Many Teas and Chinas will grow whenever the ambient temperature is warm enough. Rosa multiflora, on the other hand, goes dormant in the fall, and stays “asleep” for some time. I would expect the progeny of a cross between Multiflora and a China or Tea to segregate in the F2 for winter dormancy, but I have found no published study.
Has anyone observed this sort of segregation in other crosses of winter-dormant and non-winter-dormant varieties? Are there any published reports I’ve missed?
I have searched for information on the inheritance of winter dormancy, but most of the reports I’ve found have dealt with efforts to reduce the chilling requirements of fruit trees (apples, peaches, apricots, etc.). In breeding for hardiness in roses, it would be useful to increase the chilling requirement to delay sprouting in the Spring, as well as to select for earlier dormancy so the plants will be prepared for early frosts in the Fall.
Some roses are surprisingly hardy. ‘Gloire de Dijon’ tolerates winter better than other Teas because it has a proper dormancy, presumably with a chilling requirement that prevents it from “waking up” during warm spells during the winter. ‘Marechal Niel’ reportedly survived a winter in Oklahoma that killed various other roses that had been bred for the far north by Brownell and Horvath. I doubt that ‘Marechal Niel’ has a proper dormancy, but it does love heat – a fact that suggests it would be unwilling to grow at low temperatures.
Some roses of the far north apparently lack dormancy. They don’t need it because the continuous cold prevents them from growing. The octoploid R. acicularis suffered winter-kill at Ann Arbor, MI. And seeds of R. blanda collected in northern Michigan segregated for tenderness and hardiness when raised at Ann Arbor, 300 miles south of their original home. No doubt these “tender” seedlings would have done well back home where the continuous cold restrained their growth.
It would be interesting to cross Marechal Niel with Gloire de Dijon in order to combine the heat-loving property of the former with the dormancy of the latter. Such a cross would be more likely to give hardy offspring than any cross involving the octoploid R. acicularis or one of the R. blanda seedlings that was tender at Ann Arbor.
One more thing: I have read that the descendants of ‘Rival de Pestum’ are hardier than most other Chinas and Teas. Does anyone have experience with any of these (Comtesse du Cayla, Mme. Laurette Messimy, Madame Eugène Résal)? Does ‘Rival de Pestum’ or its offspring go dormant in Autumn?
And some notes on this subject:
The Gardener’s Monthly 2(3): 69 (Mar. 1860)
HARDINESS OF CHINA ROSES
CHARLES G. PAGE, WASHINGTON, D. C.
There is probably no variety of rose that will endure a temperature of zero Fahr. upon unripened branches, and expanded leaf buds; and there are probably very few roses that will not endure this temperature provided the wood has been fully ripened and the buds are all dormant and the sap quiet. The Gloire de Dijon is an excellent illustration. It belongs to a tender family, but is perfectly hardy here. Its hardiness is not, however, entirely intrinsic, but depends upon its habit of growth. Unlike Teas and Noisettes generally, it stops growing in the fall, and is not apt to be quickened again till the spring. It prepares for winter like a Remontant, and has proved itself here more hardy than the majority of Remontants. In that rigorous winter of 1855-6, it stood better than La Reine, Madame Laffay, Wm. Griffith, and others. This winter has been thus far very destructive to Teas and Noisettes, but the Dijon is unharmed.
http://bulbnrose.x10.mx/Roses/breeding/PageHardyBengals1860.html
The Rose Garden – Division 2, Page 124 (1848)
William Paul
The Gloire de Rosomene suffers from severe frost: the progeny is hardy.
Bot. Gazette 96(2): 197-251 (1934)
EXPERIMENTAL DATA FOR A REVISION OF THE NORTH AMERICAN WILD ROSES
BY EILENE WHITEHEAD ERLANSON
p. 207
R. acicularis from Alaska (2n = 56) responds so rapidly to a rise of temperature in spring that the flower buds are almost always completely frost-killed in April in southern Michigan. The hexaploid requires more or prolonged warmth and always flowers profusely.
