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Li, W., S. Yang, H. Cui, Y. Hua, J. Tao, C. Zhou.2017. Emerates Journal of Food and Agriculture. 29(7):518-531.

This article examines the chemical composition of peony petals especially an analysis of soluble sugars, organic acids, protein, vitamin C, total phenolics, flavonoids, and minerals. They analyzed 46 cultivars. In Chinese literature, petals used in tea have been associated with liver health, and improved body immunity. Petals harvested at full bloom also have significant nutritional value that can be used directly in food products or extracted and added to other edibles. Soluble sugars, organic acids differed little among cultivars. Other components varied among cultivars and warranted using specific cultivars for food. This project indicated that breeding for specific nutrients will be worthwhile. The problem with petals is that it takes a whole lot of petals to make 100 grams or even 1 gram dry weight. Here’s what they found:

66.5 – 177.3 mg/g fresh right soluble sugars 2.19 – 6.9 mg/g fw organic acids 6.5 – 121.6 mg/g fw soluble protein 9.7 – 30.2 mg/100g fw vitamins C 9.4 – 33.1 mg/g dw total phenolics 3.5 – 17.6 mg/g dw total flavonoids 6.4 – 11.9 g/100g dw total amino acids Na 55.8 ug/g dw Mg 1218.2 ug/g dw K 11,252.2 ug/g dw Ca 1975.4 ug/g dw Mn 8.3 ug/g dw Fe 103.5 ug/g dw Ni 10.7 ug/g dw Zn 22.8 ug/g dw Mo 1.8 ug/g dw Cr 17.3 ug/g dw

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Song, Xiuhua and Q. Wu. 2021. Urban Forestry and Urban Greening. 67: 127429. 8p.

Plant smell is a combination of low molecular weight volatile compounds released by stems, roots, leaves, flowers, fruits and/or other organs. They can have a positive or negative effect on humans. I think of roseroot, Rhodiola, whose roots have an incredible aroma of roses. Or the flowers of chocolate lily which are smelly and not in a positive way. The word smellscape is used to define the aroma of a location or landscape similar to soundscape in relation to music These authors combined hardcore chemistry using gas chromatography- mass spectroscopy with human perceptions in different garden settings by people walking down a garden path. They studied a variety of flowers, one of which was the woody (tree) peony. Their purpose was to learn how to design outdoor spaces to provide the best fragrance experience for visitors.

Like most flowers, scent is not one compound, but a mixture. For the woody peony, it was a combination of ocimene, citronellol, linalool, 1,3,5-trimethoxybenzene, and pentadecane. The overall fragrance was classed as “woody and light medicinal”. Not very attractive, I’d say! Ocimenes are known as a pleasant odor that is used in perfumes. They are believed to act as  a plant defense and have anti-fungal properties. Citronellol is another pleasant fragrance most commonly associated with oil of roses and geraniums. Linalool has a light fragrant scent used in soaps, fragranes, food additives and insecticides. 1,3,5-trimethoxybenzene has a sweet aromatic odor is combined with other chemicals to be used in colorants. Pentadecane is the main pheromone of the tsetse fly, as well as beetles, mites, fruit flies. What a combination! 

What was interesting in this study was not so much the chemicals but the complexity of studying smell. So many factors are involved, especially when including people. The amount of sunlight, the slighted breeze, air temperature, how fast a person is walking, how far away the flowers are, competing smells from other plants, not to mention the variation among people’s noses and the fact that 5 chemicals are involved. It has to be difficult to make recommendations on landscape design when there are so many variables. Of the five species they studied : Osmanthus, magnolia, wintersweet (Chimonanthus), lilac and woody peonies, the woody peony came in dead last. They recommended that smellscapes be incorporated into viewing routes so when people stop to check out the view, they get the full value of a smellscape!

S

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Anthocyanin accumulation and differential expression of the biosynthetic genes result in a discrepancy in the red color of herbaceous peony (Paeonia lactiflora Pall.) flowers. by Y. Wu, Z. Has, Y. Tang and D. Zhao. 2022. Horticulturae. Available online: https://www.mdpi.com/journal/horticulturae

The scientists were interested in learning the differences in the pigment, anthocyanin, between a pink and red cultivar of herbaceous peonies. First, I will say, that what the authors call red, to me, is a fuchsia pink. I think more on the lines of Red Charm and Francois Ortegat when I think of red. It just shows how perceptions of color change around the world and with individuals.

They also state that the herbaceous peony can be divided into nine flower color categories: red, pink, white, blue, purple, green, yellow, black and double color. Red and pink are the most popular colors. Red symbolizes passion and affection, and pink symbolizes grace, gentility and happiness.

