This doesn’t belong in the landrace section, but I think it’s novel enough to be worth talking about!
I’ve been thinking about how to create a cold temperate perennial tomato for a long time now, and I finally had a break through today whilst recovering from some kind of cold (ironic, really).
The process I outline below might in theory produce a true cold temperate perennial tomato. It involves grafting of a tomato onto a cold hardy Solanaceae rootstock, and repeate grafting of the subject generations.
Summarized version:
Step 1: Grafting
To create a cold-temperate perennial tomato, start by grafting a hardy tomato variety onto a cold-resistant rootstock from the Nightshade family. This process strengthens the tomato’s resilience to cold and wet conditions.
Step 2: Children of the Graft
After grafting, the tomato plant absorbs genetic material from the rootstock, enhancing its ability to cope with cold and light stress. To develop even hardier tomatoes, grow seeds from these grafted plants, graft them back onto the rootstock, and repeat the process. The goal is to create tomatoes that can survive cold temperate winters.
Final Thoughts
This approach closely resembles real-world experiments, and researchers have already successfully grafted tomatoes. It offers a cyclical method for achieving perenniality and hardiness in tomatoes. This method might be simpler than intergeneric hybridization because it avoids pollen incompatibility. If successful, it could challenge our understanding of tomato species, potentially resulting in a new classification like "Solanum barbarum.
Recent studies show that changes in plants caused by grafting can be passed on to their offspring, offering a way to improve crops without genetic modification. This method has been successful in various plants, including tomatoes and rice, with potential benefits for traits like ripening and seed size. It opens the door to using natural diversity in plants for more productive farming and crop breeding without the need for genetic engineering.
The proposition sounds also similar to Mark shepherds STUN (Sheer Total Utter Neglect) method although I don’t recall him talking about genetic changes from grafting. Essentially you plant a bunch of tree seeds in this case. Let them grow and evaluate for vigor hardiness and early fruit production. If you run out of space you can graft the early fruiting varieties onto the vigorous non fruiting stock. Then plant the next generation seeds and repeat.
Essentially it sounds like a lot of work. But it may be worth it for your goal.
Yes it does share similarity to Mark’s STUN method. The difference being that I really have doubts that normal evolution will yield cold temperate resistant tomatoes because I think the genetics are just not there (without the graft donating genetics), but maybe we’ll see…
An interesting idea. The grafting widens the genetic base of the tomato, perhaps only slightly, but does so nevertheless. If widening the genetic base was the goal, then grafting to a range of rootstocks (perhaps a few times) and crossing the offspring might be a partial pathway towards this goal.
Yes, this was my intuition. I talked to @ShaneS about this also and he thinks that using a rootstock sapling will maximise any genetic transfer. We could get some real franken tomatoes this way.
Make sure you follow the proper technique when doing this. There are basically two things to keep in mind.
A) Use hybrid tomato seed—particularly wide hybrid. Inbred seedlings do not have as much genomic plasticity.
B) graft the seedlings very young, if you can 7-10 days after emergence. The root stock is older.
C) Keep only 1-2 leaves on the scion growing tip, prune the rest as it grows.
The reason it should be done this way is because you want to graft to act with a high amount of selective force on the scion.
If you can keep the plant inside over winter, you don’t have to regraft from seed every generation. The longer time the scion lives being mentored (pruned) on the stock the more it will transform. That goes for its seeds as well. So for example after a few years both the tomato scion and its seedlings will have more influence from the goji as compared to living grafted for one year.
I’ve been thinking lately of doing a version of this, with the goji scion to be mentored. I have collected around 30 hybrid goji seed this year, a blend of 3 species. I’m thinking of putting a couple of them on Physalis peruviana and maybe litchi tomato.
I have a dwarf Tamarillo (Cyphomandra abutiloides) that grew well for me, but all the fruit has been bitter.
Last year I grafted a tomato sucker on it in August and it survived. Unfortunately, I took the bag (for humidity) off of it after a week. I was going to try again this Spring but I spent my time working a new area for my garden.
The dwarf tamarillo grows well, tolerates the heat and the last two winters (inland southern California). Good qualities. But I wonder if the bitterness would influence the tomato.
Nice Bruce! The bitterness could be increased in the tomato progeny, but so will other qualities that you potentially want to be there. When the process is continued for a few seedling generations, you will have enough qualities in your mutant tomato population that you can then do conventional breeding with ungrafted seed and hopefully then select out the bitterness. Its recommended to use hybrid seed for the scion, but if you do the right grafting you can mutate even inbred seed eventually. Pruning the scion is absolutely essential though or any mutants will be very hard to find if they even appear at all.
So no branching and just the leaves at the tip.
When it flowers and fruits the rootstock will be able to nourish it enough since the scion will only have 2 leaves?
Yes exactly. It may be able to branch if you keep only the apices of the branches, but generally the more leaves present on the scion the less mutation you get, and after more than a few leaves it drops to closer to zero. By the same token the more leaf biomass of the rootstock is supposed to make it more effective, but I don’t know how true or necessary that is.
Here is a photo of Capsicum mentor graft, control plant A is ungrafted while B depicts a mentor graft.
The interesting thing about this observation is that it suggests the seeds when they form in the scion are absorbing material from exosomes from the rootstock. This suggests that normal ungrafted plants package useful information into the next generation every time they undergo sexual reproduction (and that careful mentor grafting can hijack the process to transfer info between species).
If this is true, then it might be one of the many mechanisms where saving your own seed accelerates local adaptation.
