Cultivation of medicinal plants involves all the common processes and methods utilized for cultivation. of other agricultural crops. They can be raised both from seeds and by vegetative propagation.
Propagation’s from Seeds
Like any other crops drug plants are raised from seeds. This method of propagation involves the following steps:
Selection of seeds: Mature and healthy ripe seeds are selected for wowing from high yielding and disease resistant plants.
Preparation of seedbeds: Ideal seedbeds or lands are prepared by thoroughly irrigating and manuring the soil where the seeds are sown.
Sowing of seeds: The selected seeds are then sown in the prepared seedbed or land at the proper season and in the proper manner.
Transplantation of the seedlings: Where applicable, the seedlings are uprooted from the seedbeds at their proper stage of growth and transplanted to the permanent land, prepared properly to afford luxuriant growth of the transplanted seedlings.
Irrigation and weeding: Proper irrigation and weeding of the crop are done at regular intervals to ensure uncontam1nate health growth.
Protection of the crop against drought and disease is ensured by irrigation and spraying the crop with insecticides, fungicides, and herbicides.
Harvesting: Finally the crop is harvested in the proper manner at the proper time.
Propagation by Vegetative
This involves a number of methods, of which the following may be mentioned:
By the development of various vegetative organs, which give rise to new plants, like
- bulbs (e.g., Squill)
- corms (e.g., Colchicum)
- tubers (e.g., Aconite), and
- rhizomes (e.g., Ginger).
These vegetative organs are planted in large numbers to raise a crop.
By division or separation of a plant into its individual constituent aerial stems or buds (each having roots and a growing point) and planting them separately, as is done in the propagation of Garlic, Rhubarb and Gentian.
By runners of offsets as produced by many plants like Cocoyam, Mints, etc. The runners with the daughter plants are detached from the mother plant and planted.
By suckers or stolons: In this case the suckers are separated from the mother plant and planted separately, e.g., Liquorice.
By the use of cuttings: Cuttings are made by severing a stem into many parts, each having at least one node. One dipping into soil, roots and buds develop from the nodes. This method is applied in propagating large number of plants, e.g. Rose, Grapes, Coca, Vanilla.
By layers: In this method a branch or shoot is induced to produce roots by partly interrupting the food supply by removing a portion of’ the bark at one part of the stem. This part is then embedded or covered with soil and regularly supplied with water. When roots develop at the treated part the stem is severed from the plant with the roots and then planted. Propagating plants by means of layers always ensures exact duplication of the mother plant. This is a popular method of propagation, particularly with fruit trees.
By grafting and budding: These are not commonly used for propagation of medicinal plants, except for some experimental purposes. Grafting is a method of growing the foliar parts of one plant, termed as scion, on the main or side stem of another related plant, called the stock. In making a graft, two stems of equal size and age of two related plants are cut obliquely using a sharp knife or a razor blade to ensure a clean cut across. The severed parts are then exchanged, fitted together, tied with a string and covered. In a few weeks time the scion and the stock are naturally joined and the wound health. In budding, a piece of bark bearing a bud is removed from one plant and is introduced into a suitable cavity or a T-shaped slit made in the bark of another plant or stock, which finally bears the developed bud. This is largely used in Citrus plants for growing sweet orange branches on sour stocks.
By fermentation: Moulds and bacteria are propagated by a process called fermentation. In this method strains of the microorganisms are allowed to grow by seeding a small amount of the selected strain in a suitably prepared liquid nutrient medium.