Chrysanthemum Plants Research Articles

Temporary Immersion Bioreactor System as an Efficient Method for Mass Production of In Vitro Plants in Horticulture and Medicinal Plants

A temporary immersion system (TIS) bioreactor has been used as an efficient and cost-effective method for the in vitro propagation of many plant species. In the current study, the applicability of a TIS bioreactor for plantlet regeneration Chrysanthemum morifolium Ramat., Fragaria × ananassa Duch., and Cnidium officinale Makino was studied. Shoot length, a number of leaves per regenerated shoot, fresh, and dry biomass of plantlets were optimal with the TIS compared to semi-solid and liquid immersion cultures. The leaf area in cryshanthmum, strawberry, and C. afficinale were 2.87 cm2, 3.51 cm2, and 1.43 cm2, respectively, in the plants regenerated by TIS. The photosynthetic pigments were highest in strawberry plants grown in TIS bioreactor culture, and there was no significant difference between semi-solid and liquid culture while the highest values were obtained in C. officinale maintained in semi-solid culture. The chrysanthemum and strawberry plants showed a 100% acclimatization rate in all culture systems. C. officinale plants showed the highest survival rate at 96.9%, which were regenerated in the TIS. TIS bioreactor culture, thus, provides a convenient method that could be adopted for commercial in vitro propagation of chrysanthemum, strawberry and C. officinale plants.

Handelin extends lifespan and healthspan of Caenorhabditis elegans by reducing ROS generation and improving motor function.

Aging and aging-related disorders contribute to formidable socioeconomic and healthcare challenges. Several promising small molecules have been identified to target conserved genetic pathways delaying aging to extend lifespan and healthspan in many organisms. We previously found that extract from an edible and medicinal plant Chrysanthemum indicum L. (C. indicum L.) protect skin from UVB-induced photoaging, partially by reducing reactive oxygen species (ROS) generation. Thus, we hypothesized that C. indicum L. and its biological active compound may extend lifespan and health span in vivo. We find that both water and ethanol extracts from C. indicum L. extended lifespan of Caenorhabditis elegans, with better biological effect on life extending for ethanol extracts. As one of the major biological active compounds, handelin extended lifespan of C. elegans too. RNA-seq analysis revealed overall gene expression change of C. elegans post stimulation of handelin focus on several antioxidative proteins. Handelin significantly reduced ROS level and maintained the number and morphology of mitochondria. Moreover, handelin improveed many C. elegans behaviors related to healthspan, including increased pharyngeal pumping and body movement. Muscle fiber imaging analyses revealed that handelin maintains muscle architecture by stabilizing myofilaments. In conclusion, our present study finds a novel compound handelin, from C. indicum L., which bring about biologically beneficial effects by mild stress response, termed as hormetin, that can extend both lifespan and healthspan in vivo on C. elegans. Further study on mammal animal model of natural aging or sarcopenia will verify the potential clinical value of handelin.

Deposition law of flat fan nozzle for pesticide application in horticultural plants

Pesticide spraying is to protect the plants with adequate target coverage and a minimum of off-target drift. Understanding the spatial distribution characteristics of spray droplets is essential for regulating pesticide deposition, in order to investigate the relationship between the two at the mechanistic level and provide an accurate basis for nozzle selection, this study compared the characteristics of the atomization field under different pressures, angles, and flow rate types by phase Doppler particle analyzer (PDPA), the unit spatial density of droplet was used as a link to explore the internal mechanism that affects the deposition efficiency by constructing a transport model and conducting actual spraying experiments. The results showed that the cumulative distribution of droplet diameter could be perfectly fitted by the Rosin-Rammler correlation, and the deposition efficiency had a strong correlation with the peak particle size range. For strawberry and chrysanthemum plants, the optimal droplet deposition particle size ranges were 250-270 μm and 240-260 μm, respectively. This article explained the deposition efficiency from a single droplet dynamics mechanism and deposition of droplet cloud, which provided a new research idea for the study of precision plant protection. Keywords: pesticide transport, deposition, atomization field, PDPA DOI: 10.25165/j.ijabe.20221504.7502 Citation: Wu X Y, Jia Y L, Luo B, Chen C C, Wang Y X, Kang F, et al. Deposition law of flat fan nozzle for pesticide application in horticultural plants. Int J Agric & Biol Eng, 2022; 15(4): 27–38.

