Crops

Linum strictum L. ssp. corymbulosum (Reichenb.) Rouy - common flax.

Synonyms:

L. usitatissimum L. s. stricta, L. corymbulosum Reichnb., Proles elongata Vav. et Ell.

Taxonomic position.

Family: Linaceae S.F.Grey, genus: Linum L., species: Linum strictum L. - Cherepanov S.K., 1995

Biology and morphology.

2n=30. Flax is an annual plant with a single cylindrical upright slender stem, ramified only in its upper part (60 to 150 cm long). Leaves are numerous, small, linear or linear-lanceolate, sessile, covered with a waxen film.
Flax inflorescence is a raceme. Each plant has few flowers regular in their shape, double, 1.5 to 2.4 cm in diameter, light blue, blue or white in color. Petals are obovate, their edges are smooth, sometimes - crimped. Flax androecium has staminodes; the number of styles is 5. Flax fruits are egg-shaped bolls. Each has 5 lobes and does not open up when mature. Flax seeds are flat, brown-colored, and glossy. Each one has a rostellum. One thousand seeds weigh 2 to 13 g. Common flax stalks feature long spindle-shaped cells called within textile industry elementary fiber. A spindle-cell is 4 to 60 mm long. When joined longwise, bast cells (or elementary fibers) form a bast bundle. Upon mechanical treatment, these fiber bundles yield a continuous yarn called technical fiber. Elementary fibers are gummed into bundles by pectic substances. Fibrous bundles form dense rings around the stalk. Each ring consists of 20 to 40 fibrous bundles gummed together by pectic substances. Fiber quality depends on the number of bundles in a ring. The more bundles there are, the better the fiber is. Technical yarn is separated from the stalk through destruction of pectic substances by bacteria which make pectin ferment. To this end the stalks are retted. Technical yarn length is 80 to 90 % of the full stalk length. Seeds contain 36 to 39 % oil. Male sterility was first observed in flax plants.

Ecology.

Flax is a long-day plant. Common flax thrives in temperate climates with the temperature total during its vegetation period of 1400 to 2200° C. Seeds begin to germinate at 1 to 3° C. If the soil at the seed burial depth is heated to 8 to 10° C, shoots appear 5 to 6 days after sowing. Shoots survive morning and night frosts of -5° C. Flax is very hygrophilous, more so when sending out buds or in blossom. During its vegetation period flax growth rate is irregular. Ten days after sprouting flax plants reach the height of 1.5 to 2 cm. Bast cells (fibers) in flax stalks begin to take shape 6 to 10 days after sprouting. The highest daily growth rate of flax plant stalks is observed when they send out buds. 65 % fibers are formed within a relatively short period - from the fir-tree stage till the flowering stage (in 20 to 25 days). During this stage of fast growth stalks of common flax plants averagely become 4 to 5 cm longer every day. Growth of flax plants and fiber bundles' formation in their stalks are arrested at the end of the flowering stage. High soil humidity after flowering favors lodging of flax plants reducing fiber and seed yield and lowering their quality. It also retards maturity of flax. Flax is fastidious about the nutrients in the soil. It is sensible to the lack of boron. Flax thrives on medium and light weakly podzolized loamy soils with pH of 5 to 6. The vegetation period of flax plants lasts 75 to 90 days. Cultivated flax is a self-pollinating plant. Only about 5 % flowers are cross-pollinated by insects (bees, wasps, flies, etc.). In its natural environment flax is pollinated during morning hours. Early in the morning the buds of the corolla open, anthers burst, and pollen falls on the stigma of the pistil. If the weather is fair and warm, flax plants begin to blossom early, at 4 or 5 o'clock in the morning. After 4 or 5 hours of blossoming petals fall off. If the sky is overcast, the corolla opens up later. Under favorable weather conditions a common flax plant usually blossoms for 3 to 5 days, and the whole field of flax plants - for 8 to 12 days.

Distribution.

