Nicotine content

[Anders A]

How does the nicotine content in the leaves differ if you remove the flowers, top the plant and remove all the side shoots, compared to not doing so? Is there any available statistics/research on this? (there may be information about this in other threads, but I'm not good at searching here in the forum)

 

[johnny108]

For Virginia:
Improving the production and quality of Virginia tobacco through topping and suckering: a review

Radware Bot Manager Captcha

(Can’t change the link from the captcha, but copying/pasting the title into a web search will find the pdf, if the link doesn’t work)

For Burley:
Topping and suckering (ID-160) University or Kentucky

https://burleytobaccoextension.ca.uky.edu/files/topping_and_sucker_control_id160_2019.pdf

 

[deluxestogie]

In general, topping increases leaf size, increases leaf nicotine concentration, increases root growth and increases root production of alkaloids (e.g. nicotine).

"Topping cause's development and root growth, drought tolerance, reduce deployment pests, increased synthesis of nicotine"

https://www.ijabbr.com/article_12981_1cde0c9adb1ee6ad8f93e924a353a290.pdf

"Flowering and sucker production are both significant sinks of energy and other resources. Eliminating the inflorescence via topping and controlling suckers lead to higher nicotine concentrations. In fact, substantial nicotine synthesis and accumulation occurs in the days and weeks following topping."

https://acsess.onlinelibrary.wiley.com/doi/10.2134/agronj2019.04.0268

"The process of topping elicits many responses in the tobacco plant, including an increase in nicotine biosynthesis, and the secondary growth of roots."

https://www.researchgate.net/figure/The-effect-of-topping-on-tobacco-root-development-The-roots-of-tobacco-plants-were-taken_fig4_301708794

Bob

 

[Anders A]

Thanks, I'll read through what you shared.

I found this online, is it something I can rely on?

https://www.researchgate.net/figure/Changes-in-nicotine-concentrations-in-different-organs-of-tobacco-plant-at-different_fig6_6918371

 

[plantdude]

Interesting how it spikes after 6 days and takes 15 days to catch back up. It looks like the study only carried measurements out fifteen days - I'd say it's inconclusive at best for what most people do. Most people are harvesting 4-6 weeks after topping. Those graphs don't provide any information on that - does it go higher after fifteen days? Probably, but who knows. I sure hope my tax dollars weren't funding the idiot that did that study...

 

[Anders A]

Interesting how it spikes after 6 days and takes 15 days to catch back up. It looks like the study only carried measurements out fifteen days - I'd say it's inconclusive at best for what most people do. Most people are harvesting 4-6 weeks after topping. Those graphs don't provide any information on that - does it go higher after fifteen days? Probably, but who knows. I sure hope my tax dollars weren't funding the idiot that did that study...

My experience is that the plant is ready for harvest about 10-20 days after topping, and that's when I usually harvest. And I usually top when the plant starts to flower.

 

[deluxestogie]

I sure hope my tax dollars weren't funding

That study was conducted in China, and funded by the National Natural Science Foundation of China (30370842) and the Ministry of Agriculture 948 program (No: 2003-Z53). The US government has eliminated most funding for research on anything having to do with "tobacco".

Nicotine synthesis in Nicotiana tabacum L. induced by mechanical wounding is regulated by auxin
Qiumei Shi, Chunjian Li* and Fusuo Zhang

"Materials and methods​

Seeds of tobacco (Nicotiana tabacum L. K 326) were germinated in​

a mixture of 60% (w/w) peat culture substrate, 20% (w/w) ground​

maize stalk, and 20% (w/w) perlite, and grown in a seedbed in​

a naturally lit glasshouse for 60 d. Before transfer of the tobacco​

seedlings into quartz sand or nutrient solution, the seedlings were​

washed with tap water until all substrate was removed from the roots."​

One of the difficulties in conducting biochemical studies of plants is the need to simplify the growing conditions enough to limit the otherwise overwhelming number of other variables. With tobacco (in this study, K 326), a single study gives you a tiny answer about the tested variety grown under the simplified conditions. The underlying question of this study was aimed at clearly identifying the triggering chemical—auxin.

