Leaf Petiole Bending on Air Layers

[DrTolhur]

I've got two different air layers that have this weird bending occurring on the leaf petioles: one bend right where it attaches to the branch and then another one near the leaf. It's only happening on the leaves above the air layer. The trees seem otherwise healthy. One is a Japanese maple and one is a trident. Anyone ever seen this or have any idea what the cause is?

 

[Wires_Guy_wires]

Have you applied any auxins or rooting hormones?
I've noticed some plants that are highly responsive to auxins, tend to stretch those cells the most for some reason.

 

[sorce]

I reckon it's an effort to lessen sun exposure.

Sorce

 

[DrTolhur]

Wires_Guy, yes, I applied rooting hormone powder to both when I did the layers.
Sorce, not that I think you're wrong, but it seems somewhat surprising that would be since it's my understanding that the tree above the layer basically doesn't know the layer happened since it has the same nourishment from the base. Do you suppose the blocking of flow through the severed xylem could cause the leaves to become more sun-sensitive?

 

[palafr01]

I think you guys might be over thinking it. The petiole (leaf stem) bending is probably due to the reduction of water flow to these areas. I don't know which layering method the original poster used, but it looks like the water transport cells (xylem) has been constricted (if just slightly) enough to stimulate the maples to enter a water conservative state in an effort to reduce transpiration (i.e. water loss). I wouldn't worry to much, but I would be careful if temperatures get excessively hot. If I had to guess the condition will go away once the trees adapt to the constriction (either by rooting above the layer spot or by restoring proper sap flow).

 

[Wires_Guy_wires]

If the petioles are still turgid, in the sense that they aren't drooping and feel rigid. It's probably an auxin overdose.
Which isn't a bad thing. In a couple of days, maybe a week or so, they might relax.

Reduction of water loss and a plant pointing the bottom part of a leaf, with the highest amount of stomata, towards the sun doesn't make perfect sense to me.