Fiber crops hemp & flax Flashcards
Cultivation of cotton - requirements, sowing and fertilization
Requirements:
- requires ample H2O supply
- needs warm temperatures
Sowing:
- February to June
Fertilization
- Requirements not very high
Harvest of cotton
October to February
Yield would diminish in second year, replanted each year
Cultivation only in monocultures; therefore enormous pesticide requirements
Organic farming: <1% globally
Hemp systematics
Cannabis sativa, Cannabaceae
Var. indica (indian hemp), gigantea (giant), ruderalis (wild)
Dioecic plant, annual
Hemp products
Fibres, oil-rich seeds, THC
Traditional and very durable fibre for paper
Origin of hemp
China, east Asia
Dissemination - Hemp
Today mainly India & China
Banned in lots of countriees today because of high THC content of some cultivars
Flax systematics
Linum usitatissimum, Linaceae
L. dehiscens (wild, annual to perennial), L. bienne (annual, overwintering)
Products - flax
Fibres, oil-rich seeds
relatively soft and durable linen cloth was used for lots of purposes
Flax origin
Fertile crescent
Dissemination - flax
Europe, North America
Arrived in Switzerland ca. 6000 years ago
Morphology of hemp
Tall (1.5 - 4 m) annual plant grown for grain and fiber
Leaves are palmate with 7 to 11 leaflets having serrated edges
Outer protion of stem contains strong bast fibers
inner portion of stem contains hurd, which is used for paper and buliding materials
Stem cross sections
Page 6
Hemp use
Page 9
Why has hemp declined in the past 150 years?
Decreasing interest in hemp fibers and risk o addiction to THC as a drug
Hemp cannabinoids
THC = hallucinogenic compound of Marihuana
only some cultivars above the allowed content of 0.3%
Cannabidiol (CBD) is closely related to THC but does not act hallucinogenic, reduces fear & inflammations
Hemp seeds for animal and human nutrition
Contains a lot of unsaturated fatty acids
Flour can be used to make bread and other bakery products
Fatty acid coposition of linseed oil
Linolenic acid 57%
Linoleic acid 16%
Oleic acid 19%
Other fatty acids
Linseed oil is richer than any other vegetable oil in essential fatty acids of the n-3 family & has good reputation for treating a range of ailments, from heart disease to autoimmune disorders
Uses of linseed
Beeders - Seeds
Food industy - bakery products
Linseed cake
- pharmaceutical industry - medicinal plants
- feed industry - feeding stuff
Linsed oil
- Food industry - edible oil
- Lacquer and paints industry - special soaps
- chemical industry - paints, lacquer
Advantages of flax fibres
fibers are twice as strong as those of cotton and 5x as strong as those of wool
Hygroscopic, able to absorb up to 12% of own wight in water
strength increases by 20% when wet
low stretching capability
good heat capacity
resistant to high temperatures (up to 300 °C)
Disadvantages of flax fibres
Irregular fiber length and thickness
Separation of fiber from stalk tedious and relatively expensive
Uses of fiber flax (whole plant)
Long fibres - 9% textile industry
Tow (short, broken fibers) - 7% paper and textile industry
Seeds - 11 % oil chemistry, food and feeding industry
Shives (shredded, woody remainders of the hurd - 45 % panel industry
Wax - 1% cosmetic and pharmaceutical industry
Flax harvest
When leaves wither, stem turns yellow and seeds turn brown
stalk should not be cut in the harvesting process of fiber flax, but removed from ground intact
plants are pulled out of ground by hand or by machines
stalks are tied in bundles and traditionally left on field for two to eight weeks to allow retting by alternating wet and sunny conditions
Harvesting and post-harvest steps - flax
Pulling up - no cut
Rippling - pass plant through coarse combs which remove seeds and leaves
Retting - woody bark is decomposed by water
Breaking - dry plants are sent through fluted rollers to break up stem and separate exterior fibers from bast, shives are scutched
Spinning - fibers are combed and straightened in preparation for spinning
Combing - further parallelization and purification of fibres
Hemp processing
Similar as flax, but cut not pulled up
Dew retting
- harvested hemp is placed into windrows and left to desiccate until fungal organisms can complete the retting process in the stem
- requires usually only 1 to 2 weeks
- the fibres should turn golden or grayish in color and should sparate easily from the interior hurd
- stalks should have less than 15% moisture when baled and should be allowed to dry to 10% in storage out of the water
Water retting - by submerging the stems in water
Biology of hemp
commonly dioecious plant, male and female plant
Male plant: earlier harvest or one has to live with finer fibres
female plant: strogner, taller, more biomass
Linseed morphology differencies by use
Fiber flax:
- no basal branching
- plant height >= 100 cm
- use: fibers
Double purpose flax:
- little branching
- intermediate plant height
- use: fibers and oil
Linseed:
- strong branching
- low plant height
- use: oil
Breeding of monoecious plants in hemp
Male flowers and female flowers are separated
yield of monoecious plants (biomass) is lower than yield of dioecious cultivars, but fibers are more homogeneous
Flax plant flowers
May be blue or white
Flax plants with blue flowers yield the finest linen fibres
Flax flowering starts beginning of June
Flowering period can extend to several weeks
Fruit - flax
Spherical capsules
Optimal harvest point of linseed
Plants are desiccated and eeds rustle in the capsule
