Science + Defoliation??????? (results from a -single- study)

[nanners1]

So I usually post questions, this time id like to add something that i found via this podcast

https://www.kisorganics.com/pages/cannabis-cultivation-and-science-podcast-episode-43 (actually i found it through another article by some guy ëric¨, anyway)

In the podcast, Dr Allison Justice (Clemson University with a Ph.D. in Plant and Environmental Science and California Industrial Hemp Advisory Board in may 2020 . for whoever that is worth anything) explains how she went about researching defoliation in cannabis by measuring photosynthesis capability of leaves. I will not post the conclusions, hear it out for yourselves it is only 6 min)

If you forward to min 38.33
podcast (00:38:33 through 00:44:05)

 

[nanners1]

I realize, this has been commented before too.. well.. refresher for any others looking for this subject.

 

[MidnightSun72]

Sweet post my dude.

 

[Observe & Report]

Searched Google Scholar and found only a single paper by Allison Justice and it was about fungus and from 2014. Where was this defoliation science published? Maybe you could provide a link to it.

 

[nanners1]

Searched Google Scholar and found only a single paper by Allison Justice and it was about fungus and from 2014. Where was this defoliation science published? Maybe you could provide a link to it.

Oh ok, let me clarify, the study was commissioned by her, in the podcast she explains the scientist has yet to publish apparently. They basically find that defoliation for humidity control is useful specially if you defoliate leaves that are receiving less than 200 micromoles. and that also, it may increase the size of flower with a little less yield but they need to research that specifically.

The whole podcast is interesting it goes into the PK feeding craze for flower that many growers do ---- she says it might actually work for some because it is actually an overload and stressing certain plants that might respond well to that stress, but not because they are consuming that extra PK (just responding well and recovering from a lock or nute overload). but in general that yeah, its a dumb idea to up the levels of PK in flowering. etc.

 

[70's natureboy]

I did my own study last year. I defoliated 2 plants and they were my worst performers. I'm glad I didn't do more.

She say she defoliates for humidity control. That doesn't sound like a very scientific reason. Buy more dehumidifiers.

 

[nanners1]

I did my own study last year. I defoliated 2 plants and they were my worst performers. I'm glad I didn't do more.

She say she defoliates for humidity control. That doesn't sound like a very scientific reason. Buy more dehumidifiers.

I mean on medium/large scale if yield isnt affected that much (when done as outlined) it can surely be much cheaper to cut than run dehumidifiers (those things can suck power like crazy)

i mean im still not that convinced to defoliate, for starters idont have a photo sensor, so impossible to know which are getting lower than 200 µmol

 

[Apostatize]

Comments from growers who doubt defoliation's effectiveness find benefit from pruning, so clear distinction there I guess ... others believe defoliation's only beneficial in specific weeks during bloom. So, when anyone advocates defoliating, it seems necessary to clearly describe the scope of selective-defoliation and its perceived benefit (what, where, when, why, how).

If you've already pruned/made efforts to minimize popcorn and under-performing bud sites, what measurable benefit is left to accomplish by defoliating? The clearest benefit may be after bud development, during ripening. Some strains remain flexible to the end, so buds on turned over branches can be ripened an extra week+ on the other side. At that point, buds aren't going to get bigger, you're just finishing them. Seems like defoliation complements ripening, but that could just be perception v. reality.

As for research, is there research concluding that defoliation has no benefit? Without some scalable commercial benefit, it doesn't seem like there'd be a tremendous amount of interest in that research. And for medical purposes, researching issues of safety and efficacy, it doesn't seem obvious that defoliation would come up.

And is whether defoliation increases photosynthesis the right question or pursuit? Is it more important to address photosynthesis' arch nemesis, photorespiration (e.g., keep heat down, environmental controls)?

The Ecology of Photosynthetic Pathways

Plants have evolved three photosynthetic pathways, each in response to distinct environmental conditions, resulting in differences in their ecological patterns of growth and distribution.

www.nature.com

 

[warirdem]

I have a terrible experience with defoliation too. After that, I believe only in trusted information or the experience of my friends. I also studied at the bio-related faculty, so I know many helpful resources on this theme. Maybe we don't know all details about Allison's research. But at first glance, she is talking about harmful things for the plants.