I always thought it was about bigger blooms with stronger scapes to hold them up!

beckygardener said:But I am still not sure "why?" the plant breeders want to do a conversion? Bigger cells, thicker plant parts, easier to self-pollinate? What is it that most of these growers are trying to acheive by converting dips to tets? Why are they doing it? What is their ultimate goal in doing so? Do they think it makes a better daylily plant?

This is what Munson wrote:
"Why tetraploids? It is generally agreed that tetraploids have a number of advantages over diploids. Tetraploid flowers are normally larger; the colors brighter and more intense; the scapes stronger and sturdier; and the plants possess heavier substance and greater vegetative vigor. These characteristics are, in most cases, easily demonstrated when comparing a diploid control with its tetraploid version. Another major advantage lies in the greater breeding potential of tetraploids which derives from the increased number of chromosomes controlling plant characteristics. A double set of chromosomes means that each gene locus is represented four (4) times instead of two (2) times the genetic material which in turn means that characters controlled by multiple genes each contributing a small effect may be more intense in tetraploids...
[section omitted on chromosome numbers]
Consequently tetraploid genetics becomes very complex, not only because twice as many chromosomes and gene loci are involved, but also because distribution of chromosomes into the gametes may differ in pattern from one tetraploid to another.
Major criticism of tetraploid hybrids in the early years centered on their coarseness, their lack of finesse, ruffling and distinction; and a lack of variety. Further, many of the early tetraploids were subject to cracking scapes in the presence of an overabundance of water, temperature changes and/or heavy fertilization."

A disadvantage of tetraploids that Munson did not mention is that they are less fertile than diploids. As I mentioned previously it is possible that they are more self-fertile than diploids.

The greater breeding potential of tetraploids lies in certain characteristics that may be inherited in the following way. If in a diploid there are say dark red (WW), red (Ww) and white flowers (ww) then in the tetraploid version one might have dark red (WWWW), medium red (WWWw), red (WWww), light red (Wwww) and white (wwww) flowers. Some of the negative effects of being tetraploid are that in a diploid a cross of two plants that are Ww would produce one out of four seedlings with white flowers but a cross of two tetraploids that are the equivalent WWww would typically produce only one out of 36 seedlings with white flowers and in some circumstances would never produce any white seedlings. It is more difficult to find a new mutation (characteristic) in tetraploids than in diploids.

Maurice - "It is more difficult to find a new mutation (characteristic) in tetraploids than in diploids." Hmmm ... that is very interesting because I assumed it was just the opposite. How interesting all the theories and facts about the tet conversion data among breeders. I really had NO idea! This is a bit of an eye-opener!

I had also read somewhere that some tet conversions can revert back to a dip. Is that true?

BTW - The next bud on the above same plant yellowed and fell off! It looked like it was ready to open. I was so bummed when that happened. I did pull the bud apart and did see extra petals on the inside, so it appears that it too would have been a double. There is 1 more bud on that daylily, so hopefully it will actually bloom. The other daylily plant (cross of the same parents) looks like it's first bloom will be tomorrow or Wednesday. I don't think I'll see a double from that one though. The shape of the bud is completely different.

beckygardener said:I had also read somewhere that some tet conversions can revert back to a dip. Is that true?

Yes that is true.

The important part of a fan is the growing point that is located in the centre between the two sets of leaves. Technically it is called the shoot apical meristem or SAM. It produces new leaves and when the plant (fan/crown) becomes large enough (mature or adult) it produces the scape. To convert a diploid into a complete and stable tetraploid the cells in the SAM must all be converted (the roots would not be tetraploid, at least initially). It is uncommon for all the cells in the SAM to be converted to tetraploid and with time various parts of the SAM that were tetraploid may become diploid or vice versa.

Arisumi did research on converting diploids into tetraploids and how stable they were with time. He treated 410 diploid daylily plants. In the first year there were 86 that were converted into useable tetraploids that were expected to be stable. In the second year there were only 50 left. He continued checking for up to six more years and during that time another four changed ploidy.

I guess that it would be better to wait a few years to buy a tet conversion since you might eventually wind up with a dip over time. I know the tet conversion plants are a bit pricey when they first come out.

So my next question is ....if you are able to get a tet conversion to cross with another daylily .... would the other parent plant have to be a tet or could it be a dip to get viable seeds?

The other daylily with the same parents as the first daylily bloomed today for the first time. Oh my word! To my eyes it is beautiful. It is exactly as I had hoped for except I wanted a larger bloom. This first bloom is 6", the height of the scape is 24".

