North American Fruit Explorers mailing list at ibiblio

["Lon J. Rombough" <lonrom@hevanet.com>]

Colchicine causes doubling of the chromosome number in a cell.  When the chromosomes duplicate themselves, they move apart into either end of the cell, then it splits in two, with each cell having a complete set.  Colchicine prevents the duplicates from moving apart, so the cell doesn't split and ends the division cycle with twice as many chromosomes.  
There was a 'craze' of trying colchicine on many plants when the effect was discovered.  Some plants reacted well, with larger, thicker leaves and flowers and some hardly looked any different.  Daylilies were one of the more successful plants.  
In many cases, tetraploids were less fertile and didn't set as much seed, or in the case of fruit, set fewer fruits.   Later they found that while the new tetraploids weren't very fertile, you could grow seedlings and find some that had better fertility/productivity.   Used the right way, it's a very useful tool.
-Lon Rombough
Grapes, writing, consulting, my book, The Grape Grower, at http://www.bunchgrapes.com  Winner of the Garden Writers Association "Best Talent in Writing" award for 2003. 
For even more grape lessons, go to  http://www.grapeschool.com
For growing supplies and more;  http://www.grapegrowersolutions.com

On Aug 28, 2007, at 9:43 PM, Ginda Fisher wrote:

I've read that other flowers are bred from seeds exposed to colchicine, which damages (changes) the genome.  Maybe that's used to create polyploidy, I forget the details.

Ginda