The most famous experiment on ph and colour is the red cabbage extract experiment. Very wide range of colour depending on ph.
Basically cell sap ph is independent of soil. Ph of soil can effect plant uptake of chemicals and minerals, so can effect colour of flower, but not much effect, if any on cell sap ph, which is controlled by plant genetics.
Each population of plants (ie iris species etc) will have it's own mean and standard deviation. AS iris have derived from a number of species there could be a wider range of cell ph then in other species. But this has never been checked, as far as I know. But there is a lot of experimental evidence that cell sap ph can make a huge difference.
For example Bachelor Button is very blue, but it's anthocyanin is cyanidin. the red pigment in roses. It is the cell ph which results in it's blue colour.
---- Original Message ----
From: Linda Mann <email@example.com>
To: iris-photos <firstname.lastname@example.org>; iris-photos <email@example.com>
Sent: Fri, Sep 9, 2011 8:26 am
Subject: [iris-photos] Re: HYB: pigments
I've seen this mentioned several times & have wondered how the pH can
vary from one plant to another.
Does this mean the pH of the soil affects the chemistry of the pigments
Or is pH of cell sap in the vacuole intrinsically different from one
seedling to another?
Or is it some of both? Or not known?
> Also the effects of ph in cell sap in vacuole. This can be of immense importance.
Linda Mann east TN zone 7 USA