Introduction
Cultivation of crude drugs involves scientific growing of medicinal plants to produce good-quality raw materials. Proper soil, climate, water, seeds and cultivation methods help ensure high yield and correct active constituents. This chapter explains the key methods and practices involved in cultivating medicinal plants.
Factors Affecting Cultivation
- Soil: Physical, chemical and microbiological properties of soil influence plant growth. Water-holding capacity, pH and nutrient content are important.
- Seeds: Seeds must be botanically identified, pure, disease-free and have high germination capacity.
- Season: Proper sowing season and seed viability affect success. Some seeds like cinnamon lose viability quickly.
- Genetic Material: Seeds or plant parts should comply with national and international regulations, especially regarding genetically modified organisms.
Methods of Plant Propagation
Medicinal plants are propagated by two major methods—sexual and asexual. Each method has its own advantages and limitations.
1. Sexual Method (Seed Propagation)
Plants grown from seeds are known as seedlings. This is the most common method.
Advantages
- Seedlings are long-lived and produce heavy yield.
- Seeds are easy to obtain and cost-effective.
- Useful for developing new varieties through natural variation.
- Suitable for plants where vegetative propagation is not possible.
Limitations
- Plants are not uniform in growth and quality.
- Seedlings take longer to bear fruit or produce usable parts.
- Higher cost for spraying or maintaining large trees.
Seed Quality and Treatment
- Good seeds must be pure, disease-free and show high germination rate.
- Pre-conditioning treatments like scarification help in better germination.
- Some seeds require chemical treatment with gibberellins, cytokinins, thiourea, potassium nitrate or sodium hypochlorite.
- Fresh dormant seeds germinate better when soaked in potassium nitrate.
Methods of Sowing
- Broadcasting: Used for very small seeds (e.g., Isabgol). Seeds are scattered over well-prepared soil.
- Dibbling: Seeds of medium size are placed in holes (e.g., fennel, castor, papaya).
- Nursery beds: Used for expensive seeds or seeds with poor germination (e.g., cinchona, cardamom).
Special Treatments
To enhance germination, seeds may be soaked in water (castor), treated with sulfuric acid (henbane) or lightly abraded (senna). Plant hormones may also be applied.
2. Asexual Method (Vegetative Propagation)
This involves using vegetative parts like stem, root or leaf to produce new plants. It gives genetically identical plants.
Advantages
- Uniform growth and yield.
- Seedless plants like grapes or pomegranate can be propagated.
- Faster maturity and earlier production.
- Allows development of disease-resistant varieties.
Limitations
- Plants are less vigorous and short-lived.
- No new varieties can be developed.
Types of Vegetative Propagation
Natural Methods
Propagation by naturally occurring plant parts such as bulbs, tubers, rhizomes, suckers and runners.
Artificial Methods
- Cuttings: Using stem, root or leaf cuttings (e.g., berberry, citrus, rose, bryophyllum).
- Layering: Simple, serpentine, air layering (e.g., guava, jasmine, mango).
- Grafting: Whip, tongue, side and approach grafting (e.g., apple, mango, sapota).
Micropropagation (Tissue Culture)
A modern method where plants are grown from tiny plant parts like cells, embryos or shoot tips under sterile conditions. It ensures disease-free, fast and large-scale production.
Nursery Bed Preparation
Used when seeds are too small, costly or have slow germination.
Types of Nursery Beds
- Flat bed
- Raised bed
- Ridges and furrow
- Ring and basin
The choice depends on soil type, water needs and the plant species.
Irrigation Methods
Water is essential for successful cultivation. The irrigation method depends on climate, soil and water availability.
- Hand watering: Simple and economical for small areas.
- Flood irrigation: Easy but wastes water.
- Boom watering: Useful for limited areas.
- Drip irrigation: Efficient but costly.
- Sprinkler irrigation: Provides good coverage.
Good Agricultural Practices (GAP)
GAP ensures safety, quality and sustainability of medicinal plant cultivation.
- Use clean soil free from heavy metals and chemicals.
- Avoid human or animal waste as fertilizers.
- Use approved pesticides in minimal quantity.
- Irrigation water must be clean and free from contaminants.
- Document pesticide use and follow local regulations.
- Prevent contamination from industrial waste or garbage.
- Maintain pruning, shading and field hygiene.
Detailed Notes:
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