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HYB: Daylight Independent

  • Subject: HYB: Daylight Independent
  • From: Autmirislvr@aol.com
  • Date: Sun, 17 Feb 2008 08:58:59 -0500

<<There are various biological triggers for flower bloom. >>


For clarification, I'd like to revisit the subject, although it is true that I don't care what we call them so long as they bloom when I want them too!  <humor>  AND . . . I can breed others to do the same. 

For several years now, I've been trying to pin down the cause of summer bloom so that I don't send a lot of time breeding things that won't meet my goals.  After 20 something years, I've wrestled most of the concepts into submission.  It's primarily the language that has me buffaloed. 

Maybe it's the term "Daylight Independent" that is throwing me. 

I've been keeping a temperature journal for over a year.  There is indication that night time temperatures (along with rain/water) may trigger rebloomer here in June, July & August.  Although I'd really prefer early September for my viewing pleasure.   

For anyone that might be interested in hybridizing rebloomers--the same rules of gene combining apply as in regular irises, but there are more genes to take into consideration--the rebloom genes.  In addition, rebloom has it's own modifiers and/or triggers.   

Basics:  In the new judges handbook it states that there are now 5 types of rebloom.  It further states that the 1) Cyclic Rebloomers are the standard for the rebloom class.  If this is true, many of us will be left out of the rebloom game because they often don't get their act together until it's too late in our colder zones.  For my purposes, these rebloomers are too predictable.  Maybe, if they could be modified to bloom earlier? 

When a hard freeze hits KY on or around Oct 15, I lose most of my rebloom.  Not something I'm willing to tolerate IF I have a choice. 

For several years, I've been looking for irises that summer (July & August) bloom, not only for me, but in all zones.  When I find an iris, like Romantic Evening or Pure As Gold, that blooms in July in both California and Nebraska, I figure it's worth taking note. 

The garden reports that have meant the most in my search are Richards in CA and Jedlicka in Nebraska.  Both listed their rebloom by month.  It's understood their seasons would both be different than mine but the early rebloom is my focus. 

3) Repeaters . . . this class seems (to me) to mature late rhizomes (not full grown in the spring) and then bloom when mature.  There is another trigger involved, perhaps one that regulates rhizome growth, because they all bloom at approximately 6 weeks after the first rhizomes in the clump finish bloom.  (Summer Radiance made such a display in early July one year that all the neighbors congregated. ) 

Classifications 2) Multiple Blooming Irises & 4)Sporadic Rebloomers appear to me to be the same, with #2 having stronger triggers. 

Classification #2 contains the irises I'd thought to be Daylight Independent.  These irises bloom at any time they choose throughout the summer and fall, from spring freeze to hard fall freeze.  These irises do NOT need short daylight days (fall) to rebloom

Chuck, if I'm understanding you correctly, you are saying that these multiple rebloomers are all REPEATS?  They have a different trigger/modifier for rhizome growth?  There is a distinct difference in the "timing" of stalk release in the two groups. 

5) Secondary Stalk Rebloomers (according to the NEW judges manual), although rare, occur when rhizomes send up secondary stalks in the same growing season.  I'd thought these to be early REPEATERS.

In summation, we MAY have two classes of rebloomers: 1) cycle and 2) sporadic with different triggers? 

Again, I speak of TB's only. 

Betty Wilkerson/south central KY/Zone 6--My brain still scrambles on the words Allele and Gamete, (I think it's an allergy) but I'm getting much of the rest. 

-----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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