What influences flower colour?

[ohugal]

This year I've been able to provide my cacti with a cold winter's rest and a lot more sun in the growing season. As a result I've been getting more flowering plants, which makes me a very happy man. I've recently had a flowering Gymnocalycium bruchii and the flower had a beautiful pale pink colour. I compared the flower to other images of flowering G. bruchii and was wondering where the variation in intensity in flower colour comes from? Is there literature on this subject?

[greenknight]

Mainly genetic variation.

[ohugal]

When visiting a grower, someone from our local cactus society told me -regarding a flowering Stenocactus- the colour of the flower was pale because it was hybridized a lot. I'm not familiar with this, but is this what you are refering to? So soil, exposure and fertilization have little infuence on the shade of colour of a cactus flower?

[Steve Johnson]

I agree with Spence, although I do have to wonder if different fertilizers can have an influence on flower colors. Since I recently changed from the Dyna-Gro 7-7-7 I had been using for years to a more comprehensive fert regimen (Oscar, you know what it is), this will give me the opportunity to see if there are any appreciable differences in flower colors. I haven't seen signs of that yet, but I can tell you this -- compared to the relatively high P in the 7-7-7 (N = 1, P = 0.44), lower P in the new regimen (P = 0.35) has led to more prolific flowering on some of my cacti. Those are the spring bloomers, and I'll see if the summertime bloomers do it too.

[ohugal]

Well, it's the first year I've actually had so 'many' cacti blooming, so I can't compare to previous years. I thought (in habitat) certain enviromental parameters could trigger genetic differences. Are there studies why flowers have the colour they have?