The original species is L. angustifolium Huds., which is rather polymorphous and has perennial, biennial and annual varieties. L. angustifolium Huds. is distributed mainly around the Mediterranean. (Morphologically, anatomically and ecologically cultured flax varieties evolved in the following succession: narrow-leaved flaxes - procumbent flaxes - crown flaxes - fiber flaxes.) Ancient centers of flax-growing are mountainous areas of India and China, where narrow-leaved flax grows no more. Cultivated flax originated in South West and East Asia. In India flax was cultivated as a fiber crop earlier than cotton. As early as in the 4th or 5th millennium B.C. flax was cultivated for its fiber in Mesopotamia, Assyria and Egypt. Wild narrow-leaved flax and semi-cultured procumbent flaxes grow in Transcaucasia. Many monuments of Ancient Egypt reflect cultivation of flax and spinning and weaving of its fibers. In Russia flax has been cultivated since the birth of the Russian nation. All the tribes which inhabited the eastern part of the European plane cultivated flax even before the emergence of Kievan Rus. Archeological digs near the estuary of the Sheksna River in Vologda Region revealed evidence of flax cultivation in this area as early as the 3rd and 4th centuries A.D. Fiber flax varieties growing in the old hills in the North-West of the Russian Federation yield the best fiber (in the hills near the city of Pskov and the towns of Palkino, Cherskaya, Vnukovo, Opochka, and Porkhov as well as hills in the Baltic States). In those areas flax plants reach 90 to 110 cm in height. They have a straight single stem. Each plant bears 3 to 7 bolls. Pskov fiber flaxes are the source of all west-european fiber flaxes. On the Kola Peninsula, in Arkhangelsk and Vologda regions, in the North of Siberia, in Smolensk Region, in Belorus and in the northwestern Ukraine fiber flaxes are 10 to 15 cm lower, and their fiber is shorter. However, these varieties mature earlier. The first cable-twisting factory was established in the 16th century. It was the beginning of export of dressed line and cables to Western Europe via Arkhangelsk and Narva.
Famous linen used to produced in Kadashevskaya - once a suburb of Moscow. The 18th century saw a widespread cultivation of flax in Yaroslavl, Vladimir and Kostroma regions. Russian fiber flaxes originated in Central Asia whence Scythians brought them. Nowadays flaxes of the Pamirs, Kazakhstan, Ghindukush, and Cashmere are of excellent quality. In western Europe flax is cultivated as far north as 65.5° N, from the Gulf of Finland to the Pacific (northern non-chernozem regions, Omsk, Novosibirsk, Irkutsk, Chita regions, Altai Territory, the Far East). Flax was introduced to the USA, Canada, and Japan. In The State Register of Breeding Achievements Approved for Practical Application in the Russian Federation in 2004 there are 33 cultivars. Among them Pskovsky 359 and Tvertsa were approved for cultivation in certain areas in 1969 гoдa. Main cultivars are: A 29, A 93, Belochka, Lenok, Neptune, Priboi, Rusich, C 108, Sinichka, Slavny 82, Tomsky 17, Tomsky 18. 8 new cultivars have been approved foe cultivation in certain areas since 2000. The main breeding agencies are: All-Union Research Institute of Flax, Kaluga Research and Development Agro-Industrial Institute, Viatka State Academy of Agriculture, Pskov Research Institute of Agriculture, Smolensk Region A. Engelgardt State research station, Tomsk Region State Agricultural Research Station.

Economic value.

