Defoliation to promote growth an increase trunk size?

[Tambrand]

Please note that the pot is now 1" [ 2.5 cm deep and soil is 5mm builder's gravel with less than 1/3 by volume aged compost ]

Trunk in 2016 is 3" [ 8 cm ] and am now working on the canopy.
Extensions for two lower branches were less than 1 m,
Soil mix remains the same.

This is now the standard technique for me, and growing Ficus p.
Hope this helps.
Tambrand

[DustyRusty]

Please run an experiment: genetically same plant, same spot, same pot, soil etc. one chop, one don't, leave for a year then report back. Your hypothesis is different to everyone else's, but you never know, you could be the next Copernicus of the bonsai world.

[Lane]

It would seem your hypothesis assumes that an un-pruned branch does not grow, we all know it does, but does so apically so majority of growth is to the upper most areas receiving the most sunlight.

New growth + existing foliage = More resources moving through the tree = Bigger tree.

I would be keen to see the results of an experiment if you choose to do so.

[sheepdawg]

@ Rory
Yeah, I'm not preaching it as fact but I am confident in my belief and I am testing it out now, but with a much smaller sample size
But on the plus side; they're cuttings so genetic differences will be negligible.

I know my science is a hugely, gross over-simplification but I also don't think it's core logic is wrong.


@Tambrand
Why are you growing it out in a bonsai pot? Genuinely curious because my process has been to only put them into a bonsai pot when I've got the trunk size I want, primary branching at the thickness I want, and some secondary branching. To me the bonsai pot is where fine ramification is built and where the plant is presented.


@anthonyW
That's the way the man at my local nursery grows some of his trunks. I personally don't like the conical result with figs, but love it with other species (especially elms).


@DustryRusty
Experiment underway! Using some small rooted cuttings I did last summer, but unfortunately only have five
I am thinking of getting a pom-pom "ficus standard", cuttings it back then carrying this experiment out on branches it produces.

[treeman]

To add to what I just wrote: a few leaves (or even thousands of leaves) sitting on a branch will never thicken that branch. Why? Because the lateral meristems are not active.

Take 2 identical potted trees. Leave one to grow without any kind of tissue removal. Prune or defoliate or wire or do whatever you want with the other one. At the end of 2 years the first one will be thicker whether it has one branch or 10.
Take another 2 identical trees. Plant them in the ground. Treat them as you did the first 2. The untouched one will be thicker than the other three because of unrestricted root growth whether it has one branch or 10. Let them grow and they will thicken.

[Pup]

To add to what I just wrote: a few leaves (or even thousands of leaves) sitting on a branch will never thicken that branch. Why? Because the lateral meristems are not active.

Take 2 identical potted trees. Leave one to grow without any kind of tissue removal. Prune or defoliate or wire or do whatever you want with the other one. At the end of 2 years the first one will be thicker whether it has one branch or 10.
Take another 2 identical trees. Plant them in the ground. Treat them as you did the first 2. The untouched one will be thicker than the other three because of unrestricted root growth whether it has one branch or 10. Let them grow and they will thicken.

Logical Pup

[sheepdawg]

I'd like to ensure when I say defoliate, I am meaning the removal of the actual leaves only; not the growing buds. And this process would only be carried out after sufficient time has elapsed between each practice.

My resolution in my hypothesis has also increased after reading that photosynthetic efficiency decreases with increasing leaf age in many species.

Sources:
Kitajima et al., 2002, 'Decline of photosynthetic capacity with leaf age and position in two tropical pioneer tree species'
Constable et al., 1980, 'Effect of Leaf Position, Expansion and Age on Photosynthesis, Transpiration and Water Use Efficiency of Cotton'
Field et al., 1983, 'Leaf Age and Seasonal Effects on Light, Water, and Nitrogen Use Efficiency in a Californian Shrub'
Escudero et al., 2003, 'Decline in photosynthetic nitrogen use efficiency with leaf age and nitrogen resorption as determinants of leaf life span'

[sheepdawg]

And I should also add that I've come to this thinking by noticing that my figs go through "flushes" of growth, i.e. they'll put out new leaves then rest for awhile, then put out new leaves, then rest, then new leaves etc etc.

So, my thinking was "how can I force these flushes to be more frequent?"

And so my initial reading was directed at growth patterns which is (very) basically moderated through auxin-cytokinin interaction. Higher auxin means root growth; higher cytokinin means more leaf growth. So, how to increase the relative cytokinin level? Remove the sites that utilize it, i.e. the leaves. So, relatively more cytokinin results in more leaf growth. BUT! As many have pointed out the leaves are the source of energy for the plant. But this isn't true. The plant stores HEAPS of energy that it never really uses (until some trauma). Basically, I'm trying to force the plant to use it's stored energy, which would be hugely more efficient than using solar energy.

[Kevin]

Hello Sheepdawg,

(until some trauma)

Spot on, What is the Trauma Factor?
Cut one leaf, the plant is traumatised, 35+ degrees the plant is traumatised, heavy winds.....

Good on you for the plant physiological theory lessons, you have refreshed my memory, for which i thank-you.
However, i second Rory.

Kevin

[Tambrand]

@Sheepdawg,

I found that a few tropicals don't need to be ground grown to get trunk size and the first six branches.

secondly, my first attempt with this Ficus p. ended up with a very thick trunk and massive scars. Needing special techniques to
repair the damage.

This way I can get the trunk and minimal damage. Scars are small and heal rapidly.
Doing the same work on the J,B.pine, will let you guys know in a few years how it
worked out.
Thanks for asking.
Laters.
Tambrand

[shibui]

I have noted similar growth in ficus here. Even in small pots and without allowing sacrifice branches my ficus rubiginosas increase in thickness much more rapidly than most other species. Every couple of years I need to change the pot for a larger one.
Allowing extra root space and top growth increases growth even more.
Another genus that thickens in pots is Banksia. I grew some B. integrifolia in the ground and one in a 30 cm orchid pot for 3 years. All were similar trunk diameter at the end of that time.

[sheepdawg]

A study was done on defoliation of Liquidambar and their characteristics. It found there was only significant impacts on biomass accumulation at high intensity and frequency of defoliation. But the most interesting finding is that 33% defoliation resulted in an increased stem diameter (shown in Figure 1). To me this is almost a proof-of-concept but I feel that deciduous trees would be slightly different to evergreen.
Study DOI: 10.1673/031.014.107