Stem tissue, root tissue and rooting hormone

[Tachigi]

WOW Put a cover on the front and back of this Brent and you'd have a fine book I learned a good bit from this thank you for taking the time to do the research and posting this.

 

[bretts]

I appreciate the time you have put into this and I am glad you are learning some new stuff as well as me.
I am sorry to say I think there are some pionts I must still debate you on.
It seems from the reading that exogenous application of Auxin is most benificial out side of an ideal enviroment. So I can agree that in the ideal enviroment auxin is little use. But I must argue that even some of the best gardners may find themselve with a tree that has stepped out of the ideal environment. Some say that a bonsai pot is not an ideal enviroment in any case.
If a tree needed to be bare rooted and root pruned out of the ideal season we have stepped out of the ideal environment.
Being a layman as too diseases and such that might cause this situation I am hesitent to give an example of what this situation might be but lets say a tree that was given to you with root rot. Or a tree that developed a root fungus of some type and needed urgent repotting.
I understand your concern about auxin becoming a health tonic but again I stress that if there is a use for the substance we should be aware of it.




I would think your quote of Dr Linda Chalker-Scott's is a little unfair as it is out of context.

She does suggest that root stimulants MAY (her word) help in transplanting by redirecting resources to the roots instead of top growth

In actual fact she states "IBA has had some success in root regeneration in transplanted trees"
Then she goes on to say this may be by redirecting resources to the roots instead of top growth.
She also goes on to say much the same thing about NAA regenerating roots of transplanted and root pruned trees the only time she says MAY is when she guesses about why this happens.

Container growing creates an ideal environment, field growing is about overcoming soil limitations.

I thought that the oposite was accepted that field growing is the ideal enviroment and pot growing had limitations that must be overcome??

Apart from your opinion that a pot is an ideal enviroment I see no other reason to suggest that auxins are no use in container growing. And again I would ask what about if that containered tree ends up in less than Ideal conditions.
I do agree with your opinion of Dr Linda Chalker-Scott otherwise.

I find the last two sentences of this conclusion to be very interesting. This further points out my original premise that you must be very careful when trying to extrapolate the results of any experiment to a situation with different parameters.

I also find these very interesting but I wonder if it is for the same reason as you.

Unlike the growth of bare-root seedlings, plug seedling growth was not stimulated by drenching with NAA solutions. These results show that auxins have the ability to stimulate posttransplant growth of vinca, but their effects may depend on the application method, rate, and timing, and transplanting method.

I find the last two sentances interesting because it seems to back up the previous reading that Auxin can help root pruned transplanted seedlings but is of no use to normally growing seedlings that have undergone no stress.




I would think that seedlings are used for the experiments for practicality and expense of the tests I see no reason for this statement.

I found one study that concludes that NAA root treatments of a woody plant clearly had no benefit on overall plant growth. This study uses several measures for plant growth, that I think are worth noting.

This study seems to show that there was an increase in root to shoot ratio but with the measurement system they used it seems hard to conclude wether the root formation was increased or just the top growth inhibited. I would not say this

concludes that NAA root treatments of a woody plant clearly had no benefit on overall plant growth

In fact it seems to show an increase in RSR from auxin in a non stressed plant.
I also think I need some clarification on why you call this a woody plant is it the type of plant or the age of the seedling?




So too your conclusions.

NAA treatments can stimulate lateral roots in new seedlings

Yes it is fair to only state what was conducted in the experiments but I see no reason to think this would not be the same for woody mature plants. But maybe I am missing something??

Root stimulation is species dependent and in some species may be counterproductive.

I am sorry but I did not see this in the studies???

Treatment will work best with a moderate amount of nitrate and no phosphorus and no iron.

I got a bit lost in this part. I think it is a subject that will make sense at another reading. I have grasped the basics of what you say and I think I will start to use osmocote agian.

