35-50% aril/seed, with the balance being the pith. The arils range in colour from light pink to a crimson red.

The flavour of the arils and juice can range from tart to sweet depending on the variety. The arils of the pomegranate may be consumed fresh or juiced; and the juice may be further processed to produce tea, wine, pharmaceutical products and dye.

Pomegranate has an anecdotal history of health benefits and has been used in traditional medicine as a tonic for heart, throat, intestinal and blood health. Since the 2000s, there has been a considerable increase in research by western countries to quantify and better understand the nutritional benefits of pomegranate. Analytical studies show that pomegranate seeds contain high levels of vitamins C and K, antioxidants and fibre; and it has antibacterial, antifungal and antiviral qualities. Preliminary research suggests that pomegranate may be effective in reducing risk factors associated with heart disease and improving skin elasticity.

While pomegranate has been grown as an ornamental in Australian backyards for decades, commercial pomegranate production in Australia has only been contemplated and embarked upon in the 2000s. The industry is very much a ‘new’ industry and pioneering large scale orchards have struggled. However, some experienced growers consider that good opportunities exist for an Australian pomegranate industry but there is much to be learnt about sourcing true-to-type varieties and understanding the interactions between variety, region and management practices.

Facts and figures

  • In the 2000s, global demand for pomegranates doubled every three years, outstripping global supply
  • The pomegranate juice market in the USA expanded by greater than 750%, into a US$66 million retail industry between 2001 and 2005
  • Less than 1.25% of global production originates from the southern hemisphere and of that, less than 2% is produced in Australia
  • A significant opportunity exists for Australia to market a counter-seasonal product into the northern hemisphere

Production status

India is one of the largest producers of pomegranate, followed by Iran, the United States, Turkey, Spain and Israel. Less than 1.25% of world production is in the southern hemisphere (predominantly South America and South Africa), and Australia only produces 2% of that 1.25%.

There are fewer than 500 hectares of pomegranates planted in Australia, however much of this area had not reached its full potential or full production, due to poorly understood tree health problems in all regions. There are a number of smaller orchards growing pomegranates for the whole fresh and ready-to-eat arils market.

Australia imports pomegranate to meet consumer demand.

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Map of current and potential growing regions

Uses

Pomegranates have many varied uses including:

  • fresh fruit (for eating and as decorative items)
  • fresh juice
  • concentrated juice
  • arils (frozen or fresh)
  • flavouring for jam, ice-cream and confectionery
  • products such as tea
  • pharmaceutical and medicinal uses
  • dyes and decoration.

Pomegranates have a high level of polyphenols or anti-oxidants and are now being promoted as a health food, especially for the juice market. Analytical studies show that pomegranate seeds contain high levels of vitamins C and K, antioxidants and fibre; and have antibacterial, antifungal and antiviral qualities.

Production Requirements

Growing regions

In Australia, pomegranate orchards have been established in the Murray–Darling Basin, from southern Queensland (St. George), to southern New South Wales (Lachlan and Murrumbidgee valleys) and northern Victoria (Shepparton), across to South Australia (Adelaide region, the Murray Mallee, Clare Valley and the south East); and in Western Australia, near Carnarvon and south of Perth.

Soil type

Pomegranates will grow on many soil types, from pure sand to heavy clay, but produce best when grown on deep, heavy, moist loams. While soils should be moist, they must also be well drained. Heavy soils with poor drainage, such as heavy clays are unsuitable.

Soil pH(water) should be 5.5–7.0, but the plant will grow well in slightly alkaline soils. However, the trees’ performance in Australia suggests that nutrition issues related to the soil pH are significant.

Climate

The pomegranate is best suited to Mediterranean climates with cool winters and hot summers, typical of temperate climate zones in Australia although some success has been achieved in the subtropical and arid regions as well.

Pomegranate needs a long hot summer for good fruiting and grows best in warm areas, with temperatures up to 38°C, however, if temperatures are too high, fruit can suffer from sunburn. High humidity may encourage deterioration of fruit quality.

The plant is drought-tolerant and well suited to Mediterranean climates. It does not appear to have a specific annual rainfall requirement for growth, though in commercial production the timing of rainfall is important. Areas with regular summer and autumn rainfall are unsuited as fruit will become soft and susceptible to disease. Irrigation should be available to ensure consistent soil moisture is maintained because too much moisture after a dry spell late in the season can cause the fruit to split.

