How to improve resiliency of in-vitro plants?

[Simon Cole]

A rather interesting article has appeared in the journal Rhizosphere this month: <Antagonistic activity of autochthonous strains of Bacillus amyloliquefaciens and Bacillus velezensis against fungi and oomycetes associated to damping off>.

• The takeaway point is that various Bacillus strains are showing promising results for controlling Oomycete plant diseases and damping-off.
• Two compounds have been identified as primarily responsible - "Iturin A" and "fengycins".

Unlike Trichoderma strains that <struggle when immersed>, Bacillus-based Biological Control Agents (BCAs) should have good survivability in planted tanks. We will not know for certain because development is commercially sensitive, but it seems quite likely that formulated hydroponic treatments will be the first to enter the market. A shortcut would be to synthesise active compounds from these strains and apply as a treatment, but this would depend upon factors like <toxicology, safety, and environmental impact>. We wouldn't want to annihilate beneficial bacteria completely; but the research also gives us an indication of what "beneficial bacteria" really are... For as nice as it is to help the aquarium cycle and build a flourishing microbiological community, I would rather have an army of defensive microbes dedicated to protecting and stimulating my plants.

Concerning <plant immunity>, I am now convinced that the above aforementioned cultivars are genuinely affected by damping-off. I had a propagator full of in-vitro Bucephalandra which after growing successfully for a year with the help of the BCA Trichoderma viridae, gradually melted from the stems. To me, it looked like the Trichoderma were able to protect the roots but not the rest of the plants. This seems to be a fairly clear indication that mass cultivation techniques rely upon chemical fungicides and not the immunity-inducing effects associated with a balanced composition of BCAs. Since the plants are never exposed to microorganisms or biotic stress, their defensive gene expression is turned-off and this appears to be a long-term impact. Propagating in-vitro plants from other in-vitro plant tissue is obviously a shortcut that means "wild" samples do not need to be washed and sterilised, whereas the problems might go-away if they did.

There is the immense potential for "snake oil" that actually works! For instance, I was reading that Triacontonol is effective as low as 2 parts per billion - it has an interesting synergistic effect on plant immunity by stimulating photosynthesis and root growth, increasing stomatal function and photosynthesis... and it is also one of those compounds that would make plants aquarium bushy as opposed to leggy and visually unaesthetic. In certain plants <effects commence within the first 5 minutes of application>. Combine this in a formulated approach with <Comammox Nitrospira>, <Copepod eggs> (as grazers), and a selection of BCAs known to defend against plant disease (and to stimulate immunological response), then there you have it.

I have some new BCAs from Enzim Biotech Agro, including a Bacillus strain. If I'm mad enough to order again in-vitro plants that are doomed, then I shall keep you all updated. Will also keep an eye out for new publications because things are happening fast now.

 

[Fishfur]

Just finished reading the preceding pages in this thread & wanted to mention something I’ve been doing that I hope is going to significantly improve my success rate with TC plants.

Too many TC plants that I have tried to grow have melted away and every failure is a major pain in the pocketbook. So late last fall I decided to try growing them emersed instead.

I’ve since done the same with bunched & potted plants that had no roots to speak of.

I theorized that the TC plants in particular would have a much better chance to transition successfully to submersed form if they grew a nice robust root system & matured before they went underwater.

For some species, like H.pinnatifida, I’d never been successful at getting decent bunched cuttings or potted ones to transition. I very much want to succeed with pinnatifida, it’s so beautiful.

I also thought a more gradual change from perfect sterility for TC plants should make it a bit easier on them.

It’s been interesting so far. The humidity level in the boxes with their lids on but not latched down has to be over 90% - maybe over 95%. I just got some wee hygrometers so I can check on that.

I set up some translucent plastic storage boxes under grow lights on shelves and experimented with a few different substrates either in the bottom of the box or in small terra cotta pots.

Orchid moss, coco peat & vermiculite all worked for some though the vermiculite proved to be quite messy. All three are a pain to remove from roots.

Now I’m experimenting with pool filter sand - quartz sand. It’s easy to rinse off roots, can be sterilized if need be and it’s far cheaper than anything else.

A surprising number of the plants have grown in what looks like their submersed form - which was not what I expected. But they are surrounded by moist air so they’re growing emersed regardless of their form. The abundance of carbon in the air is certainly a benefit - they’re growing pretty quickly.

I wet the substrate with tank water as a very mild fertilizer but I may have to start using something a little stronger.

I’m about six months in from the first box I started with. My biggest worry was that mould would be a problem. So far I’ve been fortunate, no signs of mould have appeared. The odd wee patch of algae has shown up but not much.

A couple of species were spectacular flops - they just disappeared. But most have done well enough & a few have been outstanding.

I’m not quite at the point where I’m ready to plant any of them underwater but I will be soon & that will surely be interesting - to find out if my time has been wisely invested or not.

A couple of plants I’ve never had any luck with have done exceptionally well - among them B.heteroclita Longtails & Asiatica, The Longtails very nearly filled a box about 30 x 40 x 30 cm in size with dozens upon dozens of fernlets on every frond plus new growth on the original rhizomes.

Monte Carlo has done really well too - as well as H.pinnatifida, C.pontederifolia, C.nurii, & Hydrocotyle tripartita Mini & a couple of mosses.
It all the plants are destined for planted tanks, some will be used for terrariums.

Lagenandra meeboldii Silvrr Queen is doing well so I hope it will transition well - previous attempts with L.meeboldii Red have not.

Several smallish rhizomes of a few different Anubias & a Buce were snipped into as many pieces as I dared, to encourage multiple new shoots & so far that’s working nicely. Slow of course but multiple new shoots will eventually make a much nicer display.

I’m also trying to find the sweet spot in terms of humidity to grow emersed moss on rocks, for use in terrariums.

They are mostly growing in a submersed form in the super high humidity but the last image shows one that I grew starting with the rock in a tank with half its height above water.

It has Leptodictyum riparian moss on it ( and a lot of very sneaky riccia fluitans too. I hadn’t realized riccia would grow that way but it eventually smothered most of the moss. Live & learn, right?