This thread continues from Post #824234.
The question of whether seedlings may inherit characteristics differently from the pod parent versus the pollen parent could be quite important for professional animal and plant breeders and geneticists. That is because they are often involved with breeding for increasing food production, etc. So it is known how to objectively test for any such differences in plants. The basis for finding whether there are differences is the reciprocal cross.
If we had chosen to cross 'Dragonfly Dawn' and 'Born to be Wild' then the reciprocal crosses would be (pod parent first):
('Dragonfly Dawn' X 'Born to be Wild') and ('Born to be Wild' X 'Dragonfly Dawn').
We can label the seedlings from the cross ('Dragonfly Dawn' X 'Born to be Wild') as DDBW, and the seedlings from the reciprocal cross, ('Born to be Wild' X 'Dragonfly Dawn') as BWDD.
[to be continued with edited additions]
Edit #1
Choosing scape height (h) as plant habit characteristic and flower size (s) as the flower characteristic and relying on the values in the registered information:
'Dragonfly Dawn' h = 36; s = 7.5
'Born to be Wild' h = 32; s = 6.5
Assuming quantitative inheritance, no dominance and no differential parental effects then the expected values for the reciprocal seedlings are:
DDBW average seedling h = 34; average seedling s = 7.0
BWDD average seedling h = 34; average seedling s = 7.0
No reciprocal difference.
Assuming quantitative inheritance, some dominance for say larger size and no differential parental effects then the expected values for the reciprocal seedlings are:
DDBW average seedling h = between 34 and 36, say 35; average seedling s = between 7.0 and 7.5 say 7.25
BWDD average seedling h = between 34 and 36, say 35; average seedling s = between 7.0 and 7.5 say 7.25
No reciprocal difference.
Assuming quantitative inheritance, no dominance but a differential parental effect then the expected values for the reciprocal seedlings are:
DDBW average seedling h = between 34 and 36, say 35; average seedling s = between 7.0 and 6.5 say 6.75
BWDD average seedling h = between 34 and 32, say 33; average seedling s = between 7.0 and 7.5 say 7.25
A reciprocal difference in scape height and a reciprocal difference in flower size. Scape heights would differ on average by two inches and flower sizes would differ on average by half an inch. In a normal garden setting these average size differences would not be noticeable due to the much larger environmental variability and the small number of seedlings grown. In a research setting, depending on how well environmental differences are controlled and how many hundreds of seedlings are grown and measured (sample size) they could be shown as statistically significantly different. Whether they would be of any practical difference is another question.
In a normal garden setting, with the number of seedlings many daylily hybridizers grow, many crosses will not be able to show whether there are 'real' differences in parental effects. Those crosses where the parents have large differences in the appropriate characteristics, in this example scape height and flower size, could be used to examine possible differences in parental effects.
Edit #2
Choosing a different cross using the cultivars Stella de Oro (SdO) and Joyce's Curls (JC) we have
Stella de Oro - scape height (h) = 11; flower size (s) = 2.75 inches
Joyce's Curls - scape height (h) = 45; flower size (s) = 6 inches.
Reciprocal crosses would be Stella de Oro x Joyce's Curls (SdOJC) and Joyce's Curls x Stella de Oro (JCSdO)
The expected scape heights with no dominance or differential parental effects would be (11+45)/2 = 28
The expected flower size with no dominance or differential parental effects would be (2.75 + 6)/2 = 4.4 (rounded)
If there are differential parental effects and no dominance then the average scape height of SdOJC seedlings should be smaller than 28 and that of JCSdO seedlings should be larger than 28. There is a range of 17 inches for a maternal effect to appear in scape height.
If there are differential parental effects and no dominance then the average flower size of SdOJC seedlings should be larger than 4.4 and that of JCSdO seedlings should be smaller than 4.4. There is a range of 1.6 inches for a paternal effect to appear in flower size.
