Plant propagation is defined as the multiplication of plants by both sexual and asexual means.
Type # 1. Sexual Propagation:
Plants are raised from seeds and such plants are known as seedlings.
Advantages:
1. Seedlings are long lived, hardy, bear more heavily and are easier to propagate.
2. This is the only method of propagation in phalsa and papaya where other methods are not possible.
3. In-breeding for evolution of new varieties, the hydrids are first raised from seed.
4. Chance seedlings of very superior quality may result. Such seedlings have been of great benefit to the fruit industry.
5. Rootstocks are usually obtained by means of sexual propagation because they are hardy and develop better root system.
6. Mostly the seedlings are free from virus diseases.
7. Properly stored seeds can be kept for longer duration for future use.
8. Seeds of some fruits like citrus and mango varieties are capable of giving out more than one seedling from one seed. They arise from the cells of the nucleus and are called poly-embryonic. These nuclear seedlings can be utilized for raising uniform plants, if they can be carefully detected at the nursery stage.
Disadvantages:
1. Multiplication of these plants by sexual means results into segregation of characters and the resultant plants are never true-to-type.
2. Plants are not always uniform in growth, quality of fruit and yield as compared to asexually raised plants.
3. Plants come into bearing later than grafted ones.
4. Larger trees are uneconomical to handle, i.e., cost of harvesting, pruning and spraying is more.
5. The exact characters of any superior selection cannot be perpetuated through seed.
Type # 2. Asexual or Vegetative Propagation:
A vegetative part of a plant such as leaf, stem or root is placed in such an environment that it develops into a new plant. The new plant being a portion of the parent plant, possess all its characteristics.
Advantages:
1. The plants are generally true-to-type, uniform in growth, yielding capacity and fruit quality.
2. Most of the fruit plants like apple, mango, citrus, guava, litchi, etc. are cross pollinated and heterozygous in nature and the genetic architecture of the offspring can only be maintained true-to-type through vegetative propagation.
3. Picking or harvesting of fruits becomes easy due to the restricted growth.
4. Plants in some cases bear seedless fruits i.e. Banana, pineapple, some varieties of grapes, guava and lemon.
5. Such plants come into bearing earlier than the seedling trees.
6. The plants can be produced disease free by budding or grafting on resistant rootstocks.
7. Rootstock regulates tree size and fruit quality e.g. Apple trees remain dwarf on M9, M26 and M27 rootstocks.
8. Cross-pollination can be affected by grafting shoots of other suitable varieties on some of the branches of the self- unfruitful varieties e.g. some varieties of Almond which are self-unfruitful can be made to bear crops if pollinising varieties are grafted on some of the branches of these trees.
9. By asexual method, we can correct to some extent the initial mistakes of planting inferior varieties in the orchard by doing top-working.
Disadvantages:
1. Such plants are not so vigorous and long-lived as the seedling trees.
2. New variety cannot be evolved by this method.
3. Sometimes it is expensive as it requires special techniques.