When I read this

Which is more important, fast colonization of the roots at the expense of shoot growth, or faster shoot growth that eventually leads to a greater total plant weight? As long as the plants are otherwise healthy and the survival rates similar, I would be inclined to accept the higher total plant weight as a measure of success over a higher RSR. This would have to be decided.

I wonder if you are being fair in your thinking. I have often read that fast colinisation of the roots is exactly what you want in containerised plants as it adds structure to the soil and one would think eventually greater plant growth/wieght.




Your idea for the experiment sounds like the best field experiment proposal without destroying the test subjects.Although I would think that a pure auxin compound would be favourable for one to eliminate the other substances in Super thrive and also to show cheaper ways of using this hormone.

I found this comment a little hard to take.

I can't promise I will actually get around to doing this, but it is tempting since I am tired of typing these kind of posts.

You questioned my original post about auxins and I have answerd all your questions and seems that my statement still stands true.
You could always just give up

 

[Brent]

I would think your quote of Dr Linda Chalker-Scott's is a little unfair as it is out of context.

In actual fact she states "IBA has had some success in root regeneration in transplanted trees"
Then she goes on to say this may be by redirecting resources to the roots instead of top growth.
She also goes on to say much the same thing about NAA regenerating roots of transplanted and root pruned trees the only time she says MAY is when she guesses about why this happens.

Where are the studies? I got the impression when reading her statements that she was speculating, or inferring there was a benefit, but I can find reference to no actual studies. I suppose the conifer field studies I cited below could be used to support her argument, but again these were for seedlings, not nursery trees.

I thought that the oposite was accepted that field growing is the ideal enviroment and pot growing had limitations that must be overcome??

Field growing is ideal only in that it is a limitless pot. Other than that, there are plenty of limitations in almost any field growing situation. We are discussing tranplanting where space is not a consideration. Space is not a consideration in pot growing until after root colonization. Let's discuss one thing at a time please. If you want a high rate of survival, do you plant seeds or seedlings in native soil and take your chances, or do you sow them in pots and control every conceivable parameter?

Apart from your opinion that a pot is an ideal enviroment I see no other reason to suggest that auxins are no use in container growing.

So my entire discussion on the factors (natural auxin drivers) that favor successful transplantation and root stimulation,such as top growth, root pruning, correct fertilization, light, water, etc as factors that would either obviate or overwhelm any stimulation of lateral roots from NAA, you completely dismiss? Excuse me, but all these things are proven auxin generators or root support systems. You sir have not shown that NAA treatments can have any benefit that can be detected in beyond these factors in mature plant systems. You are speculating that is the case, but you have not shown it, nor has anyone else as far as I can see.

And again I would ask what about if that containered tree ends up in less than Ideal conditions.
I do agree with your opinion of Dr Linda Chalker-Scott otherwise.

You cannot lump all cases of subnormal growth together. You have to treat each problem individually. For example, and I speculate, an NAA treatment for a plant that has a severely impaired root system due to diseases such as Phytophora may simply be pushed over the edge rather than stimulated. We don't know. You can't just assume auxin treatment would help, it may very well hurt. Just as nitrogen feeding helps in some distress situations and hurts in others.

I find the last two sentances interesting because it seems to back up the previous reading that Auxin can help root pruned transplanted seedlings but is of no use to normally growing seedlings that have undergone no stress.

OR, it could mean that auxin treatments are worthless in some soil mixes. My point is that extrapolation is a dangerous thing, and always has to be tested.

I would think that seedlings are used for the experiments for practicality and expense of the tests I see no reason for this statement.

Perhaps, but this doesn't change the fact that new seedling root systems are physiologically different than mature root systems.

This study seems to show that there was an increase in root to shoot ratio but with the measurement system they used it seems hard to conclude wether the root formation was increased or just the top growth inhibited. I would not say this
In fact it seems to show an increase in RSR from auxin in a non stressed plant.

So, you weren't impressed with the first sentence of the conclusion?

