Macadamia integrifolia Maiden & Betche
Macadamia tetraphylla L. Johnson
Macadamia nuts, Australian nuts
Source: James A. Duke. 1983. Handbook of Energy Crops. unpublished.
- Folk Medicine
- Yields and Economics
- Biotic Factors
- Chemical Analysis of Biomass Fuels
Macadamia nuts are eaten raw or after cooking in oil are roasted and salted;
also used to make an edible bland salad oil. Rumsey (1927) recommends it as
well as a timber tree and ornamental. Years ago a coffee-like beverage known
as "almond coffee" was marketed from the seeds.
No data available.
Per 100 g, the nut is reported to contain 691 calories, 3.03.1 g H2O, 7.88.7
g protein, 71.471.6 g fat, 15.115.9 g total carbohydrate, 2.5 g fiber, 1.7 g
ash, 48 mg Ca, 161 mg P, 20 mg Fe, 264 mg K, 0 mg b-carotene equivalent, 0.34
mg thiamine, 0.11 mg riboflavin, 1.3 mg niacin, and 0 mg ascorbic acid.
According to MacFarlane and Harris (1981), the oil is high in monounsaturates
(79%) and palmitoleic acid (1625%). The composition ranges from 0.11.4%
lauric, 0.70.8 myristic, 8.09.2 palmitic, 15.624.6 palmitoleic, 3.3 3.4
stearic, 54.864.2 oleic, 1.51.9 linoleic, 2.42.7 arachidic, 2.13.1
eicosenoic, and 0.30.7% behenic acids. The oilcake contains 8.1% moisture,
12.6% oil, 2.6% crude fiber, 33.4% crude protein, and 43.3% N-free extract.
Macadamia integrifolia: Trees up to 20 m tall, with spread of 13 m;
leaves opposite in seedings, later in whorls of 3, pale green or bronze when
young, 1030 cm long, margins with few or no spines, petioles about 1.3 cm
long; flowers creamy white, apetalous, borne in groups of 3 or 4 along a long
axis in racemes, much like grapes; fruit consisting of a fleshy green husk
enclosing a spherical seed; nuts round or nearly so, surface smooth or nearly
so, 1.32.5 cm in diameter; shell tough, fibrous, difficult to crack; kernel
white, of uniform quality, shrinking only slightly after harvesting. Fl. June
through to March, some strains almost ever-bearing, flowering while fruiting.
Macadamia tetraphylla: Trees up to 20 m tall, with spread of 13 m;
leaves opposite in seedlings, commonly in 4's rarely in 3's or 5's, purple or
reddish when young, margins serrate with many spines, up to 50 cm long, sessile
or on very short petioles; flowers pink, in large racemes; fruit consisting of
a fleshy green husk enclosing one seed; nuts usually elliptical or
spindle-shaped, surface pebbled; kernel grayish; variable in quality and
shrinking some after harvest. Fl. between August and October, producing one
main crop. Between these two distinct types are numerous intermediate forms
varying in spininess of leaves, color of flower, size of nut and thickness of
Reported from the Australian Center of Diversity, macadamias or cvs thereof are
reported to tolerate drought, slope and wind. (Duke, 1978). After 1956,
Macadamia integrifolia (smooth-shelled type) and Macadamia
tetraphylla L. (rough-shelled type) are the names properly applied to the
cultivated Macadamia nuts. Prior to this time they had been generally referred
to Macadamia ternifolia. F. Muell., a distinct different species,
bearing small, bitter, cyanogenic seeds less than 1.3 cm in diameter, inedible
and never cultivated. Many cultivars have been developed and grafted trees of
promising selections have been made. Three varieties of M.
integrifolia, 'Kakea', 'Ikaika' and 'Keauhou', have been planted
extensively in Hawaii, all giving satisfactory production under a variety of
favorable conditions;. 'Keaau' has been more recently recommended for
commercial planting in Hawaii, since it is highly resistant to wind and yields
510% more than previous varieties, the entire crop maturing and dropping
before end of November. Most of the Australian crop is based upon M.
