Thats a cool question.

Of which I don't have a direct answer.

Lets say the plant looked really healthy as you propose .. in that case it would be hard to implicate lack of a mineral as the cause ....

If I really suspected lack of a micronutrient as the cause the first ones I would consider would be the metalic micronutrients since the cations of these metals often combine and affect the shape of complex protiens needed to regulate chemical pathways.

Lack of Nitrogen could also be a problem since aromatic compounds contain the element Nitrogen and "if you had a plant that was strongly growing " Nitrogen would be in great demand to sustain the high rates of photosynthesis needed to support rapid growth and to build new cells .. tissues ect..

If indeed you are dealing with Roses a mistaken ID I'd bet would be a more likely explanation.

Good Day ...

Nope not a mistaken ID....I pulled this rose out of the carton (got it by mail) and it had four flowers on it of the sweetest fragrance ...it looked like the rose I bought and smelled like it was supposed to (as in Highly fragrant) and those few flowers were so fragrant they actually wafted in the air while on my deck for a week before being planted.

It was fragrant until I put it in the ground. It has quadrupled in size and looks really healthy to me - it has put out four large flushes of flowers since I planted it - and none of them are but the tiniest hint of fragrant, and some of them had no scent whatsoever.

I can definitely see how my rose plant would have needed a ton of nitrogen at the rate it was growing so I will take care of that, thanks for the insight. I am interested to know exactly how the cations of metalic micronutrients would affect the chemical pathways off a plant - would you have a website or maybe a book title that I can read up on that?

Thanks much,
Chris

How about something simple? Like genetic predisposition? And how excess N (especially) can counteract a plant's ability to concentrate energy on color, fragrance, flowers, fruit quality, juvenility, etc. N is a very powerful inducement to vegetative growth. A plant can only allocate it's energy resources towards so many results. Vegetative growth and abundant floral production might very well weaken the ability of the plant to produce a strong scent.

Our goal should be to accomodate NORMAL growth and development, not accelerated growth and development. It's all about energy allocation.

I have a question here. Are pollinators, optimum light and temperature required for having sufficient fragrance in flowers of a healthy plant ?

I don't understand how pollinators would factor into fragrance. Adequate light and temperature, water, soluble minerals are all required for normal, healthy growth. A plant that is in a stress mode due to the surplus or deficit of any of those environmental factors may not be as fragrant as it 'could' be if it were healthy.

Plants that have the genetic makeup for strong fragrances have evolved that way as one more way to entice pollinators. Some plants may be extremely colorful, or have infrared markings, or may glow in the dark, or may disguise themselves as something else....all in the name of that great evolutionary battle.

Fragrance is determined by genetic markers. It is that simple. Plants may carry genes for height, for thorns, for fuzziness, for bright red, for aroma, for sweetness, etc.

Insect pollinators visit certain flowers 'because' they have an aroma. Flowers don't produce an aroma due to insect stimulation.

... so maybe a gene was turned off somehow and this resulted in new "mutated" growth without fragrance .. some Roses ofcourse don't have fragrance.

Good Day ...

Roses are a great example to use for this discussion! They have been bred and cross-bred; hybridized and selected. The process of hybridization and selection is very meticulous........and is ALL about genetics!

Roses have a zillion genetic markers for their incredibly variable physical characteristics. Many of the (so called) modern roses have had the fragrance gene literally bred OUT in favor of bloom size, shape, color, etc. etc. etc. The long stemmed rose grown strictly for the florist market is a prime example.

I would not call this a mutation, which implies an accident of nature. Non fragrant roses are a bi-product of years and years of genetic manipulation that ignored the importance of fragrance.

In recent years, consumers have complained about this! Yay!!! So breeders are, once again, focusing on producing roses that will fill our gardens and homes with fragrance.

To go back to the original question about a micronutrient for fragrance....let's make a comparison to humans. Can two parents, planning on having a baby, alter their diet or nutrient up-take in order to produce babies with big brown eyes? If they were both pure Scandinavian? Nope. It's all about the genetic makeup of the parents (and their parents and on and on.)

Remember, some cultural activities can alter a plant's normal physical expression of their genes. Over fertilization is one that could weaken a plant's ability to do all SORTS of things, in exchange for vigorous vegetative growth.

Hello Doria ...

So .. I'm confused LOL .. what exactly are you saying !!