Varieties

There are many cultivars of pomegranate (more than 500 throughout the world), with a range of fruit quality, varying from very sweet to very acidic flavours and with soft seeds, medium hard seeds or hard seeds. The best quality pomegranates have a good balance of sugars and acidity and soft seeds. Several varieties have been used in Australia to date but there is considerable diversity between and within varieties. Many lines are named as the same variety but have been developed from different stock and can be quite variable in their fruit characteristics.

In order to make the best decision about choosing a variety or varieties, prospective growers need to speak with tree nurseries and other growers about the best variety for a particular location.

Planting and crop management

Site selection for a pomegranate orchard should take into consideration soil type, and availability and access to irrigation water; as well as ensuring that the site receives full sun all day. There is no documented information on site preparation for pomegranates.

Pomegranate orchards are established by planting 12-month-old trees, propagated from hardwood cuttings. While it is relatively easy to strike cuttings, it is advisable to engage a specialist nursery to produce trees for planting.

Trees are planted in early spring, generally at 2­–4m apart along the row, with rows about 4-6m apart. These dimensions will vary with variety, machinery width and any existing infrastructure, such as irrigation rows or trellis established for a previous enterprise. Plants bear fruit on the terminal shoots of branches that receive good light, so production will decrease if tree spacing is too close and branches are shaded by adjacent bushes.

Pruning frequently for the first three years is required to achieve the right tree shape and remove suckers. Ongoing shape management may be required which usually consists of pruning up to twice a year.

Trees should be mulched with compost and/or organic material. Experience to date suggests that the fertiliser needs of the pomegranate are moderate compared with most fruit trees. Applications of a mixed nutrient fertiliser, each month from August to March, will ensure a good nutrient supply for the crop. Soil tests and regular petiole tests during the cropping stage, when trees reach three years and onwards, are very important to refine nutrient requirements.

The pomegranate has good drought tolerance and can also withstand short periods of waterlogging, however a consistent soil moisture content will produce the best results in terms of yield and fruit quality, particularly to stop fruit splitting at maturity. A fully mature grove planted at a high density of 1,000–1,250 plants per hectare, using some sort of trellis, will use and respond positively (yield wise) to 7–9ML/ha of irrigation water, starting with a first year requirement of 2–3ML/ha.

Pomegranates have a higher salt tolerance than most fruit crops. Salinity of irrigation water should be less than 1,000ppm total soluble salts for best results, but plants will tolerate more than 2,000ppm total soluble salts.

Wind protection is beneficial to ensure good growth, and permanent windbreaks should be considered in wind-prone locations.

Weeds, pests, and diseases

In older plantings, mowing or spraying to manage weeds is preferred to cultivation of inter-row spaces, to avoid root damage. Planting of a cover crop mixture of legumes and grasses in the inter-row is a suggested strategy to manage weeds and improve soil structure.

As commercial cultivation is relatively new in Australia, growers should remain vigilant about monitoring crop health, including ensuring that planting material is free of disease. Few major disease problems have been reported in Australian orchards to date, but mildews and rots are not uncommon. They are certainly common in orchards in the northern Hemisphere and it is expected that they will, over time, develop in Australia.

Mediterranean fruit fly occasionally damages fruit where the fruit is cracked, therefore a baiting program may be needed. The presence of this pest in any growing region means that the whole fruit cannot be exported from there to countries where this pest is not found. Queensland fruit fly is also a potential problem, and working with local fruit fly management programs is highly recommended.

There are some vertebrate pest problems for pomegranates. Parrots will attack the fruit if it is cracked, and rats can also damage the fruit. Hares and kangaroos are not a problem; rabbits have been reported to eat young leaves.

Pomegranates are susceptible to various fungal rots so preventative sprays are required from flowering onwards. Growers should consult a horticultural advisor about what is registered for control of these diseases.

Infrastructure Requirements

Pomegranate production is similar to other horticultural enterprises in terms of equipment and infrastructure required. Vehicles and machinery are required for general maintenance of the orchard (such as mowing and weed control) and to assist with harvest — the fruit is handpicked using secateurs but equipment is required to transport it back to the packing shed.

Depending on production systems, a trellising system may be used and discussing the benefits of this with an advisor or another pomegranate grower is recommended.

