Remontancy

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Re: Remontancy

by Karl K » Sun Nov 04, 2018 6:03 pm

david zlesak wrote:
Mon Aug 27, 2018 9:33 am
I LOVE the work you are doing Joe. Hopefully reshuffling the genes of your hybrids in future generations will lead to many hardy, healthy, reblooming hybrids with beautiful flowers. Dr. Roger Mitchell a number of years ago (perhaps he still is an RHA member, I haven't heard from him in awhile) wrote this very nice paper on rebloom in species rose hybrids. http://www.globalsciencebooks.info/Onli ... 46-52o.pdf
I have to admit that anyone who writes, Rosa wichurana Crépin will have to work harder than usual to get me to take the work seriously. But there is one very important point that should be repeated frequently.

"Rosa rugosa does not usually begin to bloom until plants have grown to nearly mature size (Zlesak 2001)."

This is not unique to R. rugosa. Nor is it unique to roses. Garner & Allard (1920) introduced the subject of photoperiodism. They first got together because both of them were studying the mysterious 'Maryland Mammoth' tobacco. This strain would grow like any other tobacco until it approached the normal flowering time. While other strains bloomed, MM paused briefly, they resumed its growth.

If the plants were cut down and transplanted into a heated greenhouse, they would come into bloom in the dead of winter. Seedlings started in the same greenhouse would grow until they were 3 feet or so tall, then start blooming.

Please note: they did not start blooming as soon as they produced a few leaves. They could not respond to the inducing (short) photoperiod until they were big enough.

There was some variation in the height at which the seedlings began to bloom, but G & A did not stop to wonder whether the differences were hereditary. They had enough on their plates, at the time, so I hold no grudge.

The same holds true for various fruit trees and grains and ... whatever. There is a minimum quantity of growth that must be made before inducing conditions can ... induce.

Cutting back the plants cannot get them to hurry up. It only delays them.

Van Mons (1835) discussed a variety of techniques he used to hasten the maturity of fruit trees. A bit of crowding helps, as well as shortening the laterals to encourage the main shoot to grow.

Re: Remontancy

by Karl K » Sun Sep 02, 2018 1:14 pm

It is commonly stated that the everblooming trait is recessive, and therefore not expressed in the first generation. However, there are some instances where the trait is expressed in the F1, but only in winter.

http://bulbnrose.x10.mx/Roses/breeding/WinterRoses.html

Re: Remontancy

by david mears » Tue Aug 28, 2018 4:44 pm

Thank you David, I have downloaded it to read so I can digest some of it.

Re: Remontancy

by Margit Schowalter » Tue Aug 28, 2018 10:42 am

Interesting paper. Thanks David.

Re: Remontancy

by Rob Byrnes » Mon Aug 27, 2018 10:02 am

Thanks for posting the link to that paper David!

Re: Remontancy

by david zlesak » Mon Aug 27, 2018 9:33 am

I LOVE the work you are doing Joe. Hopefully reshuffling the genes of your hybrids in future generations will lead to many hardy, healthy, reblooming hybrids with beautiful flowers. Dr. Roger Mitchell a number of years ago (perhaps he still is an RHA member, I haven't heard from him in awhile) wrote this very nice paper on rebloom in species rose hybrids. http://www.globalsciencebooks.info/Onli ... 46-52o.pdf

Re: Remontancy

by Plazbo » Mon Aug 27, 2018 3:21 am

That's kind of why I'm basing rugosa around Schneezwerg and Calocarpa. The former has demonstrated a small capacity of fertile crosses with tea/china and the latter is half china. Will see what happens in the season that's approaching. Bound to be a lot of sterile but selection over a few gens will probably make that less of an issue.

Re: Remontancy

by jbergeson » Sun Aug 26, 2018 11:42 pm

The OP Will Alderman have surprised me with the amount of growth they've put on, which is still not much but they appear to want to survive at least. I'm a little disillusioned with rugosa crosses as the blossoms seem to be inevitably smaller and shorter lived than those of either parent and they scream "Sterile!" Might just have to find the right rugosa parent. Henry Hudson has done some nice things but I no longer have one growing and will have to wait until I get one established until I can start breeding with it again.

Re: Remontancy

by Plazbo » Sun Aug 26, 2018 7:03 pm

jbergeson wrote:
Thu Jul 19, 2018 9:22 am
Plazbo, my OP Alderman seedlings that bloomed as juvies are seeming pretty weak. I doubt they will amount to anything. I do, however, have some juvi bloomers from crosses with Ann Endt, Belle Poitevine, and a rugosa seedling. We'll see how that goes.
Possibly just the juvenile phase or investment in blooming over plant growth, I've got a few seedlings from last year that were very runty and wanted to bloom but a year later and a lot of them have grown out of it....although that may be because they grew through winter with a break from trying to flower.

Re: Remontancy

by Karl K » Sun Aug 26, 2018 2:02 pm

Another aspect of hardiness that is often overlooked is optimum growth temperature.

