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Re: Re: Hyb: Daylight Independent

  • Subject: Re: Re: Hyb: Daylight Independent
  • From: Autmirislvr@aol.com
  • Date: Sat, 16 Feb 2008 22:01:10 -0500

This is true. 

Different rebloomers do different things in different climates.

My concern is performance. Immortality is only one of several that bloomed in July & August during the summers of 2005 & 2006. 

I just want them to continue to do so and to produce children that bloom during the summer months, also.  It's not uncommon for cycle rebloomers to get frozen back in the fall without showing color, here in my zone 6 garden. 

-----Original Message-----
From: irischapman@aim.com
To: iris-photos@yahoogroups.com
Sent: Sat, 16 Feb 2008 1:48 pm
Subject: [iris-photos] Re: Hyb: Daylight Independent

Different rebloomers do different things in different climates.
Immortality is almost always the first of the TBs to rebloom here, but
never before mid August. It does not show any characteristics of
daylight independence for me in my climate and not for anyone else in
this climate. A cross of Immortality X Forever Blue produced a bunch of
dogs, but no rebloomers of any sort.

There are various biological triggers for flower bloom. I've been
collecting some refferences but haven't read any of them yet.
I can't remember how many, but enough to be sure of my observations. I
also had a number of crosses with other relible early and cold weather
rebloomers, all with the same result. Whatever it is with Forever Blue,
it is different then what is causing rebloom with other rebloomers.
The cross with Victoria Falls is the only cross with TB that has
produced rebloom. Most crosses with other SDB rebloomers X Forever Blue
gives the same story. The Exception was the cross with What Again,
which produced 90-100% rebloomers, all of the Daylight independent
type., that is reblooms whenever. They all did not show the very early
rebloom that is characteristic of those that I introduced, Forever
Violet, Blueberry Tart etc.

I have never seen anything from Immortality (or any other TB) that I
would call Daylight independence. The only other plant that shows
similar rebloom is the IB Precious Little Pink.

Iris are generally triggered by the number of hours of daylight ,
coupled with all the other triggers of spring growth. They also need
the cold period to set next years bloom (estivation). Lloyd pointed out
to me that I could get a lot of rebloom that he didn't as I had colder
nights in the summer. This would suggest that a number of rebloomers
can get away with a temperature differential much less then the cold of
a full winter. These plants still seem to need the daylight triggers.
Artificially giving longer daylight (light supplements) will increase
rebloom. Sometimes a plant will have an bloom triggered in a rhizome,
but it will not have sufficient trigger size in spring to set off
bloom, even through it will respond to the daylight hours of spring.
This rhizomes will continue to grow until it reaches size to produce a
flower. This can appear to be daylight independent, but it isn't.
Trigger size is my own concept. It referees to the size of the rhizome
needed to support a bloom stalk, in terms of plant energy. I would
suspect that a lot of rebloomers have a small trigger size.

The hours of daylight to trigger a bloom can be very specific. I once
rescued some daffodils in the spring, just as they were starting to
grow. Some of them went into the garage for awhile . They didn't get
planted for a while, but took off when planted and had extremely good
plant growth and it didn't die off like other daffodils did. Then in
Fall, as the daylight hours decreased, it went into bloom, triggered by
the length of daylight hours.

Forever Blue is an extremely strong grower and it can produce trigger
size rhizomes in a shorter time then most plants. These rhizomes do
seem to need cooler evenings to produce an embryo bloom stalk, and it
does not seem to need a daylight trigger to start this bloom stalk,
only the size and perhaps cooler evenings.

Immortality does seem to need the daylight trigger for the new rhizome
rebloom. This is different then late spring bloom as the stalk was
triggered but rhizome had not reached trigger size. This does not seem
to happen in southern Ontario. Perhaps because of the later spring.
This would mean that the plants have had a bit more time for the
underdeveloped rhizomes to get to trigger size. One of the sine non
quoin of bloom is the ground/air temperature. Plants can grow in colder
temps, but it is needed to set off bloom stalk growth.

Again, I repeat, Ihaven't seen any TB rebloom here in Southern
Ontario that would seem to be Daylight independent. They all rebloom in
corespondence to spring daylight hours. Other people have reported
summer rebloom, but I suspect other reasons. and causes to trigger
rebloom, just not known

Chuck Chapman

Re: Hyb: Daylight Independent

Posted by: "Autmirislvr@aol.com"

Fri Feb 15, 2008 3:56 am (PST)

A few hybridizers are working on this trait in TB
rebloomers.? Constantly searching for irises that bloom in the summer.?


Like other traits it is stronger in some irises than others.?

Chuck, how many seedlings did you bloom from Forever Blue x

Betty W/KY/zone 6

-----Original Message-----

From: irischapman@aim.com

To: iris-photos@yahoogroups.com

Sent: Thu, 14 Feb 2008 10:16 pm

Subject: [iris-photos] Re: Hyb: Daylight Independent

The lenght of daylight hours triggers bloom in many plants, including

Iris. Thus they bloom in spring and again in fall when the lenght of

daylight hours match the trigger daylenght in spring (for rebloomers).

Forever Blue and a number of it's children don't need that trigger, but

bloom whenever a rhizome gets lare enough to support a bloom stalk.

Most SDB rebloomers rebloom her very late in Fall, just before killing

frost. This reflects daylight hours that trigers spring bloom. FB and

its children bloom when ever, and thus rebloom in very cold regions.

and troughout Summer.

Chuck Chapman

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