Author Topic: Poncirus hybrid crosses  (Read 3683 times)

gordonh1

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Poncirus hybrid crosses
« on: April 21, 2023, 09:55:18 AM »
I'm doing some armchair breeding thought experiments here, so even though I'm not experienced enough to maybe dive right in, I am inspired enough by the conversations on this forum about cold hardy citrus breeding to imagine some breeding scenarios that could potentially work for people like me, with some land that could potentially be devoted to experimenting with growing out different populations in the hopes of finding a hardy, good-tasting citrus hybrid.

Practically speaking, what do we know about the progeny of crosses between Poncirus hybrids?  Reading the breeding discussions about F2 generations showing segregation of traits, such as cold hardiness factors (dormancy, deciduousness, winter buds, etc.), presumably the same be said about taste/flavor factors.  So, the F2 generations and later generations have a probability of producing the desired combinations of cold hardiness and desirable flavor characteristics.

What about instead of an F2 generation, we have a cross between two different Poncirus hybrids, such as citrumelo x citrange or citrandarin x citrange? What can be said about the resulting generation? Let's say we grow out as many seeds as possible of such crosses, there should be some that are hardier than the Poncirus hybrids we started with, right, just like Kumin's segentranges.

I'm wondering about this now because I'm thinking that a potential strategy would be acquire a collection of Poncirus hybrids and allow them to pollinate each other, and then grow out as many of those seeds as possible, outdoors in cold climates, in the hopes of finding some hardy progeny that have the higher quality fruits.

From what I understand, the nucellar seedlings identical to the parents would be a bit of a nuisance, so to reduce the number of seeds needed, the best choices for the mother plants / seed parents in this experiment would be the Poncirus hybrids with the most zygotic seeds. Is that the citrandarins like US 852? What about others?

Also, to generate the number of seeds required for mass selection, it seems you need to rely on open-pollination, so the ideal location for this would be a place that is devoted entirely to the experiment, rather than a site that has a wide collection of citrus, which probably rules out my place unless some strategy is employed to isolate the desired parent trees, such as in a screen house. Either that, or just allow some cross-pollination to occur with citrus on site, but collect seeds from the desired mother plants, maybe the citrandarin which is mostly zygotic, and simply allow the least hardy citrus hybrids to be selected out in the cold hardiness trials.

What problems would this strategy need to overcome? Let's say we commit to starting as many seeds as possible (1000 seems doable, maybe more) per year, and employ strategies to eliminate plants at the potted seedling stage (tasting the leaves and eliminating those with undesirable flavor, maybe using a freezer test for basic minimum hardiness) before planting out to face winter trails to further reduce the number to those that are real candidates for the desired outcomes.
« Last Edit: April 21, 2023, 10:21:10 AM by gordonh1 »

kumin

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Re: Poncirus hybrid crosses
« Reply #1 on: April 21, 2023, 10:39:21 AM »
To a degree, open pollination would produce a lot of self pollinated seedlings, not necessarily a bad thing. One advantage of your proposal is the broadening of the genetic base, while keeping much of the same breeding strategy. I'm embarking on a somewhat similar path by crossing F2 Citranges with F 2 Citrandarins. Finding reliably zygotic seed parents is key to generating adequate numbers of further hybrids.

gordonh1

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Re: Poncirus hybrid crosses
« Reply #2 on: April 21, 2023, 10:58:41 AM »
Thanks yes having more zygotic parent trees would reduce the number of seeds you need from the mother plants and that would mean the problems of scale all become easier to manage.  I was thinking about the issues of scale and here's how I was thinking about some of the logistical and practical issues.

I'm thinking of three or four to five growing environments for the full breeding experiment to succeed. This would help determine the limitations of my site for doing the project.

1. Indoors with lighting. This can be where I start the seeds. I have a setup where I can start 300 3.5 to 4" pots indoors, times the number of seeds per pot, let's say 3-4, so about 1000+ seeds per year. The parent trees would have to collectively produce 100 fruits with 10-12 seeds each, that's in the range.