Use of sawdust and bark of Pinus radiata as substrates for Belgian Chrysanthemums grown for summer production

In search for alternative substrates for containerized ornamentals, potted Dgndranthema grandiflora (chrysanthemum) plants were grown in Maule Region for summer flowering, using pure fresh sawdust and sawdust plus pine bark (both from Pinus radiata) in mixes as growing media, with soluble fertilizer in fertigation. Rooted cuttings of cv. 'Marina' (Belgian type) were planted individually in 17 cm (diameter) x 14 cm (height) pots filled with different media. For 75 days, plants were kept in an unheated greenhouse under artificial long days and were fertilized weekly with a soluble fertilizer. After pinching, plants were taken outside the greenhouse to full sun conditions, and artificial short days were applied for 8 weeks. In a split plot design, 8 treatments were carried out: 4 media mixes (pure sawdust and sawdust: bark in ratios 1:1, 2:1 or 3:1 by volume), and 2 frequencies of watering with soluble fertilizer; daily and every 2 days (applying a solution of 200 ppm N, based on a soluble NPK fertilizer, with 3 replica per treatment. Plants showed a reduced growth in pure sawdust (25.5 cm height) as compared with sawdust: bark (30 to 35 cm). Media mixes and fertilization frequency affected diameter; plants in pure sawdust had a smaller diameter (34 cm) than plants cultivated in sawdust: bark (40 cm). Plants fertilized every 2 days had a smaller diameter (36 cm) than those fertilized daily (41 cm). Plants grown in pure sawdust had yellowish-green leaves, while the leaves of plants grown in sawdust plus bark showed colors close to dark green. Flowers showed different color as when grown in autumn (yellow vs. orange). Plants of all treatments bloomed on the same date. The pH of all media mixes in all measurements during cultivation time was close to 6.0. It is concluded that it is possible to grow potted chrysanthemum in all the tested media mixes, but in the case of pure sawdust, to avoid problems due to its low retention of irrigation solution, it is advisable to mix it with pine bark in a 3:1 ratio.

Performance of chrysanthemum at dark exposure under polytunnel condition

The field experiment carried out in chrysanthemum (cv. Chandrika) nursery 10 at College of Horticulture, Dapoli, Dist. Ratnagiri 2020-21 under polytunnel conditions during 2020-21 revealed that exposing chrysanthemum plants to darkness for 180 minutes using 90 per cent black shed net, showed promising results in increasing plant spread, number of branches, average leaf area, leaf area index, days required for 50 per cent flowering, flower diameter, length of flower stalk and the flower yield parameters, respectively. The shelf life of chrysanthemum flowers was extended by 24.84 days at 2°C temperature level.

Aqueous extracts from Acalypha gaumeri and Bonellia flammea for leaf blight control in chrysanthemum (Chrysanthemum morifolium)

The chrysanthemum is the second most important cut flower in the world, however, its quality and commercial value is affected by the leaf blight produced by <em>Alternaria </em>spp. The objective of this work was to evaluate the causal agent of leaf blight in Chrysanthemum, and its control with aqueous extracts of <em>Acalypha gaumeri </em>and <em>Bonellia flammea</em>. The fungus was collected and identified from leaves and stems of chrysanthemum plants. Subsequently, molecular identification and pathogenicity tests were performed on chrysanthemum plants. In the field, treatments were evaluated with weekly applications of: T1: <em>B. flammea </em>bark extract, T2: <em>A. gaumeri </em>root extract, T3: negative control (water) and T4: Captan® fungicide. Prior to the application of the treatments, plants were inoculated with the isolated fungus (2.5 × 106 spores mL-1) and severity was evaluated. <em>Alternaria chrysanthemi </em>was identified as the causal agent. Based on the severity percentage, the lowest averages of the area under the disease progress curve, the lowest rates of apparent infection, the lowest intensity of the disease and the greater effectiveness in controlling the disease were observed for T2 (165, 0.017, 8 and 67%, respectively) followed by T1 (186, 0.022, 13 y 50 %, respectively) and T4 (179, 0.023, 14 y 45%, respectively), observing a significantly different than negative control T3 (369, 0.025, 25 and 0%, respectively). Plant extracts have potential to be used as an alternative in the management of <em>Alternaria </em>leaf blight in chrysanthemum.

