Flower color intensity (was Soils and flower color)

Nathan Lange plantsman@comcast.net
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.


At 02:03 PM 5/13/2015, you wrote:
>Nathan wrote:
> >Not surprisingly, low light levels result in more faded flowers.
>Interesting. I've had the exact opposite effect with many Moraea species --
>they open with a fairly intense color that fades over time. So, for example,
>a flower will open yellow and fade to off-white. The more sun the plant
>gets, the faster they fade.
>San Jose, CA

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