Experiment 13: Controlled Pollination – Emasculation, Bagging, and Tagging

AIM

To perform emasculation, bagging and tagging for controlled pollination.

PRINCIPLE

Plant breeding is a science of changing and improving the heredity of plants and production of new varieties which are far better than the original type. Artificial hybridisation is the phenomenon used by plant breeders for crop improvement programmes.

Steps involved in plant breeding programme are collection of germplasm, selection of parents with desired characteristics, cross hybridisation among selected parents which involves emasculation, bagging, tagging and controlled pollination, selection and recombination of superior recombinants, testing and release.

Emasculation prevents self-pollination, bagging prevents contamination by unwanted pollen and tagging maintains record of parentage, date of emasculation, date of controlled pollination and name of breeder for future selection.

REQUIREMENTS

• Ornamental plants/wild plants bearing large bisexual flowers
• Magnifying lens
• Tweezers
• Small sharp scissors
• Brush - camel hair brush
• Alcohol
• Paper bags - butter paper or polythene bags
• Rubber bands
• Paper clips
• Tags
• Forceps, needle, scalpel, pocket lens

PROCEDURE

The steps given below are sequentially followed to perform the experiment of controlled pollination.

1. Emasculation:
   • It is the process of removal of anther before its dehiscence, without affecting female reproductive system, to avoid self-pollination.
   • This method is adopted for the plants having large sized flowers, e.g. cotton, pea, etc.
   • Emasculation is done with the help of pocket lens, forceps, needle, scissors, scalpel and camel hair brush.
   • Select flower buds which have not yet opened and anthers are immature.
2. Bagging:
   • The emasculated flower is immediately enclosed in a bag made of butter paper or polythene to avoid pollination by unwanted pollen.
   • This process is called bagging.
   • Bag is secured with rubber bands or paper clips.
3. Cross-Pollination:
   • As we get the female flower we dust them with the pollens of desired plant on the stigma with sterile camel brush.
   • This way we ensure controlled cross-pollination.
   • Pollens are collected from male parent with desired characters.
4. Tagging and Labelling:
   • After performing cross-pollination, tagging is done on the plant.
   • The tag includes all necessary information about the experiment like plant variety of male and female parent, date of pollination, date of emasculation and name of plant breeder.
   • The tag is fixed to the emasculated flower.

OBSERVATION

After the emasculation, bagging and tagging is done, the plant is kept under undisturbed observation and proper care of experimental plants is taken till seed setting and harvesting. This ensures the success of the experiment.

Emasculated flowers remain enclosed in plastic bags to prevent unwanted pollen. After controlled pollination, ovary swells and seeds with desired characteristics develop in the female parent plant.

RESULT

By the process of emasculation and cross-pollination under controlled conditions, the female plant will produce seeds of the desired characteristics. Successful seed setting indicates effective controlled pollination and prevention of self-pollination.

CONCLUSION

Emasculation, bagging and tagging are essential steps of artificial hybridisation for crop improvement. These techniques ensure only desired pollen fertilises the ovum, producing superior recombinants with combined desirable characters of both parents.

PRECAUTIONS

• Select flower buds that have not yet opened and anthers are immature and undehisced.
• Sterilize forceps, scissors, needle and brush with alcohol before use.
• Emasculation should be done carefully without damaging gynoecium, i.e., stigma and style.
• Bagging should be done immediately after emasculation to avoid contamination by unwanted pollen.
• Tagging should be done with correct details of male and female parents, dates and breeder name.
• Do not use very young or very old flower buds for emasculation.