The effect of potassium silicate on pest resistance and postharvest longevity in chrysanthemum plants

Chrysanthemum is one of the most beautiful flowers and probably the oldest plant grown commercially in different parts of the world. Chrysanthemum, like all other plants, is susceptible to attack by various pests and diseases. The use of silicon has been shown to minimize damage caused by insect and also increase shelf life. Thus, the objective of this work was to evaluate the effect of potassium silicate in pest resistance and postharvest longevity of chrysanthemum. The experiment was carried out in the experimental area of the Federal Institute of Education, Science and Technology of Espírito Santo - Itapina Campus, the treatments consisted of four doses of potassium silicate - Sifol® (2, 4, 6 and 8 mL L−1) and a control treatment without foliar application of potassium silicate applied to chrysanthemum cv. Zembla. Leaf application of potassium silicate reduced the incidence of cercosporiosis and thrips in chrysanthemum leaves. Chrysanthemum leaf and flower longevity increased when potassium silicate doses were applied. It is recommended for chrysanthemum cv. Zembla applications of 0.6 and 0.8 mL L−1 potassium silicate.

Systematic Review: Phytochemical Content and Pharmacological Effects of Chrysanthemum sp.

Chrysanthemum sp. is a plant often used by the community as an ornamental plant, drink, and traditional medicine. This study aims to examine the plant Chrysanthemum sp. from the aspect of phytochemical and pharmacological activity. The review method used in this study is the PRISMA method. Sources of data obtained using databases electronic from PubMed and Google Scholar. This review shows that plants Chrysanthemum sp. have phytochemical and pharmacological potential. The compounds contained in theplant Chrysanthemum sp. are morphine, genistein, hydantoin, limonene, g-terpinene, a-pinene, a-terpenyl acetate, 4-terpenyl acetate, a-calacorene, a-cedrene, b-bourbobene, elemol, 2- hexenal, and orphenadrine. Chrysanthemum sp. plants have anticancer, antibacterial, antioxidant, antifungal, analgesic, anti-inflammatory, and anticonsulvan activities.

Interaction of Light Intensity and CO2 Concentration Alters Biomass Partitioning in Chrysanthemum

Abstract Biomass partitioning is one of the pivotal determinants of crop growth management, which is influenced by environmental cues. Light and CO2 are the main drivers of photosynthesis and biomass production in plants. In this study, the effects of CO2 levels: ambient 400 ppm (a[CO2]) and elevated to 1,000 ppm (e[CO2]) and different light intensities (75, 150, 300, 600 μmol·m−2·s−1 photosynthetic photon flux density – PPFD) were studied on the growth, yield, and biomass partitioning in chrysanthemum plants. The plants grown at higher light intensity had a higher dry weight (DW) of both the vegetative and floral organs. e[CO2] diminished the stimulating effect of more intensive light on the DW of vegetative organs, although it positively influenced inflorescence DW. The flowering time in plants grown at e[CO2] and light intensity of 600 μmol·m−2·s−1 occurred earlier than that of plants grown at a[CO2]. An increase in light intensity induced the allocation of biomass to inflorescence and e[CO2] enhanced the increasing effect of light on the partitioning of biomass toward the inflorescence. In both CO2 concentrations, the highest specific leaf area (SLA) was detected under the lowest light intensity, especially in plants grown at e[CO2]. In conclusion, elevated light intensity and CO2 direct the biomass toward inflorescence in chrysanthemum plants.

Comparative metabolomics analysis revealed biomarkers and distinct flavonoid biosynthesis regulation in Chrysanthemum mongolicum and C. rhombifolium.