One thing that I did note about BOTH plants is minimal rust appearance. There are several plants growing right next to these two plants that have leaves nearly covered with rust (on the older leaves). But these two plants may possibly be showing some resistance to rust. The jury is still out on this, but I was quite surprised at so little rust with other nearby plants having a much more serious outbreak of rust at this time. I am hopeful with both plants as I really love what I am seeing with these first blooms.

ZZZ72:
Morning photo:



Side view (you can see the number of buds of potential blooms):



This shows the entire plant (behind it is it's sibling that showed the double bloom and 1 remaining bud):



Afternoon bloom:

Yay for a patterned seedling!

A Tet conversion can only be crossed with a Tetraploid.

Ashton/Terry - My thoughts exactly! Thanks!

If it reverts back to a dip, them what? Can only be crossed with a dip?

That is a beautiful seedling!

If it reverts then it can only be crossed with a diploid.

Larry - Thank you! I agree. It made my heart skip a beat when I saw it. What a rush to see a cross produce something so nice. I am very pleased with both plants so far. The first one I hope remains a double and produces taller scapes in future blooms. I am also hoping these 2 plants do have some rust resistance. (Living in Florida, that would really be an asset!)

So far, the start of daylily season is promising. I have many more seedlings that have yet to bloom for the first time, so this could really be an exciting year. What a nice way to welcome in Spring .... err.... summer. It was 87 degrees here today. Ugh.

That's a gorgeous seedling, Becky! Love it!

Very nice!

Betty and Char - Thank you!

I was working outside in the gardens until dark tonight. My last pass along the path takes me right by the daylily bed that these plants are growing in. I glanced over and saw that the bloom was still beautiful, but being dark out at this point (almost 8 pm), I got my camera and used the flash to better verify what I thought I was seeing .... it was 87 degrees today and here is the bloom still looking lovely. All I can say is .... WOW! I am so pleased with this daylily! What a bargain. I paid $12 to get BOTH seedling plants (BOGO free) plus shpg. Oh! And I didn't tell you the most unusual part .... the plant I was originally bidding on was later discovered to have not survived the winter. So this was a replacement that Rich let me pick from all his unbloomed Dragonfly Dawn seedling crosses. Boy! Did I get lucky!!!! I should have played the lotto that day!

Also .... I tried to self-pollinated it. Probably too late in the day, but worth a shot. One just never knows! The pollen was still fluffy and it stuck to the stigma. (Fingers crossed!)

Maurice - You wrote ..... "Arisumi did research on converting diploids into tetraploids and how stable they were with time. He treated 410 diploid daylily plants. In the first year there were 86 that were converted into useable tetraploids that were expected to be stable. In the second year there were only 50 left. He continued checking for up to six more years and during that time another four changed ploidy."

So that means that almost 50% converted back to a dip. Hmmmm .... are they more stable now?

beckygardener said:if you are able to get a tet conversion to cross with another daylily .... would the other parent plant have to be a tet or could it be a dip to get viable seeds?

You should only try to cross a tet conversion with a known tet. Most hybridizers who specialize in making and using tet conversions advise that tet conversions should be used as the pollen parents with the pod parents being known non-converted tetraploid plants. If the crosses are made in the opposite direction and since converted material can be a mixture of tetraploid and diploid parts and since natural pollinations can occur, then seeds produced by a converted tetraploid used as the pod parent might be normal diploids (from normal diploid tissue in the conversion and normal diploid pollen brought to the flower naturally by insects, etc.).

A converted tet that has reverted to being a diploid should be crossed with diploids. It might be interesting to investigate whether those treated diploid versions were or were not identical to their untreated diploid counterparts and if the were not identical whether the differences could be inherited by their seedling offspring.

Arisumi worked at crossing tetraploids with diploids. The failure rate is enormous but occasionally a seedling can be produced. It will nearly always be a triploid. It is important to know that Arisumi will have prevented natural pollinations. Also, since he was a research biologist he was in a position to examine any seedlings produced to verify their ploidy.

So that means that almost 50% converted back to a dip. Hmmmm .... are they more stable now?

There is no obvious reason to expect conversions to be more stable nowadays. It is possible, if there were significant changes to the methods used but I do not know of anyone who has provided numbers to show whether conversions might be more stable now. It also probably depends on the skill of the person doing the conversion.

Maurice - Thank you for your wealth of information. It's interesting that daylilies in particular have breeders doing all of this. But then again, I look at the price some of their registered daylilies go for, then I can see how they might be able to afford such experiments in hybridizing and conversions of plants.

Honestly, until I joined a daylily forum, I had no idea about the vastness of Hemerocallis. The latest and greatest seems to be endless. Is all this breeding and conversion of tets/dips causing any long (or short) term issues of concern?

Just for comparison, I put together these two collages to show how the two seedling sibling's blooms compare to the parents (Laura Mast x Dragonfly Dawn):