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Date – Phoenix dactylifera

DATE TAXONOMY

The Arecaceae or palm family is a large, distinct family of woody monocotyledonous plants, containing up to 4000 species distributed over 200 genera. The date palm, Phoenix dactylifera L., is one of three economically important fruit crops in the palm family. Coconut (Cocos nucifera) and African oil palm (Elaeis guineensis) are the other two crops, both of which are true tropical species, whereas date palm is considered subtropical.

Cultivars
There are an estimated 3000 cultivars of date palm worldwide, but just a few are important in the global market. ‘Medjool’ is probably the best known and one of the highest quality dates available. Fruit are large, soft, and ship well, making it one of the most preferred for exportation. ‘Deglet Noor’ is a high yielding, semi-dry cultivar, popular in northern Africa and the major cultivar in California. ‘Barhi’ (Barhee) originated in Basra, Iraq, and is another high yielding cultivar. It is unusual in that is lacks the normal astringency of other dates at the Khalal (middle) stage of development, and can be eaten when crisp and immature; other cultivars are eaten at later stages when dried and brown.

ORIGIN OF PHOENIX DACTYLIFERA, HISTORY OF CULTIVATION

Dates are native to the Persian Gulf area of the middle east, where they have been cultivated for at least 6000 years, longer than many other fruit crops. Date palms were one of the few crop plants that could survive desert conditions, and became a reliable source of food in an otherwise inhospitable climate. Sumerian, Babylonian, Egyptian, and other ancient people used the palm for house construction and thatching as well as for food. It was spread across northern Africa along the coast and at oases by nomadic people, where it became a staple crop. Iraq led the world in date production from antiquity until recently, and is the origin of many major cultivars. Dates were introduced to northern Mexico and California by Spanish missionaries in the late 1700s. However, it was not until the turn of the 20th century, when superior cultivars were introduced, that the California industry was born. A research station was established in Indio, California in 1904 to study date and citrus cultivation. Cultivars collected from northern Africa and the middle east were brought to the station and studied by USDA scientists, and later released to growers. A small but healthy date industry is located around Indio today.

WORLD AND UNITED STATES DATE PRODUCTION

World (2004 FAO) – 6,772,068 MT or 15 billion pounds. Dates are produced in 35 countries worldwide on about 2.9 million acres. Average yields are just over 5000 lbs/acre.

Top 10 countries
(% of world production)
1. Egypt (17%)
6. Pakistan (10%)
2. Iran (14%) 7. Algeria (7%)
3. Saudi Arabia (13%) 8. Oman (4%)
4. United Arab Emirates (12%) 9. Sudan (4%)
5. Iraq (10%) 10. Libya (2%)
United States (2004 USDA) – 18,818 MT or 41.4 million pounds. All dates are produced in extreme southern California near Indio on about 4500 acres. Industry value is $31.5 million; price paid to growers is 76 ¢/lb. Average yields in California are 9000 lbs/acre.

For the most up to date statistical data on United States and World production numbers please refer to the following two websites:

World: The Food and Agriculture Organization of the United Nations Statistics Division (FAOSTAT). FAOSTAT

United States: The United States Department of Agriculture National Agricultural Statistics Service (USDA Ag Stats). USDA Ag Stats

BOTANICAL DESCRIPTION

Special thanks to Dr. Robert Krueger, USDA Riverside, CA, for the black and white photos!

Plant
Dates are tall, straight-trunked palms, reaching 60 ft, with trees up to 30 ft used in cultivation. Trunks reach 3 ft in diameter, retain persistent leaf bases for years, and produce offshoots or suckers either at the base or higher up. Leaves are 10-15 ft long, pinnately compound palm “fronds” with spines occupying the lower third of the rachis, and leaflets the distal two-thirds. Leaves are long-lived, 3-7 years, and persistent when they die. Mature palms have over 100 leaves, producing 1-2 new leaves per month. About 100-200 leaflets are found on each leaf, up to 3 ft long, ½ to 2.5″ wide, folded longitudinally, with entire margins.

Flowers
Dates are dioecious, meaning that they have separate male and female plants. Whether staminate or pistillate, flowers are borne on a compound spadix in leaf axils, having 50-150 lateral branches. A dozen or more inflorescences are produced annually, more in males than females. Inflorescences are sheathed in a bract or spathe until just prior to anthesis. Each sex produces thousands of tiny flowers per inflorescence. Male flowers are white, fragrant, about 1/4 to ½” wide, with 6 stamens each, and females are more yellowish or cream colored, smaller (1/4″), with trilocular superior ovaries and a 3-lobed stigma.

 

Pollination

Dates are wind or insect pollinated naturally, and natural pollination can be practiced in seedling orchards with 1:1 ratios of males to females. In most commercial orchards, however, only one male is grown for every 50 females, and pollination is accomplished artificially. Traditionally, a few strands of male flowers are laid among females in inflorescence by hand. Hand pollination is laborious, requiring up to 700 man-days of work for an average sized planting. More commonly, pollen is collected from male inflorescences, dried, and stored up to a year in refrigeration if females are not immediately ready for pollination. Pollen is generally blown onto receptive female inflorescences by a machine, hand-held puffers, or placed first onto cotton balls, which then are placed into inflorescences. The period of female receptivity is as little as 3 and as many as 30 days after the female spathe opens. Fruit set is often lower with artificial pollination, but adequate, and decreases the need for thinning and reduces expense.

