Register ICMag Forum Menu Features Search Today's Posts Mark Forums Read
You are viewing our:
in:
Forums > Marijuana Growing > Cannabis Botany and Advanced Growing Science > University of Guelph paper- Flushing is a myth!

Thread Title Search
Post Reply
University of Guelph paper- Flushing is a myth! Thread Tools Search this Thread
Old 07-11-2019, 11:31 PM #1
CannaRed
Cannabinerd

CannaRed's Avatar

Join Date: Apr 2017
Location: North of the Border
Posts: 1,471
CannaRed has a brilliant futureCannaRed has a brilliant futureCannaRed has a brilliant futureCannaRed has a brilliant futureCannaRed has a brilliant futureCannaRed has a brilliant futureCannaRed has a brilliant futureCannaRed has a brilliant futureCannaRed has a brilliant futureCannaRed has a brilliant futureCannaRed has a brilliant future
University of Guelph paper- Flushing is a myth!

Here's a link to a PDF. I can't copy and paste from pdf.

Basically they used 4 or 5 different flushing techniques.

No major difference of nutrient levels between the bud samples.

One pro from flushing is saving money on nutrients for last two weeks.

https://atrium.lib.uoguelph.ca/xmlui...=8&isAllowed=y

What does everyone think?
CannaRed is offline Quote


7 members found this post helpful.
Old 07-12-2019, 12:16 AM #2
Elmer Bud
Genotype Sex Worker AKA strain whore

Elmer Bud's Avatar

Join Date: Jun 2012
Location: Sth Pacific
Posts: 3,509
Elmer Bud has a reputation beyond reputeElmer Bud has a reputation beyond reputeElmer Bud has a reputation beyond reputeElmer Bud has a reputation beyond reputeElmer Bud has a reputation beyond reputeElmer Bud has a reputation beyond reputeElmer Bud has a reputation beyond reputeElmer Bud has a reputation beyond reputeElmer Bud has a reputation beyond reputeElmer Bud has a reputation beyond reputeElmer Bud has a reputation beyond repute
Irrigation Management Strategies for Medical Cannabis in Controlled Environments
By
Jonathan Stemeroff
A Thesis
presented to
The University of Guelph
In partial fulfilment of requirements
for the degree of
Master of Science
in
Environmental Science
Guelph, Ontario, Canada
© Jonathan Stemeroff, November, 2017
Irrigation Management Strategies for Medical Cannabis in Controlled Environments
J. Stemeroff, MSc
Erratum Document for Previously Approved E-Thesis Submission
A post-approval (re)-examination of the raw data discovered unrecoverable errors in the
handling and reporting of the water potential data, with further issues regarding the nature of
the treatment differences. The general errors are:
1) Upon further review of the raw data logs it was discovered that the Control and Mild
Stress treatments were in fact the same (ref. page 38). Both treatments had the same
number of irrigation events (i.e. total water applied was the same) in all three trials.
The irrigation events were offset by 1-day but they both occurred at 2-day intervals.
a. Resolution – Any observed differences between the control and mild stress
treatment should be disregarded. Detected differences in agronomic and
metabolite production between the Control and Mild Stress treatments can only
be attributed to random chance and variation in the growth facility, not a
response to distinct irrigation regimes. Affected Figures – Disregard Control and
Mild Stress treatment effects in Figures 4.11 (page 54) and 4.13 (page 55)
2) Raw data was not properly filtered to remove erroneous readings (e.g., positive values
of plant water potential; non-sinusoidal or flat line response) resulting from instrument
fouling and condensation within the sensing chamber. The inclusion of erroneous data
resulted in skewed relationships between cumulative plant water potential and
cumulative vapour pressure deficit.
a. Resolution – Disregard the relationships depicted in Figures 4.1 (page 44), 4.2
(page 45), 4.3 (page 46), 4.4 (page 47), 4.5 (page 48), 4.6 (page 49), 4.7 (page
50), 4.8 (page 51), and 4.9 (page 52).
3) The apparent two-phase relationship between CWP and CVP shown in Figure 4.1 (page
44) and subsequently highlighted and independently analysed in Figures 4.2 (page 45)
and 4.3 (page 46), is the result of missing data (logger failure) during the middle phase
of the first growth cycle; the missing data was not properly accommodated resulting in
an apparent separation of the response relationship between early and late growth
periods. The subsequent analysis of flower cycles 2 and 3 included an analysis of this
artifact-based separation; as such, Figures 4.5 (page 48), 4.6 (page 49), 4.8 (page 51),
and 4.9 (page 52) are not meaningful as there is no data to suggest or support treating
the data as two distinct groups.
Based on the above errors, any conclusions outlined in section 6.1 (page 62-65) should also be
disregarded.
3
ABSTRACT
Irrigation Management Strategies for Medical Cannabis in Controlled Environments
Jonathan Stemeroff Advisor:
University of Guelph, 2017 Professor M.A. Dixon
Medical cannabis production is a new industry in Canada and represents a challenge
for the production of a repeatable and standardized product for medical use. A reliable and
reproducible environmental control strategy can contribute significantly to meeting this
challenge. Irrigation management and control of plant water status is one of the key
environmental control elements. To assess the effects of various irrigation management
strategies this study deployed in situ stem psychrometers to measure the water status of
plants. As a routine feedback device for irrigation control these devices are not ideal for
large-scale production so correlation with the key environment variable representing the
aerial demand for moisture (vapour pressure deficit) was assessed. By establishing a
relationship between cumulative water potential (cWP) and cumulative vapour pressure
deficit (cVPD) an irrigation management strategy that predicted plant water status based on
measurements of cVPD could be employed. Three treatments; control (irrigation events every
1-2 days), mild-stress (irrigation events every 2 days), and moderate-stress (irrigation events
every 3 days) were tested. The effects of flushing were also investigated to determine
whether it had the intended effect of reducing nutrient concentrations within the dried bud.
Through the use of psychrometers, water status (cWP) thresholds were correlated with
humidity (cVPD) thresholds and reduced irrigation frequency resulting in water use
reductions up to 45.7% which had negligible impacts on yield and cannabinoid profile.
Flushing was found to be ineffective in removing any significant amount of nutrient from the
bud.
__________________
Such is life ...
Elmer Bud is offline Quote


