Fast Growing Seedling

[Shane]

I sowed some hybrid Echinopsis (F2 'Grandiflorus' open pollinated) seed last July, kindly given to me by another forum member. After the first few months, there was one seedling that was bigger than the rest. I think I should take it out of humidity, but am afraid of disturbing the others. But I feel like I may have to do it eventually and it's only going to get worse over time

The situation

Big seedling.jpg (172.36 KiB) Viewed 1556 times

What does everyone think? Remove is?

Also, does the big one look plausibly like a Trichocereus (Echinopsis) hybrid? There enough debris mixed with the seeds I could have maybe missed a quite different looking seed. I really hope it's a super-Trichocereus hybrid, but I guess it seems more likely another seed somehow got in

[esp_imaging]

Definitely leave it alone, it isn't a problem.

[esp_imaging]

In fact, I think the problem is: Why aren't the other seedlings growing much faster?
If these are 4 or 5 months old, or more, I'd be hoping for more growth, unless they have been cool and dry-ish over winter and not growing.

[Shane]

In fact, I think the problem is: Why aren't the other seedlings growing much faster?
If these are 4 or 5 months old, or more, I'd be hoping for more growth, unless they have been cool and dry-ish over winter and not growing.

I'd never sown any Echinopsis seed before and assumed they just grew slowly. But this is not the case I guess?

I have a strong hunch about why they'd grow slowly. I've been having trouble keeping the soil wet. The moisture evaporates then condenses on the bag, eventually drying out the top layer of soil. I have no idea how to counter this

[esp_imaging]

I use small sealed plastic containers and a very mineral mix, quite damp, so the surface is always damp. I top up the water occasionally if needed.
Small pots / containers are useful, as its easy to keep all parts roughly the same dampness. Big containers may dry in the centre be wetter at the edges, where condensation runs down
Maybe you could just add more water? This will increase the risk of damping off and rot, especially if you have a lot of organic in the mix. It can be a bit of trial and error to find what works for you.
If you have a lot of seed, sow in smaller batches too, maybe a few weeks apart- so if you make a mistake, you don't risk affecting all of the seeds of the same type, and you have a chance to learn lessons and try something slightly different next time.

[Shane]

I use small sealed plastic containers and a very mineral mix, quite damp, so the surface is always damp. I top up the water occasionally if needed.
Small pots / containers are useful, as its easy to keep all parts roughly the same dampness. Big containers may dry in the centre be wetter at the edges, where condensation runs down

I use a mostly mineral mix too, maybe 30-40% organic. I've used a mix of containers, and now that you mention it, it does seem like the drying out problem only happens in the big ones. Which is really good to know

Maybe you could just add more water?

I've been doing that, though not really enough (in fact in the picture, you can see the cacti are covered in water from me spraying them, or at least you could before I compressed the image...). I think I might take the pot out of the bag and cover it in plastic wrap so there's less space for the water to hide

If you have a lot of seed, sow in smaller batches too, maybe a few weeks apart- so if you make a mistake, you don't risk affecting all of the seeds of the same type, and you have a chance to learn lessons and try something slightly different next time

Another good idea, thanks

[greenknight]

I don't see any reason to change anything, they're doing fine. As for why that one is so much bigger, F2 hybrids are more variable than F1s, you just got one that's extra vigorous.

[Shane]

[...]As for why that one is so much bigger, F2 hybrids are more variable than F1s, you just got one that's extra vigorous.

I sowed the F2 seed specifically because I was interested seeing some interesting variations. I haven't been disappointed. If the big one holds up, I plan to make some clones and use it as a grafting stock

On a related note, does anyone know why F2 is so much more variable than F1? Everyone says it is, but I haven't seen an explanation of why

[toadstar]

It has to do with how there's a greater chance that recessive genes will express themselves in the F2 generation. If you have ever played around with Punnett squares in biology class then it is easy to show this. It gets really interesting when you're dealing with multiple genes at once.
https://askabiologist.asu.edu/punnett-squares

[Shane]

It has to do with how there's a greater chance that recessive genes will express themselves in the F2 generation. If you have ever played around with Punnett squares in biology class then it is easy to show this

Ah! That makes sense. The last real biology class I took was in 7th grade, and I believe Punnett squares were a topic we learned about. I didn't really have any interest in the class as the teacher spent most of the class going off on tangents completely unrelated to anything we were supposed to be learning. But I guess I did get something from it since I know what Punnett squares and recessive genes are

[greenknight]

There are other possibilities, though. Maybe a bit of pollen from some other cactus sneaked in, or it's a stray seed from a completely different cactus. Just have to wait and see what it develops into.

[Licespray]

This is a slow show, watching cacti grow, but I’ll definitely be checking in for updates