By Ken Love
Scientific name: Punica granatum L
Origin: Iran, Afghanistan, India
One of the earliest cultivated fruit; the pomegranate is steeped in history and tradition. Mentioned in Egyptian mythology, the fruit was carried by early travelers throughout the Middle East and Northern Africa. The fruit is a symbol of Armenia. In ancient times, eating pomegranate was said to “purge the system of envy and hatred”. Recent worldwide popularity of the fruit and its juice is due to the health benefits from antioxidants in the fruit.
Spanish settlers first reported the fruit in California in 1769. The fruit is commonly referred to as grenade or granada and by the Persian names dulim or dulima. In Japanese the fruit is called zakuro and sometimes sold under that name in Hawaii. Dr. F.J.F. Meyen first reported it in Hawaii in 1825 and Hiram Bingham reported it for sale in a Honolulu market in 1831.
There are hundreds of known pomegranate varieties. The USDA germplasm repository in Davis California has 189 accessions from many parts of the world. Pomegranates can be divided into four groups based on skin color, dark red, yellow green, black violet and white. Plants do not come true to seed. Since plants do not breed true from seed, and many trees in Hawaii are seedlings, the quality in the state is highly variable. Many seedling trees have larger seeds than cultivated varieties and make up over 50% of the fruits weight. In India, the seeds are used for culinary purposes and some varieties reflect this by having 70% of the fruits weight being from seeds. A variety from California named Wonderful is found in Hawaii. Grenada, a patented variety that matures a month earlier than Wonderful is also found in the state.
The tree tolerates a wide range of soils and is very drought tolerant. Irrigation is used to guarantee fruit production, as trees will not flower in extended periods of drought.
Trees are spaced from 15 to 20 feet in commercial orchards. Generally, 20 foot spacing is used in large orchards to facilitate weeding and field maintenance. Wide spacing and planting in full sun insures that enough light reaches the fruit for coloration.
Pomegranates require an active pruning regime for the first three years in the field. After planting, the low side shoots should be cut off to form one or more trunks. The tree is a vigorous grower with many root shoots and suckers. They should be removed as they generally do not bare fruit and grow rapidly at the expense of fruiting wood. Fruit forms only at the tips of new growth. Branches should be shortened to encourage new shoots and the tree kept low to facilitate harvesting. Fertilization generally takes place in fall or winter with one half pound of nitrogen followed by a quarter pound of 6-6-6 organic fertilizer in spring. The trees reach full production in 5 to 6 years. Some producing trees in the Middle East are reported to be 200 years old.
Trees in Hamamatsu Japan after pruning.
Pests and Diseases
Pomegranates suffer some foliar damage from whitefly (Aleurodicus sp), thrips (Selenothrips sp), mealy bugs (Pseudococcus sp) and scale (Ceroplastes sp).
Wet fruit rot, (Phomopsis sp), can occur at the base of the fruit. Removing and disposing of affected fruit is advisable to prevent spread of the fungus. Fruit rot from Botrytis cinerea can occur after harvest from improper storage.
The hard shell of the fruit prevents damage from a number of insects but the base of the fruit, the calyx and stamen cluster can be home to ants, roaches and other pests. Some growers will cut this off half way through the growing cycle to prevent infestation. In Asia, it is common to use protective wrapping or fruit bags on pomegranate once the fruit is set.
This helps to prevent a number of pests and rain-born virus. It also helps with even coloration of the fruit.
Pomegranates are commercially propagated from hardwood cuttings between 10 and 20 inches in length with a rooting hormone used to insure development. Air layers are also possible. Seeds easily germinate but often produce unreliable results. Grafting is seldom successful.
Harvesting and Yield
Fruit ripens 6 to 7 months after flowering but will crack if left too long on the tree. Generally fruit are harvested once they turn color and before yellowing appears at the base.
The fruit does not continue to ripen once harvested and timing can be critical in commercial orchards. Growers in Israel and California tap the fruit listening for a metallic sound that tells them it’s time to harvest. Strong stems require the fruit be cut from the tree and not pulled off by hand. Mature healthy trees can produce 100 to 200 fruit. Kona trees at 400-foot elevation produce 3 to 5 fruit per week, throughout the year when irrigated. An older tree at 1800 feet elevation in South Kona produced more than 200 fruit from July through December.
The pomegranate has a long storage life of more than 7 months when held 32ľ to 41ľ F and a relative humidity of 80 to 85%. The fruit is susceptible to chilling injury and browning if stored below freezing.
Cost of Production
The project pomegranate tree produced an annual marketable yield of 40.0 pounds. The average market price was $5.25 per pound, and therefore the tree generated a gross revenue of $210.00 for the year. Growing costs (fertilization, irrigation, pruning and all weed and pest control) amounted to $20.42, and harvesting costs (picking, packing and delivery to market) totaled $85.10. (All labor to grow and harvest the pomegranates was assumed to be paid at an hourly wage rate of $16.00, including withholding, FICA and benefits.) Thus, the total annual operating costs, sometimes referred to as “variable costs,” were $105.52. The gross margin (gross revenue minus all operating costs) was $104.48.
