Pollination is very important. It leads to the creation of new seeds that grow into new plants..Pollination 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 pollination occurs between species it can produce hybrid offspring in nature and in plant breeding work. In angiosperms, after the pollen grain has landed on the stigma, it develops a pollen tube which grows down the style until it reaches an ovary. Sperm cells from the pollen grain then move along the pollen tube enter an ovum cell through the micropyle and fertilise it, resulting in the production of a seed. A successful angiosperm pollen grain (gametophyte) containing the male gametesis transported to the stigma, where it germinates and its pollen tube grows down the style to the ovary. Its two gametes travel down the tube to where the gametophyte(s) containing the female gametes are held within the carpel. One nucleus fuses with the polar bodies to produce the endosperm tissues, and the other with the ovule to produce the embryo, hence the term: “double fertilization”.
In gymnosperms, the ovule is not contained in a carpel, but exposed on the surface of a dedicated support organ, such as the scale of a cone, so that the penetration of carpel tissue is unnecessary. Details of the process vary according to the division of gymnosperms in question. Two main modes of fertilization are found in gymnosperms. Cycads and Ginkgo have motile sperm that swim directly to the egg inside the ovule, whereas conifers and gnetophytes have sperm that are unable to swim but are conveyed to the egg along a pollen tube.
The study of pollination 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. But how does pollination work? Well it all begins flower. Flowering plants have several different parts that are important in pollination. Flowers have male parts called stamens that produce a sticky powder called pollen. Flowers also have a female part called the pistil. The top of the pistil is called the stigma, and is often sticky. Seeds are made at the base of the pistil, in the ovule. To be pollinated, pollen must be moved from a stamen to the stigma. When pollen from a plant’s stamen is transferred to that same plant’s stigma, it is called self-pollination. When pollen from a plant’s stamen is transferred to a different plant’s stigma, it is called cross-pollination. Cross-pollination produces stronger plants. The plants must be of the same species. For example, only pollen from a daisy can pollinate another daisy. Pollen from a rose or an apple tree would not work. But how does pollen from one plant get moved to another? That matters.
How Do Plants Get Pollinated?
Pollination occurs in several ways. People can transfer pollen from one flower to another, but most plants are pollinated without any help from people. Usually plants rely on animals or the wind to pollinate them.
When animals such as bees, butterflies, moths, flies, and hummingbirds pollinate plants, it’s accidental. They are not trying to pollinate the plant. Usually they are at the plant to get food, the sticky pollen or sweet nectar made at the base of the petals. When feeding, the animals accidentally rub against the stamens and get pollen stuck all over themselves. When they move to another flower to feed, some of the pollen can rub off onto this new plant’s stigma. Plants that are pollinated by animals often are brightly colored and have a strong smell to attract the animal pollinators. Another way plants are pollinated is by the wind. The wind picks up pollen from one plant and blows it onto another. Plants that are pollinated by wind often have long stamens and pistils. Since they do not need to attract animal pollinators, they can be dully colored, unscented, and with small or no petals since no insect needs to land on them. Pollination management is a branch of agriculture that seeks to protect and enhance present pollinators and often involves the culture and addition of pollinators in monoculture situations, such as commercial fruit orchards. The largest managed pollination event in the world is in Californian almond orchards, where nearly half (about one million hives) of the US honey bees are trucked to the almond orchards each spring. New York’s apple crop requires about 30,000 hives; Maine’s blueberry crop uses about 50,000 hives each year. The US solution to the pollinator shortage, so far, has been for commercial beekeepers to become pollination contractors and to migrate. Just as the combine harvesters follow the wheat harvest from Texas to Manitoba, beekeepers follow the bloom from south to north, to provide pollination for many different crops.[citation needed] In America, bees are brought to commercial plantings of cucumbers, squash, melons, strawberries, and many other crops. Honey bees are not the only managed pollinators: a few other species of bees are also raised as pollinators. The alfalfa leafcutter bee is an important pollinator for alfalfa seed in western United States and Canada. Bumblebees are increasingly raised and used extensively for greenhouse tomatoes and other crops.
The ecological and financial importance of natural pollination by insects to agricultural crops, improving their quality and quantity, becomes more and more appreciated and has given rise to new financial opportunities. The vicinity of a forest or wild grasslands with native pollinators near agricultural crops, such as apples, almonds or coffee can improve their yield by about 20%. The benefits of native pollinators may result in forest owners demanding payment for their contribution in the improved crop results. The American Institute of Biological Sciences reports that native insect pollination saves the United States agricultural economy nearly an estimated $3.1 billion annually through natural crop production. Pollination produces some $40 billion worth of products annually in the United States alone. Pollination of food crops has become an environmental issue, due to two trends. The trend to monoculture means that greater concentrations of pollinators are needed at bloom time than ever before, yet the area is forage poor or even deadly to bees for the rest of the season. The other trend is the decline of pollinator populations, due to pesticide misuse and overuse, new diseases and parasites of bees, clear-cut logging, decline of beekeeping, suburban development, removal of hedges and other habitat from farms, and public concern about bees. Widespread aerial spraying for mosquitoes due to Nile fears is causing an acceleration of the loss of pollinators. In some situations, farmers or horticulturists may aim to restrict natural pollination to only permit breeding with the preferred individuals’ plants. This may be achieved through the use of pollination bags.
Advantages of self pollination
1) Large number of individuals are produced
2. Traits are genetically identical so advantageous traits are not lost.
3. Self pollination is generally faster.
4. Less chance of failure of pollination.
Disadvantages of self pollination
1. No variations occurs if plant gets hit by a disease there is no possibility of survival and population decreases.
2. It does not result in creation of new species.
3. Continuous self pollination results in weak progenies
Advantages of Cross Pollination
1. Causes variation in gene pool thus giving more survival advantage to the species.
2. Seedsare more viable and healthier with better germinating capacity.
3. Scope for Evolution
4.Breed new variety of species
Disadvantages of Cross pollination
1. Consumes more time and effort.
2. Natural process of pollination becomes delayed in this case.
(The author is a student Government Boys Degree College Anantnag. Views are his own [email protected] )
