Pollination: Types of Pollination

Pollination is transfer of pollen grains from the stamens, the flower parts that produce them, to the ovule-bearing organs or to the ovules themselves. In plants such as conifers and cycads, in which the ovules are exposed, the pollen is simply caught in a drop of fluid secreted by the ovule. In flowering plants, however, the ovules are contained within a hollow organ called the pistil, and the pollen is deposited on the pistil’s receptive surface, the stigma. There the pollen germinates and gives rise to a pollen tube, which grows down through the pistil toward one of the ovules in its base. In an act of double fertilization, one of the two sperm cells within the pollen tube fuses with the egg cell of the ovule, making possible the development of an embryo, and the other cell combines with the two subsidiary sexual nuclei of the ovule, which initiates formation of a reserve food tissue, the endosperm. The growing ovule then transforms itself into a seed.

It is the transfer of pollen from a male part of a plant to a female part of a plant, later enabling fertilisation and the production of seeds, most often by an animal or by wind. Pollinating agents are animals such as insects, birds, and bats; water; wind; and even plants themselves, when self-pollination occurs within a closed flower. Pollination often occurs within a species. When It occurs between species it can produce hybrid offspring in nature and in plant breeding work. It is very important thing to creation of new seeds that grow into new plants.

It brings together many disciplines, such as botany, horticulture, entomology, and ecology. The pollination process as an interaction between flower and pollen vector was first addressed in the 18th century by Christian Konrad Sprengel. It is important in horticulture and agriculture, because fruiting is dependent on fertilization: the result of pollination. The study of pollination by insects is known as anthecology.

pollination

Process

The process begins when the pollen grains from the respective flowers lands on the stigma and form a pollen tube with the style length, which connects both the stigma and ovary. After the completion of the pollen tube, the pollen grain starts transmitting sperm cells from the grain to the ovary.

Later the process of fertilization in plants will take place when the sperm cells will reach the ovary and egg cells. The seed is then released from the parent plant and making it able to grow into a plant and continue the reproductive cycle with the use of the pollination method.

Types of Pollination

  1. Self- Pollination
  2. Cross-Pollination

1. Self Pollination

It occurs when pollen grains fall directly from anther into the stigma of the flower. Although this process is quite simple and fast, which leads to a reduction in genetic diversity as the sperm and egg cells of the flower share some genetic information.

Advantages

  • It ensures that recessive characters are eliminated.
  • The wastage of the pollen grain is very less compared to cross-pollination
  • In this process, Purity of the race is maintained, as there is no diversity in the genes
  • There is no involvement of external factors like wind, water, and other pollinating agents.
  • It ensures that even a smaller quantity of produced pollen grains from plants have a good success rate in pollination.

Disadvantages

  • The vigour and vitality of the race are reduced
  • The immunity to diseases is reduced in the resultant offsprings.

2. Cross-Pollination

It refers to a complex type of pollination that allows the transfer of pollen grains from the anther of the flower into the stigma of another flower. This method leads to an increase in genetic diversity as different flowers will share and combine their genetic information to create unique offspring.