Jamie, Your discussion below to Walter et. al. relative to light was most informative or should I say enlightening. It brought back distant memories of when I was in graduate school and taking plant physiology courses that enlightened me relative to how energy from sunlight is fixed through photosynthesis. Our human construct of the world is, in our mind for a large part, based on what we sense, i.e., what we see, fell, hear, and taste. And, it is so easy for us to forget that reality to other living things, plants and animals is what they sense, which may not necessarily be the same as what I sense. My dog inside in my home on a ten-acre lot can readily distinguish between vehicles on the road where I reside that belong to my neighbors from those from elsewhere and will inform us of such in no uncertain terms. I would be completely oblivious of the non-resident vehicles without my dog. I know because of my background and experience that the light I am sensing or seeing is not for the most part what plants are sensing and absorbing when they fix energy. Regardless of that, it is remarkably easy for me to forget that fact and assume what I sense to be strong artificial light will be interpreted as strong light by plants. And, there are many very-good gardeners that have only a fussy understanding of the light absorption-spectrum use in fixing energy which obviously you have considerable technical expertise in. Your plot of the amount light absorption by plants versus wavelength and its explanation would be most enlightening to many gardeners. Therefore, may I be so bold as to suggest that you write an article for publication in some forum dealing with light absorption by plants and the use of artificial light. Something, an average gardener might comprehend. And, may I suggest your discussion include something on the use or misuse of growlights which you did not discuss in your email. I reside in North Florida where climate and day-length regimens are much different than in more northern latitudes where you and others are growing plants. We do experience some freezing weather but daylight is of shorter duration during the summer than in more northern latitudes and during the winter daylight is of longer duration than further north. And this can have major and/or minor effects on the life cycle of many plants, including irises. PS. Please excuse my overuse of “enlight…” it was impossible to resist. Vic Victor W. Lambou 272 Pine Lane Crawfordville, FL 32327 850-925-1819 Vwak@msn.com From: iris-species@yahoogroups.com [mailto:iris-species@yahoogroups.com]
Sent: Sunday, December 06, 2015 7:48 AM
To: iris-species@yahoogroups.com
Subject: Re: [iris-species] 2015 harvest germinating [1 Attachment] Mornin', Walter et all,
with my experiments, it was not simply Iris, aril or otherwise, but many different genera. The key problem is the higher temps combined with insufficient light. This leads to faster growth after germination which cannot be properly supported by the possible photosynthesis. Yes, one could simply increase the light amount, but this is a very costly road, especially in Europe where our charges are about 3-10x what one pays in the USA, and, I have not found the end result warranted the extra effort and cost. In short, those seedlings I raised in a cold-house or cold frame managed to quickly catch-up to those under lights and finally, as far as I could observe, produced superior seedlings. My extra efforts were wasted.
In a light laboratory, one does manage to obtail better seedlings, again, higher costs, but part of the reason is the actual spectrum of light used. A basic misconception is that what appears as strong light to the human eye is strong for the plants. As most will recall, photosynthesis for land plants is taking place mainly at 660nm (plus 720nm with some plants) and 420nm and 470nm. This is essentially very red and very blue light. Actually at the edge of our ability to register light as visible. Clearly, there are light sources designed for plants, which respect these needs, but many do not really offer the plants the best radiation, rather attempt to appease the human eye and are emmiting lots of (useless) light in the yellow-green part of the spectrum, which, not coincidentally, is the peak of the human light experience. The colour of our sun! In the end, we only have our eyes to judge lighting, unless we use a spectrometer.
To give you all a better idea of the light involved, I have attached a graph of chlorophyll light absorbtion. There are other light-gathering pigments involved in certain plants, but for our purposes, chlorophyll and caroteinoids are the main pigments involved.
Another factor many do not know about is the life-span of fluorescent light sources. After about 6 months they start to strongly move to the yellow spectrum. After 9 months they are pretty much useless for plants. Sodium is an option, but has a similar deficiency and is less efficient at producing light, watt for watt. The best light source would be top-line LEDs in the proper spectrum. Again, we come to an economic factor, which is why I have decided the natural light/coldframe approach was the winner.
One area I do find interesting for under light culture is giving forced arils a good start. Here, lower temps are pretty important, as none of them do much growing under high heat. Room temps are to high, IMO. On a cold windowsill with supplemental lighting, I have brought them to an intermediate size (second leaf or so) and then transfered them outside to a cold frame.
ciao für now,
Jamie V.
Cologne Am 04.12.2015 um 21:48 schrieb Walter Pickett w*@yahoo.com [iris-species]: So Jamie says he has poor results growing new arilbred seedlings over winter under lights, and Dennis says he has had good results doing the same thing with LA iris seedling. I respect both based on what they have said over the years on the internet. They both seem to know what they are doing. But I wonder if the different results are due to the species they have worked with, or on the amount of light or other conditions in their light set-up. Please keep us informed of results, and if possible, describe the conditions you are growing these seedlings in. On Monday, November 30, 2015 2:07 AM, "Jamie j*@freenet.de [iris-species]" i*@yahoogroups.com wrote: Dennis,
nice! Have you considered potting them up and over-wintering them in a coldframe? I have found seedlings do very poorly inside during Winter. They attenuate and often become quite weak by Spring. In a coldframe they growm more slowly, but we see a better root system and compacter growth. Also, roots continue to develope and grow when temps are above 4°C, while the leaves develope little, if at all, thus putting energy into the basis of the plant.
What ever you decide to do, keep taking fotos. Document for the rest of us!
cheers, Mate,
Jamie
Cologne Am 30.11.2015 um 04:29 schrieb Dennis Kramb d*@badbear.com [iris-species]: In August I started sowing my iris seeds in ziploc bags with a little bit of wet potting mix. I put them in the refrigerator and checked them frequently in the early weeks but then sorta forgot about them. I just checked them for the first time in over a month and there's a lot of activity. Here are pics of seeds germinating from the arilbred 'Rare Breed'. I intend to pot them up & grow them under lights this winter and hopefully keep them growing through spring & into summer. I've never tried this intentionally before but I've done it unintentionally with Louisiana irises. Dennis in Cincinnati
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