Re: CULT: rot aspects, roots/acclimation - long

We've also had some discussion about increases being healthier than the
original rhizome and how sometimes, rot starts in the parent rhizome and
spreads to the increases if they are still attached, but not if they are
isolated.

For whatever reason, some sources that I buy from have had more of a
problem with parent rhizomes rotting than others.  Given the level of
neglect/abuse my climate, soil, and I provide for irises, this is not a
criticism of the growers - they provide nice fat rhizomes, but maybe the
plants aren't stressed enough before they get here to get their PR
proteins stocked up.

This year, instead of temporary planting in small pots to keep them
happy until the weather & I get around to being ready for them to go
into permanent garden rows, I lined newly aquired rhizomes out in coarse
creek sand so I could look at roots.

Unlike Walter Moores, I don't shave/remove old roots.  Unless they are
dried up, old roots will often grow new branches or tiny root hairs, & I
figure my irises need all the advantage of roots they can get here.
Roots on irises that are shipped immediately after digging will usually
resume growth.

After a couple of weeks (the length of time it takes the really good
performers here to produce a LOT of new root growth, both on existing
roots and new root initiation from the rhizome), I pulled all the
rhizomes out of the sand to see what they were up to.

Some had NO new roots (and haven't grown any since).

Some had new roots on both the parent rhizome and on the attached new
small increases.

Some had NO new roots or root growth on the parent rhizome, but a LOT of
new roots and growth on existing roots.  ?? I hadn't expected that at
all.

Sooo, the immediate experiment was to carefully cut off the increases
with roots from the parent rhizome without roots and pot them all
separately.  Stay tuned, & I'll let you know what happens.  I expect the
parent rhizomes will not survive till bloom season, unless they get busy
and grow some roots of their own.

From my ancient past, I remember that some plants have 'juvenile' tissue
that is capable of doing things differently from 'mature' tissue.  Those
of you who have rooted cuttings know this - some woody plants are easier
to root using juvenile, new shoots; others root best from mature wood.
It's a trade off between the cutting having enough stored food to keep
itself alive while it makes new roots versus the existance of tissues
that can form new roots and its ability to produce the hormones etc
needed to trigger formation of roots (carbon compounds again).

So I wonder if in some cultivars, the ability to form new roots is
related to how 'mature' the tissue is.  I've seen some parent rhizomes
stay alive, with active roots, for several years, but others seem to die
after one year here.  This seems to be cultivar specific.  I don't know
if those cultivars with parent rhizomes that die after one year do that
in their place of origin (or would in iris heaven?)??

If the parent rhizone can't grow new roots in its new home, or is slow
to do so, that must put extra demands (energy/carbon storage,
water/nutrient uptake) on the increases to keep the parent alive (i.e.,
to keep it from rotting after it gets nipped hard by late freezes,
gnawed by hoppers, etc).

Donald, I've had the same experience as you in moving cultivars -
sometimes they are unbelievably delighted to be moved to a better soil
environment and grow & bloom like crazy, sometimes they decline, never
to recover, or even die.  Like they are just so overwhelmed by the
stress of the whole experience that they just give up.

IMMORTALITY has to be the best example of this kind of behavior.  Can't
figure the lady out.  People kept giving me starts that kept dying,
until eventually (after ?8? tries) she settled in.

After this near record hot, dry summer, the clumps out in the gravel
field put up a bloom stalk & the blooms produced normal looking anthers
with what appears to be normal looking pollen!  She doesn't do that here
most of the time, even in the spring.  The other clumps, one in partial
shade, one in well-tended, good soil, both with supplemental water, have
not bloomed.

By the way, Bill B., I kept meaning to say 'attaboy' for your long post
about soil organic matter.  A few things you left out <g>, thinking of
all the institutions and individuals who have devoted lifetimes of study
to soil organic matter & related issues, but a good, concise overview.
A few minor mistatements, but nothing worth worrying about as far as
irises are concerned.

Any plant physiologists out there to make sure I haven't wandered too
far off track in these rhizome rot ramblings?

Linda Mann east Tennessee USA zone 7/8

Tennessee Whooping Crane Walkathon:
<http://www.whoopingcranesovertn.org>
American Iris Society web site <http://www.irises.org>
iris-talk/Mallorn archives: <http://www.hort.net/lists/iris-talk/>
iris-photos/Mallorn archives: <http://www.hort.net/lists/iris-photos/>




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