Basal dominance physiology as it pertains to bonsai? Vs dwarf varieties?

[JonW]

Anyone have the knowledge to explain this? I can find literature on apical dominance, but not basal. I know this is an outdated and oversimplified view of apical dominance, but it occurs when the ratio of auxins relatively exceeds that of cytokinins. So I have to assume basal dominant plants (which I think would essentially be synonymous with shrubs or bushes rather than trees?) have the opposite.

I think this also gets confused with dwarf plants, which would have a low amount of or sensitivity to gibberellins. For example, there are many dwarf varieties (or cultivars) that are still apically dominant like Mikawa Yatsubusa, Shishigashira and maybe to a somewhat lesser extent, Kotohime maple. Sekka Hinoki Cypress seems to be pretty apically dominant from pictures I've seen. These all grow strong upright leaders if you let them.

Conversely, basally dominant plants may need to have lateral shoots trimmed in order to develop a clear upright leader, such as Azalea, Kiyohime Maple, Boxwoods, etc. (Of course some of these are both dwarf and basally dominant such as kiyohime and many boxwood varieties popular to bonsai).

I'm planning on getting a Kiyohime this fall and I've heard its challenging. The most common challenge I hear of is the top dying back, which I assume is caused by pruning the "apical" tip when it is already basally dominant. The result is that many of these end up "broom style," which is not my favorite as it lacks structure. Consequently, my assumption is that this plant needs to be treated opposite of typical bonsai practices: the bottom probably needs to trimmed twice as often as the top, and the top probably shouldn't be trimmed unless the bottom is also trimmed (otherwise the tree physiologically, not anthropomorphically, says "screw this apex, I'm putting my energy into lateral growth").

Having said that, some of these basally dominant plants seem to develop lateral leaders, even though they don't typically develop an apical leader. What I mean by this is strong side branches with clear secondary/tertiary branches, not just shrubby growth where all the branches are the same caliper. Can anyone explain the physiology of this? I'm assuming that, while these plants are basaly dominant, there is still a buildup of auxin in the lateral branch tips, and pruning those tips probably would lead to more a) top growth and b) more ramification of those lateral leaders).

 

[augustine]

Peter warren states in his book that Kiyota hime is good for semi cascades

 

[cmeg1]

Here is a great paper....thanks to Bjorn Bjorholm on the subject or science of cytokonin and auxin

Download the pdf

Auxin–cytokinin interactions in the control of shoot branching - Plant Molecular Biology

In many plant species, the intact main shoot apex grows predominantly and axillary bud outgrowth is inhibited. This phenomenon is called apical dominance, and has been analyzed for over 70 years. Decapitation of the shoot apex releases the axillary buds from their dormancy and they begin to grow...

link.springer.com

 

[River's Edge]

Anyone have the knowledge to explain this? I can find literature on apical dominance, but not basal. I know this is an outdated and oversimplified view of apical dominance, but it occurs when the ratio of auxins relatively exceeds that of cytokinins. So I have to assume basal dominant plants (which I think would essentially be synonymous with shrubs or bushes rather than trees?) have the opposite.

I think this also gets confused with dwarf plants, which would have a low amount of or sensitivity to gibberellins. For example, there are many dwarf varieties (or cultivars) that are still apically dominant like Mikawa Yatsubusa, Shishigashira and maybe to a somewhat lesser extent, Kotohime maple. Sekka Hinoki Cypress seems to be pretty apically dominant from pictures I've seen. These all grow strong upright leaders if you let them.

Conversely, basally dominant plants may need to have lateral shoots trimmed in order to develop a clear upright leader, such as Azalea, Kiyohime Maple, Boxwoods, etc. (Of course some of these are both dwarf and basally dominant such as kiyohime and many boxwood varieties popular to bonsai).

I'm planning on getting a Kiyohime this fall and I've heard its challenging. The most common challenge I hear of is the top dying back, which I assume is caused by pruning the "apical" tip when it is already basally dominant. The result is that many of these end up "broom style," which is not my favorite as it lacks structure. Consequently, my assumption is that this plant needs to be treated opposite of typical bonsai practices: the bottom probably needs to trimmed twice as often as the top, and the top probably shouldn't be trimmed unless the bottom is also trimmed (otherwise the tree physiologically, not anthropomorphically, says "screw this apex, I'm putting my energy into lateral growth").

