I'm curious if anyone has crossed a dwarf and microdwarf tomato and what the habit of the F1 was?

If it is simple genetics, it should be a dwarf, but if multiple genes are in play, perhaps the F1 is somewhere between the two?

I am asking because I made such a cross last year and I am considering to get a very early start (largely indoor) on an F1 to get some F2 seed, but if the habit will be full dwarf, then that is too large and I'll just grow the F1 this summer and save seeds for F2 then.

My understanding is that yes they should be dwarf. Generally what I have heard is micro x regular plant = regular, micro x dwarf = dwarf, micro x micro NORMALLY = micro but sometimes for some reason you get full sized plants. rare but it does happen.
Do far I have not managed a successful cross so can't say from experience.

I would do the grow out now!
It should be easy to tell very early if there are micros with those shorter, thick trunks. Cull those that aren't.. unless your goal is the dwarf and not the micro. Just my 2 cents.

I’ve got a few seed sown just to verify the cross took (mother was PL and father RL so it should be RL). I guess I’ll let them grow for a while and pot one up. If it gets unmanageable under lights or by patio door later this winter I can always cull it or root a sucker and keep doing that—would be faster than starting from seed.

If the F1 plant starts getting too large, you can also prune and pinch it heavily, e.g. remove all side shoots and larger leaves and top the main shoot early. You don’t really need many tomatoes to get a lot of F2 seeds, 2-3 tomatoes from the first inflorescence could be enough. Of course, gently touching and poking the flowers daily when they open is important to secure good pollination and many seeds per tomato.

Yeah pruning aggressively is a must given the light constraints I have. I've successfully fruited tomatoes indoors, I use a cheap electric toothbrush on inflorescence steams, works great!

Well I sowed seeds on New Years Day and potted up one F1 plant. Today is 42 days from sowing and about 35 from seed emergence and the 3” plant under lights in a upper 50s basement is developing its first inflorescence. I certainly didn’t expect this from a dwarf x microdwarf cross in the F1, but here we are! Maybe I’ll have F2 seed to sow by mid spring!

Looks terrific! Congrats on your new baby! And the the real fun begins with the F2s!

Well that was easy. Well done! You will have this one stabilized in no time.

What types of characteristics are you looking for?

MissS wrote: ↑Sat Feb 12, 2022 1:44 am Well that was easy. Well done! You will have this one stabilized in no time.

What types of characteristics are you looking for?

With GWR/red cross I should have pretty much any color available, so I'm hoping for great tasting, different colored microdwarfs. Multiflora will be an option, but that won't be a requirement, just going to focus on flavor/color/micro habit.

F1 doing well!!

Very cool!

So it looks like it took after it's smaller parent. Is it a Determinate variety as well?

F1 is a cross between indeterminate dwarf and indeterminate multiflora microdwarf. So far I’d say it’s kind of between both parents, so I’m thinking the dwarf and micro dwarf genetics aren’t simple as when your cross a regular indeterminate with either. It is an indeterminate growth type plant like both parents, just kinda between dwarf and microdwarf size so far. We’ll see how big it gets. I’m hoping to find some different colored microdwarfs with excellent flavor in the F2.

First ripe fruit and taste of the hybrid cross between Dwarf Emerald Giant X Red Raindrops (dwarf X multiflora microdwarf). I suppose I need to come up with a working name for this cross, going with Giant Drops. Hoping for a variety of great flavored microdwarfs in a variety of colors in subsequent generations.

The F1 fruits are 16-21g, red, hints of anthocyanin (subtle trait in Red Raindrops).

The flavor was quite delicious! Rich tomato flavor, ample sweetness and acidity. Most of the fruits from the early plant will go to F2 seed. The rooted sucker will be grown in a bucket with the rest of the dwarf tomatoes. Fruits from that plant will go for more F2 seed saving but also plenty of eating.

I don't pay a lot of attention to the taste of (nearly always red on its way to some other color) F1's, but I have noticed that F1 reds with one gf allele generally seem to be great tasting. Extra chlorophyll to convert to lycopene? IDK.

Time to do a bit of hunting in the Giant Drops F2. Hopefully I can find some micros! Starting 48 fresh seeds, hoping to find 2-4 micros to grow out and get fruit for sampling by fall.

@jmsieglaff this is so interesting, how is it progressing?

@jmsieglaff Just out of curiosity, what is different between the dwarf indeterminate and a micro indeterminate variety that you used as the parents? I think a lot of people during the selection phase struggle to figure that part out.