The subject of temperature and growth has been studied from time to time, but the needs of commercial growers of cut flowers are not the same as those of gardeners. A commercial grower wants a plant that continues growing and blooming at low temperatures (approaching freezing) to reduce heating costs. A northern gardener, on the other hand, is better off with a plant that refuses to grow at low temperatures when frost is possible.

Then again, many growers expect their rose bushes to start early and finish late. These expectations conflict with hardiness. A plant that begins growing too early in the season risks damage from late frosts. And a plant that continues growing too late in the year risks similar injury from early frosts.

Rosen (1956) found that varieties that break dormancy late suffered less damage from late March freezes than the earlier types. And plants that grew slowly were less harmed than the faster types that started at the same time.

The late season is just as important in the search for total hardiness as Bugnet (1941) observed.
"With a much longer experience, on a larger scale, in stone-fruits breeding, I am led to believe that a plant, in order to withstand our climate, needs a very early ripening of its tissues. Winter-killing, apparently, is not caused by extreme cold but rather by a too early cold snap catching immature wood, like the 30° below we had in the first part of November last. Once, at dawn, on October 12, 1930, we had 16° below zero. The next day was rather warm. None of my hardy hybrids and no native tree or shrub suffered. I have often noticed that half-hardy plum or apple trees here, unhurt by December 1, passed unharmed through the rest of the winter no matter how intense the cold."
Risley (1958) pollinated 'Skinner's Rambler' by an assortment of other roses. He chilled the seeds, but found that the time to germination varied widely (83 days to 173), according to the pollen parent. Two of these caught my attention. The offspring of 'Persian Yellow' started sprouting in 91 days, whereas those from 'Diamond Jubilee' took 160 days to come up. Both of these varieties are descended from Rosa foetida. However, 'Diamond Jubilee' is a seedling of 'Marechal Niel', a variety that loves heat and refuses to grow at low temperatures that other roses could enjoy.

The slowest seedlings to appear were from 'Queen of the Lakes', a Brownell "Sub-zero" rose.

I think that Risley got tangled in terminology. He assumed that the late appearance of some seedlings was due to a greater chilling requirement. But he was not watching to see when the seeds germinated, only when the seedlings emerged. The ability to grow (or not) at low temperature would skew the results. That is, one seedling might germinate early (short dormancy) but emerge late due to its slow growth at the stratification temperature. On the other hand, a different seedling might germinate late, then grow rapidly.

The point, here, is that growth rate can be assessed independently from dormancy-breaking. Plants that grow slowly or not at all at low temperatures will likely suffer less damage from late Spring frost and early Fall freezes.

Selection for growth temperature has been done successfully in the Calla, 'Green Goddess'.
http://www.actahort.org/members/showpdf ... rnr=766_19

Bugnet: The search for total hardiness (1941)
http://bulbnrose.x10.mx/Roses/breeding/Bugnet.html
Rosen: Resistance to Spring Freezes (1956)
http://bulbnrose.x10.mx/Roses/breeding/ ... pring.html
Allen & Asai: How Frost Damage Occurs (1943)
http://bulbnrose.x10.mx/Roses/breeding/Frost/Frost.html
Asai: Repeated freezing and thawing (1944)
http://bulbnrose.x10.mx/Roses/breeding/ ... g1944.html
Greeley: Temperature and Rose Bloom (1919)
http://bulbnrose.x10.mx/Roses/breeding/ ... y1919.html
Greeley: Night-Growth of Roses (1920)
http://bulbnrose.x10.mx/Roses/breeding/ ... rowth.html
Risley: Male controls sprouting (1958)
http://bulbnrose.x10.mx/Roses/breeding/Risley.html

http://bulbnrose.x10.mx/KKing/HeatGrowth.html

Re: Remontancy

by Karl K » Fri Aug 17, 2018 6:44 pm

I should have mentioned that 'Golden Promise' (floribunda, de Ruiter, 1972) behaves in San Jose, the way 'Golden Showers' does in Kansas. The canes stop growing in heat. San Jose heat is somewhat less scorching than Kansas heat, and 'Golden Showers' is quite happy in SJ.

'Golden Promise' caught my attention only when I was going through my photos and noted that it was blooming in December and January.
http://bulbnrose.x10.mx/Roses/Rose_Pict ... omise.html

Re: Remontancy

by Karl K » Thu Jul 19, 2018 10:44 am

Larry Davis wrote:
Wed Jul 18, 2018 10:49 pm
Goldilocks here is about the same as Doubloons, perhaps a bit worse. Allgold didn't last long either. And Golden Slippers is maybe worse than either. I mean for hardiness and BS. Beautiful flower for about 5 hours. That's why I produced Ruby Slippers (13-2).
I have seen 'Goldilocks', 'Golden Slippers' and 'Allgold' only at the San Jose Heritage. BS is not a problem there, and the summers are not as miserably hot as Kansas. So, maybe it's the heat. Le Grice was aiming for a yellow rose that did not turn turnip-y white during cool, damp weather. 'Allgold' was the result. It isn't the best shaped rose, but the color is stable ... at least in San Jose.