"In conclusion, exogenous BA and NAA applications inhibited plant height and leaf
number of C. acuminata in a hydroponic culture system, and NAA applications also inhibited
plant weight and leaf length."​

I think you are being disingenuous here. You are perfectly capable of understanding the multiple measures, and in addition I even put forth an argument in another section that TOTAL plant weight may be the BEST indicator of efficaciousness.

I also think I need some clarification on why you call this a woody plant is it the type of plant or the age of the seedling?

Peas, corn, and cress (Arabidopsis), I don't consider woody plants. These are used in most of the auxin experiments. Conifers and deciduous trees (not annuals or herbaceous perennials), are what I am calling 'woody' plants.

Yes it is fair to only state what was conducted in the experiments but I see no reason to think this would not be the same for woody mature plants. But maybe I am missing something??

Yes, you are missing the fact that to extrapolate these findings to other species and situations is merely unproven speculation. Just to give you one example: In the study above that showed lateral root stimulation in the bareroot seedling, but not the plug grown seedling. Honestly, would you have predicted that? Does that mean that auxin treatments will ONLY work in bareroot situations?

I am sorry but I did not see this in the studies???

Auxin treatment was counterproductive in the last study on C. acuminata in the last study. There was a wide range of effects among the conifer species tested.

When I read this
I wonder if you are being fair in your thinking. I have often read that fast colinisation of the roots is exactly what you want in containerised plants as it adds structure to the soil and one would think eventually greater plant growth/wieght

Yes, but how you get there may be what's important, and that's what I am arguing. In field systems initial root growth preference over top growth is a survival strategy. This builds a mass of root storage from extant leaves while suppressing shoot growth which would put a demand on the root system. This allows a plant to withstand shocks. When the roots reach a 'critical mass' they unleash a torrent of cytokinins to produce shoots. This is species dependent. Western oaks may not send up a shoot for as long as seven years, then grow four feet in year eight. Plants in containers do this too, but to a lesser degree. They usually will root colonize a bit before sending up a shoot (but this is still species dependent). Once the roots hit a wall, they begin to sense limitations and will usually go into shoot mode.

But in container plants, this is a strategy that usually is not needed. This is part of what I am talking about containers being an ideal system. They don't necessarily need that root insurance because we don't, or shouldn't, allow them to become stressed. In a container system, it might in fact be more beneficial to send up a shoot as soon as the roots can support it. Why? Because a shoot is the strongest auxin source in a plant, much stronger than an NAA drench could ever be. It is these natural auxin sources and ther support that you have consistently refused to acknowledge. This early form of usable auxin does not significantly increase lateral rooting but instead increases PRIMARY rooting which in turn send more cytokinins for more shoot growth, the reinforcing cycle. This means fast establishment. One of the things that auxin drenches do is to favor lateral growth over primary root growth. As far as I can see, that is the crux of the strategy of using them.

Thus the question becomes, which system will produce TOTAL PLANT WEIGHT more quickly? I think this is an important question. This argument also points out why you simply can't extrapolate from a simple experiment to a complete growing system.

Your idea for the experiment sounds like the best field experiment proposal without destroying the test subjects.Although I would think that a pure auxin compound would be favourable for one to eliminate the other substances in Super thrive and also to show cheaper ways of using this hormone.

Yes, in thinking about it afterward, NAA should be used alone. I think we have ruled out other possibilities and only one parameter at a time should be considered.

You questioned my original post about auxins and I have answerd all your questions and seems that my statement still stands true.
You could always just give up

I found this comment a little hard to take.

Brent
EvergreenGardenworks.com
see our blog at http://BonsaiNurseryman.typepad.com

 

[bretts]

Quote:
I would think your quote of Dr Linda Chalker-Scott's is a little unfair as it is out of context.

In actual fact she states "IBA has had some success in root regeneration in transplanted trees"
Then she goes on to say this may be by redirecting resources to the roots instead of top growth.
She also goes on to say much the same thing about NAA regenerating roots of transplanted and root pruned trees the only time she says MAY is when she guesses about why this happens.

