Hemp

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Hemp

• Matthew Leon
• Organic Seed Saving
• 5/27/04

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Cannabis sativa Linnaeus

• Member of the Mulberry Family, Moraceae
• Closely related to the Nettle family
• Annual
• Dioecious (mostly)
• Outcrosser
• Wind pollinated

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Plant Characteristics

• Rigid herbaceous stalk, 1-5 meters tall obtusely
  4-cornered, more or less fluted or channeled and
  with well marked nodes at intervals of 10-50
  centimeters.
• Outermost layers of stem include bark and cortex
  cells holding chlorophyll.
• Underlying the epidermis of the bark are many
  very long, high cellulose cells, bundles of which
  make up the primary bast fibers of hemp
• Complex structure of stem includes a woody core
  high in lignin and on processing becomes the
  material known as hurds.
• When not crowded it has numerous spreading
  branches, and the central stalk attains a
  thickness of 3-6 centimeters.
• If crowded, as when sown broadcast for fiber, the
  stalks are without branches or foilage accept at
  top and the smooth fluted stems are 6-60
  millimeters in diameter.

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Characteristics cont.

• Leaves opposite, except near top or on shortened
  branches, appearing fascicled, are palmately
  compound and composed of 5-11, usually 7
  leaflets.
• Leaflets are dark green in most varieties,
  lighter below, lanceolate, pointed at both ends,
  serrate, 5-15 cm.s long, and 1-2 cm.s wide.

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Staminate Flower Structure

• The staminate flowers are born in small axillary
  panicles, and consist of five greenish yellow or
  purplish sepals opening wide at maturity and
  disclosing five stamens which discharge abundant
  yellow pollen.

• Staminate plants die after pollen is shed

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Pistillate Flower structure

• Pistillate flowers are located in the axils of
  the small leaves near the ends of the branches,
  often crowded appears to be a thick spike.
• Inconspicuous consisting of a thin, entire, green
  calyx, pointed, with a slit at one side, but
  remaining nearly closed over the ovary and merely
  permitting the two small stigmas to protrude at
  the apex.
• Pistillate plants remain alive and green a month
  after staminate plants, or until seed is fully
  developed.

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Seed

• The ovary is one seed developing into a smooth
  compressed or nearly spherical achene, 2.5 4
  mm. Thick and 3-6mm. long.
• Seeds are dark grey to light brown in color and
  mottled.
• The seed cleaned for market usually include some
  still covered with the green gummy calyx
• Light colored seeds are often imperfectly
  developed, dark seeds are generally preferred
• Seed lasts 2-3 years

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Life cycle

• A growing season of roughly 120 days (in
  Kentucky) 90 days in Southern Europe
• Seed maturation requires another 30-45 days
• Short day (long night) photoperiod sensitive
• Therefore must be planted early (in N.
  hemisphere) to avoid premature flowering and seed
  set

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Photoperiod response

• Varieties originating at 45 degrees have evolved
  a life cycle driven by a genetically programmed
  response to the length of the night. Nights in
  temperate zone begin to lengthen after summer
  solstice when plants shift from vegetative growth
  (which has resulted in long stems) to the
  reproductive stage, so the seed will be set and
  matured by frost.
• This fact makes growing hemp in tropical zones
  difficult because the plants immediately
  experience long nights characteristic of late
  season in the north. The plants respond by going
  into reproductive phase immediately and little
  vegetative growth occurs

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Breeding tropical hemp

• One major breeding problem is to develop breed
  capable of producing hemp in the tropics. To do
  this Dr. Dave West has been trying to combine the
  photoperiod adaptation of tropical cannabis
  varieties with the internode elongation and fiber
  or seed characteristics of their Northern
  cousins.
• Identify genetic sources of the traits in
  interest cross them select within the variation
  that emerges (i.e. plants that are still
  vegetative after growing 3 months in Hawaii are
  the ones that can be bred to use for fiber
  production.

Dr. Dave West directs the Hawaii Industrial Hemp
Project, now in its fourth year. A Ph.D. in Plant
breeding and genetics, he has been an applied
plant breeder for 25 years.
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General breeding

• When growing for seed, mass selection is a common
  breeding method.
• Before the seed hemp plants are cut the grower
  goes through the field and marks the plants from
  which seed is to be saved for the seed crop.
• Plants are usually selected for the height,
  lateness of flowering, and length of internodes.
  Continued selection in this manner will improve
  the type.
• Without selection continued each season the
  general average of the crop deteriorates.
• It is more difficult to keep distinct types
  separate with hemp, being a crosser, and when
  more rougish plants succeed in reproducing their
  genes which include genotypic traits such as
  early flowering are passed to the next generation

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Uses of Hemp

• The valued primary fibers are contained around
  the hollow, woody core of the hemp stalk. These
  long, strong fibers that grow the length of the
  hemp stalk are considered bast fibers. Harvested
  when plants begin flowering.
• Seed for eating as oil, nutbutter, roasted, etc.
  
• For propagation.
• Oil can be made into a plastic which when
  combined with hurds makes quite a strong polymer.
• Core fiber is derived from the sturdy, wood-like
  hollow stalk of the hemp plant. Sometimes
  referred to as "hurds", it is up to twice as
  absorbent as wood shavings, making it an
  excellent animal bedding and garden mulch. It can
  be easily blended with lime to create a strong
  yet lightweight concrete or plaster. Its high
  cellulose content means it can be applied to the
  manufacturing of plastics. Like primary fiber, it
  is biodegradable and possesses antimildew and
  antimicrobial properties.

