Can plant varieties be over-hybridized?

Question

I have been growing a hybrid variety of Schizanthus and the plants are all hugely different in terms of leaf size, height, stem thickness and speed of growth despite being grown in exactly the same conditions. However, they are all lacking in vigour even though I am giving them the conditions they like- is it the fault of the variety? Could the variety be TOO inbred?

Answer 1

There seems to be a lot of confusion out there about the difference between "line bred" plants and "hybrids". A hybrid is actually a cross between 2 different species. Line bred means that plants within the species are crossed with one another to push a particular trait, such as bloom size or color. One of the downsides for hybrids is that over time and continuing self or sibling polination the weaker traits tend to become dominant and the line eventually dies out. Orchid breeders commonly have to recreate a given hybrid from the parent lines to overcome this problem. You get a tradeoff, bigger plants and blooms but not as hardy. Plants don't really "revert" to type, as was suggested, from hybrid stock, though there can be a lot of variance in sybling plants. Line bred plants have a LOT more variance and a lot of commercial growers don't bother to cull the weaker lines. It is very possible that the line has been carried to far and is just not very hardy.

Answer 2

It's always possible to select for a given characteristic to the point that it is detrimental to the plant as a whole. If you grew these plants from seed, I'm a little surprised that you got such variation - it's almost as though the plants aren't "true" yet. Normally I'd expect to see fairly uniform plants from a packet of seed where the characteristics are at least at the F2 stage. It sounds like you have seed or plants that are from F1 hybrids.

Certainly I'd say it's the fault of the variety - you should be getting a uniform plant from a specific variety, whether it's seed or plants that you originally planted. A shame, too - butterfly flowers are really nice!

Answer 3

If these are newly purchased seed and the first time growing them, then they aren't hybrids, in the true and honest sense. If you save seed from last season, then they are no longer hybrid, they have reverted back to their parentage and then some.

Hybrids are created from two known true breeding lines and the resulting plants are true to the cross. But when these crosses breed back onto themselves, they are mixed. For example a pink flower may be made by crossing a red with a white. But when the pink crosses with itsself, the results will be red, white and pink...that's just color. We haven't considered height, vigor, etc in the equation.

So if these are purchased as hybrid, they aren't. If you saved hybrid, then they a giant mix of the two parents.

Answer 4

are you growing them in close proximity to another variety of the plant? they may be cross pollenating. also, you may have gotten cheated on the seed. if you take seed from a hybridized plant and try to grow that seed, you'll get two breeds of plants, the mother and the father. just like breeding horses and burrows, you get a mule. if you breed a female mule with a horse or a burrow, you will get either a horse or burrow colt. also, it could be a problem with the grower. they've messed with Black Diamond watermellon seed to the point that it will make the most beautiful mellons you've ever seen, but theres no sugar in them.