Self Incompatible Tomatoes in 2020 How much Space?

[William S.]

I am wondering strategically how best to use my garden space in 2020.

One of the tomato populations that will be really interesting to grow out is a 3/4 domestic. Including 1/2 Big Hill. Joseph sent it to me and that seems an honor. I had 13 F1 plants in 2019 and saved as much seed as possible. None segregated to be elites or edible. However all 13 seemed self incompatible so must have been heterozygous. There is huge potential here for favorable segregation in the F2.
 
I will plant all the seed in 2020 or the vast majority of it (always a good idea to hold back a little). However the question then becomes how much space to give the seedlings. I suspect that if well spaced I could allow them the entire garden. However that might be excessive. So I need some kind of middle ground. Perhaps I could well space a couple rows, and crowd a couple.

Advantages crowding: less garden space. Can still save seed from favorite fruits. Expect lots of inedibility so spacing would be good.

Advantages spacing: can tell plants apart. May enable ruthless culling. Faster progress possible. With culling could make some elite to elite crosses in 2020.

For spacing to work well, plants would need quite a bit, perhaps, ten feet apart.

[reed]

Don't know how much space you have to work with or if tomatoes is your primary interest but from what you describe I'd go with wide spacing. Easier as you describe, to make your elite crosses and at ten foot spacing or maybe even less you can grow other crops between.

[William S.]

 Tomatoes have been increasingly the focus last few years.

Which other crops might work well? If I'm going to cull heavily, a lot of the tomatoes would end up removed. What if I did a tomato, then a hill of squash every five feet in a grid?

[reed]

I think that should work fine. I was just thinking of a way not to waste your garden space, about any other crop you like should work.

Only thing is, are you trying to minimize random crossing by bees so you have more control of the crosses? If so I'd go with something that might be blooming a lot at the same time to distract the bees and dilute the tomato pollen as they travel up and down the rows, maybe even flowers. I use dahlias that way between semi isolated pole beans.

Also might want some short season things, maybe some greens or something to fill in empty spots where a plant was culled.

[William S.]

One simple thought is to alternate the self incompatible tomatoes with self compatible tomatoes. Then I could grow out some of my promising F2 domestics. The two projects interact in predictable ways. Gene flow should go only from self incompatible to self compatible. Dilution would be down to 1/8 wild if got random hybrids by say interplanting with the F2 I think of as "exserted tiger".

[William S.]

Joseph had a good answer to this over on permies.com 3 feet apart, 9 feet between rows. Course I'll just pace it... 1 step apart, then 3 steps between rows.

Joseph, I am really excited about the F2 of Big Hill x W4. I'm thinking about skipping a year on many other things to give the F2 growout a lot of space. Maybe 3 steps apart ~ 9 ft or perhaps 4 steps 12 ft? Figure I should be able to grow ~300 plants from the seed I saved.

Does that sound like a good plan?

I loved the BH X W? Populations. One of my favorites came out of W4.  BH X W4 produced some lovely flavors, and also some fruits which were described as acidic.

A constant worry for me is maintaining/increasing the s-alleles in this population. Therefore, I would include some of the pennellii crosses in the grow out as well, just for the s-alleles. Also, the descendants of S pennellii, are tending towards being more fruity than those from S habrochaites.

At 9 feet separation, the plants would still be likely to grow together, but it would be easy to tell which is which. I'll probably plant 3 feet apart with rows separated by 9 feet. That'd give me enough separation that I could cull shortly after they start flowering. One year, I grew them in pots until flowering, then only planted out those with promiscuous flowers.

[Andrew Barney]

Really really close together dramatically promotes grex or landrace crossing from native solitary bees (or bumblebees) and would be most useful to new species you are growing or ones you want crossed. For F2s and others you want to segregate and cull (if it's been a few seasons)  then those round do best with more space.

[William S.]

Yeah last two years everything has been really close together. This year I'm wanting to grow the F2 of the 3/4 Big Hill line in such a way that I can tell individual plants apart. That may mean culling or even cloning in the fall. Ultimately we need to get good flavored large fruited elites to pollinate each other. All 13 plants I grew in 2019 were hard and green. A certain percentage should segregate to large tasty fruits. Joseph grew more plants and got some elites from the F1.

I may also do something like multiple rounds of selection. Plants that bloom in pots might get sorted by exsertion. Then plants that have tiny hard green cherries might get yanked. Maybe if there is time. Pick off all fruits once only tasty plants represented and let fresh fruits form. More probably I will just save and exclusively plant seed of elites. Doing a few rounds of mother only selection to gradually increase elite percentage. Probably will segregate for self compatibility in this generation too.