Lets assume as was stated earlier that a given Rose plant started as a plantthat was fragrant. What do you think could of made it stop being fragrant ?

The human comparison is a bit weak given that plants have open growth ... that is to say humans don't keep growing eyes each year.Also eye color and plant fragrance are different pathways.

Good Day ...

"How about something simple? Like genetic predisposition? And how excess N (especially) can counteract a plant's ability to concentrate energy on color, fragrance, flowers, fruit quality, juvenility, etc. N is a very powerful inducement to vegetative growth..."

Hello all and thank you for such an interesting discussion ...Mohave Kid may have had the right of it though on the Nitrogen as after reading his post I did give my rose some nitrogen. I had not fertilized it at all as the planting instructions said not to do that much the first year or it could kill it. SO...now it is beginning to pick up in fragrance again! It's still not nearly where it had been (aka - to the wafting stage of fragrance, much different than the "stick you nose in " amount of fragrance) but I think it will get there. I would imagine that newly planted roses are rather odd in their habits until they establish themselves - they are a very complex plant. Most avid rose growers say a rose needs three whole years before you see what it can do!

Thanks to everyone here!
Chris

My analogy regarding people and roses was silly, but obvious. There are no micronutrients or specialty fertilizers for perfume production. It is as genetically programmed as blue eyes or brown eyes.

Plants are programmed (again those genetics) with a set of 'normal' growth responses to correspond with all sorts of environmental variables. Normal growth for that plant, at that time, in that location, etc. If, for whatever reason, your plant was pushed to an excess growth rate (beyond the normal), it would have to allocate the carbon (energy) resources to vegetative growth rather than (say) root development or pest resistance or fragrance, etc. The same thing might happen if the root system were compromised all of a sudden, or all of the leaves attacked by black spot. The plant will have to devote carbon resources to making new roots, making new leaves and so on.

Perhaps your plants has established an equilibrium now and can once again show off its perfume. Perhaps the temperatures dictated the perfume production. We can only speculate. I've planted new arrivals into the garden that seemed so happy to be in the real world that they couldn't get down to flower production for several weeks or months. Once they settle in and slow down a bit, they perform as I would have expected.

I would surely avoid fertilizers completely unless your plants seem to indicate that they need some nutritional support. A soil test might tell you if your plants are trying to operate under a deficiency of some sort. Then, and only then, would the addition of fertilizer be a key in aroma production! Severe nutritional deficiency would dictate 'suppressed' growth in a plant, as opposed to 'normal' growth. We might not observe the signs of suppressed growth for some time, but the plant would still have to deal with it physiologically.

Orchid flowers attract male bees who are fond of collecting fragrance from flowers. Their visit to orchid flowers is just for the fragrence of the flower.They are equiped with the tecnics of extracting and collecting fragrance from the glands of the flower.During the movements in doing so they will disburse some pollens around the flower.
Presence of male bees will provide the incentive for the female bees( who may be looking for mating) to visit the site
However I could not find similar info. about roses.

This has been an interesting thread. rhizo_1 has it right on. It's all about genetics. Plants co-evolved with animals and developed strategies including fragrance, shape,color, etc. to attract pollinators. Your question is a good one too. Obviously, if your rose had fragrant flowers when you received it, it still has the genes to produce them, but something turned them off. Is a particular nutrient missing in your soil? Could be, but probably not. Your description of your rose's growth seems to rule out excessive Nitrogen since your plant put out large flushes of flowers since you planted it. Too much Nitrogen would have caused excess vegetative growth at the expense of flowers. Could be that your rose responded like herbs do when overfertilized. More likely, your rose was just diverting a chemical essential to fragrance production to root growth while it was getting established in your garden.

I was curious to see if a particular chemical was essential in fragrance production, so entered the following in a Google Search box:

plant fragrance "biochemical pathway"

I didn't read far before finding the article linked below. It explains how plants use scent to attract pollinators and also states that flowers have varying degrees of scent at different stages of growth.

If you want to reproduce the search and learn more, don't forget the quotation marks.

Here is a link that might be useful: Understanding of Floral Scents... article

My roses are more fragrant when the air temperature is warmer. That goes for the scented violets, too.

Scent appears to be a very variable characteristic of plants.

Apparently, where the plant is grown can affect both the concentrations and composition of its fragrance and essential oils.