2. Greenhouse. For potted citrus that I want to protect from the winter cold. That might be some but not all of the parent trees.

3. An outdoor orchard for the parent trees that are hardy enough to survive already (Poncirus hybrids in my zone 8a).

4. An outdoor growing area for the winter trials. How big does this area need to be?  I could probably do 100' x 25', that 2500 square feet. How dense would the trial planting be? I'm not sure if Kumin said what he was using. How many seedlings per square foot?  We would dig the survivors and replant them at a wider spacing, so the seedlings only need a minimum amount of space for one or two winter's growth.

6. An orchard area to grow out the seedlings to fruiting size. Spacing would need to large enough to allow trees to fruit, but not so large given that we'd be removing trees after they fruit, since the final selection is for fruit quality.

I don't know if my site would support the space needed for this yet, but some of the locations would be years away. To begin with, you only need the space for the mother plants and whatever seeds you might be growing.

Also, thanks to Kumin, Walt, Ilya and others who provided information and offered suggestions in various threads on these breeding projects and how to improve/optimize them. I believe my proposed scenario includes a lot of the suggestions that commenters offered, but I'm also trying to adapt those ideas to something that is realistic for my situation, in zone 7b/8a and with my various limitations and potentials.

caladri

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Re: Poncirus hybrid crosses
« Reply #3 on: April 21, 2023, 11:00:46 AM »
It seems like density and rapid, strong growth of seedlings is one of the things you'd want to get down here. In talking with more serious (as in, more serious than me) researchers, they warned repeatedly and strongly of premature selection although if you're firing enough arrows, selecting quickly is useful for throughput, and to some extent lets you balance the equation differently but achieving the same number of successes, just throwing away more successes along the way.

VEVOR will sell you a 4' x 8' grow tent, and you can have cone-tainers in 98-unit trays in there yielding 1568 seedlings. Throw in a pair of 4'x4' grow lights, and you've got something that ought to be able to get you to the point of being able to plant out quite a large number per year, right? And, of course, you'll ideally be doing your breeding such that you can select some things out at that stage.

Setup cost would be (this may be off because I'm trying to use US dollars here, but I'm used to doing math on these things in Canadian fun-bucks) on the order of $1300 plus growth medium. If you want to start a truly large number of seeds, it seems like something like that is hard to beat. (I'm limping along with a similar setup, but only about a quarter as many seedlings at a time because (1) I find potting up to be a huge burden; and (2) actually getting cone-tainers and trays into Canada is an excessively annoying burden.)

Which I guess is all to say that I feel like the growing stages are as much to be hacked to get a good result as the breeding stages. I mean, you can even just go for the pure chaos "keep tons of citrus around in an open-pollinated environment, and plant all the seeds from highly zygotic parents in the environment", and then just get enough throughput that you can justify premature selection, and literally chuck your seedlings into a calibrated freezer as soon as you're ready to select for cold tolerance, do chemistry analysis of the leaves (chewing works) as soon as possible to select out things which are producing compounds you know you don't want, etc.

gordonh1

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Re: Poncirus hybrid crosses
« Reply #4 on: April 21, 2023, 11:15:50 AM »
Premature selection is double-edged, I guess. I want fewer plants to grow, but I don't want to eliminate the holy grail. I like the idea of the taste test and freezer test, because I already know I don't want tender plants and plants that have the Poncirus flavor.  Is that too simple-minded?  I guess if we're thinking about the possible future generations, where those plants with the Poncirus flavor also are the ones with the recessive genes I need for the next generation, then yes, I have to keep them.  But if I'm already past the F1 generation where everything has the Poncirus flavor, or everything is not hardy enough, then maybe I don't lose that much if I rogue those out early.

pagnr

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Re: Poncirus hybrid crosses
« Reply #5 on: April 21, 2023, 11:49:13 AM »
I have collected a lot of Citrange and Swingle seed from various sources including Citrus arboretum blocks, fruiting Citrange rootstock suckers with the Citrus fruiting scion also still alive. Most often I have not noticed any variant types in the seedlings.
With large seed lots, it is possible to see off type variant F2 seedlings, but these are clearly still the same variety, not an outcross.
Further to that, the seed trees for commercial rootstock production are usually in mixed blocks, not isolated from other rootstock trees.
There doesn't seem to be a problem with outcrossing with polyembryonic nucellar rootstock types.
For those Citrange type rootstocks with higher % of zygotic seedlings, those are mostly regarded as variant off types, not outcrosses.
I am wondering if leaving it to the birds and the bees to do the x pollinating will get the results you are thinking of.

