From: ted.held at us.henkel.com on 2005.06.22 at 20:02:10(13028)
Well, I don't seem to have provoked much of a discussion on how aroids without chlorophyl can long survive. Feeding them with a carbohydrate base food does seem to be the only route, albeit with the risk of simultaneously feeding unwanted fungi, bacteria, and soil insects. Here are some additional thoughts.
As I pointed out before, we have the analog of parasitic plants and plant-like things, which tap into viable sap flowing in host species and make their living that way. There are also plants, such as what are known as terrestrial orchids, which pair symbiotically with soil fungi to acquire and share essential nutrients that neither can manage on their own. This orchid arrangement allows the plants to survive for several seasons underground, with no leaf production, and revive with no apparent deterioration when conditions allow. Terrestrial orchids deprived of this fragile symbiosis usually die quickly. That is why it is futile, in most cases, to try to transplant wild terrestrial orchids to home gardens. This symbiosis may either occur with aroids or be a model that can make plausible carbohydrate acquisition by some other pathway by a ghost plant.
We have to recognize here that we are speaking of two classes of essential uptakes by plants. First there are the nutrients. By this I mean the typical nitrogen, phosphorus, and potassium (NPK), so-called trace nutrients (several elements), and probably some small molecules that elude ready identification. Presumably ghost plants are able to perform this usual task as well as fully-equipped plants with chlorophyl. The second class of nutrient is the one that contains the main energy-containing substances. These compounds are the carbohydrates, fats, and proteins and comprise compounds that can be metabolized for caloric needs and the main components of tissue construction. Plants are usually thought to make these materials by photosynthesis. For animals, "food" consists primarily of these substances, acquired by eating organic matter originally built from photosynthesis. The mineral and "vitamin" nutrients are gathered al
ong the way, by and large as an incidental of normal eating. If a plant finds itself a ghost, it must receive NPK nutrients as well as calories from some source or starve.
Clearly, ghost plants are not making anything by photosynthesis because we assume that it is established science that chlorophyl is necessary for this activity. If they are able to live after exhausting their own stored materials in their seeds or bulbs, or whatever other reservoirs are available, it must mean they are getting these bulky supplies by another method. Absorption from the environment in some way seems to be the only available option.
How much caloric matter may be necessary for a plant to continue to exist may be approximated by how large its reservoir is. If a seedling's reserve weighs a gram and that reserve takes a month to deplete, then a plant of its type and size will need roughly a gram, dry weight, of solublized caloric nutrition absorbed into its system every month. If a fist-sized bulb is drawn down in a season, then perhaps 500 or 1000 grams of dry weight caloric matter may be required to keep the plant going for a season. The idea would be to figure out how to meter out this amount of material over time and devise a broth most suitable for plant uptake.
Pouring on excess amounts of material would, indeed, encourage fungi and gnats to take over. Pouring on caloric matter in a form impervious to absorption would also be a waste. But the appropriate soup, dripped in (or on) carefully seems entirely feasible.
The practical uses for such techniques may extend beyond keeping a ghost alive. It could be a method to assist a wounded plant over a rough patch in its life. It could be a method for enhancing the growth of healthy plants for other purposes. And it would be just nifty to know it is possible to do it.