'Golden Showers' is a fine rose in San Jose, but in Kansas the buds that began to open at breakfast were full blown by lunch, and dropping petals by supper. The canes stop growing in really hot weather.

Re: Remontancy

by jbergeson » Thu Jul 19, 2018 9:22 am

Don, my soil is too alkaline for rhododendrons. Rugosa roses are borderline in this soil, too, which is another reason I want to cross them with moderns.

Plazbo, my OP Alderman seedlings that bloomed as juvies are seeming pretty weak. I doubt they will amount to anything. I do, however, have some juvi bloomers from crosses with Ann Endt, Belle Poitevine, and a rugosa seedling. We'll see how that goes.

Combining hardiness and rebloom is like moving a fridge by yourself...it's a slow walk forward, corner by corner.

Re: Remontancy

by Larry Davis » Wed Jul 18, 2018 10:49 pm

Goldilocks here is about the same as Doubloons, perhaps a bit worse. Allgold didn't last long either. And Golden Slippers is maybe worse than either. I mean for hardiness and BS. Beautiful flower for about 5 hours. That's why I produced Ruby Slippers (13-2).

Re: Remontancy

by Karl K » Tue Jun 19, 2018 11:14 pm

Larry Davis wrote:
Mon Jun 18, 2018 6:58 pm
Unfortunately Doubloons isn't actually hardy below 0 F and it is one of the worst black-spotters around. Can't comment on Mr. Nash.

I'm still using a couple Doubloons offspring but most have expired naturally. Well over 100 of them.
Larry,
That's good to know, but disappointing. Fortunately, 'Doubloons' offspring 'Goldilocks' seems to be healthier, as is its grandchild, 'Allgold'. I can't vouch for the hardiness of either, though.

Re: Remontancy

by Larry Davis » Mon Jun 18, 2018 6:58 pm

Unfortunately Doubloons isn't actually hardy below 0 F and it is one of the worst black-spotters around. Can't comment on Mr. Nash.

I'm still using a couple Doubloons offspring but most have expired naturally. Well over 100 of them.

Re: Remontancy

by Don » Mon Jun 18, 2018 4:39 am

Joe, have you considered switching to rhododendrons?

Re: Remontancy

by philip_la » Sun Jun 17, 2018 2:13 pm

If it were easy...
I think you are taking the route that ultimately may lead to success. "Stirring the pot" offers little to those of us without the means to grow massive numbers of seedlings, I would think, and the harder paths will probably offer the best rewards.
I'm far enough south to have no clue as to what I'm talking about here, but several years ago, Joan Monteith shared seeds from a Mr. Nash x Rugelda cross. (She said she didn't know what she was thinking when she made the cross, but I was certainly intrigued by the concept.) If Nash is Doubloons, as speculated, the potential for cold-hardiness was in the resultant seedlings. Germination was surprisingly good and quick, and the plants had warm colors, very double flowers, and good fertility. (Alas, I was unable to keep any, and I won't pretend that the last of those seedlings appreciated central Texas very much.) Point being simply that I imagine there are probably some pretty less-than-self-evident mixes that could pan out to give you some interesting material.

Re: Remontancy

by Karl K » Sat Jun 16, 2018 1:49 pm

jbergeson wrote:
Fri Jun 15, 2018 2:46 pm
Another issue with using rugosas crossed with modern roses is that the resulting plants seem to be sterile triploids most of the time.
'Conrad Ferdinand Meyer' is a fertile tetraploid that has been used with some success in breeding hardy roses.
David Austin's English Roses (1993) p. 28

The third line we pursued was by way of the Rugosa hybrid 'Conrad Ferdinand Meyer.' At first we harbored no great hopes of success, for we feared that the resulting seedlings from a cross with this excessively vigorous hybrid would be altogether too gross in character. 'Conrad Ferdinand Meyer' was itself a cross between the very popular and beautiful Climbing Noisette Rose 'Gloire de Dijon,' and an unknown Rugosa hybrid. It also had one of the most powerful and delicious fragrances. As before, we crossed with some of our better English Rose in particular 'Chaucer,' and had one of those pieces of luck that sometimes turn up in rose breeding. Some of the seedlings from this cross were of typical rugosa appearance, while others bore absolutely no resemblance to a Rugosa Rose. It seemed that some of our hybrids had taken the genes only from the 'Gloire de Dijon' half of 'Conrad Ferdinand Meyer,' while others had inherited those from the Rugosa side. What we had in many instances were in effect hybrids of 'Gloire de Dijon.'

Re: Remontancy

by jbergeson » Sat Jun 16, 2018 10:14 am

Thanks everyone for your responses!

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