Where are the studies? I got the impression when reading her statements that she was speculating, or inferring there was a benefit, but I can find reference to no actual studies. I suppose the conifer field studies I cited below could be used to support her argument, but again these were for seedlings, not nursery trees.

I think it is very easy to read what she says the way you did you are not the first person to do it that is why I pointed it out. She definatly states that there has been some success in root generation in transplanted trees and your quote was out of context.
I did say I agreed with your opinion of Linda and she has not referenced how she came to this conclusion but the studies are all through this thread linked by you and myself.

Quote:
I thought that the oposite was accepted that field growing is the ideal enviroment and pot growing had limitations that must be overcome??

Field growing is ideal only in that it is a limitless pot. Other than that, there are plenty of limitations in almost any field growing situation. We are discussing tranplanting where space is not a consideration. Space is not a consideration in pot growing until after root colonization. Let's discuss one thing at a time please. If you want a high rate of survival, do you plant seeds or seedlings in native soil and take your chances, or do you sow them in pots and control every conceivable parameter?



Let's discuss one thing at a time please.

I did not bring this up you did here

When you read what she has to say about myths, you must bear in mind that she is talking about landscaping for the most part,……….. , and again, she is talking about field growing, not container growing, which a whole different ballgame. Container growing creates an ideal environment, field growing is about overcoming soil limitations.

I was only answering your suggestion.
In actual fact in another of Linda’s articles she refers that the hormones in seaweed which one of must be auxin are no use in the field.

"Logic suggests that the growth regulators found in sea weed extract, like any other comercaily available rooting hormone, can stimulate root development on cuttings and transplants. The suggestion is bourne out in research on both potatoes and pines in laboratory and green house applications and could have use as a root dip during transplanting. Success should not be expected (nor has been found) imn field aplications to excisting plants, as these compounds are quickly degraded by microbes and are unlikely to have any regulatory effect on nearby plant tissues."

Quote:
Apart from your opinion that a pot is an ideal enviroment I see no other reason to suggest that auxins are no use in container growing.

So my entire discussion on the factors (natural auxin drivers) that favor successful transplantation and root stimulation,such as top growth, root pruning, correct fertilization, light, water, etc as factors that would either obviate or overwhelm any stimulation of lateral roots from NAA, you completely dismiss? Excuse me, but all these things are proven auxin generators or root support systems. You sir have not shown that NAA treatments can have any benefit that can be detected in beyond these factors in mature plant systems. You are speculating that is the case, but you have not shown it, nor has anyone else as far as I can see.

I had the pleasure of dealing with a great judge a few years ago and he stated once that if a lawyer starts addressing him “ With respect your Honor” he new he was in trouble and when they addressed him”With all dew respect your Honor” he new he was in big trouble”
I guess since you are calling me Sir that means I am in trouble.

I in no way dismissed your discussion on the factors that favour succsessfull transplantation in fact I have stated peviously that there seems to be evidence that when auxin is plentiful adding more is of no use. But you seem to refuse to note that the studies show an increase in root development with the use of auxin in transplanted and root pruned specimens. I don’t think any study removed top foliage in the experiment. I see no reason why the studies quoted would have anything less than optimal conditions for the specimens. It is hard enough to source these experiments as it is surley you are not asking for a study that specifically states osmocote fertilizer being used? These experiments are not with mature specimens and yes we can only speculate on wether the same will happen with mature trees until an experiment is done to this degree but do you have ant reason to think it would not.

Quote:
And again I would ask what about if that containered tree ends up in less than Ideal conditions.
I do agree with your opinion of Dr Linda Chalker-Scott otherwise.

You cannot lump all cases of subnormal growth together. You have to treat each problem individually. For example, and I speculate, an NAA treatment for a plant that has a severely impaired root system due to diseases such as Phytophora may simply be pushed over the edge rather than stimulated. We don't know. You can't just assume auxin treatment would help, it may very well hurt. Just as nitrogen feeding helps in some distress situations and hurts in others.

