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Prunus dulcis (Mill.) D.A. Webb

Rosaceae
Almond

Source: James A. Duke. 1983. Handbook of Energy Crops. unpublished.

  1. Uses
  2. Folk Medicine
  3. Chemistry
  4. Description
  5. Germplasm
  6. Distribution
  7. Ecology
  8. Cultivation
  9. Harvesting
  10. Yields and Economics
  11. Energy
  12. Biotic Factors
  13. Chemical Analysis of Biomass Fuels
  14. References

Uses

Almonds are cultivated for the nuts, used in candies, baked products and confectioneries, and for the oils obtained from the kernels. Oil used as a flavoring agent in baked goods, perfumery and medicines. Benzaldehyde may be used for almond flavoring, being cheaper ($1.54/kg) than almond oil ($5.28–$6.60/kg). Much valued in the orient because it furnished a very pleasant oil. In Tuscany, almond branches are used as divining rods to locate hidden treasure. To this day modern English Jews carry branches of flowering almonds into the synagogue on spring festival days. There is the legendary story of Charlemagne's troops' spears (almond) sprouting in the ground overnight and shading the tents the next day. As essential oils go, there is only bitter almond oil. Sweet almond oil is used for cosmetic creams and lotions, although in a crisis, it might conceivably be used as an energy source. The gum exuded from the tree has been used as substitute for tragacanth (Duke, 1983b).

Folk Medicine

According to Hartwell (1967–1971), the seed and/or its oil are used in folk remedies for cancer (esp. bladder, breast, mouth, spleen, and uterus), carcinomata, condylomata, corns, indurations and tumors. Reported to be alterative, astringent, carminative, cyanogenetic, demulcent, discutient, diuretic, emollient, laxative, lithontryptic, nervine, sedative, stimulant and tonic, almond is a folk remedy for asthma, cold, corns, cough, dyspnea, eruptions, gingivitis, heartburn, itch, lungs, prurigo, skin, sores, spasms, stomatitis, and ulcers. The kernels are valued in diet, for peptic ulcers. (Duke and Wain, 1981).

Chemistry

Per 100 g, the seed is reported to contain 547–605 calories, 4.7–4.8 g H2O, 16.8–21.0 g protein, 54.1–54.9 g fat, 17.3–21.5 g total carbohydrate, 2.6–3.0 g fiber, 2.0–3.0 g ash, 230–282 mg Ca, 475–504 mg P, 4.4–5.2 mg Fe, 4–14 mg Na, 432–773 mg K, 0–5 mg b-carotene equivalent, 0.24–0.25 mg thiamine, 0.15–0.92 mg riboflavin, 2.5–6.0 mg niacin, and traces of ascorbic acid. According to WOI, the seeds contain 5.8 mg/100 g Na, 856 K, 247 Ca, 257 Mg, 4.23 Fe, 0.14 Cu, 442 P, 145 S and 1.7 Cl. About 82% of the P is in phytic acid. Seeds contain 0.45 ppm folic acid, 150 mg/kg a-tocopherol and 5 mg/kg g-tocopherol. The chief protein is a globulin, amandin, which contains 11.9% arginine, 1.6% histidine, 0.7% lysine, 2.5% phenylalanine, 4.5% leucine, 0.2% valine, 1.4% tryptophane, 0.7% methionine, and 0.8% cystine. The approximate fatty acid composition of the oil is 1% myristic, 5% palmitic, 77% oleic, and 17% linoleic. Sweet almond oil from Kashmir showed 0.2% myristic, 8.9% palmitic, 4.0% stearic, 62.5% oleic, and 24.4% linoleic. The essential oil is 81–93% benzaldehyde, close kin to laetrile. The hulls (fleshy pericarp) contain: 7.5% moisture, 25.6% total sugars, 7.2% reducing sugars, 4.4% tannin, 2.6–4.7% protein, 1.6% starch, 2.4% pectin, 1.1–1.2% ether extract, 12.6% cover fiber, and 4.6–6.3% ash (C.S.I.R., 1948–1976). The gum which exudes from the trunk hydrolyses into 4 parts L-arabinose, 2 parts D-xylose, 3 parts D-galactose, and 1 part D-glucuronic acid.

Description

Tree to 10 m tall, the alternate leaves lanceolate to oblong lanceolate, minutely serrate. Flowers solitary, white to pink, actinomorphic, 20–50 mm broad, appearing with or before the foliage. Fruit an oblong drupe 30–60 mm long, pubescent, the tough flesh splitting at maturity to expose the pitted stone; endocarp thin or thick; seed flattened, long-ovoid, the seed coat brown.

Germplasm

Reported from the Central Asian and Near Eastern Centers of Diversity, almond or cvs thereof is reported to tolerate drought, frost, high pH, heat, mycobacteria, nematodes, slope, and wilt (Duke, 1978). Almond description for several cvs are listed in Almond Description (AGP:1BPGR/80/88) put out in 1981. 'Cavaliera' is very early, 'Nonpareil' early, 'Ferragnes' medium, 'Marcona' late, and 'Texas' very late. (2n = 16)

Distribution

Widely distributed in cultivation now the sweet almond is said to have wild types in Greece, North Africa, and West Asia. Almond was cultivated in China in the 10th Century BC, in Greece in the 5th Century BC.