3 members found this post helpful.
Old 07-12-2019, 12:18 AM #3
Elmer Bud
Genotype Sex Worker AKA strain whore

Elmer Bud's Avatar

Join Date: Jun 2012
Location: Sth Pacific
Posts: 3,509
Elmer Bud has a reputation beyond reputeElmer Bud has a reputation beyond reputeElmer Bud has a reputation beyond reputeElmer Bud has a reputation beyond reputeElmer Bud has a reputation beyond reputeElmer Bud has a reputation beyond reputeElmer Bud has a reputation beyond reputeElmer Bud has a reputation beyond reputeElmer Bud has a reputation beyond reputeElmer Bud has a reputation beyond reputeElmer Bud has a reputation beyond repute
G `day CR

Yep flushing is a myth !
How did people flush , before hydro ? Kinda hard to remove all the nutes from soil ?

Unflushed harsh weed ? BS !

Thanks for sharin

EB .
__________________
Such is life ...
Elmer Bud is offline Quote


6 members found this post helpful.
Old 07-12-2019, 12:21 AM #4
CannaRed
Cannabinerd

CannaRed's Avatar

Join Date: Apr 2017
Location: North of the Border
Posts: 1,471
CannaRed has a brilliant futureCannaRed has a brilliant futureCannaRed has a brilliant futureCannaRed has a brilliant futureCannaRed has a brilliant futureCannaRed has a brilliant futureCannaRed has a brilliant futureCannaRed has a brilliant futureCannaRed has a brilliant futureCannaRed has a brilliant futureCannaRed has a brilliant future
Thanks Elmer! . I was in process of typing it out on my phone.

And wasn't being fast.

Much appreciated
CannaRed is offline Quote


1 members found this post helpful.
Old 07-12-2019, 12:29 AM #5
CannaRed
Cannabinerd

CannaRed's Avatar

Join Date: Apr 2017
Location: North of the Border
Posts: 1,471
CannaRed has a brilliant futureCannaRed has a brilliant futureCannaRed has a brilliant futureCannaRed has a brilliant futureCannaRed has a brilliant futureCannaRed has a brilliant futureCannaRed has a brilliant futureCannaRed has a brilliant futureCannaRed has a brilliant futureCannaRed has a brilliant futureCannaRed has a brilliant future
Quote:
Originally Posted by Elmer Bud View Post
G `day CR

Yep flushing is a myth !
How did people flush , before hydro ? Kinda hard to remove all the nutes from soil ?

Unflushed harsh weed ? BS !

Thanks for sharin

EB .
I find it interesting that even fertigating till end showed no difference in nutrients.

I wonder if those plants were in senescence and not taking up nutes. But did they fade?
Plant is supposed to uptake what it wants.

