Questions about the tobacco plant pertaining to alkaloids and growth patterns.

[waikikigun]

Some questions aimed at helping me understand the broader picture of what happens with/to the chemicals inside a tobacco plant as they develop, move around, join up or part ways along the stem, as this pertains to the concerns of the tobacco grower/processor/manufacturer/user.

@deluxestogie

• Why are the leaves at the bottom the biggest and those at the top smallest?
• Why are the small ones at the top the darkest/thickest with the highest nicotine-and-other-alkaloid content?
• Why do middle leaves, “viso” and so forth, seem to have more flavor than higher, stronger leaves? Do some sort of flavor/aroma chemicals/alkaloids get converted to “strength” elements as they’re shuttled up the stem, or …? In general it seems like the lowest, most combustible leaves have the least flavor, the middle ones have the most, and then the top ones have the least. Why is that?
• And so why are the lowest ones generally the most combustible and the top ones the least combustible? I say “in general” because I find there are frequent exceptions to this rule.

Thank you!

 

[deluxestogie]

Tough questions.

My impression is that top (corona) leaf is more intensely flavored that any lower leaf, but that its strength overwhelms the flavor. I frequently use a snippet of very dark, thick tip leaf as the sole "flavor" ingredient in a much blander filler blend. So I'll disagree with that contention.

The leaves on the bottom are the first leaves--and only leaves on the plant for the three weeks or so of their life after transplant. The roots (alkaloid factories) are still immature in their chemical production. These bottom leaves grow as large and as rapidly as their nutrition will allow. They have no shading from higher leaf yet, but they are just giant babies. During the final 5 or so weeks prior to plant maturation, all the other leaf grows, sharing nutrients and sunlight. But during that same window of time, the bottom leaves (the big babies) are already metabolically entering senescence--like tree leaves do in the autumn.

So those bottom leaves have their heyday atop immature roots, and begin to die fairly early in the season.

The biologic "purpose" of each tobacco plant is merely to produce offspring. Nothing else matters. So as the growing season progresses, nutrients as well as anti-herbivore compounds (the alkaloids we love) are differentially distributed to progressively higher portions of the stalk, and their leaves. This is all to increase the survival of the bud head. Leaf growth ceases throughout the plant more simultaneously than the sprouting and growth of new leaves at higher stalk levels. So upper leaves tend to get a shorter growing season, but with the most intense nutrition and alkaloids.

Topping the bud head causes nutrients and compounds coming up from the roots, and destined for offspring production, to be more available to non-senescing leaf. So leaf on topped plants are larger, thicker and stronger than those on untopped plants--but not so with the lowest leaves, since they are already dying or dead by this point.

My Corojo 99 plants seem to produce top leaf nearly as large as bottom leaf, though it's far more potent up top. So plant signalling and leaf growth are different from one variety to the next.

Combustibility is inversely proportional to the concentration of proteins and complex carbohydrates within the lamina. These compounds are dramatically reduced with fermentation and with time. But lower leaf starts out with a lot less, and begins to die early.

One other factor in combustion is the hygroscopic nature of tobacco. Some leaf, especially upper leaf, is able to draw and retain more moisture from the air than thinner, lower leaf. This hygroscopic prowess of upper leaf is also evident while smoking, since burning leaf produces water vapor in the smoke. So a cigar of predominantly upper leaf may ignite just fine, and burn well for the first third of the cigar, but then begin to get increasingly soggy in the head.

Whew! I'm simplifying quite a bit, and guessing to some extent, but this is my impression of these curious attributes of tobacco leaf.

Bob

 

[waikikigun]

Tough questions.

My impression is that top (corona) leaf is more intensely flavored that any lower leaf, but that its strength overwhelms the flavor. I frequently use a snippet of very dark, thick tip leaf as the sole "flavor" ingredient in a much blander filler blend. So I'll disagree with that contention.

The leaves on the bottom are the first leaves--and only leaves on the plant for the three weeks or so of their life after transplant. The roots (alkaloid factories) are still immature in their chemical production. These bottom leaves grow as large and as rapidly as their nutrition will allow. They have no shading from higher leaf yet, but they are just giant babies. During the final 5 or so weeks prior to plant maturation, all the other leaf grows, sharing nutrients and sunlight. But during that same window of time, the bottom leaves (the big babies) are already metabolically entering senescence--like tree leaves do in the autumn.

So those bottom leaves have their heyday atop immature roots, and begin to die fairly early in the season.

