Centre of Origin

In one of my previous post I point out to Mediterranean origin for black radish. Recently I came across a reference from Ian Bancroft book Genetics and Genomics of the Brassicaceae as follows:"There is some controversy as to the probable centre of origin of Raphanus sativa. It most likely originates in the Middle East or West Asiatic region. Other suggestion indicates Asiatic origins with a centre of major diversity in China".

Black Radish - Canadian seed standard

In Canada Black Radish seeds offered for sale must be graded. Each package shall meet and shall be labelled with prescribed grade in Table XIX of the Seeds Regulations.
(http://laws-lois.justice.gc.ca/eng/regulations/C.R.C.%2C_c._1400/index.html).
On retail side you most likely meet only common seeds (equivalent to VNS in USA - variety not specified). There are 2 grades for such seeds - Canada No.1 and Canada No.2 .

For small retail packages there is no requirements to label with lot number, year when seed were packaged, and weight of seed as well as germination and number of weeds. The following package is labelled as "Canada2". Most likely it stands for grade Canada No.2.

Black Radish and Frost

The wave of cold weather is over and I am eager to update you about my experimental radish plants health. I should say it is no so bad so far. Since my last publication there were eight cold nights and one cold day. Environmental Canada reported minimum and maximum temperatures for Edmonton as follows:

At the end of this cold weather I found that all plants survived either covered by glass jar or not.

Black Radish and Snow

I finished my post about Edmonton spring weather  late last night, When I wake up next morning I saw falling snow right from my bed. First what I did I looked for  weather forecast. It is  minus 7C overnight. There is no way my  plants to survive.  Another experiment to see if any plants survive covered by glass jars.

Edmonton Spring Weather

This spring the first really warm day came on April 11. My early morning biking ride  to my work place was also first time on the plus side. As the afternoon temperature hovered about 16C  I didn't resist to replant my black radish that I seeded for germination test. I know that frost will be back and I like to see how black radish will coop with temperatures below zero.

For reader who is not from Edmonton, Alberta it would be interested to know that gardening work starts here in a middle of May. However I always try to start early and early greens are coming as a reward. But you have to be ready to fail.

Below are a few pictures from 2010 season.

May 4, 2010.

May 8, 2010.

May 30, 2010

Next snow was in September.

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Vernalization

Many plants grown in temperate climates require vernalization and must experience a period of low winter temperature to initiate or accelerate the flowering process. This ensures that reproductive development and seed production occurs in spring and summer, rather than in autumn. http://en.wikipedia.org/wiki/Vernalization).

In my understanding vernalization  turns on reproductive genetic clock. It works mainly on plant with metabolic activity or imbibed seeds (germinating seeds, seedling etc). It affects not only plants grown from roots but plants on any stage of development including sprouting  seeds. Even vernalization documented on seed stage prior to seed desiccation. If it case for black radish it will explain difference in bolting related to seed source history. Vernalized seed at stage of maturity will be prone to bolting even  under optimal seeding time.

Would vernalization  be a reason for bolting in case of early seeding? Certainly yes, if you get long cool spring.  It is interesting to note that many publication  report  good resistance to low temperatures as low as minus 5 for black radish seedlings, but it is also go with recommendation for seeding when warm weather established. Thus, shifting to late seeding protect plant from vernalization.. A week of cold weather probably will not end up with vernalization. The most often referred parameters  required for black radish vernalization is 10-20 days with temperature   plus 5-8 C. It is also interesting to know that there is term “devernalization” when hot weather turn off vernalization. If you interested to know more about this subject I recommend you to read the article “Memories of winter:Vernalization and the competence to flower” (http://www.biochem.wisc.edu/faculty/amasino/pdfs/MichaelsPlCellEnv23_1145-00.pdf)

Black Radish- Names, Seeds, and Seedlings.

Black Radish scientific name is Raphanus sativus L. var. niger (Mill.) S. Kerner (Family Cruciferae [Brassicaceae]). Words "Round" and "Long" are used as a part of common name to escribe difference in the root shapes. The word "Spanish" is used in North America mainly. The following picture demonstrate difference in the root shape. Long roots seems to me derives from crosses with diakon that is closest relatives to black radish.


Picture Source:http://www.rustica.fr/articles-jardin/legumes-et-potager/radis-noir-radis-l-hiver,3144.html

 As an alternative name you can come across "Noir gros rond d'hiver". I think it is a name of old variety accepted as a common name. As far as this name I like to note the following. In the International Union for the Protection of New Varieties of Plants Black Radish Guidelines for the conduct of tests for distinctness, uniformity and stability "Noir gros rond d'hiver" name is used as the reference variety for some varietal characteristics. 
http://www.upov.int/edocs/mdocs/upov/en/tc_48/tg_63_7_proj_7_tg_64_7_proj_6.pdf

Although black radish is sold mainly as hereinloom varieties there is selection of varieties especially in the Eastern Europe. The most popular variety in Russia, for example,  is Грайворонская (Graivoronskaya). It is  late variety (about 110 days) with outstanding yield potential and resistant to bolting.

Due to significant difference in vegetation period and other varietal characteristics it is important to know your seed source. My seed source is from Oregon. In 2001 season it took 90 days to form apple size roots although per supplier label it matures in 60 days. 60 days gave me a quarter size roots only.

Germination trial in potting soil (100% emergence).