Like everything else, learning something new just leads to more questions.
CannaRed is offline Quote


3 members found this post helpful.
Old 07-12-2019, 12:29 AM #6
BongFu
Member

Join Date: Jul 2018
Location: Left of Centre
Posts: 164
BongFu has a spectacular aura aboutBongFu has a spectacular aura aboutBongFu has a spectacular aura about
Yep read this one about a year back on Glows site. No surprises there.... The idea that you could starve a plant and force it to access stored nutrients was always totally out there.
BongFu is offline Quote


1 members found this post helpful.
Old 07-12-2019, 01:45 AM #7
SandyFantasyman
Member

SandyFantasyman's Avatar

Join Date: Jan 2017
Location: Painted Hawaii, on the edge of the volcano (but when forced into reality: Canada)
Posts: 332
SandyFantasyman is a glorious beacon of lightSandyFantasyman is a glorious beacon of lightSandyFantasyman is a glorious beacon of lightSandyFantasyman is a glorious beacon of lightSandyFantasyman is a glorious beacon of lightSandyFantasyman is a glorious beacon of lightSandyFantasyman is a glorious beacon of lightSandyFantasyman is a glorious beacon of lightSandyFantasyman is a glorious beacon of lightSandyFantasyman is a glorious beacon of lightSandyFantasyman is a glorious beacon of light
Yet there will still be people who will go to their graves swearing up and down that they can tell the difference between flushed and unflushed weed.
SandyFantasyman is offline Quote


8 members found this post helpful.
Old 07-12-2019, 02:01 AM #8
Elmer Bud
Genotype Sex Worker AKA strain whore

Elmer Bud's Avatar

Join Date: Jun 2012
Location: Sth Pacific
Posts: 3,509
Elmer Bud has a reputation beyond reputeElmer Bud has a reputation beyond reputeElmer Bud has a reputation beyond reputeElmer Bud has a reputation beyond reputeElmer Bud has a reputation beyond reputeElmer Bud has a reputation beyond reputeElmer Bud has a reputation beyond reputeElmer Bud has a reputation beyond reputeElmer Bud has a reputation beyond reputeElmer Bud has a reputation beyond reputeElmer Bud has a reputation beyond repute
Quote:
Originally Posted by CannaRed View Post
I find it interesting that even fertigating till end showed no difference in nutrients.

I wonder if those plants were in senescence and not taking up nutes. But did they fade?
Plant is supposed to uptake what it wants.

Like everything else, learning something new just leads to more questions.
G `day CR

Mid to late flower the electrical charge of the roots decreases .
Equals less up take of nutes .

I hear you on the using up stored nutes angle .
But the idea that the minerals would be rinsed on back out always baffled me .

Flushed / unflushed , indoor / out door , organic / hydro .
Proof of the pudding is in the eating .

Thanks for sharin

EB .
__________________
Such is life ...
Elmer Bud is offline Quote


1 members found this post helpful.
Old 07-12-2019, 02:08 AM #9
CannaRed
Cannabinerd

CannaRed's Avatar

Join Date: Apr 2017
Location: North of the Border
Posts: 1,471
CannaRed has a brilliant futureCannaRed has a brilliant futureCannaRed has a brilliant futureCannaRed has a brilliant futureCannaRed has a brilliant futureCannaRed has a brilliant futureCannaRed has a brilliant futureCannaRed has a brilliant futureCannaRed has a brilliant futureCannaRed has a brilliant futureCannaRed has a brilliant future
I never really thought it was flushing the plant itself. I thought it was to flush the media.
__________________
"I have only read fragments of your posts. But I have read enough to know that you can grow some mean herb." Cvh
CannaRed is offline Quote


1 members found this post helpful.
Old 07-12-2019, 02:14 AM #10
aridbud
automeister


aridbud's Avatar

Join Date: May 2013
Location: the best place on earth
Posts: 6,788
aridbud is a survivoraridbud is a survivoraridbud is a survivoraridbud is a survivoraridbud is a survivoraridbud is a survivoraridbud is a survivoraridbud is a survivoraridbud is a survivoraridbud is a survivoraridbud is a survivor
I don't care for the metallic, nutrient taste on inhale/exhale.....I'll continue to flush.
__________________
Seeds have the power to preserve species, to enhance cultural as well as genetic diversity, to counter economic monopoly and to check the advance of conformity on all its many fronts.
Michael Pollan
Happiness held is the seed; Happiness shared is the flower.
John Harrigan
Instant gratification takes too long.
Carrie Fisher - RIP.
afterthought autos
We are passionate breeders growing organically in the USA and offer 27 autoflowering strains, 9 photoperiods in our decades of breeding expertise. afterthought autos - we are unique quality cannabis autoflower breeders for medical conditions and recreational stimulus. Auto breeding 13 years, and running strong!

https://www.icmag.com/ic/forumdisplay.php?f=65770
aridbud is offline Quote


13 members found this post helpful.

Post Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


All times are GMT +2. The time now is 11:17 AM.




This site is for educational and entertainment purposes only.
You must be of legal age to view ICmag and participate here.
All postings are the responsibility of their authors.
Powered by: vBulletin Copyright ©2000 - 2019, Jelsoft Enterprises Ltd.