Just cos the gods will come down and "educate" the heathens is no reason for the heathen to give it ago!BigTom said:I started typing a reply and then realised that Darrel or Ceg will undoutedly be along shortly and will do a much better job than I can
How about some Peking Duck?Bobtastic said:Open to be educated, *duck*
Pretty much it, the only thing to add is that some plants which may predominately terrestrial, but live in conditions where flooding is an occasional or seasonal events, may be able to live permanently submerged if we give them extra C02, more PAR etc. These are the plants that will usually only grow with CO2 addition.I think there, basically, three main types of plants. One type that will only live out of water, another type that can only live in water and the final type that can adapt, by changing their leaves, and will grow both in and out of water.
Well, really it's not clear exactly what the sequence of events are in your setup. It's very easy to misdiagnose unless we have a precise understanding of what, where and when.idris said:Thanks Ceg. Very informative!
So if i may cross polinate my own threads, my plants have had about 2 weeks emersed, and a high percentage of leaves have died, yet there are signs of new growth. Are the new healthier young leaves likely to already be terrestrial or if I flooded now, are they young enough that they could continue to grow as aquatic leaves?
Yes, well as noted, it's less a matter of what plants "manage" to accomplish than which plants have been programmed by evolutionary forces in this type of environment. It's also worth noting that not only the leaves have to make this transition, but the roots have to adapt to flooding as well. Within the root structure are cells which are programmed to die and rot. When the cells decay and collapse this forms a network of voids (spaces) called "Aerenchyma". This is a super-important adaptation because this is the only way that Oxygen, produced by the leaves, can be transported to the roots, which nourishes the roots and then which escapes out into the sediment to help support the aerobic bacteria. This is sometimes why we can see the sediment pearling under high CO2/light/nutrient conditions. This Aerenchyma formation technique is the definitive behavior of amazingly tall trees in the Amazon Basin. This is how trees like Mahogany survive 6 months of flooding in the rain forrest. Terrestrial plants simply aren't programmed to make these changes, so the entire plant rots away when flooded. That's what happens when you overwater your house plants or garden plants.niru said:Ceg, does this also implies that only those plants which manage to change their leaf internal wirings to suit the under water flooding can grow in the tank, and others will simply rot/decay? One never sees a rose garden in a tank?? Is this the sole/primary reason for this? And are there genetic engineering methods to modify this available?
This method is rather simple, it’s simply terrarium horticulture for the first 2-6 weeks and then the planted aquarium is filled with water after the plants are grown in and well rooted. Generally this method is most suited for lawns of HC, Glossostigma, Crypts, some stem plants, swords, dwarf clover, dwarf hygro and the like. It is particularly useful for iwagumi style rock layouts using low growing plants. Such tanks with low total plant biomass can be challenging to start up and established. While terrariums and emergent dry aquariums is hardly a new hobby, applying this to the start up phase of a submersed approach is new.
The goal of this method is avoid such labor. By starting a new tank out “dry”, with only the sediment fully saturated with water. We avoid water changes, there’s none to change (this saves us several intensive weeks of water changes and dosing carefully)! Dosing? There are no nutrients to dose. Bacteria? It’s cycling in the root zone just fine. We only need to buy a small amount of HC to make a nice lawn of foreground plants in a few weeks; these are also very well rooted. Roots add O2 to the sediment and the O2 helps increase bacterial cycling. Upon adding the water and submersing the aquarium, the bacteria will be ready, the plants will be ready and adding CO2 (or not) and dosing (or not) is all that’s needed from this point on. However, this method however will not save someone who’s not very good at keeping submersed plants to begin with, but it will give anyone an upper leg up on a new tank start up.
Some plants will adapt better than others to submersed culture. The biggest issue for plants going through this process is gas exchange. So adding plenty of CO2 and current will help. Ethylene is a gas as well as a plant hormone that is generally considered a senescence hormone. Ethylene is no long able to diffuse out easily and causes some species to melt and rot back, but the new growth will have a much better chance and already have a nice strong root system to draw on for growth of new shoots above the sediment, whereas am emergent plant from an aquatic nursery will have both the roots and shoot being transplanted and experience the shock of the tank’s water, the light, the CO2, and bacteria changes. This Dry Start Method avoids all of that. So what are the problems with this method? Folks do not want to wait 2-6 weeks for the tank to grow in well first is perhaps the biggest issue, but seeing their small clump of HC or Gloss grow in and spread, no water changes and other very helpful, less costly and labor intensive advantages might convince them.