I planted some weeks ago some seeds of T.Bridgesii some are crosses from well known clones like Psycho0 and BEN. They are growing indoor, under a DIY led lamp.

The lamp has as main light a combination of 2700/3500 K samsung LM561C leds and some added mono leds in the 630,660,730 nm for the red range and in the blue range some 430,410 and 395 nm added which means a little UVA added, just to cover the main wavelenghts that sun provides and regular warm white leds lack.

This is the spectrum and the ppfd from the light the cactii have been receiving at their germination and first weeks.

http://imgur.com/5oflI6W

I have noticed that seedlings from same batch of seeds and under similar light conditions develop different tolerancy for the light intensity, some are more reddish, this coloration has always been related in seedlings to an excess of light intensity...maybe the addition of UVA light increases this tendency as happens in other plants.

So, some specimens are..in some way..less light tolerant...it can be see in the pics..there are variations..I suposse this is a normal thing that all cactus growers have noticed.

http://imgur.com/Gi8Y5LV

http://imgur.com/3p684tb

So...this is the purpose of my post..asking if an strategy can be made selecting the more reddish or less light tolerant ones..this way less light can be used for growing them indoor..this of course is useful only in indoor conditions...Looking for red ones..this phenos ..being also T.Bridgesii that are known for needing a little less light than T.Pachanoi, will be more suitable for indoor and having less light demanding so at the end the electrical bill will be lower...

Also ..If high light intensity has a role in alkaloid production in some way...even just stressing the cactus, with this phenos also less light will be needed..

What do you think about this? Does someone knows about some information concerning cactus photobiology? Have some knowledge regarding other plants..but know nothing about Trichocereus and lighting wavelenghts etc...

At this moment, the light spectrum I mentioned above with about 250 ppfd and a photoperiod of 14/10 is working well with mature cactus like this T.B.M short form..pupping under it...pics are 9 days difference...temps 30 C

http://imgur.com/se1kocg

http://imgur.com/5m6786L

What I can say upfront. If seedlings get to much light they can stop growing completely. So it might be needed that you have to reduce the light at some time and let the seedlings get green again. Confronting the seedlings with as much light as possible might not be the fastest way to get them grow big.

I am not sure if there might really be a connection between the ability to grow fast as a seedling in bright light and the later growth speed.
Not sure if it really might be an indicator if a seedling is performing fast under artificial light.

Thanks for the comment. Yes..lots of questions regarding cactus and indoor lighting...still so much to learn..

This is a very interesting line of thought! Please keep updating us on any progress/results if you pursue this approach and select and breed in this direction.

For what its worth, my understanding is that the spines on cacti serve dual roles: defense AND protection from the sun. Cacti with many long spines per areole are more likely to handle full sun well compared to cacti with short or few spines. From my experience short spined pachanois yellow and show stress from full sun more easily than Peruvianus or Bridgesii. In fact, if you look at the photos that I posted on the first page of Wolfnippletip's cactus photo thread you will see the wide photo of the yard with the chicken coop in it. The 3 taller cacti on the left are Bridgesii then Pachanoi then Bridgesii. You can see that the Pachanoi is much more yellow and stressed from the sun than the two Bridgesii. Even Scopulicola seems to handle full sun better than Pachanoi for me for some reason.

So to me it seems that Pachanoi is the happiest in shady conditions of the active Tricho species. That may be the species to really concentrate on for what you are looking for.

All the best!

My experience is different. I had some Scopulicola seedlings which had almost no spines which grew much faster and stayed almost green all the time whereas my long spined bridgesi almost stopped growing and got really red in the same light. But there might be other factors at play as well.

I have never been to the Andes. But from what I understand the heartland of Pachanoi is in southern Ecuador and northern Peru. Peruvianus is dominant in central and southern Peru. Bridgesii and Scopulicola are from Bolivia. Of course humans have spread these species far and wide and all over the Andes. But the farther south one goes in that range the drier and more desert-like the climate becomes.

Pachanoi evolved in wetter, milder conditions compared to the others. In that habitat they are more likely to be growing under the cover of trees. Whereas the other species are more likely to be growing in drier, more open environments.

I live in a dry, hot desert. It is much hotter here than in the native range of these Trichocereus species. The cacti that are native to my area are much more heavily spined than the Trichocereus, with the exception of some Cuzcoensis and also some of the less common Trichocereus from the southern end of their range.

It is a known fact that cacti use their spines as protection from the sun. Generally speaking, cacti that grow out in the open in hot sunny climates are going to be more heavily spined than cacti that have evolved to grow under the shade of other plants or in milder climates.

And of course there is also the issue of alkaloids. Peyote has completely abandonned growing spines and instead relies on bitter alkaloids to deter predators. But it is also able to do this because it grows underneath the shade of thornscrub. A species like Scopulicola is interesting because it seems to have gone down a similar path as peyote in terms of its defense from predators, but it is also native to a dry, sunny environment.

So there are several factors at play here. But from what I see in my climate with these Trichos it seems that Pachanoi holds a lot of potential for what Nachooo is looking for. But also, I have never grown from seed so I am not sure exactly how the seedlings respond to light and heat compared to more mature plants.

Yes you can make selections based on the seedling pigment response to light spectrum, but it may not indicate a decreased tolerance to light.

Some clones are known to form more photoresponsive pigment than others and the pigments have been observed to occur in some populations even when light levels are far below optimum.

The growth rate, height and diameter of seedlings are better indicators of good tolerance of lower levels of lighting than any other aspect. The thicker a seedling is, the happier it is with the lighting. Pick the ones that grow the best, not the ones that show color, to select for light tolerance.

Is the advice I have.

You can leave seedlings in high sun exposure early on without issues if anything IME the more you stress them early on the faster they reach adulthood. Size doesn't equal maturity. I placed all my lophophora and trichocereus in full sun at 1-2 month old. The trichocereus do stall for a month however will keep growing as long as watered. The lophophora did stall quite a bit but also kept growing despite becoming very dark.

However when selecting seedlings for future propagation don't kill off early on as a cactus that was slow to adapt to the higher sunlight may surpass others in terms of growth rate later on. Select the best growers after that season not purely on the color or growth in the first few weeks.

I believe that the seedlings that grow best under extreme stress contain higher alkaloids since the alkaloids may act as growth regulators. During stressful times those with higher alkaloid content MAY grow better since they have a 'memory' of previous stress which they have adapted and will grow better in the following time it occurs. NO SCIENTIFIC BACKING other than alkaloids in other plants responding as growth regulators (not growth hormones) which it better uses water/nutrients and growth rate in different conditions.