Also You may need to be wary of selecting for vigorous hardy seedlings at the expense of other desired factors, like fruit taste.
Many citrus varieties don't do well on their own roots.
Is there any reason to think a cold hardy good tasting Ponciris hybrid will be vigorous on its own roots. That is the ideal, but it also may need to be grafted to rootstock.

kumin

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Re: Poncirus hybrid crosses
« Reply #6 on: April 21, 2023, 12:33:51 PM »
I planted the initial test plot at 20 seedlings per square foot. Survival rates were so low that the survivors were uprooted and replanted to recover space.. Advanced hardier populations will need to be planted at lower densities due to the increase in percentages of survivors. Moving forward, I expect higher percentages of survivors when crossing hardy x hardy parents.
Some of my crosses will be hardy to -5 F parent x 10 F parent. Perhaps 20 - 25% of these may be hardy.
A few of my selections approach Poncirus hardiness, however the proof remains in fruit taste.
The very hardiest trees had no dieback at prolonged 2F temperatures. A month of such temperatures would likely be the death knell for them.

gordonh1

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Re: Poncirus hybrid crosses
« Reply #7 on: April 21, 2023, 12:41:48 PM »
Pagnr, can you elaborate on the concern about open pollination not yielding the desired results?

My understanding is that each cultivar produces a characteristic percentage of nucellar seeds (clones of the mother tree) and a percentage of zygotic seeds. Some cultivars are known to produce true-to-type seeds, which is desirable in a commercial rootstock. I believe there's a source at the University of Florida that lists the percentage of true-to-type seeds for various rootstocks, many of which are citranges, so I was thinking that could be a guide for what citranges would be best to use. We would look for ones that have the lowest % true-to-type. What I don't know is if there are various factors that influence that other than genetics.

Kumin, thanks, I understand I can use very tight spacing if the expected % of survivors is low, with replanting with larger spacing for the survivors of the winter trials, but possibly being in zone 8a where winters are not reliably severe, it is likely I will face the difficulty Ilya mentioned, too many survivors because the winter doesn't provide the required culling. We only get temperatures below 10 F once in a many years, not every year.

As far as grafting the trial survivors onto rootstock, it's true I hadn't considered that.  It will be a lot more effort and therefore limit the number of selections that I can test.  I'll also need to start growing a large enough number of rootstock plants, so those will increase the need for space, too.

Walt

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Re: Poncirus hybrid crosses
« Reply #8 on: April 21, 2023, 12:44:52 PM »
As Kumin said above, selfing is not always a bad thing.  But as he said elswhere, he is planning to cross a citandarin that is about to bloom with a citrimelo.  I think it was.  It was aday or two ago that I read that post.
The ideas expressed here are good ones.  I'll point out that US 852, which was mentioned, can be a useful parent.  It is listed as 85% zygotic.  But US 1278, US 1281, and US 1282 (I hope I got those numbers right) are better at more than 95% zygotic.  But the idea is the same.
Quick turn over is good.  So after selecting for winter hardiness, sending scions south to a longer growing season would speed things up.
As for flavor, Ponciris+ is too sour but the juice with water and sweetener added is a good drink.  So selection for more sugar and less acid would make it edible.  Fewer seeds. bigger. and less hard peel Would make it better.
Kishu Seedless mandarin has a single dominant gene for seedless.  So when its pollen is used, half its seedlings will be seedless.