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Methods of Propagation for Seed

• Maturation times depend greatly on variety
• Kentucky varieties were sown from late march to
  may with best results in early april.
• Not sown as densely as for fibre hemp, seed hemp
  plants were nonetheless grown without pesticides
  or herbicides.
• Hemp plants after one month averaged 1 1/2 - 2
  feet and were starting to out-compete weeds
• After three months the crop has reached its
  maximum height and is now putting its energy into
  seed production

Data from hemp germplasm trials in Canada
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• Plants have generally not branched, resulting in
  each plant having a single, high seed yielding
  flower. Seed bearing buds range in height from 6
  inches to two feet, and their size is closely
  correlated to the height of the plant.

• Taller male plants have shed their pollen and
  died, leaving the female plants pollinated and
  developing seed.

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Harvesting for Seed and Stalk

• Occurs 4-6 weeks after male plants begin to shed
  pollen
• Combine harvest is possible

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• After the seed was combined, the lower 3.5 - 4
  feet of the stalk remained standing. This was
  later mowed and left to ret on the field. The cut
  stalk was turned several times to ensure even
  retting. After two weeks the retted stalk was
  baled and stored.
• The toughness of the stalk is apparent by the way
  the stalk has split and in some cases frayed (see
  below) when being cut by the combine.
• A small portion of the plants were very immature,
  even after close to four months of growth. These
  shorter plants in some cases were below the
  cutting bar of the combine and were left standing
  in the field.

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• The combine unloads its day's work - piles of
  fresh, and surprisingly clean hemp seed!
  Nonetheless, the seed required immediate
  attention to remove the bits of stalk (mostly
  hurds) and other vegetative matter which
  otherwise would have impeded drying.
• ...and it all came from just a few of these bags
  ('Chanvre monoique' Cannabis Sativa L. Fedora 19)
  

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Harvesting for Fiber

• As soon as crop is in flower
• For dew retting the cut stalks are left in the
  field for several weeks to allow natural humidity
  and bacteria to decompose the fiber-binding
  pectins.
• After retting fibers are readily separated from
  the core and processed.

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Fiber Characteristics

• Length average 8 (20 cm) in length, 4 - 6 ,
  1 - 2 and special lengths available upon
  request
• Luster high
• Strength high
• Elasticity low, can be treated to improve
• heat conductivity high, very cool fabric to wear
• Absorbency high
• cleanliness and washability high
• reaction to bleaches will weaken, use with care
• reaction to heat will scorch and burn
• effect of mildew highly resistant
• effect of light outdoor exposure very
  resistant
• reaction to alkalies not affected
• reaction to acids easily affected
• affinity for dyes very good

hemp under microscope 125 x magnification
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Seed Characteristics

• Both the oldest Chinese agricultural treatise,
  Xia Xiao Zheng, 16th century B.C. and other
  chinese records discuss hemp as one of the major
  grain crops grown in ancient China
• 34.6 protein easily digestible, gluten free.
  Array of 10 essential amino acids. Including
  arginine, and histidine, both of which are
  important for growth in childhood, and
  methionine and cysteine key for proper enzyme
  formation.
• 46.5 fat. Provides both EFAs (essential fatty
  acids) needed in human diet-linoleic (an omega 6
  fatty acid) and alpha-linolenic (an omega 3
  acid). On average the highest mono and
  polyunsaturated fat content of all oils, taken
  collectively, 89
• 11.6 carbohydrate fiber content of hemp seed
  flour is 40, which is highest of all commercial
  flour grains
• High content of antioxidants (92.1mg/100g)

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A little history

• The lu shi, a chinese work of the Sung dynasty
  contains a statement that the Emperor Shen (28th
  century B.C.E.) first taught the people of China
  to cultivate ma (hemp) for making hempen cloth,
  and later the seed for food.
• Traveled along trade routes
• According to Herodotus (450 B.C.E.) the
  Thracians and scythians beyond the Caspian Sea,
  used hemp, and its probable that the Scythians
  introduced it to Europe around 1500 B.C.
• Hiero II King of Syracuse (270 B.C.E.) bought
  hemp in Gaul for the cordage of his vessels.

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A little more Goode history

• By 16th Century A.D. it was widely distributed in
  Europe and used for fiber and seeds.
• In 1846 M. Herbert sent form China some Seeds of
  the Tsing-ma, great hemp, of China. Differed
  in that it reached heights of 21 compared with
  much shorter European varieties
• Chile, South America in 1545
• Hemp was introduced into America as it was
  essential to the British maritime industry.
  Fortunately it adapted quickly to climate and
  soil conditions.
• They begin to plant much Hempe and Flax which
  they find grows well and good Richard Wodenoth
  circa. 1649
• Hemp was grown throughout the country. Including
  Lancaster county Penn. and Kentucky in 1775,
  Missouri 1835, Champaign Ill. 1875, Nebraska
  1887, then to Cali.
• Note in 1857 the first Chinese hemp seed was
  imported. Since that time the common hemp of
  European origin has given its place in this
  country to the larger and better types from China

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Resources

• http//www.globalhemp.com
• http//naihc.org
• http//www.hemphasis.com/

HEMP GERMPLASM TRIALS IN CANADA
Ernest Small, Eastern Cereal and Oilseed Research
Centre, Research Branch, Agriculture and
Agri-Food Canada, Central Experimental Farm,
Ottawa, ON, Canada K1A 0C6 (e-mail smalle_at_
em.agr.ca website http//res.agr.ca/ecorc/)
and David Marcus, Natural Hemphasis, 43
Melville Ave, Toronto, ON, Canada M6G 1Y1
(e-mail dave_at_hemphasis.com website
www.hemphasis.com)