Anthocyanins contribute pink, red, purple and blue cyanic colors to petals. The authors sampled petals from early bud stages to nearly senescent stages, then analyzed them for anthocyanins, flavones and flavonoid. They found that the two cultivars did not differ in the type of color components. All had the same anthocyanin, flavone and flavonol components. Both cultivars faded over time. The difference between cultivars was a higher gene expression of anthocyanin synthesis early in bud development in the red cultivar when compared to the pink. Gene expression takes two stages- early and late. In the red cultivar, high levels of anthocyanin were expressed, whereas the pink cultivar showed low levels in early development. The anthocyanin development in the pink cultivar never caught up with the dark cultivar and it remained pale through the whole development from bud to senescence.

Abstract

Melatonin enhances stem strength by increasing the lignin content and secondary cell wall thickness in herbaceous peony. by D. Zhao, Y. Luan, W. She, Y. Tang, X Huang, and J. Tao. 2022. Journal of Experimental Botany. https://doi.org/10.1093/jxb/erac165

This research paper was just reported as a PDF of a research paper that has yet to be formally published in the Journal of Experimental Botany. I have not seen the whole article, but have included the abstract here. I think of melatonin in human biology, circadian rhythms and sleep cycles. This use is a whole new angle! I wonder what the cost would be to apply melatonin to an entire peony field??? Hm!

Cut flower quality is severely restrained by stem bending due to low stem strength. Melatonin has been shown to function in many aspects of plant growth and development, yet whether it can enhance stem strength and the corresponding underlying mechanisms remain unclear. We investigated the role of melatonin in the enhancement of herbaceous peony (Paeonia lactifloraPall.) stem strength by applying exogenous melatonin and changing endogenous melatonin biosynthesis. Endogenous melatonin level positively correlated with the lignin content and stem strength in various P. lactifloracultivars. Supplementation with exogenous melatonin significantly enhanced stem strength by increasing lignin content and the S/G lignin compositional ratio, upregulating lignin biosynthetic gene expression. Moreover, overexpression of tryptophan decarboxylase gene (TDC) responsible for the first committed step of melatonin biosynthesis in tobacco significantly increased endogenous melatonin, which further increased the S/G ratio and stem strength. Whereas silencing PlTDC in P. lactiflora decreased endogenous melatonin, the S/G ratio and stem strength. Finally, manipulating the expression of caffeic acid O-methyltransferase gene (COMT1), which is involved in both melatonin and lignin biosynthesis, showed even greater effects on melatonin, the S/G ratio and stem strength. Our results suggested that melatonin had a positive regulatory effect on P. lactiflora stem strength.

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Kumar, S., A. Malik and V. Hooda. 2021. Drying of flowers: a money-spinning aspect of floriculture industry. Journal of Pharmacognosy and Phytochemistry. Spring 10(1): 27-31.

This article from India, summarizes methods used to dry/preserve cut flowers to expand options for businesses already selling fresh cut flowers. Dried flower products have been exported from India for at least 40 years, and markets are expanding. Interesting that some New Zealand peony growers told me they tried flower drying, but silk flowers were becoming so realistic, that dried flowers were not worth the effort.

Businesses in India are looking for ways to use small flowers, those that might not be at the right bud stage for cut flowers, those with short stems, and more. The authors provide a short description of the methods for drying by air, water, sun, pressing, microwave, hot air oven, desiccation, freezing and glycerine. Most of these methods are well known and have a long history. Interesting that peonies are only listed under the glycerine method, although I have used air, sun, oven, and desiccation methods, and I have seen some beautiful freeze-dried peony flowers. I can’t say I’m a big fan of air dried peony flowers except as individual petals for potpourri. The most interesting part of the article was a list of plants suitable for foliage preservation– peonies aren’t on that list, either. https://www.phytojournal.com/archives/2021/vol10issue2S/PartA/S-10-1-124-643.pdf

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Illieva, I. 2021. Names of botanical genera inspired by mythology. GSC Biological and Pharmaceutical Sciences Online press. 14(3)8-18.

Author, Iliana Illeva, University of Forestry, Sofia, Bulgaria, explored the scientific names of plants and traced those that originated in Greek Mythology. Peonies are there, of course. The origin refers to the centuries-old use of peony roots as medicine.

“Peony or paeony: a flowering plant in the genus Paeonia, the only genus in the family Paeoniaceae. The name derives from the Greek word παιώνιος healing, saving, which has given to him by Theophrastus in honour of Paeon (Παίων), a mythical physician of the Greek gods. Paeon (also spelt Paean) was a student of Asclepius, the god of medicine and healing and is said to have discovered the uses of the peony root. Pluto saved Paeon from the wrath of Asclepius, who became jealous of his pupil, by turning him into the peony flower.”

