More on germination temperatures

[iann]

From some research papers that I found:

Four Mammillaria species (M. haageana, M. carnea, M. mystax and M. supertexta) showed best germination at a constant 25C. 15C-30C temperature variation was much worse for M. carnea and M. supertexta. 20C-35C was much worse for M. carnea, but those varying temperatures produced good germination for the other species. Nothing germinated in the dark at any temperature, except a tiny number of M. mystax. Mammillarias are known as a species that requires nurse shrubs and a relatively constant temperature is expected to favour germination. Overall germination at the right temperature was above 90% for all four species.

Four Gymnocalyciums (G. bruchii, G. quehlianum, G. monvillei, and G. capillaense) showed best germination at 15C night temperature and 25C day temperature. Constant temperature was not tested. Germination of all four was poor at 10C/20C and nonexistent at 5C/15C. G. bruchii did not germinate at 20C/35C but the other three germinated well. Nothing germinated in the dark at any temperature. Constant temperatures were not tested although Gymnocalyciums might be expected to do well at a constant temperature. Maximum germination rates were rather low although G. quehlianum germinated at up to 80%. Germination speed was also tested and faster germination was consistently obtained at higher temperatures.

[Marlon Machado]

References?

Just in case someone wants to read the same articles

Cheers,

Marlon.

[iann]

Germination Characteristics of Four Argentinean Endemic Gymnocalycium (Cactaceae) Species With Different Flowering Phenologies
Diego E. Gurvich, Guillermo Funes, Melisa A. Giorgis, Pablo Demaio
Natural Areas Journal 2008 28:2, 104-108

LIGHT EFFECT ON SEED GERMINATION OF FOUR MAMMILLARIA SPECIES FROM THE TEHUACÁN-CUICATLÁN VALLEY, CENTRAL MEXICO
J. Leopoldo Benítez-Rodríguez, Alma Orozco-Segovia, Mariana Rojas-Aréchiga, Chris Lauver
The Southwestern Naturalist 2004 49:1, 11-17

[Marlon Machado]

Thanks Ian!

Cheers,

Marlon.

[Chris43]

Thanks for these, Ian.
It is interesting that in the article on the 4 Mammillarias the optimum germination was at 25C with red light. It certainly sounds that there is no need to have your propagator on a time switch, just keep it at a constant 25C!
Does anyone know what "The red light boxes were made with red acrylic (Series Number 2424, Rhom and Hass, Mexico, D. F.) (R:FR 5 5.22, 9.297
mmol/m2/s)" actually means in terms of spectrum?

[iann]

The terms "red" and "far red" are relatively standardised in this context. Red would be around 660nm, a deep red colour but quite visible to the human eye. Far red would be around 720nm and very faint to the human eye. By some definitions "far red" is really "near infrared".

These wavelenghts correspond to the two absorption states of the Phytochrome pigments which regulate many metabolic functions in plants.

The numbers in the descriptions of each filter are simply the light intensities in the red and far red wavelength ranges. It is interesting that the "white" light apparently has an extremely high far red component, presumably from the incandescent lights used.