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 seeds of open-pollinated plants will produce new generations 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 greenhouses, tall wall enclosures, or field isolation.
Popular examples of plants produced under open pollination conditions include the heirloom tomato.
- Kearns, C.A.; Inouye, D.W. 1993. Techniques for pollination biologists. University Press of Colorado, Niwot, CO.
- Ben Watson. "Hybrid or Open Pollinated". Gardening Articles: Care :: Seeds & Propagation. National Gardening Association. pp. 1–6. Retrieved 2008-03-17.
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