Effect of daylength, light intensity and temperature on growth and flowering in roses

Journal of the American Society for Horticultural Science 97: 796–800. (1972)
Effect of daylength, light intensity and temperature on growth and flowering in roses.
Roar Moe

Increasing the daylength (from 8 to 16 or 24 h) inhibited budbreak in glasshouse roses, whereas high temperatures (21 or 27 deg compared with 15 deg C) hastened it. The initiation of flowering was promoted by high light intensity and by long days. The effect of daylength was temperature dependent. At low temperatures rose shoots differentiated more leaves before flower initiation with short days than with long days, whereas at high temperatures there was no appreciable difference between daylength responses. The rate of shoot growth was stimulated by long days and high temperatures. The final length of shoots at flowering was considerably greater with 16-h days than with shorter days, but increasing temperature and light intensity both decreased eventual shoot length. The growth of the uppermost internodes, and especially the neck of the flower shoot, was most sensitive to daylength, temperature and light intensity. The number of days from the time of cutting-back until flowering was reduced by increasing daylength, temperature and light intensity.

This is an old paper, but it suggests some of the rather cryptic differences between cultivars that may contribute to “hybrid vigor”.

The abstract of Moe’s paper does not tell us how many cultivars were studied. This is important to know, because Greeley (1919) found that the optimum growing temperature varied from cultivar to cultivar. No doubt there would also be differences in the responses to varying daylength and light intensity. And when we look at species, the differences will be even more striking.

Hi Karl,
Can you please explain in layman’s terms how and why Warren Millington can get such great results using Canadian breed roses
like Therese Bugnet,(as posted on FB). TB doesn’t thrive, and hardly flowers or set hips for me here in the Manitoba. For a long time, I thought TB was sterile. Until I saw a plant covered with hips in Nova Scotia, four years ago.
I would be delighted to hear how TB does in other parts of the world.

I don’t have nearly enough information. How do the climate and soil differ between Manitoba and Nova Scotia? I haven’t been to either province, and I have not seen ‘Therese Bugnet’.

It would be helpful if other people in the north (and not so north) would weigh in on their successes/failures with ‘Therese Bugnet’.


Therese Bugnet has grown well (bloomed well) for me, both in the Midwest (U.S.) and now in the inland pacific northwest. I did not try breeding with it in the midwest, but so far have been able to get seedlings from it here in north central Washington. Oddly, the first bush I have grew here for six years before setting a hip, only to start setting hips the last few years. I have two other bushes I only put in a couple seasons ago and they are both setting hips, so I don’t think it was a matter of age. Weather conditions influencing it? All three bushes set OP hips this year. I put pollen on two bushes (testing about a dozen different pollens). I only had hip set with one: Mary Rose. Oddly I used Theresa Bugnet pollen on other bushes and it didn’t set well either, although they set hips with other pollens.

In short I have gotten hip set with crosses, but picky. Lots of OP hips, wish I could figure out where the pollen was coming from that is working so well. I’m wondering if it is from wild roses up the hillside, as there are bushes spread out all over the hillside.

Seed germination was good on other years. This year it hasn’t started yet, though I saw one seed cracking open, so hopefully the ball is about to get rolling.
Also, I have found much better hip set on the seedlings I grew from her than Therese herself: so it may be easier moving forward depending on which direction you wish to travel (diploid or not).


Another matter has come to my attention again that might be useful.

Pollen tubes are living things. Teeny tiny plants with genes, functions and preferences of their own. Furthermore, there is around a 67% overlap between genes active in the pollen tube and those active in the sporophyte (e.g., the plant). Therefore, it is possible in varying degrees to impose environmental conditions on the pollen tubes during their short lives that we want to have expressed in the plants.

In other words, pollination at low temperatures favors the growth of pollen tubes carrying genes that favor growth at low temperatures. This was demonstrated by pollinating tomato blossoms with a mixture of pollen from an ordinary tomato, and an accession of Lypersicon hirsutum collected at an altitude of 3200m. That’s high, and that’s cold. The result was that twice as many hybrids were formed at 12/6°C as compared to crosses with the same mixtures at 24/19°C.

We should also expect variation within a species, race or strain.
"Here, we have used peach to evaluate the effect of temperature on some processes of the progamic phase, from pollination to the arrival of pollen tubes in the ovary. Within the range of temperatures studied, 20°C in the laboratory and, on average, 5.7°C in the field, the results show an accelerating effect of increasing temperature on pollen germination and pollen tube growth kinetics, as well as an increase in the number of pollen tubes that reach the style base."
The underlined phrase suggests that some of the pollen tubes are more cold tolerant than others. It remains to be seen whether pollination at lower temperatures would yield peach trees that are also more cold tolerant. Or at least more able to be pollinated at lower temperatures.

