Plant Propagation: Methods and Propagation Structures

1. Introduction

Plant propagation is the process of multiplying plants and ensuring the perpetuation of desired plant species or varieties.
It forms the basis of agriculture, horticulture, forestry, and landscape gardening, as it determines the quantity, quality, and uniformity of the plants produced.

Definition: Plant propagation is the science and art of reproducing plants by sexual (seed) or asexual (vegetative) means.

Derived from: Latin words — “pro” = forward, “pagare” = to fix or fasten → meaning to cause to grow or spread.

2. Objectives of Plant Propagation

• To multiply elite or superior varieties of plants on a large scale.
• To maintain genetic purity (true-to-type plants).
• To produce disease-free planting material.
• To shorten the juvenile phase and induce early bearing.
• To combine desirable traits (e.g., disease resistance + good fruit quality).
• To conserve rare and endangered species through vegetative means.
• To facilitate research, hybridization, and breeding programs.
• To ensure economic and uniform production of plants.

3. Classification of Propagation Methods

Plant propagation is broadly divided into two main methods:

4. Sexual Propagation (by Seeds)

4.1 Definition; Sexual propagation refers to the reproduction of plants through seeds formed by the union of male and female gametes. The resulting offspring shows genetic variation.

4.2 Process

• Pollination (transfer of pollen)
• Fertilization (fusion of gametes)
• Seed formation and maturation
• Seed germination
• Seedling growth

4.3 Advantages

• Economical and simple.
• Maintains hybrid vigor (heterosis).
• Provides variation useful in plant breeding.
• Root systems are strong and deep.
• Easy storage and transportation of seeds.

4.4 Disadvantages

• Genetic variability — plants are not true-to-type.
• Long juvenile period (delayed flowering/fruiting).
• Some plants produce sterile or non-viable seeds.
• Low propagation rate in certain species.

• Examples; Seed propagation: Papaya, Guava (for rootstock), Tamarind, Citrus (rootstock), Vegetables, and Field crops.

5. Asexual (Vegetative) Propagation

5.1 Definition

• Asexual or vegetative propagation is the reproduction of plants from vegetative organs such as stem, root, leaf, or specialized structures, without sexual fusion.
• The plants produced are clones — genetically identical to the parent.

5.2 Advantages

• True-to-type propagation.
• Early maturity and fruiting.
• Disease-free and uniform plants.
• Enables propagation of seedless plants (e.g., Banana, Sugarcane).
• Useful for maintaining hybrid varieties.

5.3 Disadvantages

• No genetic variation.
• Some vegetatively propagated plants are short-lived.
• Transmission of systemic diseases possible.
• Expensive and requires skill/labor.

6. Types of Vegetative Propagation

• Vegetative propagation may occur naturally or artificially.

6.1 Natural Vegetative Propagation

• Certain plants naturally produce vegetative structures capable of forming new individuals.

6.2 Artificial Vegetative Propagation; These are human-controlled techniques used to multiply plants under field or nursery conditions.

6.2.1 Cutting; Definition: A portion of stem, root, or leaf is cut and planted in a suitable medium to develop roots and shoots.

Types:

• Stem cutting – Rose, Grapes, Sugarcane.
• Root cutting – Lemon, Blackberry.
• Leaf cutting – Begonia, Sansevieria.

Rooting Hormones: Auxins like IBA (Indole-3-butyric acid) and NAA (Naphthalene acetic acid) enhance root initiation.

Advantages: Simple, cheap, rapid, and true-to-type multiplication.

6.2.2 Layering

Definition: Rooting is induced on a stem or branch while still attached to the parent plant.

Types:

• Simple Layering: Lower branch bent and buried – Jasmine.
• Tip Layering: Tip of shoot buried – Black raspberry.
• Mound Layering: Soil mounded around shoots – Apple, Currant.
• Air Layering (Gootee): Bark removed and wrapped with moist moss – Guava, Litchi, Pomegranate.

Advantages: High success rate; useful for hard-to-root plants.

6.2.3 Grafting

Definition: Union of two plant parts so they grow as one plant.

• Scion: The upper portion (shoot) of desired variety.
• Rootstock: The lower portion providing root system.

Essential Conditions:

• Compatibility between stock and scion.
• Proper cambial contact.
• Protection from desiccation.
• Performed during active growth season.

Types:

• Whip or Tongue Graft – Apple, Pear.
• Cleft Graft – Guava.
• Approach Graft – Mango, Camellia.
• Epicotyl Graft – Cashew.
• Softwood Graft – Mango, Sapota.

Advantages: Combines desirable traits — disease resistance + fruit quality.

6.2.4 Budding

Definition: A single bud of the desired plant is inserted into the rootstock.

Types:

• T-budding: Rose, Citrus.
• Patch budding: Guava, Rubber.
• Chip budding: Peach, Plum.

Advantages: Economical and high success rate; requires only one bud.

6.2.5 Micropropagation (Tissue Culture)

Definition: Production of plants from small tissue, cell, or organ under sterile and controlled laboratory conditions on a nutrient medium.

Stages:

• Initiation: Establishing aseptic culture.
• Multiplication: Rapid shoot proliferation.
• Rooting: Induction of roots using auxins.
• Acclimatization: Transfer to soil for hardening.

Examples: Banana, Sugarcane, Potato, Orchids.

Advantages:

• Large-scale production of disease-free plants.
• Year-round availability.
• Preservation of germplasm.

7. Propagation Structures

Propagation structures provide controlled or semi-controlled environments to ensure successful rooting, germination, and growth.

7.1 Mist Chamber

• Maintains 90–95% humidity and 25–30°C temperature using fine water mist.
• Prevents wilting of soft cuttings.
• Used for softwood and herbaceous cuttings (Rose, Chrysanthemum).

7.2 Greenhouse / Polyhouse

• Enclosed structure covered with glass or UV-stabilized polyethylene.
• Provides controlled temperature, humidity, and light.
• Used for:
  • Raising seedlings
  • Off-season production
  • Tissue-cultured plant hardening

7.3 Shade House / Net House

• Covered with shade net (35–75% shade intensity).
• Reduces light and wind stress.
• Suitable for hardening tissue culture plants and nursery operations.

7.4 Hotbed and Cold Frame

7.5 Mist Poly Tunnel

• Combination of polyhouse and misting system.
• Ensures high humidity and moderate temperature for large-scale propagation.
• Suitable for vegetatively propagated crops.

7.6 Propagation Benches and Nursery Beds

• Benches: Metal/wood structures filled with rooting medium (sand, cocopeat).
• Nursery Beds: Raised/sunken soil beds for seedling or cutting propagation.
• Provides drainage, aeration, and ease of handling.

8. Factors Affecting Propagation Success