Spatiotemporal development of Cattleya flower color: Heathii (1) example

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The greatest change in Cattleya flower color in my collection is in a primary hybrid Heathii (1) (loddigesii ‘Shorty’ x walkeriana ‘The Chairman’). I took daily indoor pictures with my iPhone during the first three days of flower opening. I used no color correction and light was from a diffuse LED overhead panel about 7 inches above the flower. The panel has settings for three different color indices. I used 4000K which in the past has best replicated what I get outdoors with morning indirect light on a mostly cloudless day. Here are the three pictures side by side.

Heathii.jpg

Cattleya (and most orchid) flower color is controlled by complicated genetics that activate and inactivate production of various pigments in different parts of the flower at different times during bud development and flower opening.

Anthocyanins mostly result in purple-red color while carotenoids more typically produce yellow coloration. Pink to white color requires low levels of both. Green coloration is due to chlorophyl. A detailed article on spatiotemporal development of flower color in Rlc. Beauty Girl was published in 2020 and is available in the link below.


The text is complicated but the abstract, conclusion, and some of the figures are helpful. Multiple mericlone plants of the hybrid would have been needed for the study. The plants were grown in a Chinese Academic Forestry greenhouse (Bejing, China) under natural light. We don’t know the amount of shading applied, but the day length would have varied from 9 hours to 14 hours through the year because supplemental light was not mentioned. The daytime and nighttime temperatures were stated as 24-30 C (75-86 F) which would be very warm nights for Cattleyas. However, I suspect they meant that winter high temperatures were about 24 and summer high temperatures about 30C. Nothing is noted about nutrition.

The study identified varying amounts of 11 carotenoids and 4 anthocyanins in four parts of the flower during bud development and day 1 and 2 of flower opening. The flower parts sampled were sepals, petals, proximal lip (hypochile), and distal lip (epichile). The pigments changed considerably over the time period and the pictures of the flower on days 1 and 2 show impressive change.

This might be a good chain in which to put your examples of impressive Cattleya flower color change with opening.
 

DrLeslieEe

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Such a fascinating article.

Colors in many orchids will congregate over the 3-5 days with the said anthocyanins and carotenoids till their final color.

Besides the loddigesii hybrids that show this quite clearly, there is a subtle change in a forma colour of cattleyas called the rosada. They start opening like semialbas with white sepals and petals that change over a few days to blush pink. This sometimes is so subtle and imperceptible that the pink can only be seen when backlit.

Btw here is a classic loddigesii colour maturation from white to pink over a few days in my collection. Hope the link works.

 
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It worked and I thought Heathii was mostly showing a lodigessii trait. You show a great progression. When I see how many pigments and genes are activating and inactivating, I realize why breeding for color is so difficult.

What other species are distinct in having dramatic color changes with flower opening?
 
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DrLeslieEe

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It worked and I thought Heathii was mostly showing a lodigessii trait. You show a great progression. When I see how many pigments and genes are activating and inactivating, I realize why breeding for color is so difficult.

What other species are distinct in having dramatic color changes with flower opening?
That’s why the great breeders record all genetic expressions (phenotype) from each plant genotype to trace the genes. Then from a sample breeding with different parents, they can infer which genes are turned on and off, recessive or dominant or the existence of gene expression.

The issue is further complicated with colour moderating components like copigments (eg heavy metals) and timed degradation of certain anthocyanins and chromoplasts that moderate final color.

The temperature can also influence anthocyanin accumulation. Petal pH can play a role in the kinds of anthocyanin expression (eg alkaline petals allow blue anthocyanins).

This is what the paper study missed. All the above factors are in play and not just the presence or absence of a gene pairs.

Other species that show dramatic color change in cattleyas include the flameas and pelorics. The colour of the flameas may grow and deepen over time
 
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I knew that multiple environmental/cultural issues would play a role in gene activation/inactivation and also in pigment stability. This is where I admit that growing orchids is for me predominantly a science experiment and NOT expressing an artistic sensitivity!
 

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I'm the opposite of you in practice lol. I grow for artistic beauty, then find out the science behind it if I am interested. For me, science follows art 😇 .
 

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