Ploidy Level

Species daylilies occur naturally in diploid (double strand DNA) and triploid (triple strand DNA) examples. While natural tetraploids could have been produced from the triploids, the main body of the current tetraploid gene pool derives from chemical conversion of hybrid diploid materials, through both plant conversion and seed conversion.

When all else is equal, the tetraploids tend to be more robust, because they have four strands of DNA, doubled from the natural diploid level. While there is recent research pointing to there being multiple levels of polyploidy in hybrid daylilies, diploid and tetraploid are still useful categories for our modern hybrid daylilies. While it will be much better understood in the future, for now we can generally rely on the diploid/tetraploid divide.

My work has focused on tetraploids from the beginning, but I also worked with diploids at the beginning of my program to study them to help in understanding how to breed the tets, and to have as a control group to compare the tetraploids to as I ran the five-year rust resistance screening program. 

Because I grew and bred a large number of fancy, modern diploid cultivars and seedlings through my rust resistance screening program, I was able to identify a good number of diploids that were exceptionally resistant with exceptional plant and flower traits. I bred within many of those lines to gauge results based on rust resistance and other specific traits. From that group I produced some excellent materials, both for gardens and for future breeding efforts.

Tetraploids, when all else is equal, are more robust than diploids, and that is what I like about them. For more information on my tetraploid breeding program and its goals, click here.