Pandan

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Re: Poncirus hybrid crosses
« Reply #9 on: April 21, 2023, 12:54:10 PM »
I've never done plant breeding ever though I'd like to one day.

I will continue to buy seeds from collectors with hardy collections with a focus on seeds from plants known to totally hardy and of decent taste. I see this as a way of getting diversity from any possible open pollinations.

I've been wondering about hydroponics as way to boost growth for us home growers for saplings before transplant and cloning, that way you can have a back up (have yet to experiment with this as I'd like)

In the past few days Ive been researching high density orchards for citrus.
« Last Edit: April 21, 2023, 01:03:46 PM by Pandan »

Pandan

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Re: Poncirus hybrid crosses
« Reply #10 on: April 21, 2023, 01:02:01 PM »
Also I think importing citrus seeds from Europe is something I plan to do one day

European citrus nthusiasts have their own hardy selections of note. For example from the other citrus forum I found the "kinga" poncirus extremely interesting: https://citrusgrowersv2.proboards.com/thread/846/alternatives-tasty-poncirus-tryout-germany

Quote
"This plant is actually a three stem cluster growing probably from one seed, it survived several winters with -20C without visible damage. One of the stems bears large fruits, juicy and quite edible."

This is a bit more strenuous than normal seed lots as they require a phyto-sanitary certificate and I think they can't be from countries with HLB (which is present in Spain and Italy IIRC, correct anything I'm wrong on)

bussone

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Re: Poncirus hybrid crosses
« Reply #11 on: April 21, 2023, 04:33:13 PM »
Is there any reason to think a cold hardy good tasting Ponciris hybrid will be vigorous on its own roots. That is the ideal, but it also may need to be grafted to rootstock.

There are reasons to grafting poncirus, but as a popular rootstock, it does do well on its own roots. You can graft it on other things if you are solely interested in increased vigor or a later wake from dormancy, but poncirus is a notoriously tolerant rootstock.

\as much as citrus is known for not liking wet feet, my nearest arboretum has three multi-decade trees that live on the muddy bank of a pond. Poncirus doesn't seem to care.

Ilya11

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Re: Poncirus hybrid crosses
« Reply #12 on: April 21, 2023, 06:10:43 PM »
In the past we discussed on several occasions this idea to keep selection on F1 level  by crossing different F1 hybrids and selecting them initially  for  better freeze resistance with subsequent search for better than poncirus fruit quality.
In  a spring 2020 I pollinated several hundreds of 5star citrumelo flowers by Dunstan pollen.
It resulted in 53 fruits giving a little bit more than 1500 seeds. Germination rate was rather high and I eliminated most of nucellar 5star seedlings by tasting their leaves.
Eventually it produced ~1000 seedlings grown under lamps under high density to the size of ~15 cm high. In January next year they were exposed to our winter conditions with few night frosts and daytime temperatures around 5C.
After that they were subjected to the gradual  artificial freezing that included  10 hours  at 0C , 2 hours at -3.5C and 3 hours at -8C. At this stage, neither  nucellar 5star nor Dunstan seedlings are able to survive.  Eighty eight hybrid survivors were planted in the open ground and for the moment I have around 80 plants, some of them reaching 150 cm height.
Most are trifoliates of different morphology, 2 are mostly monofoliates,

 six showing autumn leaf bronzing and partial leaf drop.

By tasting leaves I observed that for 4 plants  their leaves lack bitterness .



Best regards,
                       Ilya

pagnr

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Re: Poncirus hybrid crosses
« Reply #13 on: April 21, 2023, 06:38:22 PM »
Pagnr, can you elaborate on the concern about open pollination not yielding the desired results?