Chrysanthemums are traditional flowers that originated in China and have high ornamental, economic and medicinal value. They are widely used as herbal remedies and consumed as food or beverages in folk medicine. However, little is known about their metabolic composition. The aims of this work were to determine the metabolic composition of and natural variation among different species of Chrysanthemum and to explore new potential resources for drug discovery and sustainable utilisation of wild Chrysanthemum. The metabolomes of Chrysanthemum mongolicum (Ling) Tzvel. and Chrysanthemum rhombifolium H. Ohashi & Yonek. were compared using a widely targeted metabolomics approach based on liquid chromatography-tandem mass spectrometry (LC-MS/MS). In total, 477 metabolites were identified, of which 72 showed significant differences in expression between C. mongolicum and C. rhombifolium, mainly in flavonoids, organic acids and nucleotides. The flavone and flavonol biosynthesis pathway showed significant enrichment among the differentially expressed metabolites. The contents of genkwanin, trigonelline, diosmin, narcissoside, 3,4-dihydroxyphenylacetic acid, linarin, N',N'-p-coumarin, C-hexosyl-tricetin O-pentoside, chrysoeriol, acacetin and kaempferol-3-O-gentiobioside were significantly different between the two species and represent potential biomarkers. The types of flavonoid-related metabolites in the flavonoid biosynthesis pathway differed between C. mongolicum and C. rhombifolium. The mechanisms underlying the unique adaptations of these two species to their environments may involve variations in the composition and abundance of flavonoids, organic acids, and nucleotides. These methods are promising to identify functional compounds in Chrysanthemum species and can provide potential resources for drug discovery and the sustainable utilisation of Chrysanthemum plants.

First Report of Stem and Foliage Blight of Chrysanthemum Caused by Phytophthora drechsleri in the United States.

Chrysanthemum (Chrysanthemum × morifolium) plants exhibiting stem and foliage blight were observed in a commercial nursery in eastern Oklahoma in June 2019. Disease symptoms were observed on ~10% of plants during a period of frequent rain and high temperatures (26-36°C). Dark brown lesions girdled the stems of symptomatic plants and leaves were wilted and necrotic. The crown and roots were asymptomatic and not discolored. A species of Phytophthora was consistently isolated from the stems of diseased plants on selective V8 agar (Lamour and Hausbeck 2000). The Phytophthora sp. produced ellipsoid to obpyriform sporangia that were non-papillate and persistent on V8 agar plugs submerged in distilled water for 8 h. Sporangia formed on long sporangiophores and measured 50.5 (45-60) × 29.8 (25-35) µm. Oospores and chlamydospores were not formed by individual isolates. Mycelium growth was present at 35°C. Isolates were tentatively identified as P. drechsleri using morphological characteristics and growth at 35°C (Erwin and Ribeiro 1996). DNA was extracted from mycelium of four isolates, and the internal transcribed spacer (ITS) region was amplified using universal primers ITS 4 and ITS 6. The PCR product was sequenced and a BLASTn search showed 100% sequence similarity to P. drechsleri (GenBank Accession Nos. KJ755118 and GU111625), a common species of Phytophthora that has been observed on ornamental and vegetable crops in the U.S. (Erwin and Ribeiro 1996). The gene sequences for each isolate were deposited in GenBank (accession Nos. MW315961, MW315962, MW315963, and MW315964). These four isolates were paired with known A1 and A2 isolates on super clarified V8 agar (Jeffers 2015), and all four were mating type A1. They also were sensitive to the fungicide mefenoxam at 100 ppm (Olson et al. 2013). To confirm pathogenicity, 4-week-old 'Brandi Burgundy' chrysanthemum plants were grown in 10-cm pots containing a peat potting medium. Plants (n = 7) were atomized with 1 ml of zoospore suspension containing 5 × 103 zoospores of each isolate. Control plants received sterile water. Plants were maintained at 100% RH for 24 h and then placed in a protected shade-structure where temperatures ranged from 19-32°C. All plants displayed symptoms of stem and foliage blight in 2-3 days. Symptoms that developed on infected plants were similar to those observed in the nursery. Several inoculated plants died, but stem blight, dieback, and foliar wilt were primarily observed. Disease severity averaged 50-60% on inoculated plants 15 days after inoculation. Control plants did not develop symptoms. The pathogen was consistently isolated from stems of symptomatic plants and verified as P. drechsleri based on morphology. The pathogenicity test was repeated with similar results. P. drechsleri has a broad host range (Erwin and Ribeiro 1996; Farr et al. 2021), including green beans (Phaseolus vulgaris), which are susceptible to seedling blight and pod rot in eastern Oklahoma. Previously, P. drechsleri has been reported on chrysanthemums in Argentina (Frezzi 1950), Pennsylvania (Molnar et al. 2020), and South Carolina (Camacho 2009). Chrysanthemums are widely grown in nurseries in the Midwest and other regions of the USA for local and national markets. This is the first report of P. drechsleri causing stem and foliage blight on chrysanthemum species in the United States. Identifying sources of primary inoculum may be necessary to limit economic loss from P. drechsleri.