It is not too difficult to test for differences in parental effects; several established daylily hybridizers did so for themselves, presumably early in their hybridizing careers, although they probably did not rigorously follow scientific objective methods. There are some 'rules' that need to be followed to guarantee that one's results are objective and not affected by unknown factors that bias the results. We have to treat the seeds from the reciprocal crosses in exactly the same manner. We cannot choose to plant only the largest or plumpest seeds or the seeds from the first pods to mature, etc. We have to treat the seeds equally and randomly. We cannot discard the last seeds to sprout or choose only to plant the largest seedlings, etc. We cannot simply plant the seeds or seedlings from the two reciprocal crosses in one row each side by side. We could plant the seeds or seedlings in two rows but at random in each row. An easy way to do this would be to take one die from a pair of dice and roll it before planting the first seed or seedling. If it was 1, 2, or 3 then one would plant a seedling of SdOJC in the first position in row 1 and plant a seed or seedling of JCSdO beside it in the first position of row 2. If it was 4, 5, or 6 then one would plant a seedling of JCSdO in the first position in row 1 and plant a seed or seedling of SdOJC beside it in the first position of row 2. The die would be rolled again to choose which reciprocal cross to plant in the second position of row 1 and so on until done.
While the plants were growing one would water and fertilize both rows in exactly the same way and with the same amounts. When the seedlings bloomed one would measure the heights of all the scapes and of all the flowers. If there were too many then one would have to choose at random which specific ones to measure. Or one could choose a rule, before any seedling bloomed, such as to measure the height of the first scape to bloom on each seedling and to measure the flower size of the first flower to bloom on each scape, etc. Finally the average scape heights and average flower sizes would be compared for the two reciprocal crosses.
Edit #3
There has been scientific objective research with daylilies that provides evidence for whether there are genetic differential parental effects. It is "Heritability and genetic correlation in daylily selection" and it can be found at
http://link.springer.com/artic... Only the abstract is free to read but I have read and analyzed the research. They used 20 cultivars in ten sets of reciprocal crosses and looked at several characteristics including scape heights and bud counts. There were no reciprocal differences. The pod and pollen parent did not affect the seedling characteristics differently for any of the characteristics measured by the researchers.
Although my analyses (reported in the article in the Daylily Journal mentioned by Sooby/Sue) do not involve reciprocal crosses they can provide a hint as to whether there might be genetic differential parental effects in daylilies for characteristics such as scape height and flower size. Those analyses used the information reported in the AHS daylily database. There was no evidence that scape height or flower size was affected differently by the two parents. Those analyses examined the characteristics reported for seedlings and both their parents from 856 crosses for scape height and from 1,889 crosses for flower size.
I have to conclude that it is very unlikely that there are general genetic effects that cause pod and pollen daylily parents to affect their seedling offspring characteristics differently. I cannot rule out that there may be a few cultivars which when crossed with specific other cultivars produce reciprocal differences in their offspring due to genetic effects. I cannot rule out that reciprocal differences may be present in some gardens sometimes (when measured objectively and not subjectively) caused by non-genetic effects.
There are many factors that may cause reciprocal differences. Although there is no overall objective evidence for reciprocal differences in daylilies it is possible that some of those factors may operate in some daylily crosses or in some locations or under some conditions some times. One of these is maternal effects. One can think of these as effects caused by the pod parent when it is making the seed. Some pod parents may make many seeds or they make large seeds or they may provide the seeds with poor nutrition or good nutrition and so on. Characteristics of the seed can have visible effects on the seedling characteristics. Those effects can last for a long time but they usually fade away with the passage of time.
Most hybridizers do not make reciprocal crosses. That means that once they have decided to cross cultivar A with cultivar B they must decide in which direction they make the cross. Do they cross (pod parent first) cultivar A x cultivar B or cultivar B x cultivar A? Those decisions may be made completely subconsciously or they may be made at least partly consciously. There may be unknown patterns in how those decisions are made that may have effects on the seedling characteristics, at least for some time. A hybridizer might decide to use the cultivar with the higher bud count as the pod parent, or the cultivar with the most seeds per pod as the pod parent, or the cultivar with the most fans (and therefore scapes) as the pod parent. Such conscious or subconscious decisions could have unknown effects on seedling characteristics, at least for some period of time. Typically such effects would fade with time, but they might need many years to fade completely away and therefore influence conclusions.
There are also possible subjective effects if one does not measure characteristics objectively. For example, in a cross between a plant with 45 inch scapes (pod) and one with 15 inch scapes (pollen) the expected seedling average scape height would be 30 inches. If one looked at a seedling with a 30 inch tall scape, without measuring it, would one classify it as tall or short? Would one classify it as being like the pod parent or like the pollen parent? If the cross produced five seedlings with scape heights of 40, 35, 30, 25, and 20 inches and after blooming one culled and discarded the seedlings with scape heights of 25 and 20 inches and then a year or two later looked at the remaining seedlings would they be classified as more like the pod parent or the pollen parent? Hint, the seedling average is 30 inches.