Flax is a valuable fiber and oil-bearing crop. Flax fibers are used to manufacture different kinds of fabrics for clothes, bags, tarpaulins, special purpose textiles for motor-car and armaments industries. The breaking strength of flax yarn is twice as high as that of cotton yarn and three times as high as that of woolen yarn. Flax tow is used for making ropes and cords, heat-insulating materials and panels for construction industry. Linseed oil dries fast. It is used in food, printing, petrochemical, soap, paper, pharmaceutical, and paint industries, as well as for technical purposes. Both linseed and linseed oil are used in medicine. Linseed contains over 20 % protein. By-products of linseed oil extraction are oilcakes used as livestock fodder. Oilcakes are rich in valuable nutrients. Each contains 30 to 32 % protein, 3 to 5 % oil, and a considerable amount of starch. Oilcakes are high-caloric and concentrated livestock fodder. The nutritive value of 1 kg of flax oilcakes is equal to that of 1.2 fodder units. 1 kg of flax oilcakes contains about 280 g of digestible protein, 4.3 g of calcium, 8.5 g of phosphorus, 2 mg of carotene. Flax chaff is also a livestock fodder. Straw and boon are used in paper manufacturing. Fiber flax is grown as part of field crops rotation. The best precursors for flax are: perennial herbs, winter crops, potatoes, vetch and oat mix. Flax is sown early into tilled soil. It is sown into closed drills (with 7 to 8 cm between drills). 100 to 150 kg of seeds are sown per hectare. Seeds are buried 15 to 30 mm deep. Flax is gathered in at its early yellow maturity stage in a two-stage or direct way. Magnesium chlorate is the desiccation agent. Roll harvesting techniques have been recently introduced. Upon pulling the flax straw arranged in bands, a baler-machine makes rolls of 250 to 300 kg each, which are sent to flax-scutching mills. This harvesting technique is 4 to 8 times more efficient than sheaf harvesting. In order to separate the fiber flax stalks are submitted to primary treatment: they are retted, steamed, broken and scutched. Fiber flax treatment is extremely labor-intensive. One hectare yields 600 to 800 kg of fiber. In the best flax varieties the weight of fiber is 32 % of the total weight of the stalk. Intensive cultivation techniques increase the yield by 40 % (up to 15.500 kg per hectare). Primary flax treatment consists of stalk retting, drying, breaking and scutching. Flax stalks may be retted with dew, cold or hot water. While sheaf harvesting, - if flax is not to be consigned to flax-scutching mills as straw, - ready sheaves are spread out on retteries where the fiber is separated by dew retting. Main agents of flax dew retting are fungi Cladosporium herbarum and Alternaria. Cold water retting is carried out in natural waters and tanks. Flax straw may stay under water till the fiber is fully separated from the stalk or else it is kept submerged for some time and the fiber is separated from the stalks when they are spread out on the ground. During cold water retting pectic substances in flax stalks are destroyed by different bacteria. To be quickly and well cured, the humidity of the straw spread out on retteries in this period should be 40 to 60 %, and the atmospheric temperature - at least 7° C. Optimal retting temperatures are 16 to 20° C. As compared to spreading out and cold water retting, warm water retting presents some advantages. This process does not depend on environmental factors. Raw fibers can be separated outside retteries. Retting becomes 5 to 6 times faster, and flax fiber has better operating characteristics. Longer fibers are produced. Main agents of warm water retting are Clostridium felsineum and Cl. pectinovorum. Retting liquid temperature is kept at 36 to 37° C until retting is fully finished. Ready separated fiber is then dried, bound into sheaves of 18 to 20 cm in diameter and is stocked or shipped to flax-scutching mills for processing. Special care must be exercised while warm water retting of flax as all parts of the plant and its seeds may produce at thus time prussic acid.

Reference:

Vainrub A.I., Gaube V.A., Petukhov B.S. Industrial Flax Production Techniques. Leningrad: 1984
Wulf E.V., Maleeva O.F. World Stock of Useful Plants. Leningrad: 1969
State Register of Breeding Achievements Approved for Practical Application in the Russian Federation in 2004. Moscow: 2004
Davidian G.G. Fiber Flax and Hemp Cultivation. Leningrad: 1979
Zhukovsky P.M. Cultivated Plants and Their Congeners. Leningrad: 1971
Cultivated Flora of the USSR. Ed. Wulf E.V. Leningrad: 1941
Flax Cultivator's Habdbook. Comp. Trush М.М., Karpunin F.М. Leningrad: 1985
Fomenko L.D. Flax Production in Reclaimed Areas. Moscow: 1982

© Gashkova I.V.

Photo Gashkova I.V.