Yes this is pure speculation.
So we have a disease that has caused the loss of many roots and shoots we do everything we can by cutting off the dead bits and plant in free draining soil.
We have a hormone that encourages the tree to grow new roots. Should we say hey I am doing nothing because I don’t know what it will do or do we experiment and see what happens.

Quote:
I find the last two sentances interesting because it seems to back up the previous reading that Auxin can help root pruned transplanted seedlings but is of no use to normally growing seedlings that have undergone no stress.

OR, it could mean that auxin treatments are worthless in some soil mixes. My point is that extrapolation is a dangerous thing, and always has to be tested.

I think my coment is very consistant with the general findings that auxin supplement works best when the plant has stressed by pruning your soil hypothises has no foundation except for your interpretation of this one result

Quote:
I would think that seedlings are used for the experiments for practicality and expense of the tests I see no reason for this statement.

Perhaps, but this doesn't change the fact that new seedling root systems are physiologically different than mature root systems.

If the mature root systems are so different can you explain this and why you think it is so possible to make a difference.

I think you are being disingenuous here. You are perfectly capable of understanding the multiple measures, and in addition I even put forth an argument in another section that TOTAL plant weight may be the BEST indicator of efficaciousness

I am definatly not being disingenuous. I said
This study seems to show that there was an increase in root to shoot ratio but with the measurement system they used it seems hard to conclude wether the root formation was increased or just the top growth inhibited.
It is not a mater of understanding the results but about the results available. The study only gave root growth in a ratio to shoot growth and as they stated that shoot growth had decreased it could be said that is the reason for the increase in RSR. They hinted in one sentence that there was extra root growth but to say there was from the information provided that would have been disingenuous

The use of auxin has been stated as reducing top growth in favour of root growth so this study just reinforces that. I think many bonsaist would be interested in this type of growth!

and in addition I even put forth an argument in another section that TOTAL plant weight may be the BEST indicator of efficaciousness.

Yes and I answerd that as well.

Quote:
Which is more important, fast colonization of the roots at the expense of shoot growth, or faster shoot growth that eventually leads to a greater total plant weight? As long as the plants are otherwise healthy and the survival rates similar, I would be inclined to accept the higher total plant weight as a measure of success over a higher RSR. This would have to be decided.

I wonder if you are being fair in your thinking. I have often read that fast colinisation of the roots is exactly what you want in containerised plants as it adds structure to the soil and one would think eventually greater plant growth/wieght.

I wonder though if less leaves and stems but more roots can result in a lighter plant overall?

Yes it is fair to only state what was conducted in the experiments but I see no reason to think this would not be the same for woody mature plants. But maybe I am missing something??

Yes, you are missing the fact that to extrapolate these findings to other species and situations is merely unproven speculation. Just to give you one example: In the study above that showed lateral root stimulation in the bareroot seedling, but not the plug grown seedling. Honestly, would you have predicted that? Does that mean that auxin treatments will ONLY work in bareroot situations?

It seems to me that auxin results are fairly consistant as being reduced top growth and increased root growth I see no reason not to hypothisis that this will be the same for a mature specimen.

Yes I did expect this in fact I was waiting for a study that showed no extra root growth with added auxin because the specimens were not stressed. Bare root seedlings are stressed plug seedlings are not.

What is an evergreen seedling plug?
Germinated from seed and grown in trays for one to two years, seedling plugs are often transplanted by wholesalers for field growing because they are already growing in a "plug" of dirt. They generally don't experience as much stress during transplanting as bareroot trees, and can be planted at almost any time of year.

Quote:
Root stimulation is species dependent and in some species may be counterproductive.

I am sorry but I did not see this in the studies???

Auxin treatment was counterproductive in the last study on C. acuminata in the last study. There was a wide range of effects among the conifer species tested.

I think this study showed pretty consistent effects for added auxin. Reduced top growth and although as stated RSR with reduced top growth does not give enough evidence to conclude there was extra root growth or not.

