Flower color intensity (was Soils and flower color)
Nathan Lange (Wed, 13 May 2015 18:13:29 PDT)

Hi Mike,

I should have written, "low light levels during flower development
result in lighter flowers." My use of the word "faded" was
inappropriate. I intentionally avoided any mention of flower aging or
senescence in my previous comments since those topics confound the
developmental causes of flower color intensity. It's not that your
observation is "opposite" of my comment. Your observation during the
aging and senescence of the flowers is a different topic during a
different developmental stage of the flower than what I was talking
about before. I was not talking about changes in flower color
intensity with regard to flower age or senescence.

For more info on flower senescence, I refer you to the chapter,
"Physiology of flower senescence," in "Plant cell death processes,"
co-authored by yours truly.

As you point out, Moraea, like many other genera, has flowers that
fade in color intensity with age. If you could manage to flower the
same Moraea species in question under lower light conditions with the
same tissue temperature, the resulting flowers would very likely be
lighter in color when they first open compared to flowers of plants
grown under higher light levels. With regard to your observation,
"The more sun the plant gets, the faster they fade," this is not at
all surprising and you may be observing an increased rate in floral
senescence due to higher temperatures since the floral tissue itself
is likely warmer in full sun, even if the apparent air temperature
remains the same. As we all know, flowers senesce faster at warmer
temperatures. Also, the flowers in full sun could be lighter in
general from the innate higher temperatures associated with being in
full sun. I have no idea how sensitive Moraea flowers are to
temperature with regard to color intensity. Without a number of
carefully controlled experiments, it's difficult to say which
environmental factor is the most important at any point during
development for any given species.

The separate effects of light and temperature are often difficult to
delineate without the proper controls especially if one's light
source is the sun. People's anecdotal observations are always biased
toward the light that they can see. Temperature itself is invisible
and is frequently one of the most misunderstood and under appreciated
environmental factors in the horticulture.

Nathan

At 02:03 PM 5/13/2015, you wrote: