Re:HYB: Daylength independent
I have listed several factors that I suspect contribute to rebloom. To
start with, rebloom is abhorrent to mother nature. She has worked
valiantly to prevent rebloom as it is a suicide gene for plants in
nature. The idea of flowers is for reproduction, and each species has
selected time for bloom that is most conducive to survival. This
includes blooming at a time that attracts pollinators, when plant has
the energy reserves, and has time for the seeds to mature. So, biomass,
vernalization and photoperiod are the most relevant factors. The need
for vernalization is there so plant won't bloom in warm falls when it
will not be able to produce seeds and the plant would die from frost.
As you may note, any rhizome that is in bloom at frost time is dead by
spring. It also can cause rot in nearby rhizomes. It is only because of
the increased vigour, rapicidity of growth and fast increase that they
survive in our gardens Where plants don't have to compete against all
of mother nature. That is less weeds , added fertilizer and more room
to grow into then would be found if plant were in the wild (or at least
better conditions then in wild) Thus all rebloomers benefit from
increased plant hardiness. This can involve various factors.
1) extra vigour , particularly so plant can still survive after
blooming rhizomes are killed by frost. This means not so much hardiness
as lots of increase.
2) Shorter maturity time for rhizomes. This means that an increase can
mature to bloom size faster then average.
3)Early spring bloom may be an additional factor or a reflection of
item #2, that is earlier maturity or faster growth.
4) Smaller trigger size for rhizome. This is a term I use to indicate
size of the rhizome needed to trigger a bloom stalk and support it.
Some of the Schreiner's iris need to nave large rhizomes before they
bloom and a number of them don't bloom in cooler climates as there
just is not the time to produce size needed in the growing season
available. The AB Walker Ross for instance can set up a bloom stalk on
a rhizome that in only 1" in diameter.
5) Will bloom with smaller number of leaves (less biomass needed)
6) Secondary bloom stalk on a rhizome, such as we get with Vanity.
7) Will grow at cooler temperatures. Two examples of this are Heather
Carpet and Evergreen. Heather Carpet SDB greens up in spring about 6-8
days before anything else. Evergreen a TB, remains green in garden for
much longer then other TBs.
8) Continues to grow in hot weather, that is doesn't release hot
temperature chemicals as soon and is not as harmed by hot temperatures
9) Extra strong root growth. There have been reports of rebloomers
having a more fibrous root system, and longer roots
10) Reduced need for DLI (Daylight Integral) . This is a measure of
amount of light energy a plant receives. A combination of light
intensity and hours of light. Plants need energy from the sun in order
to perform their biological functions. The less they need, the more
of their energy can go toward bloom production.
11) Shorter period for bloom stalk development. That is for example, a
change from 14 days from photoperiod trigger to bloom to a 10 day
period from photoperiopd trigger to bloom.
12) More efficient in gathering environmental resources, water and sun
These factors may not be entirely independent of each other.
These are the plant vigour components that I can think of. These are
not needed for rebloom but most rebloomers should have some of these
factors in order to be able to survive the "rebloom defect" I say
defect as it is a defect of mother nature and an anti survival trait..
To produce rebloom we need some modifications of the bloom triggers.
Some I can think of are
1) Flower bud differentiation at higher temperatures and earlier in
season. That is, the apical growth tissue in rhizome has to change
from producing leaves to producing a flower with all its flower parts.
This by itself will not produce rebloom.
2) Reduced need for estivation. There has been found various alleles
for estivation in different plants. For example winter versus spring
wheat. Winter wheat differs from spring wheat in the gene for
estivation.. Winter wheat needs to be planted in fall and to have a
winter estivation in order to bloom and produce wheat. Spring wheat
does not need that. In the green guinea pig (ardabopsis) they have
found three estivation alleles, that is three different forms of the
genes controlling need for estivation. This could be a gene that
changes estivation from being a obligate (absolutely needed) to a
facilitative . Facilitative means that estivation is not absolutely
needed, but will increase bloom. These are known to be various forms
of the vernalization gene function. It could also be that less time is
need for estivation For example, several days of cool wether may be
enough to trigger a bloom. I would suspect that this factor combined
with #1 is what is behind the regular reliable rebloomers. The bud
differentiation occurs early and then we have a quick estivation and
voila, fall rebloom. When we have #1 we have the California
rebloomers. They need more estivation and the longer growing season
3) A reversal of the sequencing needs of biomass and photoperiod.