Seedlings of R. blanda from northern Michigan segregated into tender and hardy individuals at Ann Arbor, 300 miles south of their natural habitat.
http://bulbnrose.x10.mx/Roses/breeding/Erlanson/ErlansonRevision1934.pdf
New Phytol. 37:72-81. (1938)
PHYLOGENY AND POLYPLOIDY IN ROSA
By EILEEN W. ERLANSON, D.Sc.
pp. 77-78
A plant of octoploid R. acicularis from Alaska was transferred to Ann Arbor, Michigan, where it leafed out soon after the first April thaw and was frequently badly damaged by frost in May. In some seasons all the floral primordial tissue was destroyed and no flowers were produced. The alternating thaws and frosts which are a feature of continental climates between 40 and 50° of latitude North, may militate against the spread southwards of octoploid races in Rosa. The Alaskan octoploid thrived at Pasadena (Erlanson, 1934) in southern California, and came into flower early in February, 3 1/2 weeks before the hexaploid type.
http://bulbnrose.x10.mx/Roses/breeding/Erlanson/ErlansonPhylogeny1938.html
American Rose Annual p. 103 (1943)
Maurice H. Merrill
Normal, OK
In my garden the Brownell and the Horvath productions, bred for resistance to winter cold in northern latitudes, so far, with the exception of Mabell Stearns, have displayed a susceptibility to severe, and often fatal, winter injury. In contrast, the hardiest, least winter-harmed bushes I have today are Old Blush, a China which is close to a Tea, and a nameless waif I acquired on our farm, where it had been brought by the tenant’s wife who found it at a roadside filling station. Federation shows much more damage from this last winter than do three young Marechal Niel plants, not yet fully established. All this leads me to the none-too-profound suggestion that the qualities which make for hardiness in the long, severe northern winters, in which a rosebush can hibernate like a bear, may not facilitate survival in the open winters of the Upper South, particularly our western portion, punctuated with occasional periods of severe weather.
http://bulbnrose.x10.mx/Roses/Rose_Pictures/M/marechalniel.html
American Rose Annual 41: 118-122 (1956)
Difference In Resistance To Spring Freezes In Rose Varieties
Dr. H. R. Rosen
In general those varieties which have an inherent tendency to break their dormancy ahead of other varieties are apt to suffer more from late spring frosts and freezes. For example, Climbing Mme. Edouard Herriot, one of the most beautiful and hardier sports of a Hybrid Tea when it is dormant, having withstood temperatures below zero while unprotected in my own garden, has the habit of breaking its dormancy considerably ahead of such varieties as Paul’s Scarlet Climber, New Dawn, Bonfire, and Chevy Chase. It had much new growth and numerous blossom buds when the March freezes struck and although about twenty years old, it was completely killed. On the other hand, while the other varieties just mentioned suffered a loss of 50 to 90 per cent of their wood, all of them survived.
Another factor which tended to obscure the relationship of winter hardiness to resistance to spring freezes is rapidity of growth. Contrary to what might be expected, those varieties which made the most new growth prior to the freezes were the ones which were hurt the worst. Thus in the fungicidal test plots where two old standard varieties have been used for many years, Etoile de Hollande and Edith Nellie Perkins, the former suffered far worse than the latter although both broke their dormancy about the same time, as they usually do. Etoile de Hollande usually makes about twice the growth in a given length of time, as it did prior to the freezes. Out of 88 plants of this variety, 49 were completely killed and the remainder were set back to such an extent that they probably fell far below average in seasonal amount of growth and of blossom production, while of 96 plants of Edith Nellie Perkins, only 34 were lost and the growth and seasonal blossom production of the remainder appeared to have suffered very little. However, as no blossom counts were made this year because of loss and injury, the data are incomplete.
http://bulbnrose.x10.mx/Roses/breeding/Rosen_Spring.html
American Rose Annual 26: 111-115. (1941)
The Search for Total Hardiness
Georges Bugnet
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.
Native trees here, as a rule, put out their leaves around the middle of May and drop them near the end of September. Roses have also to be brought to an early ripening of their tissues.
http://bulbnrose.x10.mx/Roses/breeding/Bugnet.html