The article includes a lot of genera familiar to northern gardeners: Achillea, Anemone, Angelica, Artemisia, Cypripedium (in Greek means sandal of Venus; today known as lady slipper orchid), Dianthus, Gentiana, Heracleum, Iris, Nymphaea, Oplopanax (Greek for panacea juice – cures all ills), Parnassia, Silene, Valeriana, Veronica and many more. An interesting read for anyone who likes history and etymology! http://gsconlinepress.com/journals/gscbps/sites/default/files/GSCBPS-2021-0050.pdf

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Flower growers are always looking for other products or marketing methods to add value to their main product- fresh cut peonies. I see a lot of ads and information about peony artwork, medicinals, tea, cosmetics, calendars, photography, and so much more. However, these researchers show that connections might occur in areas one would never expect. At least for me, I would never have guessed that peony pollen could be a food supplement for fish! My question is, how do they harvest peony pollen, and what quantities make such an endeavor economical! Plus you have to like carp!

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Scientists at North Carolina State University conducted research into storage temperatures of peonies as cut flowers using three temperatures: -3.1C, 0.7C and 3.5C (26.4, 33.2 and 38.3F) in one experiment and -0.6C (30.9F) in another. Cut flowers were harvested mostly in stage 2 but some in earlier stages of opening. They were wrapped in newspaper and placed in boxes that were lined with a polyvinyl wrap and kept in cold storage for up to 14 weeks. Their experiment showed that tolerance to cold temperatures is cultivar dependent and lowering the temperature to 0.7 C 33.2F) and even -.6C (30.9) can extend the storage life without sacrificing (or increasing) vase life. As with a lot of other trials, pulsing with a sucrose solution did nothing for peony vase life.

It is interesting to compare these trials with ones held in Alaska where vase life can be much longer (7-10 days). I have seen a lot of peonies stored for 2 months or more, and the flower quality simply does not compare to flowers held for 4 weeks or less (34F, 1.1C) We also showed that for at least the first two weeks, chilling extended the vase life of peonies. The big issue, however, is translating it into the practicalities of commercial storage. Most storage facilities in Alaska, for instance, would experience refrigeration problems, freeze up, at these very cold temperatures. Retrofitting facilities to work at these low temperatures would be expensive. It most likely would require a facility dedicated to very low cold storage, something like a CA storage facility that was filled with flowers once, kept at a steady at freezing temperatures, monitored religiously to make sure temps didn’t dip suddenly, then opened up 14 weeks later.

For many years the minimum temperature for peony flower death has been -1.6C (29F). This study has not pushed the boundaries beyond those known limits.

Jahnke, N. J. M. Dole, Ben A. Bergmann, Guoying Ma and P. Perkins-Veazie. 2020. Extending cut Paeonia lactiflora Pall. storage duration using sub-zero storage temperatures. Agronomy. 10(11):1694. https://www.mdpi.com/2073-4395/10/11/1694

Abstract: Cut peonies (Paeonia lactiflora Pall.) have a relatively short vase life and limited availability due to seasonal production. Cultivars Festiva Maxima (FM), Monsieur Jules Elie (MJE), and Sarah Bernhardt (SB) stored at 0.7 C had a longer flower open time at 12 weeks of storage compared to those held at 􀀀3.1 or 3.5 C, while the flower bud time was unaected. The flower open time of FM and MJE was no dierent for stems stored at a sub-zero temperature of 􀀀0.6 C for 16 weeks compared to non-stored stems. Flower quality, opening, and lack of deformity was reduced at 16 weeks of storage in comparison to non-stored flowers, but higher for stems stored at 􀀀0.6 C compared to 0.7 C. Pre-treating stems before storage with pulses of a commercial hydrator solution or a 200 gL􀀀1 sucrose solution for 2 h at 4 C had little commercial significance compared to non-pulsed control stems. The total phenolic content, malondialdehyde, and superoxide dismutase were not eective indicators of open time or quality loss. This study is the first to demonstrate the successful use of a non-freezing, sub-zero storage temperature for peony, and the first to store cut peonies for 16 weeks, despite an increased risk of reduced flower quality.

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This paper highlights the use of flowers as a source of healthy phytonutrients. The review from the University of Warmia and Mazury, Poland is an extensive literature search of >100 species species that have been harvested for culinary and medicinal purposes. The list is amazing and includes traditional standards such as saffron, violets, calendula and dandelions. Buried in the middle is the peony, Paeonia lactiflora that is a source of the phytonutrients, gallic acid, quercetin, epicatechin, chlorogenic acid, ferric acid, ruin, dihydrokaempferol, apigenin and kaempferol. Considering the content of edible flowers is 70 – 95% water, imagine how many flowers would have to be harvested to get usable quantities of these chemicals for use in teas, tinctures, medicines and more for a world market. On a local scale, with small manufacturing companies, it might just be a niche market for all those too-open blooms in the cut flower peony field.

 Skrajda-Brdak,M., G. Dąbrowski, I Konopka. 2020. Edible flowers, a source of valuable phytonutrients and their pro-healthy effects – a review. Trends in Food Science and Technology. 103(2020):179-199.