...is it something I can rely on?

As with all primary research in any science, a single study is only a single datum. Multiple studies that seem to indicate similar results may usually be considered more reliable. Regardless, subsequent studies may alter our conclusions. In reading any research, I always read the methodology, to understand the limitations of the stated conclusions. There is a lot of bogus stuff out there.

Bob

 

[plantdude]

My experience is that the plant is ready for harvest about 10-20 days after topping, and that's when I usually harvest. And I usually top when the plant starts to flower.

I may have inadvertently hit a nerve with my insomnia fueled grouchiness about less than perfect graphs and "scientific research". That wasn't my intent. If a 10-20 day harvest time after topping works for you, go with it. With our longer growing season most people in warmer climates are looking about 4 weeks + after topping for harvest. The graphs showed only 15 days out which was excessively short for my time frame given what I usually do for harvesting after flowering and a little frustrating because I am also curious about what a longer time frame would have revealed. The error bars on the graph were not listed as standard deviation or standard error (it can make a big difference) and no post hoc tukey HSD or t test was used to show significance, which to me makes me question what was presented - not trying to sound like a nerd, there is just a lot of stuff presented in graphs that are often not statistically sound and can be misleading sometimes.

So to answer your question about are the graphs something you can rely on... Yes, maybe, no. I didn't read the paper (which would probably have cured my insomnia), but just going strictly by the graphs I probably would be hesitant to take it as gospel. You're in a cooler climate than I am so your up against a harder time frame than me. If you're harvesting 10-20 days after topping maybe you're hypothetically losing a little more nicotine content than going out 4+ weeks after topping, but is that going to be much of a game changer in the grand scheme of things? Probably not, you have some good looking plants and are getting a great harvest - better than mine will be anyway after our screwy year here. With snus it's easy enough to manipulate "perceived" nicotine strength with alkalizer or throwing in a little Rustica or making a tobacco tea concentrate.
Personally I don't worry too much about nicotine content and even let a few of my plants flower each year to attract hummingbirds. I try to remind myself sometimes it's best not to overthink things and enjoy the small pleasures that nature provides.

 

[WillQuantrill]

I may have inadvertently hit a nerve with my insomnia fueled grouchiness about less than perfect graphs and "scientific research". That wasn't my intent. If a 10-20 day harvest time after topping works for you, go with it. With our longer growing season most people in warmer climates are looking about 4 weeks + after topping for harvest. The graphs showed only 15 days out which was excessively short for my time frame given what I usually do for harvesting after flowering and a little frustrating because I am also curious about what a longer time frame would have revealed. The error bars on the graph were not listed as standard deviation or standard error (it can make a big difference) and no post hoc tukey HSD or t test was used to show significance, which to me makes me question what was presented - not trying to sound like a nerd, there is just a lot of stuff presented in graphs that are often not statistically sound and can be misleading sometimes.

So to answer your question about are the graphs something you can rely on... Yes, maybe, no. I didn't read the paper (which would probably have cured my insomnia), but just going strictly by the graphs I probably would be hesitant to take it as gospel. You're in a cooler climate than I am so your up against a harder time frame than me. If you're harvesting 10-20 days after topping maybe you're hypothetically losing a little more nicotine content than going out 4+ weeks after topping, but is that going to be much of a game changer in the grand scheme of things? Probably not, you have some good looking plants and are getting a great harvest - better than mine will be anyway after our screwy year here. With snus it's easy enough to manipulate "perceived" nicotine strength with alkalizer or throwing in a little Rustica or making a tobacco tea concentrate.
Personally I don't worry too much about nicotine content and even let a few of my plants flower each year to attract hummingbirds. I try to remind myself sometimes it's best not to overthink things and enjoy the small pleasures that nature provides.

NERD! Haha. I prime ligero at 5 weeks if not longer after topping here in MO. Thats if my self-restraint holds out that long because at this point my Imidacloprid has worn off and the bugs are lurking in the shadows. Kind of a game of chicken.