Both can also vary with the time of the year or season.

Nitrogen can increase the quantity of the chemicals involved in scent as can water stress.

Both temperature and relative humidity have effects as does the time of the day.

I did a quick search of the abstracts referencing 'flower' of the journal Flavour and Fragrance but did not find any indication that micronutrients were involved in fragrance production.

A second quick browse of the structure of some enzymes involved in the important stages of fragrance production also did not find any involvment of micronutrients.

Here is a link that might be useful: Flavour and Fragrance Journal

Would like to use another approach... in inorganic chemistry a reaction between a acid (HCl) & a base (NaOH) yealds a salt (NaCl) & water... in organic chemistry a reaction between a acid (R-COOH) & a alcohol (R-OH) yealds a Ester & a water... Many of these esters are "fragrant" & are the product of normal digestion... (many are further broken down to finnaly produce CO2 + water + energy)
Shift to peppers... Capsicum is a normal by product (waist material) of pepper metabolism ( and under the control of genes) & when the plant is under "stress" the % by weight of capsicum produced is increased & when active growth the % by weight is reduced,
NOw to roses .. the production of esters that are fragrant is under genetic control & my suggestion... the % by weight is increased by stress & reduced by "active, rapid growth" .

Fragrance is due to evaporation of "Essential Oils " containd in the petals pf the flowers.Evaporation of essential oils depends upon temperature and may be different for different flowers.Temperature, again, depends upon time of the day and also has seasonal variation.
Howere there is some exception to this.Nocturnal Jasmine emits fragrance only during night (i.e. in absence of light ) of hot summers.

"Apparently, where the plant is grown can affect both the concentrations and composition of its fragrance and essential oils. "...

yes! that is exactly it...WHY is that?..in physical terms this must be due to the composition of the soil, ie trace elements and such , no? And I know that there are certain clays, for instance, that have upwards of 65 minerals and trace minerals...so we are maybe Not talking about just the few standard elements like NPK or even the basic micronutrients. What if fragrance depends upon tiny amounts of trace elements or even the right kind of michorrizhal symbiosis?

Chaman... isn't "being able to SMELL fragance" due to the evaporation of essential oils? This assumes essential oil content is IN the flower petals to be evaporated and that is the core question. What if it's not in the plant? (and no we are not back to genetics , for if the plant Could put out fragrance before in its life we assume it HAS the genetics to do that throughout its life right?)

I think essential oil content is also why scent varies with time of year and temperature level, etc etc ...it's a matter of evaportion stats with that, not so much the creation of essential oil molecules themselves that are simply waiting for the proper temperatures / humidity / conditions to be released.

I did try a small experiment with my rose flowers related to this. I picked a flower and held it in my hand - lots more heat and humidity applied in other words - and I still could not , in the summer, get any fragrance to emit. It just didn't seem to be there. Now later on in the year after I noted some fragrance, I would go pick a flower that was not currently emitting fragrance to my nose , and did find that when I held it in my hand - raising the relative temp and humidity levels around it - that I could begin to smell something.

physical terms this must be due to the composition of the soil, ie trace elements and such , no?

Not necessarily. Everything can differ between locations and many of those factors are known to affect fragrances and essential oils.

However, here is an interesting abstract of the effects of Nitrogen, Calcium, etc on the essential oil content of mint.

ESSENTIAL OIL PRODUCTION AND QUALITY OF MENTHA ARVENSIS L. GROWN IN NUTRIENT SOLUTIONS

Authors: Nilson Borlina Maia, Odair Alves Bovi, Marcia Ortiz Mayo Marques, Newton do Prado Granja, Quirino Augusto Camargo Carmello

Production and quality of Mentha arvensis L. essential oil grown in pots irrigated with eleven nutrient solutions were evaluated. The objective of this work was to determine the components of a nutrient solution for commercial use which would allow maximum oil yield and high menthol content. An automatic solution dispenser system was specially developed. The system consisted of a group of reservoirs equipped with individual pumps and eletric buoys.

A modified Hoagland # 1 solution was the starting point for the formulation of testing solutions and was also used as control. Ten solutions were prepared from the basic solution. Double and half strength solutions for N, P, K, Ca and Mg were prepared in such a way that the plants were grown in solutions containing three concentrations of each nutrient focused in this study.

