Friday, June 8, 2012

Rouging the Carosello

Over the last few years I have been growing different varieties of cucumber-melons. For the most part, I have been growing each new variety in isolation. That is until now. I planted one friend’s carosello variety only to later learn that the variety was not pure. Some cucumber plants produced small long dark-green fruit, others produced short light-green fruit, some produced long light-green fruit with dark green blotches, while a few produced short light-green fruit with dark-green splotches.

Off-Type Long Carosello (Cucumber-Melon)

Light-green Short Carosello

Long Carosello with Splotches

When I had initially planted this variety I thought that the majority of the cucumber plants would be producing the short light-green fruit with dark-green splotches. As soon as I found that the seed was not pure I began “selfing” the plants (pollinating the female flowers using male pollen from the same plant). Selfing is usually considered a negative thing for outbreeding plants (plants that do not have a flower that can pollinate itself). This is because there is little genetic variability in the offspring. However, when one specific cucumber variety has been bred with another variety, its genetic variability is pretty high.

More Long Carosello with Splotches

So now I am getting rid of all the unwanted fruit and plants to make room for the cucumber variety with the traits I desire. This process of getting rid of the plants with undesirable traits is called “rouging”. It will probably take a few generations of rouging and selfing before my plants produce a uniform cucumber variety. Then I’ll need to grow it out for a few more generations before it becomes a completely stable variety. I will know that I have a stable variety when most of the plants I grow produce few off types (cucumbers that do not match the type I am seeking for).


Unwanted Plants going into the compost pit

In the meantime, I am saving a few of the interesting cucumber types, eating a lot of immature cucumbers, and adding a lot of cucumber vines to my compost pile. Even when things don’t go right the first time it’s nice to know you can eat or compost your failures.

Some off-type cucumber-melons ready to eat

6 comments:

  1. I found among the cucurbit family, cucumber is the hardest to save pure seeds. I grew one type of carosello cucumber last summer. But it was a small variety type about 5 cm call 'Bari' cucumber that I got from our local seed-saver group. I only manage to collect just a few seeds on them but I am not sure whether it is pure or cross-pollinated. I only can check the purity at the end of this year again, if the seeds were properly collected by me. So far, I have not come across carosello cucumber variety in our local seed company here in Australia.

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    1. Thank you so much for your response Malay-Kadazan girl,
      I love that you grow much of the same things I do!
      Thank you for telling me about your experience with the carosello. I think that there is a great potential for these varieties as they do fairly well in the extreme heat - at least they have for me. The smaller "Bari" variety is one of the most common grown in the United States, along with what we call the Armenian cucumber. Are there any other melon cucumbers that you grow?

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  2. I am interested in understanding the process of "rouging" outliers in my butternut breeding work. After 20 years, I am finally working an excellent promising self pollinated cross of a standard variety with a hybrid, one of 47 such back-crosses done in 2014. Last year evaluated 17 of these in an open field test planting and #33 had all I was looking for and minimal variability among 6 test plants. It has pretty much the characteristics desired, and i currently have 34 specimens of 2014 #33 planted. I believe I need to self pollinate again each of the 34, and select the best of these as individual new lines, but I have not gotten confirmation. First male flower opened today, need to know what to do real soon. See www.ptandjb.com for my squash breeding work.

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    1. Hi there Paul Traceski,

      To begin with, I find your last name interesting because it is very close to mine (Tracy).

      So, it sounds as if you already know what you are doing!

      I am currently working on a line of melons. Once you self-pollinate this last batch and save the seed, you may want to plant out as much of the seed next time around to do two things: to determine how stable the new line is and to create a "land race". By planting out a large population from the preferred inbred line, you will increase genetic diversity. As a result, you will end up with an enhanced ability for the population to better deal with various environmental stresses (ie. drought tolerance, powdery mildew resistance etc.)

      Despite what modern genetic engineering would have us believe, rouging and selection are how most vegetable varieties have become what they are today.

      I look forward to hearing more about your results!

      Happy Gardening!

      -Jay

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  3. Thank you for your valuable information, I now know what to do for the next 3 weeks. Are there any technical/how-to-do-it articles that explains this in detail? Carol Deppe's original Breed Your Own Vegetable Varieties got me started, but the information on the rouging process was vague, and so far have not found either relevant technical publications or a subject matter expert willing to talk to me. It is getting harder and harder to do the physical work required, want to finish this breeding line, a much improved LI cheese type butternut.

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    1. Dear Paul,

      I would highly recommend The Organic Seed Grower – A Farmer’s Guide to Vegetable Seed Production by John Navazio. There are a few other books I have also read on the subject, but this one is the most comprehensive. As vegetable breeding is a favorite topic of mine, you will find some more resources from the books link on the web version of my blog.

      You have done a lot more with breeding than I ever have. I mainly rely on other's breeding and select when I find a variable I am interested in.

      Please let me know if you find anything else.

      Best Wishes,

      -Jay

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