Normally there needs to be adequate biomass before the photoperiod
stimulus (appropriate night time length) signal triggers bloom. If the
photoperiod signal provides a plant change that is retained, then an
increase in biomass will trigger a bloom. This is what would seem to be
occurring with the plants that put up some summer or "whenever" bloom.
4) Decrease in photoperiod sensitivity. That is, it doesn't need to be
as precise. That is, for example, instead of a trigger of night length
of 12to 12.1 hours it would have a trigger period of 11.5 to 13 hours
of night time. This would result in earlier bloom in spring and in
5) Change from a daylight increasing trigger to a directional
independent photoperiod trigger. Some plants are triggered to bloom
buy a certain nighttime length, but only during times the night time
hours are decreasing. Some by the same length of night , but only when
the length of night time hours are increasing (eg poinsettias and
6) Daylight independence. That is bloom whenever the plant has
sufficient energy and biomass. the only examples of this are Forever
Blue and its children, such as Blueberry Tart, Autumn Jester, Forever
Violet and summer Recall. These plants also have a gene modification
of estivation needs as many of the increases that bloom have never been
through a winter. There also is very short maturation times of
rhizomes. There can be three generations of bloom in a season. The
rhizome blooms, then the increase blooms and then the increase on the
Some speculation on genetics of rebloom. I can think of a number of
experiments that could be done with a growth chamber. And to think I
once turned down an offer to get one for free. A growth chamber is
basically a walk in fridge with shelves for plants and a massive number
of flourescent lights. It has a number of controls so you can set
duration and timing of lights. It can also be programed for temperature
so you could control the temperature the plants are in. Very expensive
to run, a lot of electricity. With this you could check the conditions
for initialization of flower buds and need for estivation and compare
various reblooming and non reblooming plants. Now if I had a contact at
Date: Wed, 20 Feb 2008 13:42:18 -0500
Subject: Re: [iris] Re: HYB: Daylength independent
Pat, the problem here is that we have two classes that could be called
radom.? We have the cold climate rebloomers like Immortality which
frequently summer rebloom in zones 7 and below, and then we have the
warm climate rebloomers that frequently summer bloom in zones?8 and up.
The Judge's Handbook classifies them as "multiple bloomers" and
"sporadic rebloomers."? This is the recently revised terminology.?
The terms everbloomer and continuous bloomer were misleading as they
are neither continuous or everblooming.???
As Linda mentioned earlier, I'm of the opinion that it is, possibly,
one set of genes with different triggers or modifiers.?
Perhaps it shoule be called random bloom.
- -----Original Message-----
From: Pat Norvell <email@example.com>
Sent: Wed, 20 Feb 2008 10:25 am
Subject: Re: [iris] Re: HYB: Daylength independent
Perhaps it shoule be called random bloom. PN
- ----- Original Message ----
From: Linda Mann <firstname.lastname@example.org>
Sent: Tuesday, February 19, 2008 6:58:58 PM
Subject: [iris] Re: HYB: Daylength independent
Someone here has suggested whenever blooming is a more accurate
description than everblooming. & that probably comes closer to what I
mean by everblooming - day length independent, blooming at
times, but not usually continuous bloom. At least not yet... ;-) I
guess I should quit calling them everbloomers, but it's simpler to say
and easier to type than daylength independent. Maybe summer blooming
Some of the Sutton's rebloomers sound like they are continuously in
bloom for them from spring till fall.
One year, IMM bloomed 5 times here from spring freeze till fall freeze
that's more or less late April-early May thru some time in October.
Bloomstalks each month.
But it wasn't really continuous bloom, and like I said before, few
stalks for the number of fans. Eventually, I'd like some seedlings
would bloom every month, but fewer fans per stalk and less temperature
sensitive. TBs, not IBs.
Re: my previous wish about crossing the sibs from FB & IMM -
oops....lapse of attention on my part. I forgot about fertility issues
I really wish is that I had been able to cross some of the
non-reblooming half sibs I have from IMM - stubbornly uncooperative,
mostly thanks to the weather.
<As for the term "ever blooming" could you provide a working definition
Linda Mann east Tennessee USA zone 7/8
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