Ramblings about Sun Vs Shade

[teonanacatl]

i would first like to say that this is really just ramblings with no specific final conclusion, just stating some things ive recently learned and tying them into stuff about cacti potency (by typing them into some form of context i understand the stuff better).

Plants grown in full sun have higher CO2 assimilation rates then plants grown in shade. In full sun the assimilation rate is limited by Rubisco and the electron transport chain. Faced with this fact the plant has and interesting predicament (providing it has adequate nutrients), produce more Rubisco or to leave as is. Producing more Rubisco isnt a easy thing, this is a massive enzyme which doesnt just carboxylase but also photorespires. so by making moer Rubisco this increases N (+ other nutrients) content in leafs thus attracting herbivores to this yummy nutritous meal. So the plant can then increase the amount of alkaloids to disuade animals from eating it, this to is highly taxing on the plants. The point of stating that is cacti grown in full sun may increase Rubisco content inorder to make use of more light, thus increasing mescaline level (if it is infact used to deter animals) to protect its self. but this will only happen if the required nutrients are present.

The otherside of the story. M S Smith has stated a few times that etioliated light green branches contained higher mesc and im sure everyone has heard that leaving a cutting in the dark increases potency. Plants like cacti which need full sun (cant be adapted to shade and still grow well) when placed in shade/darkness will etioliate, why you ask?? Auxin is a plant hormone which is responsible for, among other things, elongation of the cells near the apical meristem, auxin is sensitive to light. which is why when light is shone on one side of the plant it grows to that side, auxin on the other side is shaded and causes cells to elongate, but auxins on the light side are destroyed and therefore the cells dont elongate. So a cactus placed in low light etioliates cos of large amounts of auxins, well these compounds contain N and are quite valuble to the plant, so here we have the same possible senario as above, plant produces lots of animal detering compounds to protect its bounty of nutrient rich stem. A cutting placed in the dark will have a limit to how much protective alkaloids and auxins it can make because it isnt obtaining nutrients from anywhere, but a plant placed in relatively dark location will be able to utilise avalible minerals in the soil.

see i told you just rambling on, these are the things which go through my head on a day to day basis as i take concepts i learn in chemistry, botany and biochem and relate them back to the magic plants in my yard i hope you enjoyed that and that maybe you will now try growing 3 clones, one in full sun, one in full shade and one in darkness

[Evil Genius]

Double post

Edited January 6, 2016 by Evil Genius

[Pisgah]

quote:

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could it be possible that the cacti are producing their alkaloids to attract people or animals who carry their parts and seeds all over the deserts to assure the surviving of the species?

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Hell yeah! Finally we hear it. Michael Pollan wrote this great book called "The Botany of Desire" that talks about four human desires and four plants that have been human cultivars for ages, and the desires that these plants evoke. he talks about exactly these things, that plants manipulate our desires to create new niches for themselves. The four plants are apples, tulips, cannabis, and potatoes. Cacti should be added to this list, it seems...

[teonanacatl]

my guess is growing in full sun is ideal for them as they have many ways to protect themselves against photodamage and being CAM plants have evolved was to deal with arid climates. plants however dont utilise all the light in full sun (2000 micro mol quanta/m2/s) most stop CO2 assimilation at 1000 micro mol quanta/m2/s.

[toby]

I have some good plants (good in sun where i used to live) that have been in shade for the past year.

But with all the variables taken into account my results won't mean much at all i guess?

[M S Smith]

teonanacatl, any previous comments I made where not about etiolated plants, but about plants that where thinner in diameter, and therefore generally grown in partial shade. Anecdotally I have found that those plants grown in less light seem to maintain higher alkaloid concentrations. One article I have regarding usage in Peru mentions thinner T. pachanoi columns as being held in more esteem than larger diameter ones.

Just thought I'd clarrify for the better good.

~Michael~

[Rev]

Hey Michael

I read that too

i think in

Douglas sharon

"The san pedro cactus in peruvian folk healing"

chapter 4 pg 114-135

in

Peter T furst 1972

"Flesh of the gods"

excellent book! i got it thru amazon too

[teonanacatl]

sorry michael if i wrongly quoted you what i ment in the overall picture was that growing in less sun (whether etioliated or not) would mean less auxin was destroyed,, etc what i said above.

[M S Smith]

teonanacatl, no troubles mate...ah shit, I mean Sir.

Yep, I think that's the article too Rev. And BTW, Eileen is growing nicely. Sweet plant.

~Michael~