Having said that, some of these basally dominant plants seem to develop lateral leaders, even though they don't typically develop an apical leader. What I mean by this is strong side branches with clear secondary/tertiary branches, not just shrubby growth where all the branches are the same caliper. Can anyone explain the physiology of this? I'm assuming that, while these plants are basaly dominant, there is still a buildup of auxin in the lateral branch tips, and pruning those tips probably would lead to more a) top growth and b) more ramification of those lateral leaders).

Perhaps this is what you are setting at
When developing Bonsai one needs to adapt pruning techniques to the species and the individual response in order to gain the desired outcome!
That is the reason why one needs to read the tree and balance ones response. Understanding the science behind it is useful but not necessary.
Great example of basally dominant is Zelkova and Hornbeam. Lateral shoots off to the races and apical shoots weak!

 

[JonW]

Perhaps this is what you are setting at
When developing Bonsai one needs to adapt pruning techniques to the species and the individual response in order to gain the desired outcome!
That is the reason why one needs to read the tree and balance ones response. Understanding the science behind it is useful but not necessary.
Great example of basally dominant is Zelkova and Hornbeam. Lateral shoots off to the races and apical shoots weak!

I didn't know that about Zelkova and Hornbeam - I would have thought the opposite, but never worked with either. I agree, you need to read the tree, but it is interesting to know the physiology behind it. I find understanding this helps me read the tree better. When you know you are rebalancing the hormones to shunt nutrients and energy (rebalancing energy) to other parts of the tree, it all starts to make a bit more sense, at least to me. Reading the tree helps with what to do now, understanding the science helps you predict the reaction and how that will influence the future. And I'm just curious - I find it interesting.

 

[River's Edge]

I didn't know that about Zelkova and Hornbeam - I would have thought the opposite, but never worked with either. I agree, you need to read the tree, but it is interesting to know the physiology behind it. I find understanding this helps me read the tree better. When you know you are rebalancing the hormones to shunt nutrients and energy (rebalancing energy) to other parts of the tree, it all starts to make a bit more sense, at least to me. Reading the tree helps with what to do now, understanding the science helps you predict the reaction and how that will influence the future. And I'm just curious - I find it interesting.

I find it very interesting as well, the rest of the story is the way individual circumstances can vary the direction needed. With time the focus can become more tuned in to the way a portion of the tree is responding to techniques applied. This becomes particularly important in developing structure as primary branches grow at different rates or lateral shoots appear sporadically. Or even simply when dominance must be stopped to assist grafts to take hold and then resumed for development.
The underlying knowledge provides a confident base to act upon.

 

[Wires_Guy_wires]

I think there's been a terminological mix up and I'd like to address it before it spreads as a common name.

Correct me if I'm wrong, please.

Most monocots and some eudicots grow from basal disks/plates. Like onions, leek, tulips and even dionaea. Grasses too.
They are basal dominant because all growth originates from that basal disk. They grow, more or less, upside down; stuff is added at the bottom end, not at the top. The actual oldest and least growing parts are at the top. The buds form at the bottom only, there is no apex thus they cannot be apically dominant.

We don't grow monocots - with the exception of some palm and banana trees - as bonsai. I think this partially explains some confusion. The entire literature on basal dominance doesn't refer to trees at all, it's mostly about bulbous plants.

Please use the term lateral dominance to avoid confusion. You'll find way better information.

Have a nice day!

 

[garywood]

Like Frank and Wire said, there is too much confusion in trying to “classify” growth tendencies when just observation of a given tree is enough. The genetic diversity in Japanese maples alone is a books worth of study in pruning technique.

 

[Leo in N E Illinois]

As an orchid growing friend once said to me "It ain't rocket science, why make it sound like rocket science?" to which he replied to himself, "Oh wait, I AM a rocket scientist." , as he was, working on developing extreme high power lasers at the Argonne National Labs.

Most of the science in this field is done on economic crops, as that is where the grant money lies. Extrapolating into species typically used for bonsai is guess work at best. The end result, we still have to rely on anecdotal reports such as Acer 'Koto Hime' is apically dominant and Acer 'Kiyo Hime' is laterally dominant.

But I do know I enjoy making the mind work, once in a while.