Ecology

Ranging from Cool Temperate Moist to Wet through Subtropical Thorn to Moist Forest Life Zones, almond is reported to tolerate annual precipitation of 2.0 to 14.7 dm (mean of 11 cases = 7.5) annual temperature of 10.5 to 19.5°C (mean of 11 cases = 14.8) and pH of 5.3 to 8.3 (mean of 7 cases = 7.3). Almond does well in the hot, dry interior valleys of California, where the nuts mature satisfactorily. The leaves and nuts are less subject to attack by disease-causing fungi in the hot, dry climate than under cooler and more humid conditions. It has a low winter chilling requirement. Because of this low chilling requirement (or short rest period), and the relatively low amount of heat required to bring the trees into bloom, the almond is generally the earliest deciduous fruit or nut tree to flower, hence extremely subject to frost injury where moderately late-spring frosts prevail. Almonds need ample rainfall or irrigation water for maximum production of well-filled almond nuts. Trees have been planted in certain areas where supplies of water are inadequate for other fruit or nut crops; however, yields of nuts were low. In general, conditions favoring peach production will also favor almonds. The almond tree has been successfully grown on wide range of soils. It is a deep-rooted tree and draws heavily on the soil which should be deep, fertile, and well drained. Sandy loams are best. Since sandy soils are often deficient in plant food elements, careful attention must be paid to proper fertilization of the trees. Almond trees have high N and P requirements. Sandy soils are easy to cultivate and cover crops are comparatively easy to grow on them provided they are properly fertilized

Cultivation

In India, trees are raised from seedlings, the seeds usually having a chilling requirement. Seeds are sown in nurseries, the seedlings transplanted after about one year. For special types, as in the U.S., scions are budded or grafted on to bitter or sweet almond, apricot, myrobalan, peach or plum seedlings. Trees are planted 6–8 m apart and irrigated, in spite of their drought tolerance. Application of nitrogenous and/or organic fertilizers is said to improve yield. Trees should be pruned to a modified leader system. All types are self-sterile so cvs or seedlings should be mixed.

Harvesting

Fruits occur mainly on shoot spurs, which remain productive up to five years. Bearing trees may be pruned of surplus branches to about 20% of the old-bearing wood. Tree exhibiting decline may be severely cut back at the top. In India, the trees bear from July to September. Fruits are harvested when the flesh splits open exposing the stone. The flesh is then removed from the stones manually or by machine.

Yields and Economics

In 1970, the U.S. imported ca 9 tons bitter almonds, compared to 13 tons in 1969, mostly from France. In 1971, commercial almond production in the United States was centered in California, which produced more than 99% of the domestic marketed nuts. California's production of inshell nuts during the past 9 years had nearly tripled. It reached about 140,000 inshell tons in 1970. Only sweet almonds are grown commercially. Imports, largely from Spain and Italy, vary widely from year to year, ranging from about 280 to 1,700 tons on the inshell basis for the past 7 years.

Energy

According to the Wealth of India (C.S.I.R., 1948–1976), average California yields are ca 400 kg/ha but they attain over 1,200 kg/ha. However, for Baluchistan, WOI reports 2,375 kg/ha, basing this on an optimistic yield of 7.3 kg for each of 325 trees/ha. Yields of 2–3 kg per tree seem more realistic. Duke (1978), however, reports seed yields of 3000 kg/ha. With an oil yield of 50–55%, it is easy to project oil yields of 1500 kg/ha. With recommended pruning to 20% of the old-bearing wood, several MT firewood should be available from the pruning.

Biotic Factors

Prominent diseases in India include "shot hole" caused by Clasterosporium carpophilum (Lev.) Aderh., "white spongy rot" due to Fomes lividus K1, "brown patchy leaf rot" due to Phyllosticta prunicola (Spiz) Sacc., "brown rot" due to Sphaerotheca pannosa (Wallr.) Lev. and a mosaic disease due to virus plague almond. The chrysomelid Mimastra cyanura Hope and the almond weevil Myllocerus laetivirens Marshall feed on the leaves. The San Jose scale Quadraspidiotus perniciosus Comstock is minor problem. The almond moth Ephestia cautella Wlk. infests shelled almonds and dried apricot, currant, date, fig, peach, and plum.

Chemical Analysis of Biomass Fuels

Analysing 62 kinds of biomass for heating value, Jenkins and Ebeling (1985) reported a spread of 20.01 to 18.93 MJ/kg, compared to 13.76 for weathered rice straw to 23.28 MJ/kg for prune pits. On a % DM basis, the orchard prunings contained 76083% volatiles, 1.63% ash, 21.54%fixed carbon, 51.30% C, 5.29% H, 40.90% 0, 0.66% N, 0.01% S, 0.04% Cl, and undetermined residue.

Analysing 62 kinds of biomass for heating value, Jenkins and Ebeling (1985) reported a spread of 19.38 to 18.17MJ/kg, compared to 13.76 for weathered rice straw to 23.28 MJ/kg for prune pits. On a % DM basis, the shells contained 73.45% volatiles, 4.81% ash, 21.74% fixed carbon, 44.98% C, 5.97% H, 42.27% 0, 1.16% N, 0.02% S, and undetermined residue.

Analysing 62 kinds of biomass for heating value, Jenkins and Ebeling (1985) reported a spread of 18.22 to 17.13 MJ/kg, compared to 13.76 for weathered rice straw to 23.28 MJ/kg for prune pits. On a % DM basis, the hulls contained 71.33% volatiles, 5.78% ash, 22.89% fixed carbon, 45.79% C, 5.36% H, 40.60% O, 0.96% N, 0.01% S, 0.08% Cl, and undetermined residue.

References

Complete list of references for Duke, Handbook of Energy Crops
Last update Thursday, January 8, 1998 by aw