 A B S T R A C T Background: Edible flowers have been used for their therapeutic properties for ancient times. Many sources indicate, that edible flowers have many beneficial activities like anti-anxiety, anti-cancer, anti-diabetic, anti-inflammatory, antioxidant, diuretic, anthelmintic, immunomodulatory and anti-microbial. People use it also in culinary applications, because they improve the aesthetic value, taste, flavour and appearance of dishes. Scope and Approach: This study expands knowledge on the content and composition of low molecular phytochemicals of edible flowers and the pro-healthy activities of their extracts or preparations. It is focused on showing flowers which are the best sources of individual compounds and on recent findings with the use of flower extracts or preparations in various cell-lines, animal and human models. Key findings and Conclusion: Performed comparison of composition includes simple phenolic acids, flavonols, flavanols, flavons, anthocyanidins, carotenoids and tocols. Species with the highest content of selected compounds are highlighted. Unique components of some flowers such as crocin, nimbolide, oleanic and ursolic acids, and acteoside are also mentioned. The potential activity of edible flowers for human health was analysed based on in vitro models with the use of various cell-lines and in vivo models with animal (mostly mice and rat) and human trials. The majority of the reviewed studies confirm the pro-healthy activity of edible flowers or their extracts. 

 

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These authors conducted experiments with stem strength on 8 cultivars of Chinese peonies, P. lacitflora. They were interested in learning if lignin and/or cellulose were the main components of stem strength (lignin won). In a previous article, they found that stem strength could be significantly improved by spraying plants with silicon or nano Calcium carbonate. In this study they tested 8 cultivars that had different stem strength qualities, four with poor stem strength where the stem could not hold up the fully opened flower, and four with great stems:

We have all seen this in peony fields. I think the cultivar that could easily top the list of strong stems in my research plots is ‘Sarah Bernhardt’, but we have all seen the wimps that simply do not hold up even in a vase.

The authors measured stem diameter and length and concluded that stem diameter was a great indicator of stem strength, whereas there was no correlation with stem length. My first question was, “Where did they measure diameter?” It’s not really clear. They mention sampling the top 12 cm of the stems, but I’m not sure if it was close to the bud where the stem naturally flares or further down. The stem diameter for the top row of cultivars ranged from 3.6 mm to 4.6 mm (+ about 0.4 mm). The cultivars on the bottom row ranged from 2.7 to 3.0 mm diameter. Wow– that’s not much of a difference between the smallest (3.6mm) diameter on a straight stem and the largest (3.0 mm) diameter on a cultivar bent nearly in half!  Hm! There was a bigger difference in digital force measurements  to test mechanical strength. The top row ranged from 16.4 to 21.9 Newtons mechanical strength whereas the bottom row was 6.9 – 9.7N.

Dr, Mingchu Zhang (University of Alaska Fairbanks) and I have done a bit of work on measuring stem strength in peonies, and we have found that there are so many variables, it is difficult to pinpoint one overriding factor. Obviously, from this study, anything that can increase lignin deposition in cell walls will be beneficial. How does that translate to a grower? Not sure yet. We do know water stress, nutrient stress and growth rate all impact stem strength. So dues the cultivar, but also the “pecking order” of the buds. Even within one plant, the first buds to emerge are usually the strongest, but as nutrient reserves are used up, the buds that appear later in the season can be very weak. It is definitely worth looking at Calcium carbonate or silicon as a supplement to promote stronger stems, but I think there will always be a few wimps at the end of the season.

Daqiu Zhao, Wenbo Shi, Xing Xia, Yuhan Tang, Jun Tao⁎Jiangsu Key Laboratory of Crop Genetics and Physiology, College of Horticulture and Plant Protection, Yangzhou University, Yangzhou, 225009, PR China ABSTRACTStraight stems are highly important to herbaceous peony (Paeonia lactifloraPall.) cutflowers. To clarify whetherthe microstructural and lignin characteristics are associated withP. lactiflorastem mechanical strength, eightcultivars were used to study their anatomical structure, secondary cell wall, lignin deposition, lignin content andstructure, lignin biosynthetic enzyme activity and related gene expression levels. The results showed that stemdiameter was a direct indicator estimating its mechanical strength. Simultaneously, the number of vascularbundles, area of vascular bundles, number of duct perforations, ratio of xylem to cross-section and thickness ofsecondary cell wall had significant positive correlations with stem mechanical strength. Moreover, three ligninmonomers were all detected in the stem, and the contents of S-lignin, G-lignin and total lignin in high stemmechanical strength cultivars were higher than those in low stem mechanical strength cultivars as a whole, andlignin was deposited in the cell walls of the sclerenchyma, vascular bundle sheath and duct. Additionally, cin-namate 4-hydroxylase (C4H), cinnamyl alcohol dehydrogenase (CAD) and polyphenol oxidase (PPO) activities inhigh stem mechanical strength cultivars were higher than those in low stem mechanical strength cultivars as awhole, andCADmight be the key gene among detected lignin biosynthetic genes. Consequently, microstructuraland lignin characteristics were closely correlated with stem mechanical strength inP. lactiflora. These resultswould provide useful information concerning the physiological mechanism of stem strength. Postharvest Biology and Technology 159 (2020) 1110430925-5214/ © 2019 Published by Elsevier B.V.T