The pomegranate gross margin is the amount of money available to pay all the ownership costs associated with the pomegranate enterprise. Ownership costs, sometimes referred to as “fixed costs,” include the value of land used (rent or rent equivalent or mortgage and property taxes), the value of the capital investment (such as the tree establishment cost and buildings and vehicles), the value of the management, and the value of any unpaid labor. (All paid labor is already included in the gross margin.) Ownership costs, unlike operating costs, will vary substantially from farm to farm and will depend largely on how the farming operation is financed and on economies of scale. Each grower will have to calculate his total farm ownership costs and then allocate an appropriate portion of these costs to each enterprise on the farm. Now the profitability of the pomegranate enterprise can be determined by subtracting the pomegranate enterprise’s share of the total ownership costs from the gross margin for pomegranates.
The cost and return data are what was obtained from the 12 Trees Project site and other locations. Yields and costs were based on optimal growing conditions for one or more trees at various locations; different results will be obtained under different growing conditions. The prices used were actually obtained in 2005 and 2006. There is no guarantee that these prices will continue, especially if production increases significantly. These costs and returns are simply a starting point for growers to make their own estimates.
Packaging, Pricing and Marketing
In large production areas in California the fruit is packed in boxes by size with the calyx or stamen end up, often in molded plastic trays to prevent bruising. In Hawaii the fruit is often sold at autumn farmers markets in boxes. It is also sold to hotel chefs who prefer fresh locally grown pomegranates to treated imports. Wholesale prices run from $2.00 to $2.50 per pound. Fruit sold at farmers markets on the Big Island sells for $.50 to $2.00 each based on size.
Food Uses and Nutrition
Food Value Per 100 g of Edible Portion
Moisture 72.6-86.4 g
Protein 0.05-1.6 g
Fat 0.9 g
Carbohydrates 15.4-19.6 g
Fiber 3.4-5.0 g
Ash 0.36-0.73 g
Calcium 3-12 mg
Phosphorus 8-37 mg
Iron 0.3-1.2 mg
Sodium 3 mg
Potassium 259 mg
Carotene None to Trace
Thiamine 0.003 mg
Riboflavin 0.012-0.03 mg
Niacin 0.180-0.3 mg
Ascorbic Acid 4-4.2 mg
Citric Acid 0.46-3.6 mg
Boric Acid 0.005 mg
Health Benefits- Pomegranate juice can help prevent hardening (arteriosclerosis) of the carotid arteries. The seeds, which are used as a spice in India, are high in fiber.
The fruit is high in antioxidants including phenolic compounds and anthocyanins.
Pomegranate syrup on pineapple banana sorbet
24 cups sugar
6 split Hawaiian vanilla beans
12 ripe bananas
6 tablespoons pomegranate syrup
4 cups water
Peel core and trim pineapple. Peel bananas.
In medium saucepan, dissolve sugar in 4 cups of water over moderately high heat. Add vanilla bean and let mixture infuse until cool. Pass though chinois to remove any solids.
Puree pineapple and banana in a food processor. Add sugar mixture and process just until mixed. Stir in pomegranate syrup. Pour mixture into ice cream maker and freeze until firm.
Drizzle additional pomegranate syrup before serving.
Pomegranate and green tea ice cream.
Is funded by the Western Sustainable Agriculture Research and Education (WSARE) USDA-CSREES competitive grants program. Fifty-four Hawaii Island chefs, fruit buyers and growers were invited to select the types of fruit they would like to see commercially available, based on their desire to utilize the fruit in culinary applications. In selecting the final 12 fruits, considerations were given to seasonality and harvest times so that the availability of harvested fruit and on-farm labor needs were spread out over the year.
Fruit trees were planted and brought into production at a demonstration orchard at the Kona Pacific Farmers Cooperative on Napoopoo Road in the South Kona District. During the course of the three-year project, fruit from this orchard, as well as additional fruit purchased from area farmers, were donated to the West Hawaii Community College culinary school. Culinary student chefs developed recipes to be published on the project web site < http://www.hawaiifruit.net/12trees.html> and in a book in the final year of the project. Members of the cooperative as well as members of the Hawaii Tropical Fruit Growers - West Hawaii association and any other interested growers were encouraged to plant these trees. The goals of this project were to increase profitable agricultural diversification and to develop a consistently high quality, year-around supply of tropical fruit for local markets.
References and Further Reading
Kumar, G.N.M. (1990). Pomegranate. In: Steven, N., Shaw, P.E. and Wardowski, W.F. (eds). Florida Science Source (FSS) Inc., Lake Alfred, Florida, pp. 328-347.
Sudiarto and Rifai M.A., 1992. Punica granatum L.. In Coronel, R.E. & Verheij, E.W.M. (Eds.): Plant Resources of South-East Asia. No. 2: Edible fruits and nuts. Prosea Foundation, Bogor, Indonesia. pp. 270-272.
Popenoe W. 1920. Manual of Tropical and Subtropical Fruits. The Macmillan Company
Morton, Julia F., 1987. Fruits of Warm Climates
UH-CTAHR Integrated Pest Management Program
Knowledge Master database
University off California Fruit and Nut Research Center
University of Nevada Cooperative Extension Bulletin
The author is grateful to Drs. R. Bowen, B. Brunner, K Fleming, R. Paull and F. Zee for their valuable contributions to this manuscript.