Breeding and Seed Production of Ornamental Crops (2+1)

Procedure of Hybridization (Contd..)

Steps involved in hybridization are:
4) Bagging:

• Immediately after emasculation, the flowers or the inflorescences are enclosed in suitable bags (preferably butter paper bags pierced with needle) of appropriate size to prevent random cross-pollination. In cross pollinated crops, the male flowers are also bagged to maintain the purity of pollen used for pollination.
• The bags may be made of paper, butter paper, glassier or fine cloth. The bags are tied to the base of inflorescence or to the stalk of flower with the help of thread, wire or pins designed for the purpose.
• The bags can be removed usually 2-3 days after pollination after the danger of cross-pollination is over.
5) Tagging:

• The emasculated flowers are tagged just after bagging. Tags are available indifferent sizes. In most of the crops, circular tags of about 3 cm diameter, or rectangular tags of 3 x 2 cm are used. The tags are attached to the flower or the inflorescence with the help of thread. The following information is recorded on the tags with a carbon pencil.
• Date of emasculation
• Date of pollination
• Details of the cross i.e. names of the female and the male parents. The name of the female parent is written first, and that of the male parent is written later e.g. A x B denotes that A is the female parent and B is the male parent.
6) Pollination:

• Application of mature, fertile and viable pollens on the top of receptive stigma with an objective to carry out fertilization is known as pollination.
• For carrying out hybridization it is a prerequisite that the pollens should be viable and stigma be receptive.
• Generally the fresh pollen from mature anthers should be used for pollination because in most cases the time of anther dehiscence falls within the duration of stigma receptivity and both generally coincide with the opening of flowers. Anthers generally dehisce during morning; the exact time varies with the species.
• The duration of pollen viability after anther dehiscence varies greatly from one species to another, e.g., a few minutes in wheat and oats to a few hours in maize.
• The pollination procedure consists of collecting pollen from freshly dehisced anthers of the male parent and dusting this pollen onto the stigmas of emasculated flowers.
Techniques of pollen application:

1. Pollen grains are collected in a petri dish/bag, and are used for dusting the stigmas of females inflorescence e.g. in antirrhinum, pansy etc.
2. Mature anthers are collected from the flowers of male parent. The pollen is liberated on a clean petri dish and applied to the stigmas with the help of a camel hair brush, pieces of paper, tooth pick or forceps.
3. Anthers are collected and allowed to burst directly over the stigmas.
4. The flower which has to act as male parent is plucked and pollens are dusted onto the stigmas with gentle tapping on female flowers e.g. in marigold female lines are dusted directly with the pollen parent to bring about pollination.
5. The spike of male inflorescence is shaken over the emasculated inflorescence just when the anthers are about to dehisce. As a result, the exposed stigmas are covered with pollen.
Harvesting and Storing the F₁ Seeds:

• The crossed heads or pods should be harvested and threshed. The seeds from each cross should be kept separately and, preferably the seeds should be kept along with the original tags.
• The seeds should be dried properly before storage. Improper drying of seeds may cause rotting of seeds, fungal attack or pests problem during storage.
• It is essential that the hybrid seed must not be mixed with any other seed.
• Hybridization has resulted in the development of new varieties in almost every floricultural crops including rose, chrysanthemum, gladiolus, lilium, marigold, petunia, pansy, stock, other annual crops etc.