From the Handbook of Energy Crops, unpublished
by James A. Duke
Morus alba L.
Moraceae
White mulberry, Russian mulberry, Silkworm mulberry, Moral blanco
Uses
Folk
Medicine
Chemistry
Description
Germplasm
Distribution
Cultivation
Harvesting
Yields
and Economics
Energy
Biotic
Factors
References
Uses
Trees
are extensively grown (e.g. southern Europe, India) for their leaves as
food for silkworms. Fruits may be eaten raw or cooked. Fruits are an
ingredient of a particularly seductive drink known as Mulberry Wine.
Wild birds, poultry, and hogs are fond of fruits. Mulberry leaves are
sometimes eaten as a vegetable and are useful as a cattle fodder. Being
nutritious and palatable, they are said to improve milk yield of dairy
animals. Wood is valued for sporting goods due to its elasticity and
flexibility when steamed, being considered as good as ash. Sapwood is
white to yellowish-white, heart-wood golden brown, darkening after
exposure; light to moderately heavy, straight-grained, not liable to
split, but shows tendency to warp, moderately durable under cover, easy
to work and finish, used mainly for hockey sticks, tennis and badminton
rackets and racket presses, cricket bats, house building materials,
agricultural implements, and furniture. Furnishes a medium grade fuel
wood. Stem bark is fibrous and used in China and Europe for paper
making. Twigs are used as binding material and for making baskets.
Trees often used as ornamentals, roadsides or boundary markers (Reed,
1976; C.S.I.R., 1948–1976).
Folk Medecine
According
to Hartwell (1967–1971), the fruit juice is used in folk remedies for
tumors of the fauces. Reported to be antidotal, antiphlogistic,
antitussive, antivinous, astringent, bactericide, diaphoretic,
ditiretic, emollient, escharotic, expectorant, fungicide, laxative,
nervine, purgative, refrigerant, restorative, sedative, tonic, and
vermifuge, white mulberry is a folk remedy for aphtha, armache, asthma,
bronchitis, bugbite, cachexia, cold, constipation, cough, debility,
diarrhea, dropsy, dyspepsia, edema, epilepsy, fever, headache,
hyperglycemia, hypertension, inflammation, insomnia, melancholy,
menorrhagia, snakebite, sorethroat, stomatitis, tumors, vertigo, and
wounds (Duke and Wain, 1981). Medicinally, fruits are laxative,
refrigerant in fevers, and used locally as remedy for sore throat,
dyspepsia, and melancholia. Roots and bark are purgative, anthelmintic,
and astringent; leaves considered disphoretic and emollient; a
decoction of leaves being used as a gargle for inflammation of throat
(Reed, 1976).
Chemistry
Per
100 g, the fruit is reported to contain 87.5 g H2O, 1.5 g protein, 0.49
g fat, 8.3 g carbohydrates, 1.4 g fiber, 0.9 g ash, 80 mg Ca, 40 mg P,
1.9 mg Fe, 174 IU vit. A, 9 mg thiamine, 184 mg riboflavin, 0.8 mg
nicotinic acid, and 13 mg ascorbic acid. Dry leaves contain 18–28.8%
protein, 11.3–0.7% MgO, 0.8–13.6% soluble sugars, 0.6–1.4% P2O5, 2–3.9%
K2O, 1.4–2.4% CaO, 0.2–0.7% MgO, 0.8–1.8% Al2O3, 0.05–0.26% Fe2O3,
1.8–2.6% SiO2, and 0.3–0.56% SO4 (C.S.I.R., 1948–1976). Substances
which attract the silkworm larvae to the leaves have been identified as
citral, linalyl acetate, linalol, terpinyl acetate, and hexenol, the
first 3 being more effective. b-sitosterol (ca 0.2% in leaves), along
with some sterols and a water-soluble substance, is the main factor
which stimulates the biting action; the amount of food eaten by larvae
