Mendel experiment with peas

Source: Own work | CC BY 4.0

Mendel experiment with peas

You may have seen the mention F1 or F1 hybrid on a pack of seeds or in a catalog.

What does that mean?

F1 is the first generation of a hybrid.

When two parents are crossbred, the descendants have a some characteristics of one or both parents.

This is done to have descendants with more beautiful flowers, greater yield, disease resistance, bigger or smaller…

Depending on whether the genes are dominant, recessive or codominant, the result varies:

  • dominant: all descendants have the property of the parent with the dominant gene
  • recessive: none of the descendants have the property of the parent with the recessive gene
  • codominant: the characteristics of both parents are expressed

In the diagram at the right, you can see how this works in Mendel’s experiment with the pea (Pisum sativum):

  • 1 parent with purple flowers is crossed with 1 parent with white flowers
  • F1 = first generation of offspring, all flowers are purple (the purple color is dominant on the white color)
  • F2 = second generation offspring, 75% of flowers are purple and 25% are white
Codominance in Rhododendron

Source: darwin cruz

Codominance in Rhododendron

What does this mean concretely for plants?

For plant seeds marked as F1 hybrid, all descendants are uniform: they all have the property that makes them interesting.

So when you plant those seeds, all descendants are the same.

However, if you harvest and sow the seeds of those F1 plants, the descendants do not all have the same property.

Are F1 seeds sterile?

I read somewhere on the internet that F1 means that the seeds are sterile. That’s actually wrong: F1 seeds of some hybrids may be sterile while they may be viable for other hybrids (think of the cross of horse and donkey, the descendants are always sterile).

However, in agriculture, some seed suppliers (like Monsanto) produce F1 seeds that are deliberately engineered to be sterile. This way, the farmer must buy new seeds each year.

In traditional farming, the farmer keeps a part of his harvest to sow next year, which is impossible with those sterile F1 seeds.

And now you know why there is a massive increase in suicides in India among small farmers who became even more indebted because they had to buy fresh seed every year.

For the small gardener this is of little importance: a pack of seed of ornamental plants or vegetables is quite cheap and you can easily buy a new package every year.

So what does F1 really mean for the ornamental garden or vegetable garden?

1. All plants have the same characteristics

2. If you sow seeds from F1, the offspring will deviate from the parents and vary