How to selectively breed a plant?

Question

Let's say I ordered seeds of a plant online. Then, I plant the seeds and grow a few plants. Then I take the seeds that the plants produced and separate them based on each plant. Is it possible that I could then use those seeds to continue growing plants that have a desired characteristic? For example, if I wanted to grow taller and taller plants could I just keep planting seeds from the tallest plant? Or would I need to use a different method or technology to do this?

Answer 1

The seeds of a plant are not genetically identical to the mother plant. They contain (usually) half the genetics of the plant from which they are collected, and half from the plant that produced the pollen that fertilized the flower on the mother plant. This is best thought of as human mother and fetus: the fetus carries half the genetics from the mother carrying it, but not all. To truly select for a trait by seed, you need to pollinate the plant with favorable characteristics with pollen from the same plant (if they are self-fertile) or another plant with the same characteristics (if they are not self-fertile). The easiest way to do this is by enclosing the plants in a screen to prevent wild pollinators from interfering and then transfer the pollen from one stamen to the stigma using a soft-bristled paintbrush. If the desired plant can be propagated vegetatively ( ie cuttings, division, etc.) then those offspring would be genetically identical to the desirable mother plant.