Growth, nutrient content and essential oil of the plants were evaluated. High levels of N promoted increase in leaves weight, but less oil content (0.97%) with low menthol content. Higher levels of Ca and Mg, and low level of P enhanced the leaves oil content (1.37; 1.52 and 1.41 respectively), without significant alterations in quality.

N and Mg important interactions were observed, affecting menthol content in the oil. As the N levels rise, the menthol response to Mg contents in the solution is positive. In solutions with low concentrations of N, the menthol content in the essential oil increases as the Mg concentration decreases (negative response).

Continuing with the factors that affect the essential oil of mint both the length of the daylight and the amount of UV-A radiation causes changes in the composition and quantity of the essential oil. Both of these factors change during a growing season (and differ by locations).

There is an enzyme involved in carotenoid metabolism in Petunia called carotenoid cleavage dioxygenase. One of the products of this enzyme is ionone a volatile produced by the flower. This enzyme is apparently dependent on ferrous iron, and affected by circadian rhythms.

It is possible that if iron is limiting then the enzyme will be affected.

The tomato carotenoid cleavage dioxygenase 1 genes contribute to the formation of the flavor volatiles b-ionone, pseudoionone, and geranylacetone
The Plant Journal (2004) 40, 882Â892

Circadian Regulation of the PhCCD1 Carotenoid Cleavage Dioxygenase Controls Emission of b -Ionone, a Fragrance Volatile of Petunia Flowers
Plant Physiology, November 2004, Vol. 136, pp. 3504Â3514

Non-heme iron oxygenases
Current Opinion in Chemical Biology 2002, 6:193Â201

... this is all interesting but has anyone read about Roses and fragrance loss ?? I have not seen this problem mentioned in basic Rose books ...

Ofcourse Coffe growers attribute it's charecteristics to the environment it is grown and the wine industry has vintage years ect. ?

Good Day ...

Thank you admmad...such great info!

Mojave Kid I have not seen anything related to rose fragrance in basic rose books beyond simply mentioning whether it has fragrance (the genetics) or not and to what degree. Maybe this is because roses are seen as a finicky plant ? (too many variables in other words?)

I have already decided that I will move my rose to another location in my yard next spring. What will be interesting is to see whether I notice continuous fragrance production in this new location, even though I will effectively be setting the plant back yet again by transplanting it.

I suppose I should have the soil tested in both locations, but I'm not feeling that motivated :) I do have a light meter, however it's not a very good one so I suspect I will not notce any UV light changes in either location...still, I'll find my meter and give it a try...

In addition, I checked the company I got the first rose from and notice they have more of that rose available. I will order another of the same rose from them and plant it in the same place as the old rose has vacated. And we'll see what happens.

Whitejade I am glad you mentioned soil tests as the balance of micronutrients in the soil is delicate. Some are required by enzymes to function but at the some time inhibit other enzymes. If a soil is deficient in a particular micronutrient, because so many enzymes will be affected the plant will typically not look healthy but very obviously sick with substantial symptoms. There would be a small range of concentrations where the micronutrient was present in just enough quantity that the vital processes were functioning normally and only optional processes were switched-off or down (such as fragrance).

Mojave_Kid I do not know of any work on fragrance loss in roses. If there was it would likely be on a case-by-case basis as there are so many possibilities and each garden that suffered might well have a different reason.

However, that is not as serious as it seems. Living organisms by and large share the same mechanisms for creating the same products. If petunias produce a certain volatile chemical then if roses produce the same chemical it is likely to be by the same genes/enzymes and from the same precursors (sources) [biochemical pathways] and be affected by the same factors.

However, roses are used in some fragrance research. One of the most prominent rose volatiles is orcinol dimethyl ether. From (O-Methyltransferases Involved in the Biosynthesis of Volatile Phenolic Derivatives in Rose Petals. Plant Physiology, August 2002, Vol. 129, pp. 1899Â1907)

"The aroma of roses (Rosa hybrida) is due to more than 400 volatile compounds including terpenes, esters, and phenolic derivatives. 2-Phenylethyl acetate, cis-3-hexenyl acetate, geranyl acetate, and citronellyl acetate were identified as the main volatile esters emitted by the flowers of the scented rose var. "Fragrant Cloud." from
(Volatile Ester Formation in Roses. Identification of an Acetyl-Coenzyme A. Geraniol/Citronellol Acetyltransferase in Developing Rose Petals Plant Physiology, April 2003, Vol. 131, pp. 1868Â1876)