Innovative technologies for cloned plants adaptation

Chrysanthemum plants are popular with amateur gardeners and breeders. It is widely used in landscaping cities, parks, and also for bouquets. Plants are notable for longer flowering and a bright color of flowers. Extracts of chrysanthemum plants contain various biologically active substances with bactericidal properties and are used in pharmacology and dentistry. The objective is to develop an effective technology for rapid in vitro reproduction and adaptation of chrysanthemum microclones. The objects of the study were chrysanthemum plants of three varieties: Bacardi, Korean Dawn, and Snow White. Semifloscules and flower buds were used as primary explants. The explants were cultured on a Murashige and Skoog (MS) nutrient medium containing mineral salts, as well as various growth regulators: 1) 1 mg L-1 BAP + 0.5 mg L-1 IAA; 2) 15% Aminoven solution 3 mL L-1 ; 3) Stimul 1 mL L-1 ; and 4) a hormone-free medium. Microshoots were adapted using an aeroponic system. Unrooted microshoots were used for adaptation. The GrowPlant X-Stream 120 propagator was used as equipment for adaptation. The frequency of adventious budding depended on the hormonal composition of the nutrient medium. Aminoven in the nutrient medium led to the induction of the formation of adventitious buds on average in 85% of cases. The same indicator averaged 72% on the Stimul-containing medium. In a BAP-containing medium, the considered indicator was the same with the control variant (hormone-free medium). The Snow White explants had the highest regenerative activity, Bacardi was second, and Korean Dawn was third. Studies have shown that the efficiency of adaptation of unrooted microshoots under aeroponic conditions is significantly influenced by the composition of the nutrient medium during micropropagation. Thus, preliminary cultivation of microshoots in vitro on Stimul and Aminoven-containing media led to the rapid formation of the root system and active growth of the aerial part. In these variants, the shoot growth index (I) was 0.65-0.71, and specific rate (µ) was 0.89-1.1 mm day-1.

The effects on adventitious root formation caused by chrysanthemum stunt viroid in Chrysanthemum morifolium and C. seticuspe

AbstractChrysanthemum stunt viroid (CSVd) is a disease agent caused by a viroid from the genus Pospiviroid. The CSVd pathogen infects chrysanthemum plants and causes severe symptoms of stunting and significant yield loss in cultivation. Although many studies have focussed on this issue, the mechanism of CSVd‐infection remains to be clarified. In particular, the effects of CSVd on the underground parts of infected plants are not yet fully understood in Chrysanthemum. Here, we investigated whether the effects of CSVd on the root formation of infected plants varies among cultivars and wild Chrysanthemum species, C. morifolium and C. seticuspe, using transcribed RNA and in vitro assays. Furthermore, to compare infected plants with uninoculated plants, we assessed the symptoms and measured the CSVd RNA accumulation levels in several tissues using RT‐qPCR. Our findings indicated that CSVd‐infected plants exhibited severe root formation symptoms in both C. morifolium and C. seticuspe. RT‐qPCR revealed CSVd accumulation in the root tips and similar patterns of CSVd accumulation in each organ of C. morifolium and C. seticuspe. We propose that in vitro assays are useful for determining root formation in CSVd‐infected chrysanthemum plants. Such investigations are necessary to better understand CSVd infection in Chrysanthemum species and plant defences against such diseases.

Phenotypic Characterization and RT-qPCR Analysis of Flower Development in F1 Transgenics of Chrysanthemum × grandiflorum.