is controlled by the concentration of b-sitosterol. Protein
perparations from young mulberry leaves form an excellent supplement to
protein-deficient diets. Non-protein nitrogen accounts for ca 22% of
the total nitrogen in young leaves and ca 14% in mature leaves. Amino
acids identified in the free form are: phenylalanine, leucine, valine,
tyrosine, proline, alanine, glutamic acid, glycine, serine, arginine,
aspartic acid, cystine, threonine, sarcosine, gamma-amino-butyric acid,
pipecolic acid, and 5-hydroxy pipecolic acid. The leaves are a good
source of ascorbic acid, with 2–3 mg/g, of which over 90% is present in
the reduced form. They contain also carotene, vitamin B1, folic acid,
folinic acid, and vitamin D. Phytate phosphorus accounts for 18.2% of
total phosphorus. Volatile constituents identified in steam-distillates
of the leaves are: n-butanol, beta-gamma-hexenol, methyl-ethyl
acetaldehyde, n-butylaldehyde, isobutylaldehyde, valeraldehyde,
hexaldehyde, alpha-beta-hexenal, acetone, methyl-ethyl ketone,
methyl-hexyl ketone, butylamine, and acetic, propionic, and isobutyric
acids. Leaves also contain calcium malate, succinic, and tartaric
acids, xanthophyll and isoquercitrin (quercetin 3-glucoside) and
tannins; adenine, chorine, and trigonelline bases are present in young
leaves. Analysis of leaves gave (dry weight basis): protein, 14.0; EE,
6.8; NFE, 49.7; total ash, 13.8; calcium (CaO, 2.74; and phosphorus
(P2O5) 0.45% (C.S.I.R., 1948–1976). According to Hager's Handbook, the
wood contains 0.3–0.44% morin, dihydromorin, dihydrokaempferol,
2,4,4',6-tetra-hydroxybenzophenone, maclurin, and ca 2%
hydroxyresveratrol. Seeds contain 33–38% fatty oil (with linoleic-,
stearic-, oleic-, myristic-, palmitoleic-, and arachidic-acids) and ca
25% protein (List and Horhammer, 1969–1979).
Description
Small
to medium-sized monoecious or dioecious shrub or tree, up to 15 m tall,
wide-spreading, round-topped, trunk attaining 60 cm in diameter; leaves
alternate, stipulate, variable in shape, lobed or unlobed, cordate,
dentate, acuminate, long-petiolate, 12 x 8 cm on fruiting branches, up
to 25 x 20 cm on vigorous non-fruiting branches, usually smooth above,
glabrous or pubescent along veins beneath, thin, light green; flowers
small, greenish-yellow, in dense spikes to 2 cm long; sepals 4; stamens
4; pistils with two styles; staminate spikes soon deciduous; pistillate
spikes maturing into an aggregate fruit (syncarp) of drupelets; syncarp
ovoid to oblong-cylindric, 1–5 cm long, white, pinkish or purplish to
nearly black, edible long before ripe, sweet, but insipid; seeds brown,
1–1.2 mm long, 12,000–13,000/oz. Fl. Mar.–May, fr. Summer.
Germplasm
Reported
from the China-Japan Center of Diversity, white mulberry, or cvs
thereof, is reported to tolerate disease, drought, frost, hydrogen
fluoride, low pH, poor soil, salt, shade, slope, and weeds (Duke,
1978). It is also said to tolerate aerial sprays of 2,4,5-T but not
ground treatment. Numerous cvs have been adapted in various
silk-producing regions of the world, differing in their adaptability to
various soils and climates (as those suited for cold climate, for areas
with severe winters, or for mild climate; some are early, others late
or intermediate); resistance to diseases; food value of leaf for
silkworms; and suitability for use as stock or scion in grafting.