 

male (left) and female (right) date inflorescences still partially enclosed in the spathes

Fruit
Fruit are drupes, 1-3″ long, dark brown, thick skinned, with thick sweet flesh and a large seed in the center. Unlike other drupes, the endocarp is thin and membranous, instead of thick and bony. Immature fruit are green, yellow, or red. Several hundred to just over 1000 fruit are borne in each bunch, which can weigh up to 80 pounds. Fruit go through 5 distinct stages as they mature over 6-8 months, given the following Arabic names: Hababouk, Kimri, Khalal, Rutab and Tamar. Fruit grow rapidly in the first 2 stages, then turn their characteristic color, lose water, and accumulate sugar in the Khalal stage, and finally ripen completely in the last 2 stages. Fruit thinning is practiced at pollination time, or sometimes 6-8 weeks after pollination. Thinning is accomplished by bunch thinning, where some strands or portions thereof are removed, or by complete bunch removal, or both.

close ups of individual flowers, female (left) and male (right)

GENERAL CULTURE

Soils and Climate
Soils – deep, well drained loamy soils, most tolerant of crop plants to high pH and salinity, commercial fruit production requires considerable water. Flood irrigation is applied several times per year.
Climate – hot, dry climate, pollination and seed set disfavored by temperatures below the mid 70s F, tolerate higher temperatures than most other fruit crops; mid-summer temperatures of 100-110 °F are typical in date production, can tolerate light freezing (to 20-23 F) in winter, a cool winter helps to synchronize flowering and ripening of fruit, extremely resistant to wind damage.

Propagation
Dates are propagated by offshoots, which are suckers growing from the trunks.

Rootstocks – None

Planting Design, Training, Pruning

Dates are planted about 25-35 ft apart, yielding about 50 plants per acre on average. A tendency toward slightly higher densities of up to 60 or so per acre has occurred more recently. Cultivars such as ‘Khadrawy’ that are dwarf can be planted at much higher densities. Very little pruning and training is involved in the production of any palm fruits. Dates have persistent leaves, which must be pruned off to allow access to fruit and crowns; old fruit stalks are pruned off as well.

DATE HARVEST, POSTHARVEST HANDLING

Special thanks to Dr. Robert Krueger, USDA Riverside, CA, for the black and white photos!

Maturity
At full maturity, dates are dark brown and have very low water content. However, they may be harvested prior to full maturity for special markets. In the Khalal or 3rd of 5 developmental stages, dates are firm, crisp, moist (50-85% water content), and have their characteristic color, usually red or yellow.

Harvest Method
Dates are hand harvested, generally by cutting entire bunches at one time. In some cases, individual fruit may be picked, where bunches are shaken to remove only the ripe fruit. Each palm may be picked up to 8 times over a period of 2-3 months to obtain consistent maturity.

Postharvest Handling
Fresh dates (Khalal stage) are washed and packed in 10 lb cardboard boxes still on the stems. Immature and over-mature fruit are removed, as well as damaged or small fruit at the proper maturity. In regions that can expect rain at harvest, fruit are harvested a bit early and dehydrated; areas with hot, dry winds at harvest may rehydrate fruit in water to improve texture and taste. Dates may be pitted prior to packing, depending on intended market.

Storage
Dates at full maturity store remarkably well compared to other fruits, owing to their low water content. Ripe dates do not experience chilling injury, and can be stored at 32-34°F for a year or more if humidity is kept below 20%. Fresh dates (Khalal stage) can be stored for up to 8 weeks under the same conditions.

THE DATES’S CONTRIBUTION TO DIET

Dates are generally eaten out of hand. Pitted dates are sold for out of hand consumption, and often used in baking. Date paste is used for cake fillings and other processed products. Date syrup is used as a sweetener; fruit are pressed, and the juice is concentrated and filtered. Alcoholic beverages can be made from fermenting date syrup or juice. Dates are low in fat and protein, but higher in vitamins and minerals than many other fruits and vegetables. Apart from the fruit, the meristem can be eaten like heart ‘o palm, and flour can be derived from the pithy trunk.
Per capita consumption of dates is only 0.12 lb/ year, about half the consumption rate of the 1970s and 1980s.

Dietary value, per 100 gram edible portion

Moist dates (“Khalal” and “Rutab” stages) Dried dates (“Tamar” stage)
Water (%) 30-85 10-25
Calories 142 284
Protein (%) 1.8 3.0
Fat (%) 1.0 0.5
Carbohydrates (%) 37 73
Crude Fiber (%) 3.5 5.2
% of US RDA*
Vitamin A 18 12
Thiamin, B1 51.3
Riboflavin, B2 46.7
Niacin 34 94.5
Vitamin C 66.7 8
Calcium 4.3 73.8
Phosphorus 43.8 78.8
Iron 60 300
Sodium <0.1 0.2
Potassium 138

* Percent of recommended daily allowance set by FDA, assuming a 154 lb male adult, 2700 calories per day.