tetraphylla, with some orchards of grafted M. integrifolia
varieties. Among the medium-to-thick shelled selections, used mainly for
processing, are: 'Richard', 'Tinana', 'Our Choice' and 'Hinde'. For
rough-shelled types, mostly grown for table purposes, are: 'Collard', 'Howard',
'Sewell' and 'Ebony'. Varieties showing hybrid characteristics are: 'Oakhurst'
and 'Nutty Glen'. 'Teddington' is a hybrid with thin shell. (2n = 28,
Native to coastal rainforests of central east Australia (New South Wales and
Queensland). Introduced in other parts of tropics, as Ceylon, and commercially
grown in Hawaii and France, at medium elevation.
Ranging from Warm Temperate Dry (without frost) through Tropical Moist Forest
Life Zones, macadamias are reported to tolerate annual precipitation of 7 to 26
dm annual temperature of 15 to 25°C and pH of 4.5 to 8.0. Macadamia grows
best in rainforest areas, along coasts with high humidity and heavy rainfall.
However, it is tolerant of adverse conditions when once established. Inland,
tree thrives in some localities but crops are usually lighter than when grown
near coast. Trees produce a deep taproot and relatively few lateral roots;
therefore, they need protection of windbreaks in exposed areas. Under orchard
conditions, trees are shapely, robust, and more heavily foliaged than they are
in rainforest. Grows well on wide range of soil, but fails on infertile
coastal sands, heavy clays or gravelly ridges. Yields well on deep,
well-drained loams and sandy loams. Slopes steeper than 1 in 25 should be
planted on the contour, and every precaution taken to prevent soil erosion.
Propagation by seed is not difficult, but seedlings are variable in production
and nut characteristics, and so of little value for commercial plantings.
Freshly harvested nuts are best for germination, but require 3090 days before
germination. Propagation usually by cuttings, marcottage and side-tongue
grafts. Rootstocks for grafting are readily grown from seed by ordinary
nursery means. Grafting in Macadamia is more difficult than in most nut trees
due to hardness of wood. Best results obtained when seedling rootstocks
are side-wedge grafted with selected scions. After-care of graft similar to
that practiced in other trees. Budding is much less satisfactory than
grafting. Most suitable time for transplanting young trees to orchard is from
February to April in Australia and in Hawaii, when rainfall is good and
sufficient soil moisture available. Taproot should be severed about 30 cm
below ground about 6 weeks before time to transplant to allow fibrous roots to
develop. Roots are very susceptible to exposure and should not be allowed to
dry out during transplanting. Grafted trees should be planted with the union
well above ground level and watered immediately. Since trees have a tendency
to grow tall, young trees when about 75 cm tall, should be topped little by
little to produce a few evenly spaced limbs, thus developing a strong, rounded
symmetrical tree. Little pruning is required in bearing trees except to
discourage leaders, to reduce lateral growth, to let in light, and to make
cultural and harvesting operations more favorable. Pruning should be done
toward end of winter after crop is harvested. Macadamia grows best in soils
with good supply of humus. Farmyard manure may be added and green manure crops
can be grown between trees in summer. Under orchard conditions, regular
applications of fertilizer are required, as a 8:10:5 formula, at rate of .45 kg
per tree per year of age, a maximum of 4.5 kg. Fertilizer should be applied in
early spring just before trees make new growth and start flowering. Zinc
deficiencies seem to be a problem with this tree, the symptoms being small,
yellowish or slightly mottled leaves which are bunched together, crop
retardation and poor shoot growth. Condition corrected by application of
foliar spray in early spring after first flush of growth, at rate of 4.5 kg
zinc sulfate, 1.3 kg soda ash (or 1.7 kg hydrate lime) in 100 gal water.
However, spray is effective at any period of year if symptoms are obvious.