Quote:
When I read this
I wonder if you are being fair in your thinking. I have often read that fast colinisation of the roots is exactly what you want in containerised plants as it adds structure to the soil and one would think eventually greater plant growth/wieght

Yes, but how you get there may be what's important, and that's what I am arguing. In field systems initial root growth preference over top growth is a survival strategy. This builds a mass of root storage from extant leaves while suppressing shoot growth which would put a demand on the root system. This allows a plant to withstand shocks. When the roots reach a 'critical mass' they unleash a torrent of cytokinins to produce shoots. This is species dependent. Western oaks may not send up a shoot for as long as seven years, then grow four feet in year eight. Plants in containers do this too, but to a lesser degree. They usually will root colonize a bit before sending up a shoot (but this is still species dependent). Once the roots hit a wall, they begin to sense limitations and will usually go into shoot mode.

But in container plants, this is a strategy that usually is not needed. This is part of what I am talking about containers being an ideal system. They don't necessarily need that root insurance because we don't, or shouldn't, allow them to become stressed. In a container system, it might in fact be more beneficial to send up a shoot as soon as the roots can support it. Why? Because a shoot is the strongest auxin source in a plant, much stronger than an NAA drench could ever be. It is these natural auxin sources and ther support that you have consistently refused to acknowledge. This early form of usable auxin does not significantly increase lateral rooting but instead increases PRIMARY rooting which in turn send more cytokinins for more shoot growth, the reinforcing cycle. This means fast establishment. One of the things that auxin drenches do is to favor lateral growth over primary root growth. As far as I can see, that is the crux of the strategy of using them.

I have not refused to acknoledge that shoots send out auxins I don’t know were you get this from that is auxin basics?
What you say sounds great and explains what you mean by containers being an ideal system but even you state that it might be beneficial to send up a shoot as soon as the roots can suport it so what is rong with encouraging root growth until this time with added auxin?

Is there a time when added auxins can be of benefit. With the studies and discussion I still see a big possibility.
Will auxin work on more mature trees the way it does seedlings I see no reason why not.

Quote:
You questioned my original post about auxins and I have answerd all your questions and seems that my statement still stands true.
You could always just give up

I found this comment a little hard to take.

Maybe if you leave it in it’s original context it will go down easier

Quote:

I can't promise I will actually get around to doing this, but it is tempting since I am tired of typing these kind of posts.

You questioned my original post about auxins and I have answerd all your questions and seems that my statement still stands true.
You could always just give up

 

[irene_b]

Can you fellas (when this thread is over) Please post your cliffnotes?
Mom

 

[Brent]

I'm going to leave this now. I can't really see that we are getting anywhere. I have presented nearly all the arguments I can to back up my position, and they haven't convinced you. I am probably never going to convince you that auxins are not going to make a difference in a situation like the experiment I described until I actually do the experiment. And who knows, maybe I am wrong and there will be a difference. I must say that from your arguments that you haven't convinced me that auxin treatment should benefit more mature transplants in a nursery situation. That is the only situation in which I am qualified to really judge. To say that you don't see why something shouldn't work, doesn't mean that it will. I get slammed with the truth of that nearly every week.

Brent
EvergreenGardenworks.com
see our blog at http://BonsaiNurseryman.typepad.com

 

[bretts]

I think I should leave this discussion with a few of the studies that have been put forward that show that auxins; can/do increase root growth in trees of varietties that we use in Bonsai. It shows there is use for auxins by gardeners nurserymen and bonsaists. There is no reason put forward why this would not be the same for a more mature tree. I agree that all the answers have not been answerd and Brent's practises very well may take away any use for added auxins in various applications.
I think it is clear though that added auxins do have interesting reactions to stressed or root pruned specimens and there is evidence to back up many peoples claims that they have improved success when using auxins in many forms including Superthrive and Sea Weed Extract.
I think it will be of benifit if some practicle uses are experimented with to see where these reactions can be of use instaed of both sides using opinion to debunk the other.