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Attached is an article I wrote that summarizes the Alaska peony industry today. It covers how the industry got started and how it has matured over the past 18 years. As most growers will attest, it hasn’t been easy, and world competition is heating up. The industry is still in its infancy, and it will take many years to learn if it is truly viable.

2019 Alaska Peony industry

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The attached video was made in 2018 by Dr. Beverly Gerdeman, Washington State University who studied the identity and life cycles of thrips in Alaska.

Thrips and Lygus in Alaska

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JingqiXue, YeTang, ShunliWang, YuqianXue, XianwuLiu, and XiuxinZhangPostharvest Biology and Technology     Volume 155, September 2019, Pages 11-19; https://doi.org/10.1016/j.postharvbio.2019.05.007

This article verifies what most of us have known for quite a while– dry storage is recommended for peonies. This article stored flowers for 3 days or 23 days at 0 – 4C temperatures. Best quality and vase life were in flowers stored dry.

Herbaceous peony (Paeonia lactiflora Pall.) is one of the most important cut flowers worldwide, but the short natural florescence seriously affects its industrial development. In this study, the cut peony ‘Yang Fei Chu Yu’ was preserved in dry storage (DS) and wet storage (WS), respectively, at 0–4 °C. We set two treatments of short- and long-term storage (S-tS, 3 d; L-tS, 23 d). We assessed the postharvest performance; determined the changes in starch, sucrose, glucose, and fructose; and then analyzed the expression of a subset of representative genes that regulate starch and sucrose metabolism by RT-qPCR. When compared to WS, our results indicated that DS treatment exhibited significantly higher vase quality of cut peony after both S-tS and L-tS. For S-tS, this effect should be due to faster starch consumption during storage of 1–3 d and sucrose hydrolysis at the beginning of the vase period. The change in starch hydrolysis can be attributed to increased expression of PlSPS1 and PlSPS4 as well as decreased expression of PlSUS4, whereas the sucrose metabolism should be associated with the inducing of PlSUS3 expression. During S-tS, PlCWIN1may positively and PlVIN1 may negatively affect vase quality by adjusting water use efficiency. Inducing expression of PlCIN1 and PlCIN2 may also improve cut flower quality, probably via other pathways. For L-tS, the higher level of glucose and fructose content at the end of the period may be more beneficial in improving vase quality. The increasing expression of PlSUS3 and the decreasing expression of PlVIN1 as well as the inducing expression of the three PlCINs may regulate this process at the transcriptional level. Based on these results, we recommend that DS is used for cut peony cold storage within a prescribed period, regardless of the storage time.

 

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Andrea R. Garfinkel , Katie p. Coats, Don L. sherry & Gary A. Chastagner

Science Reports https://www.nature.com/articles/s41598-019-43165-y.pdf

Genus Botrytis contains approximately 35 species, many of which are economically-important and globally-distributed plant pathogens which collectively infect over 1,400 plant species. Recent effortsto genetically characterize genus Botrytis have revealed new species on diverse host crops around the world. In this study, surveys and subsequent genetic analysis of the glyceraldehyde-3-phosatedehydrogenase (G3PDH), heat-shock protein 60 (HSP60), DNA-dependent RNA polymerase subunit II (RPB2), and necrosis and ethylene-inducing proteins 1 and 2 (NEP1 and NEP2) genes indicated thatBotrytis isolates collected from peony fields in the United States contained more species diversity
than ever before reported on a single host, including up to 10 potentially novel species. Together, up to 16 different phylogenetic species were found in association with peonies in the Pacific Northwest, which is over a third of the total number of species that are currently named. Furthermore, species were found on peonies in Alaska that have been described on other host plants in different parts of the world, indicating a wider geographic and host distribution than previously thought. Lastly, some isolates found on peony share sequence similarity with unnamed species found living as endophytes in weedy hosts, suggesting that the isolates found on peony have flexible lifestyles as recently discovered in the genus. Selected pathogenicity, growth, and morphological characteristics of the putatively newBotrytis species were also assessed to provide a basis for future formal description of the isolates as newspecies.