"1,3,5-Trimethoxybenzene is a key component of the Chinese rose odor". From (The Key Role of Phloroglucinol O-Methyltransferase in the Biosynthesis of Rosa chinensis Volatile 1,3,5-Trimethoxybenzene Plant Physiology, May 2004, Vol. 135, pp. 95Â102)

"However, that is not as serious as it seems. Living organisms by and large share the same mechanisms for creating the same products"

..well yes and no....amino acids are the building blocks of even the volatile compounds and according to something I have read there are at least 500 various amino acids being used in the world (at present count) ...and we all know that the plant kingdom uses some different ones than animal kingdom. Has anyone done studies on which basic amino acids roses depend on and whether or not this varies much or at all between fragrant and non-fragrant roses...or even between roses and the plant kingdom in general?

Whitejade

"Over 250 nonprotein amino acids have been identified in plants (Swain, 1977). A number of these compounds are intermediates in the synthesis and catabolism of the protein amino acids (Lea and Norris, 1976). However, many of these non-protein amino acids may play roles as defensive agents."

From (Polyamines, nonprotein amino acids and alkaloids, http://www.hort.purdue.edu/rhodcv/hort640c/polyam/polyam.htm)

You are correct in that there are many potential amino acids but they are not directly involved in the production of plant volatiles. Many of the volatiles are terpenoids and are produced by the non-mevalonate pathway from carbohydrate precursors (building blocks).

Amino acids are the building blocks of proteins and enzymes are proteins. Plants manufacture their amino acids. Enzymes are required for the production of the volatiles and act as catalysts in the chemical reactions that build those volatiles.

You are also correct that if a rose produces a volatile such as orcinol and that if a civet cat also produces orcinol it probably does not do so using the same enzymes as the rose. However, in general, when different species are compared the genes are relatively well conserved between species in their functions and their metabolic pathways are similar. Evolution, gene duplication, mutations, etc do occur and make absolute generalizations difficult but overall it is reasonable to assume similarity between reasonably related species than to assume complete dissimilarity.

The metabolic pathways for the production of specific scent volatiles are likely to be more similar between roses and carnations, snapdragons, etc than different.

This research examined genetic differences between two rose cultivars, Fragrant Cloud and Golden Gate:
(Rose Scent: Genomics Approach to Discovering Novel Floral
FragranceÂRelated Genes, The Plant Cell, Vol. 14, 2325Â2338, October 2002,) and is available as a PDF file at http://biology.lsa.umich.edu/research/labs/pichersky/references/pub24.pdf

In general, modern genetic research often involves identifying, extracting or otherwise obtaining the DNA for specific genes from plants and inserting those genes into bacteria to build quantities of the enzymes involved. The bacteria typically are able to build normally functional enzymes using their own amino acid pathways so I expect that differences in amino acids are not likely to be important to most metabolic pathways in plants.

I found an interesting article on this...in case the link doesn'/t work here it is
http://www.sciencenews.org/articles/20050924/bob10.asp

What is even more incredible to me is that I am only an hour from Ann Arbor and here they have been doing such rare work on fragrace all this time so close by . It's always such a small world...and an interesting one.

Here is a link that might be useful: Article on scent

It is my understanding that the active ingredient in the smell and taste of an onion is a sulfur compound. Vidalia onions are mild because they contain a relatively small amount of that sulfur compound, a condition that arises by growing them in soil that has a low sulfur content. The same onions, grown in a higher sulfur soil, have a stronger "onion" smell and taste.

I agree that genetics is probably the most important factor in determining fragrance, but I wouldn't rule out that trace elements can play a role. Even borderline trace elements like cobalt could conceivably play a key role.

So it is plausible to me that a "normally" fragrant plant could display subnormal fragrance based on a nutritional deficiency -- the onion being one such example.

MM

Perhaps get a soil analysis? Also are your roses in full sun, partial sun, for how long? Have you investigated any of the other possibilities?

Well it's been about 2 years since I originally posted this question....so I was surprised to see a repsonse now however I can tell you that my rose has since recovered itself and its fragrance. It is definitely one of my favorite rose scents. I think the biggest thing I did was supply more nitrogen.