Importance of the Plant
Cannabis sativa L. (family Cannabinaceae) is an ancient plant with various applications. Its narcotic effect was recognized from ancient times, when it was taken as a narcotic drug in India and in several countries of Asia and some parts of Africa.
Some cultivars, especially those growing in Northern Europe and North Asia produce high-quality stem fiber, suitable for weaving and spinning, whereas others are interesting as oil plants, containing relatively high vegetable oil (20%-40%) in the seeds.
The plant has different chemovarieties, with more or less neutral and acidic compounds.
The taxonomy of the plant has raised some problems. Earlier, the Indian or hashish variety was considered as a separate species, and the taxonomy of wild hemp was not clear. At present the taxonomic division is accepted as Cannabis sativa var. culta and var. indica (family Cannabinaceae)
Distribution and Cultivation Areas
On the basis of growing area and drug reserves, the territorial distribution of hemp production can be characterized as follows:
Production of Industrial Fiber (over 1000 ha): Bangladesh, China, Cyprus, India, Japan, Korea, Pakistan, Syria, Thailand, Turkey, Austria, Bulgaria, Czechoslovakia, France, Federal Republic of Germany, German Democratic Republic, Greece, Hungary, Italy, Poland, Portugal, Romania, Spain, Sweden, Yugoslavia, U.S.S.R.
Countries with a Registered Drug Reserve: Bangladesh, Belgium, Czechoslovakia, Finland, France, India, Ireland, Israel, Jamaica, the Netherlands, Portugal, Saudi Arabia, Suriname, Switzerland, United Kingdom, U.S.A till 1983 (Bernath 1985).
Figures on the production of nonfiber hemp are only estimates, thus, the UN data on illegal hemp production in 1983 are only a rough guide. In this respect, North and South America deserve special mention: the estimated production area is 1548 km2 in Brazil (in the Amazon and Rio Negre regions), 100000 ha in Columbia, 2035 ha in Jamaica and 2679 ha in Mexico. In the Far Eastern regions of Asia, including Oceania and Australia, only 40-80 ha of illegal hemp production has been discovered, but judging by the size of the reserves destroyed, the proportions are considerably higher. In 1983, for instance, 117298 u. cannabis were destroyed in India, 950645 u. in the Philippines, and 179682 u. in Thailand.
Conventional Practices in Propagation and Improvement
Hemp plants are propagated by seed. The space for seed placing is 20×20 cm. Sowing time, March-April; harvesting time, August-September. For the textile industry the production of fibers starts with soaking, when by the effect of bacteria in the soaking water the parenchyma tissues disintegrate, then fibers are easily prepared by tapping and cleaned mechanically and chemically.
Hemp sorts improved for the textile industry are 2-3 m tall, slightly ramificated. In some cases, unisex hemps are selected, the quality of stem fibers in female plants being higher. The unisex one is a steady variety.
Necessity for Amplification of Unconventional Methods
Because of the variability, both in cannabinoid content and composition of fiber, hemp needs continuous biochemical control. One of the basic aims of Cannabis improvement is to produce plants with good fiber production and at the same time to keep the low level of THC content. In the course of this biochemical investigation of the Cannabis plant, a thorough understanding of the biosynthetic pathways for cannabinoids and regulation processes by hormone addition has emerged.
Agricultural, textile, industrial, and security aspects of narcotic drugs called for the improvement of reliable Cannabis plants in which the cannabinoid content is genetically more stable at the same time. For this type of work tissue culturing seems to be an adequate method.
Medicinal and Aromatic Plants I (1988)