My point is that I am in a Citrus growing area, and often collect Citrange, Swingle, ( also Rough Lemon ) fruit from seeds for rootstocks from various garden trees,
where the rootstock has taken over, or partly taken over, ( so there is a half rootstock half scion fruiting tree ).
As these trees are usually in gardens with other Citrus, there should be opportunity for random cross pollination.
I don't think I am seeing any significantly different seedlings to indicate this happens.
For commercial rootstock seed production, trees are in arboretums or rootstock tree seed blocks.
Again there should be ample opportunity for cross pollination.
From these rootstock seed trees, tens of thousands of Citrus rootstocks are grown.
There are issues of off type zygotic seedlings, more or less % with the various types of Citranges.
I don't think there is any issue with rootstock seed being out crossed to neighbouring trees.
Some Citrange types produce higher % of zygotic, but these don't seem to be outcrossed, they are off types of the same variety.
Zygotic seedlings do not necessarily need to be the result of outcrossing to another Citrus, they can be self crossed to the same variety, possibly the same flower.

There may be flowering period timing issues as to why the outcrossing is not seen, ie the flowering period of two adjacent varieties does not overlap enough.
Also there may be pollinator behaviour issues. Bees may not move between trees, but work the same tree and rarely hit another tree to X pollinate.
When seed saving heirloom vegetable varieties at risk of X pollination, there are strategies to reduce this by interplanting other species to buffer the pollen movement by bees.
For mixed rows of Fava broad beans, type A type B type C, if you only collect seed from the middle of each type, it is unlikely that bees have jumped between types along the same long row. Only the adjacent plants in the row are likely to be crossed. If you plant peas between the broad beans types in the row, the chance of X pollination of varieties is further reduced due to bee movement behaviour.
There may be ways to reverse this and optimise  X pollination.

Secondly with random pollinations, you will have no idea where any successful seedlings have originated, parent wise.
You may be able to guess the parents from characteristics, but if you want to repeat a cross to get more versions of the same, you will have to start from scratch.
Another point to consider is the way you grow out the seeds.
If you mix all the seeds from all the fruit from one tree and grow them in one lot, you will see random odd seedlings.
If you grow the seed from each fruit separately in its own pot, you can track pollination events and related crossed seedlings.
ie if you grow a container of 100 citrange seeds from ten fruit and find 7 off types, you will have an off type rate of 7/100.
If you grow the seed of each fruit separately, you may find that 5 off types came from only one fruit, and are likely X pollinated ??
The other 2 off types may be both in lots from different fruit, and are likely zygotic.
Hopefully you can then distinguish the characteristics off off type zygotic vs X pollinated seedlings.

Initially you may not want to extensively X pollinate, as it is a lot of work.
You may be able to filter results by separating seed lots by fruit extraction.
You may find differences in % off types, vigour, disease resistance.
If you mix all seeds from all the fruit from all trees in one season, you will have random unrepeatable results.
The more you seperate the seed lots, the more you can see patterns.
Labelling is very important, it can be hard to keep track of what's what as they build up.
« Last Edit: April 21, 2023, 07:43:32 PM by pagnr »

gordonh1

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Re: Poncirus hybrid crosses
« Reply #14 on: April 22, 2023, 12:57:21 AM »
Thaks, Pagnr, that makes sense and I like that it's based on personal experience with various rootstocks in citrus orchards.

If some of the zygotic seedlings are also self-pollinated by the same tree, then that reduces the odds even beyond the percentage of nucellar vs. zygotic seeds.

As you mentioned vegetable breeding, I'm aware that different species have different pollination behaviors, such as strongly outbreeding species such as some types of squash, versus strongly inbreeding species such as tomatoes. Well, there are physical reasons for tomato flowers pollinating themselves, as their flowers are mostly closed up and don't allow pollinators access to them enough to effectively spread pollen. But I suppose sometimes it is not a physical barrier, but a biochemical one that prevents self-pollination in some species.  Also, I'm aware that even different species in the same genus can differ in whether they allow pollination by their own pollen. Some Lilium species are self-fertile and some are not. I have also heard that some Pinapple Guava varieties are self-fertile and some are not.

I gather that citrus is generally self-fertile, but some species and varieties such as Clementine oranges, some mandarins, and some tangerines either set more fruit with pollination from another variety or perhaps require a pollinator.   I wonder if the citrandarins are not self-fertile.