Andrea Garfinkel completed a genetic analysis of Botrytis species that she found in Alaska Peony fields as well as several other locations. The article describes her analysis of gray mold she found on peonies. The taxonomy is quite complex but the bottom line is, there is significantly greater biodiversity of Botrytis species in the US than has ever been reported, especially for a single host species, the peony.

“The relative frequency of Botrytis species collected from peony differed by survey region. In Washington and Oregon (combined), the majority of samples were identified as B. paeoniae (51%), followed by B. cinerea (29%). Only 8% of the samples (n = 6) collected in Washington and Oregon (all of which were collected in Washington) did not belong to either B. cinerea, B. paeoniae, or B. pseudocinerea. On the contrary, 37% of the samples found in Alaska were species other than B. cinerea, B. paeoniae, or B. pseudocinerea, closely followed by isolates that were identified as B. cinerea (40%).

Basically, Alaska has the greatest diversity of Botrytis species of all regions tested, and a great majority of the samples could not be identified to known species. The authors speculated that maybe because Alaska is quite young in agriculture and still has a lot of wilderness, the diversity could originate from surrounding areas. It is not known how many of these new types are actually pathogenic on peonies. Yet another study, I’m sure!

 

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A.R. Garfinkel1,a and G.A. Chastagner2

Acta Horticulturae 123: 199- 206. ISHS 2019 DOI 10.17660

 

Abstract

The most important step in any effective disease management strategy is proper diagnosis. Therefore, in an effort to assist growers with disease management, herbaceous peony (Paeonia lactiflora) samples were collected and submitted to our lab from 12 states in the United States to determine the range of diseases present in both landscape and commercial settings. Both morphological and molecular techniques were used in the identification of pathogens isolated from peony flowers, leaves, stems, and roots. Trials were conducted to confirm the ability of all pathogens to cause disease on healthy peony tissue. This survey revealed new species-host-state combinations in several states as well as five different fungal genera that had not previously been identified on peonies in the country: a Botryosphaeria sp., up to 3Colletotrichum spp., Mycocentrospora acerina, a Phoma sp., and Pilidium concavum. Each of these pathogens have only been reported a few times worldwide and there is correspondingly little to no information available on their management. Given the need for growers to address these emerging disease issues, we outline potential management strategies for fungal peony pathogens. Our recommendations take into account general fungal disease management tools, published information on the specific biology of these organisms, observations of peony diseases over our years of fieldwork, and examples from other pathosystems that have been successful in managing diseases caused by the pathogens we have found on peonies.

 

This article is one of several to come out of Andrea Garfinkel’s PhD thesis where she collected samples from Alaska grower’s fields as well as other locations. It is a practical summary of methods that can be used to manage the variety of fungal diseases that show up in peony fields. Below is a summary of recommended management steps:

1. Reduce leaf wetness: many fungi need moisture on the leaves to grow and spread. Avoid overhead irrigation or water early in the morning so leaves can dry during the day.
2. Try to minimize the spread of disease by spores. Remove diseased tissue throughout the growing season, Some fungi are spread via air currents and are difficult to contain. Others such as anthracnose, tan spot and licorice spot can also be moved via water splashes. Again avoid overhead irrigation.
3. Petal tissue is extremely susceptible to Botrytis growth. Petals that fall during the season and land onto leaves or even the soil can be food for the growth of Botrytis disease. Remove all petals from the fields and do not allow petals to fall anywhere in the garden. They will quickly become infected.
4. Prevent overwintering. Remove diseased tissues at the end of the growing season and cut as close to the soil level as possible to remove all foliage from the field.
5. If the disease is found in the soil, it might require removal of the entire plant plus soil as well as adjacent plants. Avoid overwatering and make sure soils are well drained
6. Apply appropriate fungicides. The full article lists some possible chemicals for management.
7. Choose resistant or tolerant cultivars. ‘Kansas’ is extremely susceptible to Cladosporium leaf blotch, whereas ‘Sarah Bernhardt is quite resistant.
8. Remove weeds from fields that can be hosts for diseases. Mycocentrospora red spot (licorice spot) also grows well on weeds growing near the stems of peonies.
9. Avoid wounding of plant to prevent entry of disease. This is especially true for Phomopsis disease.

 

 

 

 

Diversity of endophytic fungi of Paeonia lactiflora Pallas and screening for fungal paeoniflorin producers. by Xiaozhong Cheng, Zhiwen Wei, Shunchang Pu, Min Xiang, Aolei Yan, You Zhang and Xiaomei Wang. FEMS Microbiology Letters https://doi.org/10.1093/femsle/fny263

This article has nothing to do with cut flower peonies but everything to do with the medicinal aspect of peonies but with an interesting twist. . Endophytic fungi are ones that live symbiotically within the tissues of the host plant, and in most instances, cause no harm. In many plants, they have been shown to improve crop yields, and there is a lot of research to develop fungal inoculants that can be applied to the plant or seeds to promote growth. Paeoniflorin is one of the most important medicinal ingredients in peony roots, seeds, leaves and stems that has been used for hundreds of years in traditional Chinese herbal medicine

In this study, the researchers were not so much interested in peony plant growth as they were in studying the fungi that inhabit peony plants. They found 16 different taxa inhabiting the roots, leaves and stems including Alternaria, Aspergillis and Penicillium species. All of these fungi were found to produce paeoniflorin, and one species, Aspergillis flavus, produced sufficient quantities that led the authors to conclude this fungus could be isolated and “farmed” – grown in cultures – specifically for the purpose of producing paeoniflorin for medicine.