Enhanced Seedling Root Development in Eight Conifer Species Induced by Naphthalene Acetic Acid
D. A. SEABY and C. SELBY
Department of Agriculture Newforge Lane, Belfast, BT9 5PX, Northern Ireland
Seedlings of eight conifer species, Pinus contorta, Pinus sylvestris, Pinus nigra, Larix kaempferi, Picea abies, Picea sitchensis, Pseudotsuga, nenziesii and Abies grandis, were treated with auxin, in pot and nursery experiments. Dilute solutions of naphthalene acetic acid (NAA) were applied at two treatment times, just before and just after cotyledon expansion. Lateral root numbers were increased by up to 20 times on responsive species. Sensitivity varied considerably, the three pine species showing a much greater response than the two species of spruce. In most cases the mean number of induced roots increased steadily with increasing auxin concentration. Forest nursery results showed that NAA could provide an inexpensive method for stimulating lateral root formation near the soil surface. Practical nursery aspects of treatment are briefly discussed.



Titre du document / Document title
Auxins affect posttransplant shoot and root growth of vinca seedlings
Auteur(s) / Author(s)
VAN IERSEL M. (1) ;
Affiliation(s) du ou des auteurs / Author(s) Affiliation(s)
(1) Department of Horticulture, Georgia Station, The University of Georgia, 1109 Experiment Street, Griffin, GA 30223-1797, ETATS-UNIS
Résumé / Abstract
Transplanting often causes root damage, and rapid root growth following transplanting may help to minimize the effects of transplant shock. The objective of this study was to determine the effects of NAA and IAA on posttransplant growth of vinca (Catharanthus roseus L.). Bare-root seedlings were germinated in a peat-based growing mix and transplanted into diatomaceous earth 10 days after seeding. Immediately after transplanting, seedlings were drenched with several concentrations of IAA or NAA (62.5 mL/plant). Both auxins increased posttransplant root and shoot growth, but the response was dose-dependent. The maximum growth occurred at concentrations of 10 mg.L[-1](IAA) or 0.1 mg.L[-1] (NAA). The growth-stimulating effect of these auxins decreased at higher rates and NAA was highly toxic at 100 mg.L[-1], killing most of the plants. Unlike the growth of bare-root seedlings, plug seedling growth was not stimulated by drenching with NAA solutions. These results show that auxins have the ability to stimulate posttransplant growth of vinca, but their effects may depend on the application method, rate, and timing, and transplanting method. Chemical names used: 1-naphthaleneacetic acid (NAA); 1-indole-3-acetic acid (IAA).



The Effect of Auxins on Pinus contorta Seedling Root Development
C. SELBY and D.A. SEABY
Department of Agriculture Newforge Lane, Belfast, BT9 5PX
Primary lateral root production on Pinus contorta seedlings was increased 5–10 fold by immersion in auxin solutions. Watering auxin solutions onto P. contorta seedlings growing in soil or compost induced the development of large numbers of primary lateral roots in the root collar region. The number of primary lateral roots which developed depended mainly upon the auxin used and its application rate, seedling age and to a lesser extent on the soil characteristics. Instability of transplanted pines is partly due to their lack of primary lateral roots and their inability to regenerate new ones after planting out; this instability may be overcome by using auxin treated seedlings. Potential practical applications of this technique are discussed.

 

[irene_b]

Brent and Brett.
I would like to Thank You both for this most interesting in depth topic and hope that in the near future it can be explored further.
Mom

 

[Brent]

Just for the record. I believe I cited all three of those studies.

Brent

 

[Jay Wilson]

Brent and Bretts,
I want to thank you both again for this most informative and interesting thread. THANKS!!!
It's given me lots of food for thought and also shows how a discussion with differing veiwpoints can be civil and polite.
Thanks again for taking your time to resaerch this subject and posting it in language that even I can understand.

Jay