I was looking for a note I thought I’d put on HelpMeFind and found this one I posted in 2013.

Reading Zukofsky’s 80 flowers - 1989 - Page 214
Michele J. Leggott

Nitida means “shining” and, according to Gray, the rose flowers “in evening with fragrance of Convallaria”; that is, lily-of-the-valley.

Evening scented flowers are typically pollinated in the evening.

Rhodora 28(328): 56-57 (April 1926)
Botanizing in Newfoundland
M. L. Fernald
But we found two other species which we had not previously thought of as peculiarly fragrant. One was the ubiquitous Rosa nitida Willd. This shrub was in such beautiful condition that we yielded to the temptation to put some into our collecting boxes, although herbaria are full of Newfoundland specimens. Opening our boxes in the evening, we were surprised by a delicious and pervading fragrance as of tuberoses (Polianthes tuberosa L.). This came from the flowers of Rosa nitida and our respect for the common rose of southern and central Newfoundland vastly increased.

Planta 218(3): 468-478, 2004
Rhythmic emission of floral volatiles from Rosa damascena semperflorens cv. ‘Quatre Saisons’
Picone, J.M., Clery, R.A., Watanabe, N., MacTavish, H.S., and Turnbull, C.G.,

The control of rhythmic emission of floral volatiles emitted from Rosa damascena semperflorens cv. Quatre Saisons throughout floral development under various light regimes was studied. 2-Phenylethanol was the major volatile emitted in addition to monoterpenols, oxidised monoterpenols, monoterpenes and aromatic compounds. All detected volatiles were emitted rhythmically, with maximum peaks coinciding 8—10-h into a 12-h photoperiod. For some compounds a secondary, nocturnal peak was apparent. The primary and secondary maxima both occurred at approximately 24-h intervals. Rhythms appeared to be regulated endogenously: rhythmic emission continued upon exposure to continuous light or continuous darkness, and a phase shift in emission was induced upon inversion of the photoperiod. Additionally, emission continued after flower excision. A similar profile of free volatiles was stored within the floral tissue, together with glycosidic forms of 2-phenylethanol (>99% β-d-glucoside), benzyl alcohol, citronellol and geraniol. Regression analysis indicated a significant decrease in glycosylated 2-phenylethanol through the photoperiod. These results suggest that glycosylated volatiles stored within petals may be a source of rhythmically emitted volatiles.

The author does not inform us about which of these visitors are effective pollinators. Even so, it is an interesting beginning to the study.

Trans. of the Academy of Science of St. Louis 6(14): 441-442 (Apr 26, 1894)
Flowers and Insects: Rosaceae and Compositae
By Charles Robertson

ROSA HUMILIS Marsh.— The flowers expand several centimetres. The stamens are turned outwards so strongly that insects landing near the center of the flower are likely to touch the stigmas before becoming dusted with pollen from the same flower. Nectar is wanting. The principal visitors are bumblebees and other large bees, which collect the pollen, and a common beetle, Trichius piger, which feeds upon it. Small bees may collect the pollen without touching the stigmas.

The blooming time of Rosa humilis is from May 22 to July 8. Anthophora abrupta :female_sign:, whose time of flight is from May 13 to the last of June, seems to depend for pollen almost exclusively upon this rose.

On twelve days, between May 22 and June 20, I observed the following visitors :—

Hymenoptera — Apidae: (1) Bombns virginicus Oliv. ☿ ; (2) B. americanorum F. :female_sign:, ab.; (3) B. separatus Cr. :female_sign: ; (4) Anthophora abrupta Say :female_sign:, ab.; (5) Synhalonia speciosa Cr. 9; (6) Ceratina dupia Say :female_sign:; Andrenidae: (7) Halictus conifusus Sm. :female_sign:; (8) Augochlora pura Say :female_sign:; (9) Agapostemon viridula F. :female_sign: — all collecting pollen.
Coleoptera — Scarabaeidae: (10) Trichius piger F., ab.; Chrysomelidae: (11) Diabrotica 12-punctata Oliv.— both feeding on pollen.

ROSA SETIGERA Michx. — The flowers resemble those of Rosa humilis, but the styles cohere in a column, which enables the stigmas to touch a visiting bumblebee a little more readily. I have noted the flowers in bloom from June 16 to July 4. June 16 I saw them visited for pollen by (1) Bombus americanorum F. :female_sign:; (2) Anthophora abrupta Say :female_sign:; and (3) Trichius piger F.