How plausible would apple-sized raspberries be?

Question

In one of my settings, the people have domesticated the wild raspberry plant, and selectively bred it for larger and larger berries. Would it be plausible for these berries to reach the sizes of apples (or larger), or would this not be possible due to things like the biology of raspberry plants/soil richness/etc? If it were possible/plausible, what could/would these large raspberries be like, and what would the raspberry plants themselves look like if they had such large fruit?

(Since raspberries are made of small round parts, I am imagining they would either be made of many more or much larger of these small round parts.)

The kind of answer I am looking for would be something along the lines of "raspberries of that size would/wouldn't be possible because of X, and if they were possible they could look/taste like Y or Z, and the plants would look like ABC"

Answer 1

• Columbia Giant, a new blackberry cultivar developed and released by ARS. A Link to ARS article(not much useful info there).

Thornless blackberries are almost there, almost. So I guess it isn't too far fetched to breed a raspberry for size.

People already did the same with a lot of fruits which are minuscule in nature but can be humongous in farms like pomelos, pumpkins, bananas and cucumbers. Actually some pumpkins can get larger than a person.

Possible? Certainly so...maybe not naturally, unless some really picky animals decided to only eat the largest fruits and and thus spread only the seeds with gigantism genes.

I don't know much about raspberries but with thornless blackberries at least it seems that bulbs get larger and more numerous at the same time.

Answer 2

It's plausible that you could make raspberries the size of apples, but you probably wouldn't like them very much.

The two problems are that raspberry plants are not strong enough to support apples, and that the flesh of raspberries themselves is not strong enough to hold itself together at an apple-like size. (This is a consequence of the square-cube law, which governs the size of many things).

Your raspberries would work if they grew on the ground, but that's gross.

Otherwise, both the plant and the berries themselves would have to get stronger. Woody plants are no problem, but big, tough raspberries are not much like raspberries.

Answer 3

From experience growing raspberries, probably not. Raspberries grow on canes that bear many berries at a time. Even at current sizes, the canes often need to be tied to supports, or the weight of the berries drags the cane to the ground. You'd have to breed canes with the strength of tree limbs. Even that might not work, since in years when my trees (apple, peach, pear, quince &c) set a lot of fruit, I need to thin it out or have branches broken by the weight of the ripening fruit.

OTOH, you could certainly breed apples that are about the size of large raspberries. Some crabapple varieties are pretty close now.

PS: Another reason is the growth habit of raspberries. They have an underground crown which is perennial, and which sends up canes every year. The canes are what bear the fruit, and only do so either the first or second year, then they die. So the canes never have time enough to become strong enough to carry lots of large fruit.

PPS: Now if you want to do a bit of genetic engineering, combine raspberries with roses. Some varieties of roses can develop trunks that are almost tree-like, so with proper pruning they should be able to support large fruit.

Answer 4

From a biological standpoint there is no reason why an apple sized raspberry should not evolve. However it is very difficult to imagine exactly what selection pressures would be necessary.

Depending on circumstances such a fruit might well be similar to but a little different from a traditional raspberry. There could be more segments, the skin might be a little tougher, the connection to the stem might be more robust to hold the weight and the stems themselves might be thicker and bigger.

But in principle its very doable.

Answer 5

Probably easier to gene modify grapes to taste like raspberries. You have a plant that can already bear large weights of fruit. Or you could do the same with a peach, and each peach would be like one of the little balls on the raspberry.

Now could you breed a plant to have the taste and texture of good steak...