North American Fruit Explorers mailing list at ibiblio

[Jwlehman@aol.com]

In a message dated 1/28/2013 3:27:19 PM Eastern Standard Time, 
tanistanis@hotmail.com writes:

> Please correct this if wrong.  If I remember my botany, some plant 
> nutrients move upwards in the interior part of the stem, while others move 
> downwards in the cambium just under the bark.  Both have an effect on the 
> dwarfing of a graft.  If you switch the topwork &rootstock cultivars of an 
> interstem combo, you are asking the 'assembly line' to run in the opposite 
> direction.  I would like to see side-by-side comparisons, before relying on 
> doing 
> many for expected production.   

All wood growth takes place at the cambium layer. Inward develops the xylem 
where nutrients flow upward. Outside the cambium layer is the phloem, where 
sugars are fed back down to nourish the root system. Surrounding that is 
the cork and bark. There is some over simplification in this explanation. 

I've never used interstems therefore can't speak from experience. But I 
understand the dwarfing effect can be only temporary, that is only a few 
years 
then normal growth returns. My guess is because when new xylem and phloem 
grow from the cambium layer they work normally that is the cells now are 
orientated normally.