For cut flower growers, it is interesting to learn of these fungal associates of the peony plant. One wonders which, if any, could be used as an inoculant to enhance growth or suppress diseases in our peonies. Just a thought!

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Identification of floral fragrances and analysis of fragrance patterns in herbaceous peony cultivars by

Song, C., Q. Wang, J A. Teixeira da Silva and X. Yu.

2018. Journal of the American Society for Horticultural Science. 143(4):248-258

This article is about herbaceous peony fragrance. The authors from China and Japan examined 30 different cultivars using both test panelists who voted on the intensity of fragrance as well as chemical analysis using automatic thermal desorption-gas chromatography/mass spectrometry. The authors isolated 130 volatile organic compounds of which 72 were part of the scent components of peonies. Nine of the compounds were newly identified when compared to earlier studies, but they hint that the previous authors were working on cut stems whereas they were sampling flowers in the field. It is possible that just in the process of cutting, some scent compounds are lost. Some of the compounds they isolated were in fact due to the instruments and methods used to analyze the scent compounds. It shows how tricky it is to study scent when even the solvents used have a scent!

And think about the complexity of breeding peonies for scent when you are working with 72 different compounds!

The authors concluded that some cultivars had sufficient quantities of scent organic compounds that the flowers could be harvested by the chemical industry for perfumes, air fresheners, toothpaste and more. Here is their summary:

No detectable aroma: Cultivars: Carina, Joker, Red Magic, Etched Salmon, Lovely Rose and Fairy Princess

Light fragrance with nonobvious aroma (not quite sure what nonobvious aroma means): Cultivars: May Lilac, Roselette, Red Charm, Prairie Moon, Cytherea, Scarlet O’Hara, Coral Sunset, Old Rose Dandy.

Moderate aroma: Cultivars: Sorbet, Sarah Bernhardt, Lemon Chiffon, Lian Tai, Zhong Sheng Fen, Gao Gan Hong, Zi Feng Yu

Intense Fragrance: Duchess de Nemours (rose fragrance), Cream Delight (lily frag), Going Bananas (lily frag with slight fruity and woody scent), Yang Fei Chu Yu (Orange blossom frag.), Zhu Sha Pan (orange blossom frag.), Qiao Ling (rose frag.).

The Cultivars, Lemon Chiffon, Cream Delight, Old Rose Dandy and Going Bananas have a distinctive lily scent which is attributable mostly to a compound called linalool. Coincidentally, this chemical is the predominant aroma in Lily-of-the valley (Convallaria majalis)! It is used to produce essential oils and other flavors. And by the way, they are all yellow peonies!

The cultivars, Sarah Bernhardt, Sorbet and Duchess de Nemours all had a rose scent with the main compound being  (R)-citronellol. This compound is used in the production of perfumes, essences, spices, flavored foods and rose tea.

This is an interesting comparison, but I am sure, environmental conditions especially temperature would influence the intensity of fragrances. It would be interesting to grow some of the fragrant cultivars under different outdoor conditions to see if intensity can be enhanced even further. Or maybe our northern environment not only produces large flowers but also mega quantities of scent!

 

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The attached research summary suggests that the use of nano-silver particles in the vase water will increase vase life in peonies by 4 days. It does this partly through reducing bacteria in the water that can plug up the stems, as well as influencing the water balance in cut stems. The article includes a lot of links that explore the environmental concerns of using such chemicals.

Peony Vase Life

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The dynamics of starch and sugar utilisation in cut peony (Paeonia lactiflora Pall.) stems during storage and vase life E.F. Waltona,∗, H.L. Boldinghb, G.F. McLarenc, M.H. Williamsa,1, R. Jackman 2010. Post Harvest Biology and Technology 58:142 – 146. Peony carbs vase life.

