Better combinaison for get maximum heterosis effext

[Adrian]

The conditions of the heterosis effect seem very surprising in the tomato,
What is the better combinaison for get the maximum heterosis effect and the better F1?

Cross the two better plants of the garden?

Cross the most weak plant with the better plant of garden?

Cross the two mosts weaks plants of the garden?

Cross a medium plant with the better plant of the garden?

cross two medium vigorous plants

Someone has also getting hybrids 3 ways more performants than the hybrid 2 ways?

The most part of my hybrids 3 ways don't seem more performants than my hybrids 2 ways.F1 x the most weak plant seem a good idea for you?

Thank you for your experience

[Tim DH]

Hi Adrian,
     By using an F1 to make your hybrids you will not get reproducible results.

     In a (true) F1 all of the seed is identical, because each parents is only able to provide identical gametes.

     The gametes produced by an F1 are highly variable.

     You may get a 'good' plant from seed which has an F1 parent, but it will be a lottery!

     The 'good' plant itself will not prove to be a stable parent, AND you will be unable to re-create it, because you will be unable to remake that particular combination of gametes.

[Adrian]

Test of F1 between the most weak plant x the better plant
((Green giant x tiny tim)F4 pink) X ((canestrino di lucca x andine cornue) x roman candle F2)

[Adrian]

Tim DH, as i have little of time its more easy for me to take a F1 as male parent. A F1 give a lot of flowers, its more efficient if i must repeat the cross.

A croce between two F1 is interested?

[Steph S]

I think Tim's point is that you can't really answer those questions that you asked, if the parents are unstable - because each F1 seed will be genetically different, and whatever you are looking for in the way of 'heterosis' effects will be variable from plant to plant.  So you won't get a general answer to any of those questions.

There's nothing wrong with using F1 in a cross, but the real benefit of crossing unstable plants is to get a broader look at the diversity available in the cross, by growing large numbers of the F1.  You sort of skip ahead to a highly variable population in the first generation.   There is also the possibility of dislodging linkages or obtaining outliers that wouldn't be so easy to find by growing each OP x OP to stability, I think.

Ultimately the point of any cross is to combine desired traits from two parents.  So if you have a weak plant that needs strengthening to be productive (but has other traits that you like) then I would cross it with a more vigorous plant to bring the trait, as you're doing here.
If you think about plant architecture, fruit size, truss architecture, earliness, reliable set, and all the things that make a plant more fruitful or less so, then you need to bring those traits to your weaker plant, and choose a parent with the traits that it needed.

[Alex]

To achieve maximum heterosis, parents must be very different genetically, originate from different parts of the world, or, in the best case, be different species altogether. If you're growing cultivated tomatoes, crossing them with wild tomatoes will produce desired heterosis. If you read thread https://opensourceplantbreeding.org/forum/index.php/topic,642.msg17965.html#msg17965 , a feral cultivated tomato from Texas was crossed with a stable wild hybrid from the Galapagos Islands, resulting in a very strong heterosis—a result unattainable by simply crossing different varieties.

[Adrian]

Thankyou Alex, Steph S and Tim DH
https://www.researchgate.net/publication/290428271_Performance_of_single_double_and_three-way_cross_hybrids_in_tomato_Lycopersicon_esculentum_Mill

I have found this report. Infortunately crossed two F1 seem not very efficient.

[Roland]

As expected, three-way cross hybrids were most uniform followed by double cross hybrids.
https://www.researchgate.net/publication/290428271_Performance_of_single_double_and_three-way_cross_hybrids_in_tomato_Lycopersicon_esculentum_Mill

Why as expected?

[Tim DH]

I agree Roland,
That's a very curious presumption to make. Does it mean that individual three way X hybrids were 'most uniform' with themselves (unlikely, I'd expect that to be the single X hybrids) OR that all the three way X hybrid as a group were 'most uniform' (unlikely, I'd expect that to be the double X hybrids group.

From my perspective, the most interesting thing I can glean from the data is that the most productive single X Hybrid (true F1s) out yielded the most productive parent by 191%. The most productive three way X hybrid out yielded the most productive parent by 134% and the most productive double X hybrid out yielded the most productive parent by 118%

Just to confirm that. ... The least productive F1 out yielded the least productive parent by 199%

So my take away point would be. ...

If you are interested in (almost) doubling the productivity of your favourite Open Pollinated varieties start making F1s! !! !!!

[Roland]

This publication is of poor quality. It fails to mention the names of the parental lines or specify which parents were used for each cross. Consequently, there is no way to verify if entirely different varieties and crosses were actually being compared.

[Steph S]

You have to watch out for your wording too, and consider what your real goals are.
It's possible to get "maximum heterosis" by crossing two unfruitful varieties and increasing them by quite a lot because the baseline production is so low.
So you might have 'maximum heterosis' but still a low yield compared to others.

I duly admire and hats off to anyone who can weigh out the fruit from every plant in order to compare.  It's a big job. (I have done it once!)