Japan has about 700 types of which 21 are extensively cultivated. Most important cv grown in India is M. alba var. muticaulis
Loud., fast growing, adapted to field culture, and giving high yield of
large, tender, thick leaves. In India, mulberry is either grown as a
field crop (plants kept in form of bushes and the leaves harvested
several times a year for the multivoltine race of silkworms) or as a
tree (leaves harvested only once a season for rearing univoltine races
of silkworms). In Bengal, cultivation of the var. atropurpurea
along borders of bush plantations has been recommended. Largest acreage
of mulberry in India is in Mysore, where more than 75% of total
mulberry raw silk production occurs. There has been some selection of
mulberry in India, the selection 'K.M.', in West Bengal, gives 50% more
leaves than local types, and is popular in Mysore for grafting
purposes. Also strains 'Selected I' and 'Selected V' evolved in Mysore
are promising. Forty-four cvs, some local, others introduced, have been
studied in Thailand. The Russian cvs (M. alba var. tatarica)
are often planted as windbreaks, as they are very hardy and thrive
under greatest neglect. For this purpose, they are planted 2.6–7 m
apart, making excellent screens and standing pruning well. Used as
rootstocks for other mulberries, they are very popular in the Great
Lakes Region of the United States. Raised from seed and quite variable,
the fruits are inferior, suitable only for birds. 'New American',
considered the best cv, 'Trowbridge' and 'Thorburn' are the leading
kinds of fruit-bearing mulberries for the North. (2n = 28).
Distribution
Ranging
from Cool Temperate Steppe to Warm through Tropical Very Dry to Moist
Forest Life Zones, white mulberry is reported to tolerate annual
precipitation of 4.4 to 40.3 dm (mean of 28 cases = 9.8), annual
temperature of 5.9 to 27.5°C (mean of 28 cases = 16.6), and pH of 4.9
to 8.0 (mean of 23 cases = 6.7) (Duke, 1978, 1979). According to Wyman
(1974), it tolerates average annual minimum temperatures of -10 to
-20°F (-23.3 to -28.9°C). White mulberry grows well on wide variety of
soils. It withstands drought, once well established. However, it is
liable to wind damage. In India, it is cultivated up to 3,300 m
elevation, but can grow as well at sea-level.
Cultivation
Mulberry
trees can be propagated by seeds, cuttings, or graftings. Seeds should
be treated with camphor water before sowing to ward off disease. Thin
layer of soil and ashes spread over seed after sowing. Beds kept moist.
Seeds germinate in 9–14 days, depending on the season. When seedlings
are about 7.5 cm tall, they are thinned and weeded. For bush
mulberries, seedlings 10–15 cm tall are used as transplants; for trees,
seedlings are allowed to grow 1.3 m and trained before transplanting.
Cuttings
are obtained from exhausted bushes at pruning time. Branches are cut
into pieces 22–30 cm long with 3 buds and planted immediately.
Sometimes cuttings are tied into bundles and kept buried in soil 6–9 cm
deep, kept watered, and after about a month when buds have shoots about
5 cm long, are taken out of mud and planted. Cuttings root quickly, and
with cultivation and irrigation, they may attain a height of 75 cm in 6
weeks.
Mulberry plants from seedlings are more expensive, but
give better plants than those from cuttings. Seedlings usually planted
2 to a pit 4" pits spaced 60–75 cm apart.
Root grafting is
usually practiced in India. Stocks are seedlings of any type; the scion
are selected from high yielding, quick-growing types with large leaves
of good food value. Rooted cuttings are planted in pits or furrows. In
dryland culture, pit system is uged. Cuttings placed in prepared pits,
30 cm in diameter and 22 cm deep, spaced 75 cm apart, in rows 75 cm
apart. Planted in July after SW monsoon has set in. Usually 3 cuttings
are put in each pit and watered; 75,000 to 120,000 cuttings/ha. When
irrigation is used, cuttings are planted in furrows in April or May, 10
cm apart, the furrows being 22 cm apart. With this very close planting,
110,000 to 200,000 cuttings/ha are required.
Grafted plants
develop a better root system than those from either seedlings,
cuttings, or layerings, and are used exclusively in Japan. Grafted
trees are planted 1.6 m apart each way, about 4,000/ha, and are
especially suitable for irrigated areas. Various techniques are
employed to prune and train mulberry plants. After each pruning, the
field is cultivated and manured.
Harvesting
Fruits
are picked or shaken on drop cloth's when in season. Not being
attractive for marketing, they are usually consumed locally.
For
harvesting leaves, mulberry bushes under irrigation attain a height of
about 1.3 m in 10 weeks, when the leaves are ready for picking. Under
rainfed conditions, first picking may be done 12–17 weeks after
planting. About 10 pickings per season for irrigated plants and 6 or 7
for rainfed crops.
