Cross-pollination is the transfer of pollen from one plant of the same species to another. This allows for the maintenance of genetic diversity and the generation of novel adaptations via genetic recombination, and many plants have characteristics that favour cross-pollination over self-pollination.
Pollen release and stigma receptivity can be separated in time (dichogamy) or space (herkogamy), and both strategies are frequently used. Dichogamous flowers can either release pollen before the stigma is receptive (protandry) or only after the stigma is receptive (protogyny). Protandrous flowers are vulnerable to self-pollination if viable pollen remains in the anther when the stigma becomes receptive, though this can provide some protection against poor pollination. Similarly, protogynous flowers can protect against poor pollination by extending stigma receptivity after anthers dehisce.
The length of the filament or style usually provides a physical separation between the anthers and the stigma in herkogamy. Pin flowers have the stigma above the anthers, whereas thrum flowers have the opposite. Another mechanism for cross-pollination is heterostyly, in which flowers within a species can occur in either a pin or a thrum form so that pollen from one flower form is deposited on an insect in a location that matches the location that contacts the stigma in the second flower form.
Cross-pollination, also known as heterogamy, is a type of pollination in which sperm-laden pollen grains are transferred from one plant’s cones or flowers to another’s egg-bearing cones or flowers. Cross-pollination occurs in both angiosperms (flowering plants) and gymnosperms (cone-bearing plants), and it aids in cross-fertilization and outbreeding. Pollen movement can occur through wind, as in conifers, or through symbiotic relationships with various animals (e.g., bees and certain birds and bats) that transport pollen from plant to plant while feeding on nectar.
Pollen is transferred from the anthers of one flower to the stigma of another in this type of pollination. The two flowers in this case are genetically distinct from one another. Cross-pollination is always dependent on another agent for pollen transfer. Pollination agents include birds, animals, water, wind, and insects. Cross-pollination can take several forms depending on the agent of pollination:
Water is used to pollinate these flowers. The flowers are frequently small and unnoticeable to other agents. They don’t have a strong fragrance or a lot of colour on their petals. The pollen has been modified to float in water.
The pollinating agents in this type of pollination are animals such as humans, bats, birds, and so on. The pollen in zoophilous flowers is designed to adhere to the animal’s body, allowing it to be easily transported from one flower to another.
Wind pollination is used to pollinate these flowers. Like zoophilous flowers, these flowers are small and inconspicuous. Another important characteristic of wind-pollinated flowers is their lightweight, which allows them to be easily carried by the wind. Pollen grains are very light, non-sticky, and occasionally winged.
Insect pollination is used to pollinate these flowers. These flowers are often visually appealing with bright petals and fragrant to attract insect visitors. They frequently have broad stigmas or anthers to allow insects to perch on them. Many insect-pollinated flowers secrete nectar, which attracts bees, butterflies, and other similar insects. The pollen grains in these flowers are frequently spiny or have extensions that aid in adhering to the bodies of the insects.
Birds are responsible for pollinating these flowers. This type of pollination is found in only a few flowers and birds.
Advantages of cross-pollination
- Cross-pollination is advantageous to the plant race because it introduces new genes into the lineage as a result of fertilisation between genetically distinct gametes.
- Cross-pollination improves offspring resistance to diseases and environmental changes.
- The seeds produced as a result of cross-pollination are vigorous and vital.
- If there are any recessive traits in the lineage, they are eliminated through genetic recombination.
- It is the only method by which unisexual plants can reproduce.
Disadvantages of cross-pollination
- There is a significant waste of pollen grains that must be produced for fertilisation to occur.
- Due to gene recombination, there is a high likelihood that desirable characteristics will be lost and undesirable characteristics will be added.
Prevent Cross Pollination by Growing One Species of Plant
One strategy is to grow only one variety of species in your garden. Cross-pollination is unlikely if you only have one variety of plant species in your garden, but there is a very small chance that a stray pollinating insect will carry pollen to your plants. If you want to grow more than one variety, you must first determine whether the plant is self or wind and insect-pollinated. Most flowers are pollinated by wind or insects, but some vegetables are not.
Preventing Cross-Pollination in Wind Or Insect Pollinated Plants
Wind or insect-pollinated plants require pollination from flowers on other plants (of the same or different varieties) to produce healthy seeds. To avoid cross-pollination, plant different varieties 100 yards (91 metres) or more apart. This is not normally possible in a home garden. Instead, choose a bloom from which you will later collect seeds from the fruit or seedpod. Swirl a small paintbrush inside the flower of a plant of the same variety and species as the one you’ve chosen, then swirl the paintbrush inside the flower you’ve chosen. If the flower is large, you can close it with string or a twist tie.
Cross-pollination is the transfer of pollen from one plant of the same species to another. The length of the filament or style usually provides a physical separation between the anthers and the stigma in herkogamy. Pin flowers have the stigma above the anthers, whereas thrum flowers have the opposite. Cross-pollination occurs in both angiosperms (flowering plants) and gymnosperms (cone-bearing plants), and it aids in cross-fertilization and outbreeding. The two flowers in this case are genetically distinct from one another. Cross-pollination is always dependent on another agent for pollen transfer. . The flowers are frequently small and unnoticeable to other agents. They don’t have a strong fragrance or a lot of colour on their petals. . Pollen grains are very light, non-sticky, and occasionally winged. Cross-pollination is advantageous to the plant race because it introduces new genes into the lineage as a result of fertilisation between genetically distinct gametes.