Anyway, I just picked up a Kishu mandarin that I found at a local nursery. It seems that citrus is being sold more and more in Western Washington.  I was wondering how many of the trees that were selling would end up dead of cold weather in a few years.  But the Kishu is obviously for crossing with the best of the Poncirus hybrids to see if I can follow Walt's idea and get a nice seedless fruit. So obviously for that I need to be more deliberate in my crossing and properly learn how to emasculate a flower and then isolate it.  I guess it can't be too hard.
« Last Edit: April 22, 2023, 01:24:36 AM by gordonh1 »

gordonh1

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Re: Poncirus hybrid crosses
« Reply #15 on: April 22, 2023, 01:09:47 AM »
Ilya, thanks for providing some of the details that might allow us to perfect our methods. A very specific set of temperature parameters that is known to be fatal for the parent plants lets you save space, time, and effort, so that is a welcome improvement, especially in areas where we don't have a reliably cold winter every year. I look forward to hearing about the results of your crosses. I imagine several people will start producing ever higher quality Poncirus hybrids. The potential is there, but the big factor is time it takes to grow the plants to maturity, and in some cases, space to grow them. But I guess the efforts of multiple breeders in different continents working separately but sharing techniques and perhaps exchanging some seeds or plants will hasten progress, that is unless government shipping restrictions don't get too much in the way. I'm 52 years old, so I hope to have many generations of citrus trees ahead of me, if I'm fortunate enough to have long life and health.
« Last Edit: April 22, 2023, 01:11:47 AM by gordonh1 »

mikkel

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Re: Poncirus hybrid crosses
« Reply #16 on: April 22, 2023, 02:33:25 AM »
Pagnr, can you elaborate on the concern about open pollination not yielding the desired results?

For mixed rows of Fava broad beans, type A type B type C, if you only collect seed from the middle of each type, it is unlikely that bees have jumped between types along the same long row. Only the adjacent plants in the row are likely to be crossed.

In my experience, it is impossible to get varietally pure fava beans if there is only one plant of a different variety nearby. Even if the varieties are separated by other non-species plants.

A friend who works at the university did a study using fava beans as an indicator of bee activity in the open landscape, since favas are notoriously cross-pollinated. Although no obligatory outcrossers.


mikkel

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Re: Poncirus hybrid crosses
« Reply #17 on: April 22, 2023, 03:01:24 AM »
This winter, I sowed many hundreds of seeds of more exotic varieties such as Haruka, Shekwasha, Kabosu, and others, hoping to find hybrids with other varieties. Crossings among themselves or with rootstock varieties that have bloomed unnoticed. There is variance among the seedlings, even surprisingly so in some varieties, but so far no definitive off-type or even Poncirus-related hybrid.

In my own pollination attempts, I have found that pollination with Ichang Papeda produces hybrids in a lot of cases (off the top of my head, I would even say in all cases). This is true even for varieties that usually produce nucellar seeds. Ichang Papeda also often produces seedlings that bloom after just a few years, including hybrid seedlings. Ichang Papeda has the characteristic of blooming first on the lower branches, not like Poncirus at the top at a certain height. It seems to be a different pattern and is also appearing in some hybrids, leading to earlier flowering.

pagnr

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Re: Poncirus hybrid crosses
« Reply #18 on: April 22, 2023, 03:46:04 AM »
Pagnr, can you elaborate on the concern about open pollination not yielding the desired results?

For mixed rows of Fava broad beans, type A type B type C, if you only collect seed from the middle of each type, it is unlikely that bees have jumped between types along the same long row. Only the adjacent plants in the row are likely to be crossed.

In my experience, it is impossible to get varietally pure fava beans if there is only one plant of a different variety nearby. Even if the varieties are separated by other non-species plants.

A friend who works at the university did a study using fava beans as an indicator of bee activity in the open landscape, since favas are notoriously cross-pollinated. Although no obligatory outcrossers.