This article published in 2010 from NZ scientists examines the quantities of carbohydrates in fresh cut peony stems stored up to 8 weeks at 0C and compared them with flowers still attached to the plant. The idea was to determine if there was sufficient carbs in the cut stems to promote max. vase life or should they try to increase carb production in the field or add carbs to the vase water  to extend vase life

They used ‘Sarah Bernhardt’ peonies. Fresh cut stems that had not been stored (control) opened in about 4.9 days and remained at the full bloom stage for an additional 9.1 days. Field flowers had a similar vase life. Flower buds stored 8 weeks opened much more rapidly in 1.9 days and remained at the full bloom stage for 7.1 days. At the beginning of vase life trials, non structural carbs made up 27% of bud dry weight and during flower opening, carb concentrations declined to only trace amounts. The biggest decrease occurs just as the petals begin to unfurl. At the same time total sugars increased and peaked when flowers had fully opened, then gradually decreased as the flower senesced. The main sugars were fructose and glucose.

Flowers still in the field showed that the amount of sugar moving into a stem  during flower opening was about 3.2 g or about 14.3% of dry weight of the whole stem or 42% of the dry weight of the open flower. It would follow, then, that adding sugars to the vase water of fresh cut stems might extend vase life by improving carbohydrate levels in the flowers and stems. However, when comparing the flowering sequence between flowers in the field and fresh cut flowers, there is no difference in the number of days flowers take to open or in the total vase life. The authors conclude that even though there is a big influx of carbs into the stem and flower, carbs are not a limiting factor in vase life.

They propose, instead, that the big difference is in what happens to the starches. In  cold storage, starches are hydrolyzed (broken down into simpler sugars)  in the tissues within the first two weeks, something that does not occur in field or fresh cut flowers. This resulting massive availability of sugars leads to very rapid flower opening in stored flowers and shorter vase life. So how do you slow starch hydrolysis in storage?

 

 

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The following paper is an exhaustive anatomical look at flower bud initiation in herbaceous peony identified as Chinese Peony. Flower buds of cultivar, ‘Dafugui’ were sampled exhaustively, fixed in an alcohol solution (FAA), then embedded in paraffin. The blocks of paraffin were then sliced into very thin sections, stained with different cellular dyes, and examined beneath the microscope. This process, by itself, deserves applause for the sheer patience it requires of the authors because the photos you see do not just happen by chance. The researchers have to sample hundreds of buds and examine thousands of thin sections before they find the exact stages of flower bud development they seek. I know a bit about this because I conducted a similar study of flower buds of lingonberry, Vaccinium vitis-idaea, for my PhD thesis years ago. It tested every iota of my patience—seeking the very early stages of flower bud initiation that are not visible with the naked eye. In regards to lingonberry, the vegetative buds showed the transition to flower buds way back in June (Fairbanks, AK) long before you could actually tell there was a flower bud present.

There are other methods of discovering this transition from vegetative buds to flower buds, but they all require harvesting a lot of buds and guessing when the flowering structures will show up. For most flowers, lingonberries and peonies included, the vegetative bud starts out as a dome shape similar to the eraser on a pencil. A trigger or triggers– could be photoperiod, age of the plant, nutrition, genetics, temperature, etc.- induces that dome to flatten out into a series of rings that give rise to a ring of sepals, another inner ring (or more) of petals,  then a ring(s) of stamens and finally the pistils. From the side (longitudinal section), they look like bumps.  In peonies, it is even more interesting because a lot of the stamens sometimes transition into petals, thus forming petaloid stamens.

The timing of these events is interesting both from the botanical standpoint of which factors might be triggering the development of flower buds but also the environmental factors that might be involved in interfering with this transition. For instance, freezing weather in autumn might stop the process of flower bud initiation and development. Maybe poor root growth and lack of nutrients prevents the transition from happening or it happens partway so the flower bud aborts.

In these Chinese flowers growing at the Heilongjiang Forest Botanical Garden, flower bud initiation begins in early September. The sequence is like this:

Early September – Flower bud initiation

Early to late September –Flower bud bract differentiation

Late September to mid October – Sepal formation

Mid October – late Nov – petal formation

Mid November – Early March – male stamen formation

April – female pistil formation

Pollen development, maturation of the anthers occurs in late winter and the female ovules develops during early spring for flowering that occurs in early to mid May.

Think about all the environmental factors that could impact this developing flower bud from September through flowering in spring. It is mind boggling to think of all the weather factors, insect pests, diseases that could interfere with flowering.

In Alaska, we have no idea when flower bud initiation begins, and the whole process would have to stop in late autumn when the ground and buds freeze. All of this development would resume some time in spring and is, no doubt, one reason why Alaska flowers bloom so much later than lower latitudes. We know that peony flower bud initiation is not mediated by photoperiod, but what are the triggers that initiate that transition from vegetative to flower buds? Anyone for a PhD?

Peng, M. FL Huang, FJ Meng, BZ Hu, XF Chen, R Luo, N Li, RF Wang, Y Zhao, QW Zou, CT Wu and JL Dai. 2017. Reproductive Biology of the Chinese herbaceous perennial peony (Paeonia lactiflora Pall.) using the paraffin method. Φyton International Journal of Experimental Botany. 86:296-305.   Peony flower bud initiation