Plant Propagation: Success of plant propagation depends on a thorough knowledge of the growth of the plants, choice of suitable methods and technical skill as well. Propagation may be done by two methods - Sexual methods or by Asexual methods.
Sexual Propagation: It is done by raising plants by means of seeds which are formed due to the fusion of male and female gametes within the ovule of a flower.
Seed: It is defined as a miniature packed plant ready for sowing with nourishing tissues and a protective cover.
A seed consists of 3 basics parts namely-
1) Embryo (the dormant plant ready to germinate)
2) Endosperm (the food reserve)
3) Testa (the seed coat)
Advantages of Seed/Sexual Propagation -
There are a number of advantages linked to the sexual method of propagation of plants. Some of them are -
- Sexual propagation is easier and cheaper than the asexual propagation method.
- Some of the plants (Papaya) do not respond to asexual propagation method and are thus inevitably propagated through seeds.
- Sexually propagated plants live longer, have extensive root systems and are heavy bearers as compared to asexually propagated plants.
- Hybrids can be propagated through seeds only.
- Seedlings are mostly free from viral diseases.
Disadvantages of Seed/Sexual Propagation -
However, there are some disadvantages also which cannot be overlooked. They include -
- Most of the fruit plants are heterozygous in nature and multiplication of these plants results in segregation of characters and resultant plants are never true to type. This will result in loss of color, taste and vigor in the new plants different from their parents.
- Seedling raised plants are generally tall and spreading type causing considerable problems for carrying various management practices.
- As seeds lose viability soon, hence, should be sown immediately after extraction from the fruits.
- Plants raised from seeds take longer time to come to bearing.
- The beneficial influence of rootstock on scion cannot be explored in sexual propagation.
Advantages of raising seedlings in a nursery -
Another process involved in sexual propagation of plants is raising seedlings in a nursery and consequently transplanting them into the fields in future. The advantages of this method include -
- Nursery raising provides special attention during the first few weeks after germination.
- It is easier and economical to look after the young and tender seedlings growing in the nursery bed in small areas rather than in large permanent areas.
- Most of the fruits crops propagated through vegetative means requires special skills and after-care before being transplanted into the main field and this is possible in a controlled condition in the nurseries.
- Cuttings are best rooted in mist chambers which are integrated parts of a nursery.
- Direct sowing method is not successful when compared to transplanting of seedlings raised in the nursery.
- It also provides more time for pre-planting preparations.
Vegetative/Asexual Methods of Propagation -
Asexual method of Propagation: In this method of propagation, the plants are obtained from a vegetative portion of the mother plant instead of seeds.
Advantages of this method -
- In some fruit plants like bananas, which do not bear seeds, this is the only method of propagation.
- The plants are generally true-to-type, uniform in growth, yielding capacity is good and also the fruit quality.
- Has a short juvenile phase, thus comes into bearing earlier than seedling plants.
- The advantages of rootstocks can be obtained by budding or grafting susceptible varieties on resistant/ tolerant rootstocks.
- Plants have restricted growth, thus cultural practices and harvesting are easy.
Disadvantages of this method -
- New variety cannot be evolved by this method.
- Plants are not as vigorous and long lived as the seedling trees.
- Germplasm conservation requires a lot of space and is expensive as compared to storage of seeds.
Methods Of Vegetative/Asexual Propagation -
I) Cuttings: In this method, plant parts such as stem, root or leaf are cut from the parent plant and placed under favorable conditions to form roots and shoots. Thus, producing a new
Advantages of Cutting -
- It is the cheapest method of vegetative propagation.
- It is used for clonal multiplication of root stocks.
TYPES OF CUTTINGS: It is classified into Stem cuttings, Leaf cuttings and root cuttings.
• A) Stem cuttings: It has 4 types, as follows;
• 1) Hardwood cuttings: Cuttings taken from the mature woody shoots, length of the cutting should be of 20 to 50 cm with 2 to 3 nodes, cuttings are made from the previous
seasons growth that is in the dormant season. The cuttings root easily in mist chambers. Various fruit crops are commercially propagated through this method.
• 2) Semi hardwood cuttings: Are prepared from partially mature but tender woody shoots, cuttings are taken in early morning when the cells are fully turgid.
• 3) Softwood cuttings: These are prepared from the soft succulent perennial portions of woody perennials, here care should be taken to maintain high humidity to prevent drying due to moisture loss by transpiration. The cuttings shall be of 8 to 15 cm in length with 2 to 3
nodes/buds, cuttings are done in March-April or May-September. These cuttings root in 15 to 30 days of time.
• 4) Herbaceous cuttings: These are the tender succulent special leafy parts from the stem of
herbaceous plant. The terminal 7 to 12 cm of a healthy shoot is cut and
basal leaves are removed without disturbing the upper leaves.
• B) Leaf Cuttings:
• i) Fleshy leaf or the leaf blade and petioles of many plants are used. New plants arise at the point where the veins are cut. High humid conditions are needed for success in leaf
• ii) Leaf-Bud Cuttings: These are made from a leaf blade, petiole and small piece of the stem with a dormant axillary bud. Usually practiced in Lime, Lemon, Blueberry etc. The roots
are formed at the base and the dormant bud develops into a
new shoot system.
• C) Root cuttings: Here the new shoots are regenerated from a piece of root. This method is usually followed in Apple, Guava, Pear, etc.
• Definition: This method involves joining two plant parts together in such a way that it will grow together into a single plant is called grafting.
• Root stock: The plant part that gives rise to the root system and into which a bud or shoot sets is called a stock plant. It is highly strong and resistant in nature.
• The scion: refers to the desired superior and premium variety of plant which is grafted or budded on to a stock plant and forms the shoot system.• Inter stock: It is that plant part which is placed in between the rootstock and scion to tie over the problem of incompatibility.