HYB: a minor correction

What I said about non-producing parent X SA assumed the non-producer carried *no* SA factor.  There would be two different Punnett squares for no factor and one factor, of course.  I do tend to leave out assumptions and jump across steps, something one has to watch in the type of work we're setting out to do.
 
All four cross types, even if the specific crosses don't have exactly the same parents (which in our first year won't in several cases) or aren't made in the same direction (reverse crosses will be forced in some situations by availability and/or season of bloom, availability of pollen or simply fertility--some irises are very difficult to pod--an example of which is ROMANTIC EVENING) the ratios would be the same or similar provided the non-SA parent in cross types 1 and 2 have the same genetic makeup.  They won't.  Some will have one, some two, possibly some even three non-SA factors.  We'll just have to make judgments when we go to combining numbers from different people.
 
One standard procedure in data analysis of the type we will be doing is to hold out the most extreme counts--one from each end of the scale--from the combined count, at least initially.  The possibility of contamination of the cross and thus the ratios is substantially reduced (but not eliminated) by doing that.  Then, if adding them back in does not change the ratios significantly, the assumption the crosses were "clean" can reasonably be made and the numbers increased.  I want to mention this now, as being held out of the initial combined count and distribution pattern is not going to be a criticism--it is just standard practice in statistical arrays and has very solid logic behind it.
 
Our counts, regardless how large, are not going to match the "theoretical" arrays anyway.  Genetics is not as simple as our assumptions.  *Nothing* that happens in the real biochemical stew that makes up a living organism is a "single factor" unless one is measuring a particular enzyme or hormone that is manufactured directly by the DNA sequence.  Complex expressions such as form, color and so-on have many steps between the chromosome sequence and the end result.  A recent suggestion in the study of Gladiolus anthocyanin pigments suggests there are *at least* twenty steps in the synthesis of the pigment, each step governed by a different DNA sequence.  We refer to those pigments as if they were a single, simple phenomenon.  They are not.  They are a sequence of events, not *an* event.
 
Don Spoon in his correspondence with Robin Shadlow has suggested that SA _expression_ has to do with some behavior of the growth hormones.  This is highly likely--an assumption I make for two reasons.  Don Spoon knows what he is talking about--this is his academic field--and also from the work I've done with fruit trees in training and controlling fruiting vs. vegetative growth, all of which is under hormonal control.  The techniques we used worked because we were manipulating growth hormones with various strategies, such as scoring the bark, or "bending & twisting" or using wooden braces to reposition branches relative to the vertical.  Most if not all the techniques used to get "old mothers" to sprout new rhizome growth in iris use similar techniques for the same reasons.
 
Being under hormonal control, if that is in fact the case, it is not at all surprising that SA traits are so variable.  The ratios of hormones and their relative concentrations and gradients are easily affected by pH, position, day-length, temperature and all sorts of other factors.  We may find ourselves learning more than we expected.
 
Neil Mogensen   z 7 western NC 

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