The biologic "purpose" of each tobacco plant is merely to produce offspring. Nothing else matters. So as the growing season progresses, nutrients as well as anti-herbivore compounds (the alkaloids we love) are differentially distributed to progressively higher portions of the stalk, and their leaves. This is all to increase the survival of the bud head. Leaf growth ceases throughout the plant more simultaneously than the sprouting and growth of new leaves at higher stalk levels. So upper leaves tend to get a shorter growing season, but with the most intense nutrition and alkaloids.

Topping the bud head causes nutrients and compounds coming up from the roots, and destined for offspring production, to be more available to non-senescing leaf. So leaf on topped plants are larger, thicker and stronger than those on untopped plants--but not so with the lowest leaves, since they are already dying or dead by this point.

My Corojo 99 plants seem to produce top leaf nearly as large as bottom leaf, though it's far more potent up top. So plant signalling and leaf growth are different from one variety to the next.

Combustibility is inversely proportional to the concentration of proteins and complex carbohydrates within the lamina. These compounds are dramatically reduced with fermentation and with time. But lower leaf starts out with a lot less, and begins to die early.

One other factor in combustion is the hygroscopic nature of tobacco. Some leaf, especially upper leaf, is able to draw and retain more moisture from the air than thinner, lower leaf. This hygroscopic prowess of upper leaf is also evident while smoking, since burning leaf produces water vapor in the smoke. So a cigar of predominantly upper leaf may ignite just fine, and burn well for the first third of the cigar, but then begin to get increasingly soggy in the head.

Whew! I'm simplifying quite a bit, and guessing to some extent, but this is my impression of these curious attributes of tobacco leaf.

Bob

Thank you very much for your super clear and helpful answers. I really appreciate you taking the time to share your knowledge.

I don't want to press my luck, but I had a few small questions while I read it, which I've put in bold here:

"
“My impression is that top (corona) leaf is more intensely flavored that any lower leaf, but that its strength overwhelms the flavor. I frequently use a snippet of very dark, thick tip leaf as the sole "flavor" ingredient in a much blander filler blend. So I'll disagree with that contention.”

Subjectively, how do you experience strength overwhelming flavor? I just experience very little aroma, and it makes me feel there is something aromatic that just isn't there, compared to a viso priming of a similar/same plant.


The leaves on the bottom are the first leaves--and only leaves on the plant for the three weeks or so of their life after transplant. The roots (alkaloid factories) are still immature in their chemical production. These bottom leaves grow as large and as rapidly as their nutrition will allow. They have no shading from higher leaf yet, (What is the significance of that? Is it just incidentally reflective of the fact that the plant still wants to grow those leaves to use them for photosynthesis? And then why does it "give up" on these leaves sooner than others? Just because there's a natural lifespan to the plant and it might as well quit first on the leaves that are farthest from the buds, since it would take more energy to get to get the energy produced by photosynthesis up the stem from the bottom?) but they are just giant babies. During the final 5 or so weeks prior to plant maturation, all the other leaf grows, sharing nutrients and sunlight. But during that same window of time, the bottom leaves (the big babies) are already metabolically entering senescence--like tree leaves do in the autumn.


My Corojo 99 plants seem to produce top leaf nearly as large as bottom leaf, though it's far more potent up top. So plant signaling (I feel vague on what signaling means here) and leaf growth are different from one variety to the next. Which seems pretty fascinating in itself.


One other factor in combustion is the hygroscopic nature of tobacco. Some leaf, especially upper leaf, is able to draw and retain more moisture from the air than thinner, lower leaf. This hygroscopic prowess of upper leaf is also evident while smoking, since burning leaf produces water vapor in the smoke (how does it do that?). So a cigar of predominantly upper leaf may ignite just fine, and burn well for the first third of the cigar, but then begin to get increasingly soggy in the head.

Whew! I'm simplifying quite a bit, and guessing to some extent, but this is my impression of these curious attributes of tobacco leaf."

Thanks again.

 

[deluxestogie]

I'm flailing here to adequately answer.

With regard to strength vs flavor, I simply experience intense flavor from top leaf when the total quantity of top leaf is much lower, than when it is a larger proportion of the blend.

I can't explain a plants' priorities (other than in evolutionary terms). Bottom leaf does its primary job of providing the roots with sugars for metabolism, then they start to die. A guess would be that so late in the leaf's lifespan, it simply can't go to nicotine college to improve its job prospects. These leaves are often fairly bug-eaten already, by the time the roots can gin up adequate defenses to channel up to them. (But leaf senescence continues to work its way up the stalk, giving up on lower leaves for higher leaves. So the leaves we harvest mature from stalk bottom to stalk top.)

