a while back, I had a discussion with another forummer concerning cuttings and the amount of leaves on each. I stressed that it was important to have leaves on cuttings as photosynthesis continues to be an important process during the process of rooting, supplying the necessary food to sustain the cutting. But somehow it wasnt very easy getting the idea across.
I did this layman experiment a while back, but thought I'd do it again since I was doing some slashing at that time.
Guess there's no need for details of the procedure, but quite simply:
3 variables - No leaves (bare stem cutting), leaves cut in half, full length of leaves left on stem.
-different sp/hybrids used, 1 of each to each variable
-different portions of stem used (since tip cuttings usually root faster), but equal amounts of each type of stem section for all 3 variables
-same stem length and number of leaves borne on each
-same rooting technique, conditions, time, etc. applied to all
humid corner of the garden
medium: perlite with other random additions
quite shaded, so they got very little light - not because thats what cuttings need..but more like there wasnt enough space so they got shoved into a corner instead. (must admit they were quite poorly taken care of)
Here are the results
cuttings expt by lamwn, on Flickr
cuttings expt - leaf full by lamwn, on Flickr
cuttings expt - leaf half by lamwn, on Flickr
nothing much to see here
cuttings expt - leaf none by lamwn, on Flickr
Some 'discussion' points:
1. the experiment doesnt show that leafless cuttings dont work - its just my lousy growing conditions that resulted in all of them dying.
2. the same experiment done in drier conditions and with higher light intensities may have resulted in higher mortality rates in the 'full leaf' cuttings, since they would have lost more water through transpiration.
Aside from the obvious correlation between surface area of leaves and extent of root growth, think the only other thing that can be inferred is that photosynthesis in foliage of a cutting supplies the bulk of energy required for its rooting process, so stored energy in the Nep cutting plays a less significant role, unlike in the case of woody cuttings of other ornamentals where no leaves are required on the cutting.
Hope this is useful,
PS: cuttings are mirabilis 'red', mirabilis 'pink', mirabilis x Coccinea, sibuyanensis x maxima, thorelii x truncata, viking. Need to give them away now that experiment is done..please PM me if you would like them:)
This post has been edited by Lam_wn: 02 February 2011 - 05:11 PM