Best time for picking leaves is in the
evening. Harvested leaves are stored in small loose heaps in cool room
and protected from heating, fermentation, or drying out. Bushes may be
productive for as many as 15 years, after which old plants are pulled
out, the land planted to a green manure crop and then replanted to
mulberry bushes.
Yields and Economics
Yield
of mulberry leaves varies according to the soil, moisture supply,
manuring, and cultural practices. Bushes grown under rainfed conditions
yield 4,000–7,000 kg/ha annually; under irrigation, from 10,000–14,000
kg/ha and selected varieties, as 'Selected I' and 'Selected V' yield as
high as 22,000 kg/ha. Yields of leaves from tree mulberries are not
available. Different trees vary greatly in fruit production.
Sericulture
is the most important commercial use for white mulberry. Young, fully
developed leaves are best for feeding silkworm larvae. In Thailand,
local silkworms produce 300–800 m of fiber per cocoon compared with
1,600 m for Japanese silkworms, and 1,400 m for a cross between them.
Those of us who have seen solid coats on the ground of white fruits of
the white mulberry or red to purple fruits of other species, realize
that there is a lot of sugar there that could be converted to alcohol.
Energy
Finding
rather high yields of ethanol in peracetic acid treatments and four
days incubation of the sawdust, Lee commented, "the yield of ethanol
from wood sawdust can be increased from 1% to 6% if the treatment for
delignification is improved.
It is concluded that Populus species and Morus show great potential for ethanol production. We have established about 300,000 ha of improved, fast growing Populus hybrids (mostly P. x euramericana and P. alba x glandulosa)
throughout the country. In Korea...a 45,000 ha plantation has been
established with mulberry trees mainly to produce leaves for
silkworms... Most of the stems and branches produced by mulberry trees
so far are utilized for heating or cooking and as a supporting material
for horticultural crops.
Recently, preliminary studies on
yields of ethanol from mulberry trees show promising possibilities.
Also, if the conversion of mulberry tree biomass to fuels is
economically feasible, planting mulberry trees will be greatly
advantageous to Korean farmers.
Other fuel sources might be
organic wastes, mill residues, logging residues and agricultural
by-products such as rice, barley, or wheat straw. Remarkable yields of
energy may be expected on the assumption that the biomass produced from
all existing plantations is converted to fuels" (Lee, no date). With
10% sulfuric acid sawdust hydrolyzed for one hour yields 28% sugar.
Biotic Factors
The following are listed as affecting Morus alba, in Agriculture Handbook No. 165: Acrospermum foliicolum, Agrobacterium rhizogenes (hairy root), Armillaria mellea (root rot), Botryosphaeria ribis, Cercospora moricola (leaf spot), Cercosporella mori (leaf spot), Ciboria carunculoides, Cytospora sp. (twig canker), Dermatea mori, Dothiorella sp., D. mori (canker, twig blight), Fusarium lateritium var. mori (canker, twig blight), Gibberella baccata, Helicobasidium purpureum (root rot), Massaria epileuca, M. olivacea, Meloidogyne spp. (root knot nematodes), Mycosphaerella mori (leaf spot), Myxosporium diedickei (twig blight), Nectria sp. (canker), Nectria cinnabarina, Nectria verrucosa, Phymatotrichum omnivorum (root rot), Physalospora obtusa, Polyporus farlowii (heart rot), P. gilvus (wood rot), P hispidus (heart rot), Pseudomonas mori (bacterial spot, blight), Rosellinia aquila (root rot), Schizophyllum commune (wood rot), Sclerotinia sp. (canker), Sphaeropsis sp., S. sepulta, Stereum cinerascens (wood rot), Tryblidiella nigrocinnabarina, T. rufula var. microspora, Valsa morigena, Valsaria insitiva, and the leaf mottling virus.