All plants perform movement (in the form of growth) in response to auxins and a tiny number of additional signal molecules. They make roots spread and branch. They determine if a growth area in a leaf axil will sprout a sucker or remain dormant. They trigger the budding process, which causes particular leaves to grow into sepals and petals (they are just modified leaves, like fingernails are just modified skin). The primary source of auxins is the growth tip at the top of the plant (the apical meristem). It is transported down the stalk (and is affected by gravity). At the roots, auxins stimulate root lengthening and branching. At leaf axils, auxins suppress suckering.

When a stalk is laid flat by a wind storm, leaf axils on the now-upper side of the stalk immediately sprout suckers, since the auxins from the apical meristem drain down the stalk channels along the lower side, and don't reach the upper side. If a perfectly upright stalk is topped (the apical meristem removed), then nearly every leaf axil will initiate a sucker sprout.

Water vapor in the smoke: When you completely combust a simple hydrocarbon, like methane, all you get is CO2 and water as the products of combustion. When you burn trashier stuff (like tobacco), you get CO2 and water, plus CO and bunches of other organic volatiles. The white ash is nothing but residual minerals. It's the same reason your body produces so much water vapor (think of fogging a window with your breath). That water is the result of our cells' combustion of glucose (within a tightly controlled chemical cycle). Our body's metabolism produces CO2 and water, plus all the trashy stuff.

Bob

 

[waikikigun]

I'm flailing here to adequately answer.

With regard to strength vs flavor, I simply experience intense flavor from top leaf when the total quantity of top leaf is much lower, than when it is a larger proportion of the blend.

I can't explain a plants' priorities (other than in evolutionary terms). Bottom leaf does its primary job of providing the roots with sugars for metabolism, then they start to die. A guess would be that so late in the leaf's lifespan, it simply can't go to nicotine college to improve its job prospects. These leaves are often fairly bug-eaten already, by the time the roots can gin up adequate defenses to channel up to them. (But leaf senescence continues to work its way up the stalk, giving up on lower leaves for higher leaves. So the leaves we harvest mature from stalk bottom to stalk top.)

All plants perform movement (in the form of growth) in response to auxins and a tiny number of additional signal molecules. They make roots spread and branch. They determine if a growth area in a leaf axil will sprout a sucker or remain dormant. They trigger the budding process, which causes particular leaves to grow into sepals and petals (they are just modified leaves, like fingernails are just modified skin). The primary source of auxins is the growth tip at the top of the plant (the apical meristem). It is transported down the stalk (and is affected by gravity). At the roots, auxins stimulate root lengthening and branching. At leaf axils, auxins suppress suckering.

When a stalk is laid flat by a wind storm, leaf axils on the now-upper side of the stalk immediately sprout suckers, since the auxins from the apical meristem drain down the stalk channels along the lower side, and don't reach the upper side. If a perfectly upright stalk is topped (the apical meristem removed), then nearly every leaf axil will initiate a sucker sprout.

Water vapor in the smoke: When you completely combust a simple hydrocarbon, like methane, all you get is CO2 and water as the products of combustion. When you burn trashier stuff (like tobacco), you get CO2 and water, plus CO and bunches of other organic volatiles. The white ash is nothing but residual minerals. It's the same reason your body produces so much water vapor (think of fogging a window with your breath). That water is the result of our cells' combustion of glucose (within a tightly controlled chemical cycle). Our body's metabolism produces CO2 and water, plus all the trashy stuff.

Bob

Thank you very much. I have a few words to look up in the morning....I'll do it after coffee because I know that auxin is going to lead me down a (very pleasant) biochem rabbit hole.

b

 

[deluxestogie]

You might consider auxin as a Dr. Jekyll / Mr. Hyde growth hormone. It stimulates certain processes in certain parts of the plant, and simultaneously inhibits other processes in other parts of the plant.

Plants have no nervous system (electrical wiring) or brain (central switchboard). But they nonetheless engage in communication between distant parts of the plant body, in order to coordinate "movement" (growth) to the plant's advantage. Lacking nerves, which propagate chemical signals within our own bodies using electrical, high-speed lines for the long-distance stretches, plants patiently wait for the chemical signals to physically migrate to the appropriate plant parts. [It's the very same approach that mammal hormones take--slow motion communication.]

