Dennis616 said:
1. Is there anything different about hybridizing dips as opposed to tets? Any very general “rules” or things that happen more commonly when crossing dips? About 15% of my daylilies are dips and I would like to try my hand at a few crosses, but wondering if I need to approach that differently...
A couple of different things between diploids and tetraploids. Generally diploids tend to be fussier in crosses. The self-incompatibility system is stronger in diploids. What this system does is prevent (or reduce) self-pollinations from working to produce seeds/seedlings. However, whenever a species has such a system it also affects crosses between unrelated plants that simply carry the markers to prevent crosses from working. In tetraploids such systems tend to breakdown more often than not and that seems to be the case in daylilies.
Crosses between related diploids will tend to produce weaker offspring than those between related tetraploids. Diploids should tend to show stronger and quicker inbreeding depression than tetraploids.
Tetraploids tend to have changed characteristics from diploids, such as larger cells and thicker tissues.
Tetraploids have a wider range of genetic possibilities than diploids. Where a diploid might have a range of three a tetraploid has a range of five levels of a characteristic because of the number of combinations possible when there are four copies versus two copies of a gene. Thus diploids might be X/X - 10, or X/x - 6, or x/x - 2, but tetraploids could be X/X/X/X - 20 or X/X/X/x - 16 or X/X/x/x -12 or X/x/x/x - 8 or x/x/x/x - 4 or the tetraploid could be X/X/X/X 10, X/X/X/x - 8, X/X/,x/x - 6, X/x/x/x - 4 or x/x/x/x - 2.
In diploids one might have a situation in which flowers could be red (R/R or R/r) or yellow (r/r). In the equivalent tetraploids one might have R/R/R/R - deep red, R/R/R/r - medium deep red, R/R/r/r - medium red, R/r/r/r - light red r/r/r/r - yellow. This tends to be the sort of thing that happens.
2. Why do I keep reading about hybridizers leaving dips to focus on tets? Is it because is it “easier” to get changes in tets?
Genetically it is more difficult to get changes in tetraploids than it is to get them in diploids. It would be interesting to know whether tetraploids are less stable than diploids otherwise.
4. When using a white daylily as a parent with a colored daylily, does it frequently lighten the color of the colored daylily, or just "yield" completely to the colored daylily, or just random results?
In daylilies the results would more often be closer to lighten the colour or otherwise change the colour by small differences (quantitative) rather than yielding completely to the darker colour (qualitative). Simple dominance and recessive relationships are not typical in daylilies.
