Citrus Growers Forum

GregMartin · Posted: Tue 09 Jul, 2013 7:22 pm

Thomasville is on my list of plants (including Juanita, Early St. Anne and a few others) that will be crossed back to Poncirus...the resulting plants to be crossed again with others that were hardy citrus x Poncirus such as citchangsha.

Scott_6B · Posted: Tue 09 Jul, 2013 9:58 pm

Greg,
FYI, my Early St. Ann seems to produce very little pollen.

I would be curious to know if anyone has ever tried crosses with C. latipes. It is purported to have similar hardiness as C. ichangensis. Here's the description of the fruit taste: "Fairly juicy, not bad taste at first, then unpleasant aftertaste." Seems not too bad for something that is potentially quite hardy. Laughing

http://www.citrusvariety.ucr.edu/citrus/latipes.html

buddinman · Posted: Wed 10 Jul, 2013 2:08 am

In my 40 plus years of growing citrus, primarily satsumas there has never been a citrus with trifoliata in the back ground that is worth while to propagate, this includes the dragon lime that was found growing at tree search farm, Houston Texas in the 80s.

Marches · Posted: Tue 03 Sep, 2013 9:39 pm

Millet wrote:

I had a seedling tree that originally produced some pentafoliate leaves. I posted it on the forum some time back. However, the tree no longer produces any pentafoliate foliage. Why it did as a VERY young seedling, now none, I have no idea. - Millet

Sometimes juvenile plants have very different leaves. Figs are totally weird when it comes to foliage - they can drastically change the shape of their leaves in a matter of weeks for now apparent reason.

Marches · Posted: Tue 03 Sep, 2013 9:44 pm

Till wrote:

Hello Greg, it encourages me that you are with me. Hope we have one day something selfbred to exchange.

To your question Sylvain:
I want to make it more probable that all the hardiness genes necessary come together in one plant. Therefore I want to cross F1 plants back to Poncirus and also hardy F2 plants back to Poncirus. Thereby I create plants with over 50% of Poncirus genes. It is very likely that those plants have fruits much like those of Poncirus (so Swingle about cicitranges). But that may change in the next generation. Therefore I plan to create another generation by selfing with the F2 and F3 plants. So I plan with two generations. Might be doable in 10-15 years. And as far as I know nobody has done it before.
I hope that plants with more than 50% of Poncirus genes also produce more zygotic offspring than citranges. (As a rule fertility increases when the two cromosome sets are more similar. Hope that is also the case in these crosses.)
What I want to do sounds like a very frustrating long term programme. But I expect that the backcrosses with Poncirus will already be interesting. We have for instance a Segentrange in Europe, called Sanford Curafora, which can withstand -12°C and has good fruit. This plant crossed with Poncirus might give us Citrandarins which are hardy close to -20°C. I would be glad to have such plants even though the fruit might be good for nothing else than a lemonade or marmelade. Wish me luck! For I am crossing Sanford Curafora at the moment. Hope I get some seeds. Unfortunatelly the plant is said to have every few seeds if any. (If I don't succeed I cross the opposite direction next year.)

Sounds like a nice plan. First I think we must find superior strains of Poncirus though.

ilyaC wrote:

Till,

Do not quite understand what you are trying to achieve crossing citranges or citrumelos with poncirus. Fragrant hardy decorative poncirus? These crosses even theoretically will never give edible hybrids with poncirus level hardiness.

Both hardiness in poncirus and "good" smell and taste in citruses are determined by dozens of genes spread all over genome.
Theoretically, they can be separated and combined in one plant by crossing several poncirusXcitrus F1 plants and selecting among thousands, may be even millions of zigotic seedlings.
This is in parallel with what modern hybridizers of garden roses are doing in order to get new breeds. Kordes in Germany is selecting few new varieties out of millions seedlings.

Taking into account scarcity of true zygotic mothers among F1 poncirusXcitrus hybrids, long juvenile period and large size of citrus trees a similar program for hardy citruses will require a huge investment.
The cost can be reduced only if DNA markers both for hardiness and "good" taste are known, so the selection by culling can be done early. But for the moment we are rather far from this understanding.

Of course just serendipity can some time work, so it is still worth to try like Dr. Brown and others have been doing in the past.

This would be a lot easier if citrus just grew as annuals. Laughing

Do you think crossing other citrus with Citrus ichangensis would be better? Presumably the nasty flavours of Poncirus wouldn't be there, but the hardiness wouldn't be as good either.

Marches · Posted: Tue 03 Sep, 2013 9:51 pm

Till wrote:

Hi Sludge, just try. Your idea could be really good since C. ichangiensis is said to suppress the resin taste - at least according to Dr. Brown. I am thinking about (Poncirus X C. keraji) * Nagami. That may be sweeter. However, Thomasville is the only sweet citrangequat. So not so encouraging for somebody hoping for sweetness.

Interesting. If that's the case, what does the fruit taste like?

Till · Posted: Thu 12 Sep, 2013 5:53 am

Yes, that is a good question. We can only try and wait for the fruit...

Till · Posted: Thu 12 Sep, 2013 7:06 pm

I have got an idea or question today: Are we absolutely sure that the bitter taste of Poncirus hybrids come from Poncirus genes? The question sounds stupid because that seems to be obvious. However, I got doubts. My reasons:
1) Many Citrus plants have a gene for bitterness.
2) It can be regarded as a fact that all Citrus plants contain the feature of trifoliate leaves even though it remains hidden until it breaks out under Poncirus influence.
So if the trifoliateness can serve as an analogy then it might be that not only Poncirus genes create the bitterness but that they also activate the hidden bitterness of the other crossing partner (orange, lemon...). That would mean that even though we breed the Poncirus genes out a kind of bitterness may remain as monofoliate F2 hybrids occasionally produce trifoliate leaves because this feature has been partially activated.

What do you think? Are these thoughts too farfetched?

Given they were reasonable we may try to suppress the expression of bitterness by vegetative hybridisation. I would be very interesting in any experiments of others that show how vegetative hybridisation helps. (I have red the article in the form already.)