Since root system is rather close to surface, shallow cultivation for weed
control should be practiced. Summer cover crops, as cowpeas, and autumn green
manure crops may be grown between trees until harvest time. Grazing cattle on
weeds and grass in orchards has the advantage of adding animal manure.
Nuts mature in 67 months after flowering and must be allowed to ripen on the
trees. Usually the nuts fall to the ground when mature, but in some cvs remain
on trees and must be removed with rake. Nuts are picked up from the ground by
hand or are raked up. After harvesting, nuts are dehusked, usually with an
improvised corn-sheller, washed, placed on wire trays for about 6 weeks to dry
out, graded and shipped to market. Machinery for cracking shells has been
designed for processing purposes, in addition to several efficient
hand-operated crackers, which produce a kernel undamaged. Kernels which are
broken during cracking are used by confectioners. Shelled kernels deteriorate
rather quickly unless kept in vacuum-sealed jars. Processed nuts when roasted
and slightly salted keep extremely well.
Most trees begin bearing at 67 years, others at 1015, vegetatively propagated
trees bearing earlier. Yield records vary widely. Trees flower for 3 to 12
months, various strains producing fruits over a long period. Some cvs have a
definite fruiting season. With great commercial potential in the tropics,
macadamia makes an excellent dooryard tree. In addition to production of nuts
in Australia, production in Hawaii in 1970 amounted to 5750 tons valued at
$.217/lb. Production is being developed in South Africa, Paraguay, Costa Rica,
Jamaica, Samoa and Rhodesia.
According to Saleeb et al. (1973), nuts of M. integrifolia and M.
tetraphylla are equal in oil content with an iodine value of 75.4 and 71.8,
respectively. They describe a method for partially extracting the oil (614%
of the weight of intact oven dry kernels), rendering them more attractive,
digestible, and less fattening, while diverting 14% of the weight to oil
production. Australian estimated yield of about 45 kg/tree annually; in
Hawaii, yields average 135 kg/tree. New cvs are known to yield as much as 3.75
MT/ha, averaging 1 ton of kernels, which should contain more than 700 kg oil/ha
renewably (oil makes up 6575% of the kernel).
Macadamia trees are attacked by Gloeosporium sp. (Blossom blight) and
Macrophoma macadamiae. Nematodes isolated from trees include:
Helicotylenchus dihystera, H. erythrinae, and Xiphinema americanum
(Golden, p.c. 1984). In Hawaii, the Southern green stinkbug is a serious
problem, damaging about 10% of the seed (Monroe et al., 1972)
Analysing 62 kinds of biomass for heating value, Jenkins and Ebeling (1985)
reported a spread of 21.01 to 20.00 MJ/kg, compared to 13.76 for weathered rice
straw to 23.28 MJ/kg for prune pits. On a % DM basis, the shells contained
75.92% volatiles, 0.40% ash, 23.68% fixed carbon, 54.41% C, 4.99% H, 39.69% O,
0.36% N, 0.01% S, and undetermined residue.
Complete list of references for Duke, Handbook of Energy Crops
- Duke, J.A. 1978. The quest for tolerant germplasm. p. 161. In: ASA Special
Symposium 32, Crop tolerance to suboptimal land conditions. Am. Soc. Agron.
- Jenkins, B.M. and Ebeling, J.M. 1985. Thermochemical properties of biomass
fuels. Calif. Agric. 39(5/6):1416.
- Monroe, G.E., Tung Liang, and Cavaletto, C.G. 1972. Quality and yield of
tree-harvested macadamia nuts. USDA, ARS 42196:19.
- Rumsey, H.J. 1927. Australian nuts and nut growing in Australia. Part I. The
Australian nut. Sidney.
- Saleeb, W.F., Yermanos, D.M., Huszar, C.K., Storey, W.B., and Habanauskas, C.K.
1973. The oil and protein in nuts of Macadamia tetraphylla L. Johnson,
Macadamia integrifolia Maiden and Betche, and their F1 Hybrid. J. Am.
Soc. Hort. Sci. 98(5):453456.
Last update Wednesday, January 7, 1998 by aw