Some observations on Paclobutrazol's effects on orchid cuttings.

[KultureShock]

(edit: Paclobutrazol has also been shown to induce flowering in orchids grown in vitro. simply add 1mg/l paclobutrazol to your tissue culture medium.) Here are some observations i made while trying to reduce mold problems in flower stem cuttings grown in vivo that i thought some of you might find interesting/useful.
in an attempt to deal with the mold issue i made up three solutions of paclobutrazol(a triazole fungicide and plant growth regulator).The concentration of each was 1mg/L, 2mg/L, and 3mg/L respectively. 4 stem cuttings were completely immersed in each(a total of 12) of the solutions for 15 minutes and 4 stem cuttings were planted in vermiculite without being soaked in a paclobutrazol solution they did however get a small amount of Keiki paste applied to each to break dormancy in the stem cuttings. After the 15 minute soak all the cuttings were planted in vermiculite and also given a small amount of Keiki paste to break dormancy.

Now this is where things get interesting. The group of stems that were soaked in 3mg/L paclobutrazol all had swelling of the nodes on the 3rd day, the group with 2mg/L had swelling of the nodes on the 5th day and the group receiving 1mg/L had swelling on day 7 as did the group that did not receive paclobutrazol. This shows a direct corelation between the amount of paclobutrazol applied and the time in wich it takes to break dormancy in a phalaenopsis orchid. Also all of the node's began to grow on every cutting that was treated with paclobutrazol where as the group that did not receive paclobutrazol only had 2 of the 4 cuttings start to grow wich suggests that paclobutrazol can increase the overall success rates of Keiki paste application.

i plan on doing so more experiments using orchids that dont generally respond to Keiki paste to try and come up with a paste that will work on them but i dont have plants of other species to experiment on so it will be a while but check back now and then for updates. Also i will be adding pictures once i get a camera.


P.s. i would love everyone's input and possibly some suggestion on how i can improve my trials, also if anyone has a species of orchid that doesnt respond to keiki paste they would like to donate to the experiment or knows where you can buy orchids in canada it would be greatly appreciated and extremely helpful.
Best regards,
Kevin Disher
KultureShock

I know nothing about growth regulators etc. but this link might help with finding orchids in Canada:
Canadian Orchid Vendors

[Ray]

That's very interesting, Kevin. Keep us posted.

One caveat, though - just because the nodes are swelling, it doen't mean the outcome is what you'd want...

[orchidsarefun]

are all keiki pastes created the same ? In your experiment you appear to have used keiki paste in all samples; what if you hadn't ?

[KultureShock]

Hey ray, i know that the swelling doesnt guarantee that their is going to be keiki formation but it does show a that there is a much better chance, i will keep you all posted as to how it turns out in the end.
Oh and orchidsarefun not all Keiki Pastes are made the same but they all have a cytokinin as the main ingredient (usually benzylaminopurine) the other ingredients are usually only their to increase absorbtion into the plant, but in some cases complimentary hormones such as brassinosteroids and auxins are added to reduce stress on the plant caused by keiki formation.

And the reason i used keiki paste on all of the cuttings is because this didn't start out as an experiment and i wasnt expecting the paclobutrazol to do anything except prevent rot in my cuttings so in order to ensure keiki formation in a timely manner i added the keiki paste to the nodes of each cutting. If i hadn't added the Keiki Paste i dont think dormancy would have been broken in the nodes at all even with the paclobutrazol treatment but i could be wrong... if anyone has a phalaenopsis that is currently in flower and would like to try applying straight paclobutrazol to the nodes i will supply the paclobutrazol as i am really curious to see the results and dont want to wait months for my orchids to rebloom.

Once one of my Orchids decides to flower again i will repeat the process without the keiki paste.
After i noticed the effects it was having on my cuttings i did some quick research online and found out that there have been a couple studies done showing that paclobutrazol has additive effects when used in combination with benzylaminopurine increasing the overall number of shoots formed. I also found a study saying that when used in combination with indole butyric acid it increases the number and width of roots formed and it also was the only way to get some plants to root(can't remember which ones right now) . I find this extremely interesting as the mode of action of both occurences is unknown and in general hormones that cause rooting prevent shoot growth and vice versa so for paclobutrazol to be able to take on a different role depending on the substance it's applied with is pretty crazy and cool in my opinion it would be interesting to see if it has additive effects with any other hormones
I can't find the links to them right now but once i do i will post them.
If you have anymore questions please dont hesitate to ask and if you have any suggestions on variables i should add to the experiment for next time let me know and i will do my best to incorporate them.
Best regards,
Kevin Disher
KultureShock