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Comparison

Triploid vs diploid

What does it mean when an apple variety is called a triploid?

In short

Most apple cultivars are diploid, carrying two chromosome sets. A triploid carries three, which disrupts the even division of chromosomes during pollen formation and leaves the pollen mostly non-viable.

The practical consequence is entirely about orchard planning. A triploid still needs pollen to set fruit, but it cannot return the favour — so an orchard containing one needs at least two compatible diploid cultivars flowering at the same time, one to pollinate the triploid and another to pollinate the first.

Triploids also tend to be vigorous and to bear larger fruit, and they are over-represented among old cultivars that arose as chance seedlings. Being triploid says nothing about juice quality or classification.

The two things being compared

Each side described in its own terms first, so the table below has something to hang on.

Where they differ

Dimension by dimension. Where a row needs a qualification, it carries one rather than being simplified until it fits.

Triploid and Diploid compared. Neither column is the baseline the other is measured against.
DimensionTriploidDiploid
Chromosome setsThree.Two.
Pollen viabilityLargely non-viable.Viable.
Can pollinate othersNo, for practical orchard purposes.Yes, given overlapping flowering.
Needs pollination itselfAlmost all apples are self-incompatible, so the requirement for a partner is not specific to triploids.Yes, and so requires two compatible diploids in the planting.Yes, from one compatible partner.
Vigour and fruit sizeOften more vigorous, with larger fruit.Varies by cultivar with no ploidy-linked pattern.
Breeding useAwkward as a parent; seed set is poor and progeny are irregular.Straightforward.
Bearing on cider qualityNone. Ploidy is orthogonal to acid, tannin and sugar.None, for the same reason.

Notes under a dimension name qualify the whole row, not one column.

When Triploid is the relevant one

The circumstances in which this is the thing being described, rather than a reason to prefer it.

When Diploid is the relevant one

The circumstances in which this is the thing being described, rather than a reason to prefer it.

A misconception worth clearing up

This comparison exists partly because of the claim below, which is repeated often enough that most readers arrive holding it.

Commonly said

Triploid varieties are sterile and cannot produce fruit.

What is actually the case: It is the pollen that is largely sterile, not the tree. A triploid sets fruit perfectly well when pollinated by a compatible diploid; what it cannot do is pollinate anything else.

Related comparisons

Distinctions that turn on the same thing, or that this one is routinely confused with.

What people ask next

Questions readers ask about the things this page mentions. Each one goes to the section that answers it rather than to a page written to receive the question.

Where to go next

Sources

What this page rests on. Where a source is marked as registered rather than read, CiderHQ is recording that the body is authoritative on the subject without claiming to have worked through the document itself. See our evidence policy for what each state means.