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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 energy

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 provides this. 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 fall. 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 chrysanthemums) 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 increase blooms.

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 a University.....

Chuck Chapman

Date: Wed, 20 Feb 2008 13:42:18 -0500
From: autmirislvr@aol.com
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 <patsiris@sbcglobal.net>
To: iris@hort.net
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 <lmann@lock-net.com>
To: iris@hort.net
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 unpredictable
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 is

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 that
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
with IBs!

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.

Chuck said:
<As for the term "ever blooming" could you provide a working definition
of this.>
- --
Linda Mann east Tennessee USA zone 7/8

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