Open pollination
Encyclopedia
Open pollination is pollination
by insects, birds, wind
, or other natural
mechanisms, and contrasts with cleistogamy
, closed pollination, which is one of the many types of self pollination. Open pollination also contrasts with controlled pollination, which is controlled so that all seeds of a crop are descended from parents with known traits, and are therefore more likely to have the desired traits.
The seed
s of open-pollinated plant
s will produce new generation
s of those plants; however, because breeding is uncontrolled and the pollen (male parent) source is unknown, open pollination may result in plants that vary widely in genetic
traits. Open pollination may increase biodiversity
.
Some plants (such as many crops) are primarily self pollenizing
and also breed true
, so that even under open pollination conditions the next generation will be (almost) the same. Even among true breeding organisms, some variation due to genetic recombination
or to mutation can produce a few "off types".
Hybrid pollination, a type of controlled pollination in which the pollen comes from a different strain
(or species
), can be used to increase suitability, especially through heterosis
. The resulting hybrid strain can sometimes be inbred
and selected for desired traits until a strain that breeds true by open pollination can be developed. The result may be referred to as a hybrid inbred or inbred hybrid strain. To add some confusion, the term "hybrid inbred" also applies to hybrids that are made from selected inbred lines that have certain desired characteristics (see inbreeding
). Such hybrids are sometimes designated F1 hybrid
, i.e. the first hybrid (filial) generation whose parents were (different) inbred plants.
One of the bigger challenges in maintaining a strain by open pollination is avoiding introduction of pollen from other strains. Based on how broadly the pollen for the plant tends to disperse
, it can be controlled to varying degrees by greenhouse
s, tall wall enclosures, or field isolation.
Popular examples of plants produced under open pollination conditions include the heirloom tomato
.
Pollination
Pollination is the process by which pollen is transferred in plants, thereby enabling fertilisation and sexual reproduction. Pollen grains transport the male gametes to where the female gamete are contained within the carpel; in gymnosperms the pollen is directly applied to the ovule itself...
by insects, birds, wind
Wind
Wind is the flow of gases on a large scale. On Earth, wind consists of the bulk movement of air. In outer space, solar wind is the movement of gases or charged particles from the sun through space, while planetary wind is the outgassing of light chemical elements from a planet's atmosphere into space...
, or other natural
Nature
Nature, in the broadest sense, is equivalent to the natural world, physical world, or material world. "Nature" refers to the phenomena of the physical world, and also to life in general...
mechanisms, and contrasts with cleistogamy
Cleistogamy
Cleistogamy or automatic self-pollination describes the trait of certain plants to propagate by using non-opening, self-pollinating flowers...
, closed pollination, which is one of the many types of self pollination. Open pollination also contrasts with controlled pollination, which is controlled so that all seeds of a crop are descended from parents with known traits, and are therefore more likely to have the desired traits.
The seed
Seed
A seed is a small embryonic plant enclosed in a covering called the seed coat, usually with some stored food. It is the product of the ripened ovule of gymnosperm and angiosperm plants which occurs after fertilization and some growth within the mother plant...
s of open-pollinated plant
Plant
Plants are living organisms belonging to the kingdom Plantae. Precise definitions of the kingdom vary, but as the term is used here, plants include familiar organisms such as trees, flowers, herbs, bushes, grasses, vines, ferns, mosses, and green algae. The group is also called green plants or...
s will produce new generation
Generation
Generation , also known as procreation in biological sciences, is the act of producing offspring....
s of those plants; however, because breeding is uncontrolled and the pollen (male parent) source is unknown, open pollination may result in plants that vary widely in genetic
Genetics
Genetics , a discipline of biology, is the science of genes, heredity, and variation in living organisms....
traits. Open pollination may increase biodiversity
Biodiversity
Biodiversity is the degree of variation of life forms within a given ecosystem, biome, or an entire planet. Biodiversity is a measure of the health of ecosystems. Biodiversity is in part a function of climate. In terrestrial habitats, tropical regions are typically rich whereas polar regions...
.
Some plants (such as many crops) are primarily self pollenizing
Pollenizer
A pollenizer or polleniser, sometimes pollinizer or polliniser is a plant that provides pollen.In American English, the words pollenizer and pollinator are often confused: A pollinator is the biotic agent that moves the pollen, such as bees, moths, bats, and birds...
and also breed true
True breeding organism
A true breeding organism, sometimes also called a pure-bred, is an organism having certain biological traits which are passed on to all subsequent generations when bred with another true breeding organism for the same traits...
, so that even under open pollination conditions the next generation will be (almost) the same. Even among true breeding organisms, some variation due to genetic recombination
Genetic recombination
Genetic recombination is a process by which a molecule of nucleic acid is broken and then joined to a different one. Recombination can occur between similar molecules of DNA, as in homologous recombination, or dissimilar molecules, as in non-homologous end joining. Recombination is a common method...
or to mutation can produce a few "off types".
Hybrid pollination, a type of controlled pollination in which the pollen comes from a different strain
Strain (biology)
In biology, a strain is a low-level taxonomic rank used in three related ways.-Microbiology and virology:A strain is a genetic variant or subtype of a micro-organism . For example, a "flu strain" is a certain biological form of the influenza or "flu" virus...
(or species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
), can be used to increase suitability, especially through heterosis
Heterosis
Heterosis, or hybrid vigor, or outbreeding enhancement, is the improved or increased function of any biological quality in a hybrid offspring. The adjective derived from heterosis is heterotic....
. The resulting hybrid strain can sometimes be inbred
Inbreeding
Inbreeding is the reproduction from the mating of two genetically related parents. Inbreeding results in increased homozygosity, which can increase the chances of offspring being affected by recessive or deleterious traits. This generally leads to a decreased fitness of a population, which is...
and selected for desired traits until a strain that breeds true by open pollination can be developed. The result may be referred to as a hybrid inbred or inbred hybrid strain. To add some confusion, the term "hybrid inbred" also applies to hybrids that are made from selected inbred lines that have certain desired characteristics (see inbreeding
Inbreeding
Inbreeding is the reproduction from the mating of two genetically related parents. Inbreeding results in increased homozygosity, which can increase the chances of offspring being affected by recessive or deleterious traits. This generally leads to a decreased fitness of a population, which is...
). Such hybrids are sometimes designated F1 hybrid
F1 hybrid
F1 hybrid is a term used in genetics and selective breeding. F1 stands for Filial 1, the first filial generation seeds/plants or animal offspring resulting from a cross mating of distinctly different parental types....
, i.e. the first hybrid (filial) generation whose parents were (different) inbred plants.
One of the bigger challenges in maintaining a strain by open pollination is avoiding introduction of pollen from other strains. Based on how broadly the pollen for the plant tends to disperse
Biological dispersal
Biological dispersal refers to species movement away from an existing population or away from the parent organism. Through simply moving from one habitat patch to another, the dispersal of an individual has consequences not only for individual fitness, but also for population dynamics, population...
, it can be controlled to varying degrees by greenhouse
Greenhouse
A greenhouse is a building in which plants are grown. These structures range in size from small sheds to very large buildings...
s, tall wall enclosures, or field isolation.
Popular examples of plants produced under open pollination conditions include the heirloom tomato
Heirloom tomato
An heirloom tomato is an open-pollinated heirloom cultivar of tomato. Heirloom tomatoes have become increasingly popular and more readily available in recent years...
.