In addition, Browne (1968) lists the following as affecting this species: mulberry yellow net virus; Cephaleuros virescens (Algae); Auricularia
auricula-judae, Botryosphaeria obtusa, Cerotelium fici, Cerrena
unicolor, Corticium salmonicolor, Diploidia morina, Fomes robiniae, F.
senex, Gibberella moricola, Hendersonula toruloidea, Inonotus
cuticularis, I. hispidus, Macrophomina phaseoli, Nectria coccinea,
Phloeospora mori, Phyllactinia guttata, Phyllosticta morifolia,
Polyporus squamosus, Sclerotinia fuckeliana, S. sclerotiorum,
Sphaeropsis mori, Thyrostroma mori, Valsa ambiens, and Xylaria polymorphs (Fungi). Dendrophthoe falcata, Loranthus sp. (?), Viscum album (Angiospermae); Tetranychus telarius (Acarina), Anoplophora
chinensis, Apriona cinerea, A. germari, Batocera rufomaculata,
Celosterna scabrator, Gonocephalum vagum, Mimastra cyanura,
Olenecamptus bilobus, Phryneta leprosa, Sthenias grisator, and Taeniotes scalaris (Coleoptera). Aleuroplatus
pectiniferus, Ceroplastes ceriferus, Chunrocerus niveosparsus, Drosicha
stebbingi, Hemiberlesia lataniae, Icerya purchasi, Parasaissetia nigra,
Parthenolecanium persicae, Planococcus kenyae, Pseudaulacaspis
pentagona, Pseudococcus filamentosus, Pulvinaria maxima, and Quadraspidiotus perniciosus. (Hemiptera). Anacanthotermes macrocephalus (Isoptera); Acria
emarginella, Archips micaceanus, Ascotis selenaria, Diacrysia obliqua,
Euproctis lunata, E. sulphurescens, Glyphodes pyloalis, Hyposidra
talaca, Indarbela tetraonis, Labdia semicoccinea, Metanastria hyrtaca,
Penicillaria nugatrix, and Spodoptera litura. (Lepidoptera). Choroedocus illustrius, and Schistoceria gregaria (Orthoptera). Reed (1976) adds the following: Aecidium mori (rust), Cytospora atra (bronze canker), Diplodia butleria (stem rot), Ganoderma applanatum (white sap rot), G. lucidum (heart rot), Polyporus tulipiferae (white spongy sap rot), Thyrostoma mori (Coryneum mori, causes reduction in leaf production), Trametes badia (butt rot), and Ustilago haesendockii (smut leaf). Nematodes include Melodoigyne javanica and M. sp.
According to Reed (1976), insects causing most damage to mulberry are: Phenococcus hirsutus
(sucks sap of stem, leaf or petiole, causing severe curling and
crinkling of leaves and swelling and twisting of apical regions), Pseudodendrothrips ornatissima (thrips), and white grubs and termites.
References
Agriculture Handbook 165. 1960. Index of plant diseases in the United States. USGPO. Washington.
C.S.I.R. (Council of Scientific and Industrial Research). 1948–1976. The wealth of India. 11 vols. New Delhi.
Duke,
J.A. 1978. The quest for tolerant germplasm. p. 1–61. In: ASA Special
Symposium 32, Crop tolerance to suboptimal land conditions. Am. Soc.
Agron. Madison, WI.
Duke, J.A. 1979. Ecosystematic data on economic plants. Quart. J. Crude Drug Res. 17(3–4):91–110.
Duke, J.A. and Wain, K.K. 1981. Medicinal plants of the world. Computer index with more than 85,000 entries. 3 vols.
Hartwell, J.L. 1967–1971. Plants used against cancer. A survey. Lloydia 30–34.
Lee,
D.K. No date (ca 1981 or later). Biomass Products as an Energy Source.
J. Nat. Acad. Sci., (Republic of Korea) Nat. Sci. Series 19:239–253.
List, P.H. and Horhammer, L. 1969–1979. Hager's handbuch der pharmazeutischen praxis. vols 2–6. Springer-Verlag, Berlin.
Reed, C.F. 1976. Information summaries on 1000 economic plants. Typescripts submitted to the USDA.
Wyman, D. 1974. Wyman's gardening encyclopedia. MacMillan Publishing Co. Inc., New York.
Last update Wednesday, January 7, 1998 by aw
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