# Polyploid

> A polyploid plant carries more than two full sets of chromosomes, such as a triploid (three) or tetraploid (four); in cannabis these are almost always bred deliberately.

- Canonical: https://genetixbay.com/knowledge/glossary/polyploid.html
- Also written: polyploidy, triploid, tetraploid, polyploids, chromosome doubling
- Glossary category: Genetics and breeding · Evidence: Supported
- Status: Draft: awaiting expert review · Updated: 2026-10-31
- Licence: CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0/), attribute "GenetixBay cannabis glossary"

A polyploid has more than two complete [chromosome](https://genetixbay.com/knowledge/glossary/chromosome.md) sets. In cannabis the relevant types are tetraploids (4n = 40), usually made by treating seedlings or tissue-culture shoots with chemicals that block cell division and double the chromosomes, and triploids (3n = 30), produced by crossing a tetraploid with a [diploid](https://genetixbay.com/knowledge/glossary/diploid.md).

## In practice

Triploids are the main commercial interest. Their uneven chromosome number makes meiosis fail, so they are largely sterile and set very little seed even when pollen drifts in. That makes them attractive for outdoor and [hemp](https://genetixbay.com/knowledge/glossary/hemp.md) crops near pollen sources. Kurtz et al. (2023) used triploids to show that the dose of the [autoflowering](https://genetixbay.com/knowledge/glossary/autoflower.md) [allele](https://genetixbay.com/knowledge/glossary/allele.md) changes flowering time and plant height.

Tetraploids are larger-celled and sometimes larger-flowered, but bigger plants do not automatically mean more [cannabinoids](https://genetixbay.com/knowledge/glossary/cannabinoid.md). Claims of higher potency from polyploidy are not consistently supported. Polyploid lines also inherit in more complex ratios, so [stabilising](https://genetixbay.com/knowledge/glossary/stabilisation.md) them is slower.

## Don't confuse with

- **Diploid**: the normal two sets.
- **Polyhybrid**: a hybrid with many ancestors. Unrelated to chromosome number, despite the similar word.
- **Mutation**: polyploidy changes whole chromosome sets, not single genes.

## Related terms

[Diploid](https://genetixbay.com/knowledge/glossary/diploid.md), [Chromosome](https://genetixbay.com/knowledge/glossary/chromosome.md), [Mutation](https://genetixbay.com/knowledge/glossary/mutation.md), [Tissue culture](https://genetixbay.com/knowledge/glossary/tissue-culture.md)

## Read more

- [Tissue culture basics for cannabis growers and breeders](https://genetixbay.com/knowledge/breeding/tissue-culture-basics.md)

## Sources

1. Kurtz LE, Brand MH, Lubell-Brand JD. 2023. Gene dosage at the autoflowering locus effects flowering timing and plant height in triploid cannabis. Journal of the American Society for Horticultural Science 148(2):83-88. https://doi.org/10.21273/JASHS05293-23
2. Monthony AS, Page SR, Hesami M, Jones AMP. 2021. The past, present and future of Cannabis sativa tissue culture. Plants 10(1):185. https://doi.org/10.3390/plants10010185