You might say that plants make "choices"--decisions. But this occurs only as a trend within a group of plants, over many generations. The bad decisions are punished by less effective production of offspring.

The hair follicles on the top of my head have been allowed to die, before the rest of my body. I haven't the slightest notion why such a phenomenon arose in humans to start with, and persists in humanity, mostly in males. But is seems to have little impact on reproductive effectiveness, when viewed at a population level. So it is not punished.

Tobacco loses its lower leaves before the blossoms have done their job. This seems to go unpunished.

Bob

 

[Yvan the terrible]

This tread should be renamed “all the things I always wanted to know but was afraid to ask”. Great read and info.

 

[waikikigun]

You might consider auxin as a Dr. Jekyll / Mr. Hyde growth hormone. It stimulates certain processes in certain parts of the plant, and simultaneously inhibits other processes in other parts of the plant.

Plants have no nervous system (electrical wiring) or brain (central switchboard). But they nonetheless engage in communication between distant parts of the plant body, in order to coordinate "movement" (growth) to the plant's advantage. Lacking nerves, which propagate chemical signals within our own bodies using electrical, high-speed lines for the long-distance stretches, plants patiently wait for the chemical signals to physically migrate to the appropriate plant parts. [It's the very same approach that mammal hormones take--slow motion communication.]

You might say that plants make "choices"--decisions. But this occurs only as a trend within a group of plants, over many generations. The bad decisions are punished by less effective production of offspring.

The hair follicles on the top of my head have been allowed to die, before the rest of my body. I haven't the slightest notion why such a phenomenon arose in humans to start with, and persists in humanity, mostly in males. But is seems to have little impact on reproductive effectiveness, when viewed at a population level. So it is not punished.

Tobacco loses its lower leaves before the blossoms have done their job. This seems to go unpunished.

Bob

Thank you. You just saved me six hours.

 

[waikikigun]

This tread should be renamed “all the things I always wanted to know but was afraid to ask”. Great read and info.

"All the things I ever wanted to know about the tobacco plant but was afraid to ask" was the original title of my question.

 

[waikikigun]

You might consider auxin as a Dr. Jekyll / Mr. Hyde growth hormone. It stimulates certain processes in certain parts of the plant, and simultaneously inhibits other processes in other parts of the plant.

Plants have no nervous system (electrical wiring) or brain (central switchboard). But they nonetheless engage in communication between distant parts of the plant body, in order to coordinate "movement" (growth) to the plant's advantage. Lacking nerves, which propagate chemical signals within our own bodies using electrical, high-speed lines for the long-distance stretches, plants patiently wait for the chemical signals to physically migrate to the appropriate plant parts. [It's the very same approach that mammal hormones take--slow motion communication.]

You might say that plants make "choices"--decisions. But this occurs only as a trend within a group of plants, over many generations. The bad decisions are punished by less effective production of offspring.

The hair follicles on the top of my head have been allowed to die, before the rest of my body. I haven't the slightest notion why such a phenomenon arose in humans to start with, and persists in humanity, mostly in males. But is seems to have little impact on reproductive effectiveness, when viewed at a population level. So it is not punished.

Tobacco loses its lower leaves before the blossoms have done their job. This seems to go unpunished.

Bob

Follow-up re: leaves.

Do leaves grow in the same way? Not sure why they would, since they're not sending nutrients "up" to buds, but it has that look. Tips are smallest and crustiest, base area is often wider and thinner, etc. So is the tip the youngest with the most alkaloids in it, are the base and then perimeter edges the oldest, or...?

Thank you.

b

 

[deluxestogie]

I don't know the answer. The primary task of leaves is to photosynthesize sugar, which is then transported down to the roots.

A leaf forms its entire shape very early on. If a budworm eats a tiny divot into a baby leaf, the the missing lamina (the hole) gets larger in proportion to growth of the leaf. So my guess would be that the leaf is not growing out from the stem to the periphery, but rather all the laminar cells and their supporting secondary veins expand in concert.

Bob

 

[waikikigun]

I don't know the answer. The primary task of leaves is to photosynthesize sugar, which is then transported down to the roots.

A leaf forms its entire shape very early on. If a budworm eats a tiny divot into a baby leaf, the the missing lamina (the hole) gets larger in proportion to growth of the leaf. So my guess would be that the leaf is not growing out from the stem to the periphery, but rather all the laminar cells and their supporting secondary veins expand in concert.

Bob

Thank you. Very interesting about the hole. Maybe by the time I've finished The Overstory I'll know the answer to that one....

b