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Behaviour of polyploid crops
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- Polyploid plants tend to be larger and better at thriving in early succession habitats such as farm fields. In the breeding of crops, the tallest and best thriving plants are selected for. Thus, many crops (and agricultural weeds) may have unintentionally been bred to a higher level of ploidy.
- The induction of polyploidy is a common technique to overcome sterility of a hybrid species in plant breeding. In some situations, polyploid crops are preferred because they are sterile. For example, many seedless fruit varieties are seedless as a result of polyploidy.
- Such crops are propagated using asexual techniques such as grafting. Polyploidy in crop plants is most commonly induced by treating seeds with the chemical colchicine.
Examples of polyploid crops
- Triploid crops : banana, apple, ginger, watermelon, citrus
- Tetraploid crops : potato, cabbage, leek, tobacco, peanut, kinnow, pelargonium
- Hexaploid crops : chrysanthemum, bread wheat, triticale, oat, kiwifruit
- Octaploid crops : strawberry, dahlia, pansies, sugar cane
- Some crops are found in a variety of ploidy. Apples, tulips and lilies are commonly found as both diploid and triploid. Bananas are available as diploid, triploid, tetraploid, and pentaploid. Daylilies (Hemerocallis spp) cultivars are available as either diploid or tetraploid. Kinnows can be tetraploid, diploid, or triploid.
- A survey of the chromosome numbers of the species in a genus or a family shows that these species generally fall into a polyploid series. The species are grouped together under a taxonomic head because of certain morphological resemblances and relationships.
- They may be crossable or may not hybridize at all with one another. However, the chromosome numbers of the species show a general relationship, i.e., they form multiples of a common basic number. The chromosome numbers of the family Solanaceae may be considered as an example.
| Crops
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Ploidy level
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| Capsicum annum nigrum
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12
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| C. annuum
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24
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| Datura fastuosa
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24
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| D. metal
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24
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| D. stramonium
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24
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| Hyocyamus labus
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36
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| H. canadensis
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72
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| Nicotiana sylvestris
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24
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| N. tabacum
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48
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| N. digluta
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72
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| Physalis philadelphica
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24
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| P. peruviana
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48
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| Solanum marginatum
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24
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| S. muricatum
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24
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| S. alatum
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48
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| S. tuberosum
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48
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| S. nigrum
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72
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| S. nigrum var. gigas
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144
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