An irrigation system is essential. Ultimately, drip irrigation gives the best control but flood irrigation can work well in the first few years while the orchard is establishing and to spread capital costs. Overhead sprinklers cannot be used as water on the fruit can affect quality and encourage disease. A soil moisture monitoring system will enable effective and efficient water management.

A packing shed, typical to most horticultural farms, is required to grade, treat, store and pack the fruit.

Harvesting & Processing

Pomegranate fruit is ready to harvest from March to May, with some regional variation. Trees may reach full production three to five years after planting. At full production, growers can expect yields of 10 to 20t/ha. Some varieties in Australia have yielded up to 30t/ha, but that level of production has not been sustained.

The fruit must be removed from the tree using clippers/secateurs. The stem is strong and thick; fruit cannot be pulled from the tree without damaging the fruit and/or tree.

The fruit needs to be carefully handled as it is easily bruised and will crack when too mature. It will also crack if there is too much rainfall in autumn, high humidity, poor watering or high winds. Mechanical harvesters are not available for pomegranates.

Pomegranates will only keep for a day or two without cold storage, then should be kept at 5-7°C with 80% humidity – they may keep for up to 6 months in high grade cold stores. Fruit destined for fresh fruit markets and outlets is graded and packed in single layer trays, such as those used for stone fruit. The fruit must be treated with an appropriate fungicide prior to storage.

Whole fruit may be delivered to a processor, where the arils (the red juicy pulp and its associated seed) are extracted and sold as packaged fresh fruit. With vacuum packaging, arils can be kept for six months.

Pomegranate juice is also another product and as well as being consumed fresh, the juice is used to produce wine and grenadine. After extraction, the waste material can be used for pharmaceuticals and cosmetics.

Makets & Marketing

Global demand for pomegranate and pomegranate products is growing quickly, with industry participants reporting that in the first decade of the 2000s, demand doubled every three years to significantly exceed global supply. Less than 1.25% of global production originates in the southern hemisphere, indicating the excellent opportunity that Australia has to supply counter-seasonal product to the northern hemisphere, as well as supply fresh product to the domestic market.

Early ventures into pomegranate production have had mixed outcomes. Some growers and processors have secured contracts supplying fresh fruit and extracted arils to major supermarkets during the Australian production season. Imported product fills the void other times of the year. Smaller-sized producers sell product to local retailers and markets. Some large developments (100–200 hectare plantings) have not succeeded.

Risks & Regulations

Risks/challenges

The overall risk of producing pomegranates in Australia is because it is a very new industry, where there has been little variety development or refinement of management practices for Australian conditions or different production regions. Selecting the right variety and producing fruit with the right characteristics is critical to winning and maintaining markets.

preliminary assessment of a potential pomegranate industry for Australia, published in 2009, reported that establishing a central germplasm collection and ‘typing’ varieties would be important in developing a new industry, to provide new growers and potential buyers of subsequent fruit with a degree of certainty of what they are purchasing.

A lack of critical mass is a challenge for existing and new growers. Securing markets is difficult if the volume of production is not sufficient to meet contracts and provide consistent supply from year to year.

Regulatory considerations

There are no regulatory considerations specifically regarding the production of pomegranates.

Awareness and adherence of biosecurity is critical when obtaining planting material from overseas. Pomegranates grown in Australia thus far are relatively free of significant pests and diseases. To maintain this relative freedom, planting material must only be imported according to the Australian Government’s biosecurity requirements.

Awareness of control programs and quarantine restrictions for fruit fly are important for market access and for the sustainability of horticultural regions.

Publications

Publications/information

The current pomegranate situation in Australia RIRDC report (2014)

Pomegranate growing NSW Department of Primary Industries Agfact H3.1.42 (2002)

Pollination Aware Case Study: Pomegranate RIRDC Case Study (2010)

Pomegranates in Western Australia published on website of Department of Food and Agriculture, Western Australia (2018)

Pomegranate: preliminary assessment of the potential for an Australian industry RIRDC report (2009)

An R&D Strategy for the Australian Pomegranate Industry RIRDC report (2009)

Image Gallery

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Pomegranate fruit on the tree

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Pomegranates packaged for transport

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Cut pomegranate fruit revealing the edible flesh

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Ripening pomegranate

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Washed pomegranate fruit

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Pomegranate pulp and seeds