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Red/Purple veins on my plants
- Thread starter Bobby86
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What degrees of pigmentation correspond to what ranges of pH? This is very interesting.Bobby86 said:
Are there similar advantages to more-pigmented phenotypes, such as purple-leaved ornamental C. annuums? Do purple-leaved land-race C. chinense strains like CGN 21500 or Mata Frade have any other advantages?harry said:
Would the darker color of purple foliage absorb more heat, causing increased leaf burn under some circumstances? I know it helps protect against UV, outdoors, but i also wonder if it has the same PAR requirements with respect to indoor light.
@Bobby86: Purple streaking of stems and leaves can be a symptom of phosphorus deficiency, but is also a trait that occurs naturally in some specimens of many plant species.
Similarly, pale yellow-green color of apical foliage (young branch-tip leaves) is usually a symptom of "trace-mike" (a.k.a. "trace micronutrients" -- iron, zinc and/or manganese) deficiency... but many strains of Capsicum chinense also feature yellow-tinted apical foliage when healthy.
The plant looks healthy, althought it's coloration could be interpreted as symptoms of both deficiencies. I'd guess that it's perfectly healthy. I may not have enough experience with peppers yet to be 100% certain, but that's my guess.
@mikeg from the wiki. Anthocyanins can be used as pH indicators because their color changes with pH; they are pink in acidic solutions (pH < 7), purple in neutral solutions (pH ~ 7), greenish-yellow in alkaline solutions (pH > 7), and colourless in very alkaline solutions, where the pigment is completely reduced.[5]
There is the odd plant that has produced less pigment on the stems and veins than in previous seasons despite exposure to direct sunlight. I hadn't thought much of the fertiliser rotation supplying little by the way of Calcium nutrient since the tap water is hard. In the past I observed too much of white salt precipitating out of solution and forming a layer of scum in the plant saucers.mikeg said:
After noticing that the residue was insoluble in water and unaffected by vinegar I figured it was Calcium sulfate. I took the precipitation of Calcium sulfate as a hint the pH of the mix in various plant pots was on the acidic side due to its increased solubility in acidic solutions. After a couple applications of a teaspon of Calcitic lime one of my red Rocoto plants improved in vigour and now has fresh stems and veins with a hint of purple. This is not a colour shift that you would expect after looking at the photo of pH indicator created from red cabbage on the wikipedia page Bobby linked to (Anthocyanin - Use as pH indicator).
I have a couple of ornamental Capsicum annuum varieties that produce purple leaves in sunlight. The darkest of the two is the dwarf Ebony Fire chilli cultivar that was bred in Australia. I have seen plants of this variety stand up to >35 °C in direct sunlight.mikeg said:
I had considered obtaining and growing CGN 21500 and Mata Frade to see if it would stand up to the harsh summer conditions here. The most prolific Capsicum chinense varieties here do have some ability to produce anthocyanin that is visible on the stems.
I agree that the plant does for the most part appear healthy. The patterned texture of the leaves does hint at the hunger some Capsicum chinense varieties have for Calcium.mikeg said:
An idea that came to mind is one of us could grow one of the varieties that produces dark purple leaeves and then apply the process used to create pH indicator from the leaves of cabbage but using dark chilli plant leaves. This would require the sacrifice of much of the foliage of an ornamental chilli plant.Bobby86 said: