Re: HYB: ? pigments - blends vs mixing

I will try to be concise as possible about this very complex subject,
Linda.  I suspect there are a lot of others on the list who could answer
your questions, but I have puzzled over these questions since I first
got involved with TB's back in the late 1940s and early 1950s and am
happy to try to share what I have learned..

The essential thing to remember is that there are *only* two primary
pigment groups, 1) the anthocyanins (blue to warm violet) and
2) the carotinoids which include three or four variations on carotene,
(yellow to warm yellow) plus lycopene.(orange-red, looking pink in iris
petals, richer and deeper in the beards, and if Rick Ernst's work with
OSU is successful, red to red-orange in petals too--in the near future,
hopefully).

There are several other pigment families, nearly all closely related to
or derived from the two primaries, several of which do count in colors
as they appear, but for the moment we can ignore them in looking at your
questions.

Linda asks: "By blend, I mean two or more colors on a petal that can be
seen as separate colors up close (i.e., parts of the petal are blue,
parts of the petal are yellow) and the colors are streaked or fade in
and out from one color to the other. === I guess my first question is
whether or not that is what most hybridizers mean by 'blend'."


Neil responds:
That is true of many early blends, such as Dolly Madison, ancestral to
many modern irises, especially pinks.  The term, (originally
"squalens"), however, referred to *any* color that was neither some form
of either yellow or blue, but involved both in conspicuous presence,
regardless the distribution.

When the distribution is very smooth and predominantly one
color--(yellow in some variation) or violet-blue (in its
variations)--the early classifications, and even now some modern ones,
will say things like "blue-pink," or "pearly grey tones," or any other
such intermediate description.  "Rosy violet with a copper undertone" is
another example.

The Sass blends like Rameses or Prairie Sunset had very smooth colors
compared to most then-contemporary varieties.  Today I suppose we would
put them in the "brown" group.

Linda continues: "=== Are different pigments present in blends than are
present in smooth colors?"

Neil responds:
No.  The genetics and chemistry of the pigments is the same.  The
difference is due to relative quantities of pigments and the physics of
additive and subtractive color perception, a function of the human eye
and information processing in the brain, not in the pigments themselves.
Some of the minor pigments and co-pigments get mixed into this matter,
but again, we'll ignore them for the time being.  TWOI in an Appendix
has a chart of pigments found in a number of varieties prominant at the
time of the work.  A surprising number of the chemical compounds noted
are not identified--"unknown."  They can and do have an effect on
expressed color but are difficult to detect and identify even with
sophisticated tools such as chromotography.

Linda continues:  "=== Are different pigments present in blends than are
present in smooth colors?"

Neil responds:
No.  The same answer as the question directly above can be given.

Linda asks further:  "=== If the same pigments are involved in both
blends and smooth colors, as a pollen dauber, what do I need to know to
get one vs the other?"

Actually, knowledge of genetics and pigments does not make great irises.
Such knowledge can guide choices of parents, but astonishing things show
up in seedling patches regardless what the breeder knows.  "Like makes
like" doesn't even work much of the time.  Criss-crossing wildly
different colors and types can give some remarkable results.

Help does come, to some degree, from recognizing that *patterns* of
distribution in pigments, such as the yellow standards on the outside,
white on the inside, banded yellow on the edges; falls white banded
yellow with yellow backsides, when crossed with browns or reds, or those
"blends" that have brownish violet standards, blue-violet falls with
brownish violet edge band, give banded yellows and banded violet-blues,
usually.  The latter are the result of a violet-blue self occuring
together with the banded yellow pattern.

Breeding blends that show distinctive zones of colors with selfs will
more often result in seedlings with zones than seedlings with colors
smoothly applied.  That yellow intense color in the hafts is a strongly
dominant feature, but can drop out in some seedlings.  There are often
surprises though.  Plicatas, for instance, can and do show up in the
most unexpected places from time to time.  It makes hybridizing rather a
fun adventure.

Linda:  "In particular, I'm thinking about reds, 'caramel' brown/tan,
and orange."

Neil responds:
Conventional reds (Dynamite) are very smooth, rich red-violets with warm
yellow also present.  You can see this if such a red is crossed with a
dominant white.  The progeny sort out to yellows, blends and violets,
more or less.  The F1 might be all blends and yellows, depending on the
genetics of the white and of the red.

Carmel to brown colors are essentially the same as reds, except the
yellows are less warm, I suspect, with some greenish tone to them, and
the dosages or proportions of the pigments is different, the violet
pigment much lighter..

What were called "oranges" in early work were blends on the order of
carmel colors.

Since the advent of expressed lycopene in the late '20s (Dr. Loomis in
Colorado and others) to early '40s when the pigment was actually first
recognized widely due to the work of David Hall north of Chicago, the
modern oranges are a combination of at least two different carotenoids,
one of which is lycopene, another beta-carotene with perhaps others
besides.  Chuck Chapman has already addressed this and can answer much
more fully than I.

Linda concludes:  "Seems like there are orange blends (various shades of
yellow orange to pink orange) - are the same pigments involved?"

Neil responds:
Mostly.  In many of the cases, xanthophylls are probably involved.  The
main difference has to do with the separate distribution genetics for
the lycopene and beta-carotene.  Alpha-carotene is a derived product
from lycopene and its presence reduces the amount of lycopene presence,
so it is not normally a major factor when lycopene is expressed in these
color patterns.

One of the most beautiful color patterns is exemplified by Schreiner's
Champagne Waltz.  The standards are warm apricot-toned yellow with a
deeper pinkish flush up from the base of the standards.  The falls are
white with a band the color of the warm apricot-yellow of the standards.
The beard appears red.  Visitors never fail to notice it and "oooh" and
"aaah" to the host's delight.

There are a number of varieties of kindred sort.  They just keep getting
better and better.

I hope this has been helpful.

TWOI has major sections devoted to pigments and colors.  The text is
well worth a study, even if it is nearly thirty years old.  The pigments
haven't changed, nor have the patterns of distribution by and large.
The information is quite relevant.

Neil Mogensen  z 7  Reg 4  western NC mountains

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