That was a strategy from a heirloom seed grower. They only retained mid row seeds for variety conservation, and claimed that was adequate without covers or bagging.
Last time I grew a lot of Fava bean varieties, I separated the varieties with about 10 m of pea plants, and spaced the rows of Favas about 10 m apart with rows of peas in between. Also separated by rows of grape vines. Going by seed colour in later years, this seemed to be ok, but there were a few hybrid plants among some lots.
« Last Edit: April 22, 2023, 10:05:22 AM by pagnr »

1rainman

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Re: Poncirus hybrid crosses
« Reply #19 on: April 23, 2023, 06:08:24 PM »
I would rather see someone crossing dwarf meyer lemon with tangelos and oranges. It's the only dwarf citrus I got that stayed small.enough for a container and produced well. I would rather go the container route. I had a dwarf tangerine that was almost small enough if only someone crossed it with meyer.

1rainman

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Re: Poncirus hybrid crosses
« Reply #20 on: April 30, 2023, 08:12:22 PM »
Actually I just saw on the website in Europe they have a lot of meyer lemon crosses. One of them is with a dwarf sour orange. The hybrid is very cold tolerant and fruit is good for cooking or lemonade type drinks with orange flavor. It is dwarf enough to grow in a container.

While not as cold tolerant as poncirus this would be a good start for breeding. The fruit is edible. Maybe cross with Florida 119, Dunstan grapefruit or satsuma or something. And put all those in the mix. Grow it in Georgia or north Carolina where it's fairly warm but colder than most citrus grow or do them as container plants or greenhouse. The end result I would buy. The poncirus would need to be highly diluted such as using fl 119 and Dunstan grapefruit in the mix. But then crossing with more edible stuff like meyer lemon, satsuma etc. Then some sour orange in the mix. Maybe cold tolerant pomelo in the mix. That sort of thing. Mostly dwarf.

Meyer lemon is the best all around plant. Fruit is only slightly bitter when fully ripe. Edible right off the tree. Very small dwarf plant especially the dwarf version grows well in containers. Decent cold tolerance. It would be the one I would cross in the mix most often. Meyer x desert lime in the mix would be good but seems a lot of those are misidentified desert lime crosses with a grapefruit or something. Seems hard to find the real thing. Desert lime would be good in the mix for disease resistance and cold tolerance. Poncirus crosses unless it's really diluted in the mix don't seem worth eating.

mikkel

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Re: Poncirus hybrid crosses
« Reply #21 on: May 01, 2023, 01:54:22 AM »
Actually I just saw on the website in Europe they have a lot of meyer lemon crosses.
Hi 1rainman, do you have a link?

gordonh1

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Re: Poncirus hybrid crosses
« Reply #22 on: May 01, 2023, 09:52:05 AM »
While other breeding projects may be interesting, there is still a desire for a citrus hybrid that can grow in the landscape in colder climates. I have potted citrus, and so do other hobbyists in my region, but that's not a substitute for a landscape tree. Potted trees don't become a permanent fixture to outlast the occupancy of their tenders, and the same is true of trees that are strung with Christmas lights and wrapped in blankets every time it gets cold.

Poncirus hybrids have the potential, like Poncirus itself, to withstand all that my climate can deliver. That's not the case with most other citrus. Even Yuzu is marginal here and can be killed down to the roots. The same is true north of zone 8 in many other parts of the world. We need hybrids with the tree characteristics needed to withstand the cold winter, probably including deciduous leaves, dormancy to prevent too early growth, and early ripening.

kumin

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Re: Poncirus hybrid crosses
« Reply #23 on: May 01, 2023, 09:57:51 AM »
I'll say you're right on the bullseye. What's likely needed is a Poncirus tree that hopefully produces a Citrus fruit that ripens before Winter.
« Last Edit: May 01, 2023, 02:40:48 PM by kumin »

Walt

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Re: Poncirus hybrid crosses
« Reply #24 on: May 01, 2023, 02:28:14 PM »
I just posted a couple of posts on another thread that could have been posted here.
https://tropicalfruitforum.com/index.php?topic=50899.0;topicseen
Most of you on this thread probably know everthing I put on those posts so I put it there where there were some with less background although some are on both threads and giving good advice.

 

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