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Abgeschickt von Camiel F. de Jong am 02 Mai, 2002 um 21:26:48
I liked the discussion about the acaules a lot but I still want to shove in some of my ore! At the moment I have around 100 deflasked acaule seedlings coming along. The oldest are deflasked more than one year ago. The ones that emerged last year have emerged again this year. The plants were planted in a mixture of sand and sphagnum peat 50/50 and watered only with water to which a spoon of cider vinegar on 3 L was added. They were grown in my cellar under artificial lights. The plants are much bigger as compared to the previous year. Recently, I checked the pH of the substrate and it was around 4.6, somewhat too high. The pH of the substrate of another batch of acaule seedlings in my cellar I potted up a few weeks ago was 3.7. Yet another batch was potted up in autumn and standing on my balcony. The plants grew well but lately I noticed a water-soaked lesion on one of the leaves. With acaule this means trouble caused by a pathogen. I cut off the leaf under the lesion to prevent spreading of the infection. When I checked the pH of the substrate it was 5.9! This is much too high. When I put 1 spoon of vinegar on 3 L water the pH decreased to a value of around 4.6. Consequently, to correct the pH of the substrate to a value of around 4 I put in a lot more vinegar (around 50 mL!). We had a lot of rain and 5 days later I checked the pH again and it had risen again to 5.6. I think that these results may be an explanation for the all too common failure to grow acaules. The substrate may be acidic initially but with watering or with heavy rain fall the acids are washed out resulting in a rise in pH. This does not occur in my cellar where the plants only receive acidic water and the pH stays low. I was surprised to find that by heavy rain the pH of the substrate could rise so quickly as I presumed that the substrate would have a much higher buffering capacity. A good indication of the low pH is that only acaules and no weeds or mosses grow in the containers with acaules whereas in other containers containing the same substrate but not watered with vinegar weeds and mosses thrive. Some mosses started to grow in the container on my balcony but they died immediately after the pH correction. Conclusion: In culture, the pH of the substrate should be checked regularly. If this is not done the pH may rise unnoticed and pathogens that are present may avail themselves of the opportunity and attack the plants.
Two years ago I was in New Hampshire and I found a lot of acaules there. They were mostly growing under pine trees but hardly under maple trees. They stood often amidst blue berries in a compact dry soil full of roots of blueberries or surrounding trees containing roughly 50% fine sand and 50% organic material (No, I did not dug up the plants). The decay of the fallen needles of the pine trees render the soil acidic in an ongoing process. On these findings I based my substrate of 50% lime- and salt-free sand and 50% peat. The peat is acidic. I do not use pine needles since I have to get them in the woods risking also taking home a lot of pathogens or pests with the needles.
Another interesting point is that after a while a fungus starts growing in my vinegar. Apparently it lives on the vinegar. Also in the soil the vinegar may be food for microorganisms. As I said before, the acaule seedlings in my cellar grew very well. An interesting speculation is that these plants are so well adapted to soils containing a lot of organic acids that the plants may even use them as a carbon source. In other words: the vinegar might be a nice and welcome snack for the plants! In some plant tissue culture media organic acids are also used as a carbon source instead of sugars. It is known from acaules that some years they do not emerge but stay underground. This may be well in support of the speculation that they use the organic acids as a carbon source which makes them more independent of photosynthesis.
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