Gene silencing is the epigenetic regulation of any gene in order to prevent gene expression at the transcription or translation levels. Among various gene silencing techniques, RNA silencing (RNAi) is notable gene regulation technique that involves sequence-specific targeting and RNA degradation. However, the effectiveness of transgene-induced RNAi in F1 generation of chrysanthemum has not been studied yet. In the current study, we used RNAi-constructed CmTFL1 (white-flowered) and CmSVP overexpressed (yellow flowered) transgenic plants of previously conducted two studies for our experiment. Cross hybridization was performed between these intergeneric transgenic and non-transgenic plants of the winter-growing chrysanthemum selection “37” (light pink flowered). The transgene CmSVP was confirmed in F1 hybrids by RT-PCR analysis, whereas hybrids of CmTFL1 parental plants were non-transgenic. Besides this, quantitative real-time PCR (qPCR) was used to explain the molecular mechanism of flower development using reference genes. Intergeneric and interspecific hybrids produced different colored flowers unlike their respective parents. These results suggest that generic traits of CmSVP overexpressed plants can be transferred into F1 generations when crossed with mutant plants. This study will aid in understanding the breeding phenomenon among intergeneric hybrids of chrysanthemum plants at an in vivo level, and such transgenics will also be more suitable for sustainable flower yield under a low-light production system.

The transcription factor CmLEC1 positively regulates the seed-setting rate in hybridization breeding of chrysanthemum

Distant hybridization is widely used to develop crop cultivars, whereas the hybridization process of embryo abortion often severely reduces the sought-after breeding effect. The LEAFY COTYLEDON1 (LEC1) gene has been extensively investigated as a central regulator of seed development, but it is far less studied in crop hybridization breeding. Here we investigated the function and regulation mechanism of CmLEC1 from Chrysanthemum morifolium during its seed development in chrysanthemum hybridization. CmLEC1 encodes a nucleic protein and is specifically expressed in embryos. CmLEC1’s overexpression significantly promoted the seed-setting rate of the cross, while the rate was significantly decreased in the amiR-CmLEC1 transgenic chrysanthemum. The RNA-Seq analysis of the developing hybrid embryos revealed that regulatory genes involved in seed development, namely, CmLEA (late embryogenesis abundant protein), CmOLE (oleosin), CmSSP (seed storage protein), and CmEM (embryonic protein), were upregulated in the OE (overexpressing) lines but downregulated in the amiR lines vs. wild-type lines. Future analysis demonstrated that CmLEC1 directly activated CmLEA expression and interacted with CmC3H, and this CmLEC1–CmC3H interaction could enhance the transactivation ability of CmLEC1 for the expression of CmLEA. Further, CmLEC1 was able to induce several other key genes related to embryo development. Taken together, our results show that CmLEC1 plays a positive role in the hybrid embryo development of chrysanthemum plants, which might involve activating CmLEA’s expression and interacting with CmC3H. This may be a new pathway in the LEC1 regulatory network to promote seed development, one perhaps leading to a novel strategy to not only overcome embryo abortion during crop breeding but also increase the seed yield.

Insidious flower bug, Orius insidiosus (Say) (Hemiptera: Anthocoridae), predation on western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), on Transvaal daisy, Gerbera jamesonii, cut flowers and chrysanthemum, Tanacetum × grandiflorum, plants under laboratory and greenhouse conditions

The insidious flower bug, Orius insidiosus (Say) (Hemiptera: Anthocoridae), is a generalist predator that feeds on western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), larvae and adults. Our study involved a series of experiments conducted under laboratory and greenhouse conditions from 2017 to 2020 to: 1) determine the number of insidious flower bug adults that should be released to manage western flower thrips populations below damaging levels, 2) assess if integrating the insidious flower bug with the insecticide spinosad (Conserve®) is a viable alternative plant protection strategy, and 3) determine if short (<12 h) or long (>12 h) day lengths/photoperiods affect insidious flower bug predation on western flower thrips under greenhouse conditions. We found that releasing three or four insidious flower bug adults was most effective in managing western flower thrips populations on chrysanthemum, Tanacetum × grandiflorum, plants with the mean number of western flower thrips adults and larvae per chrysanthemum plant < 10. We determined that spinosad can be used with the insidious flower bug to manage western flower thrips populations. Finally, we ascertained that insidious flower bug predation was not affected by short [10.5:13.5 (light:dark hours)] or long [14.5:9.5 (light:dark hours)] day lengths/photoperiods. Consequently, greenhouse producers can release the insidious flower bug anytime during the growing season, even from fall through winter, to manage populations of western flower thrips on chrysanthemum. In addition, greenhouse producers can integrate spray applications of spinosad with the insidious flower bug as long as the applications do not negatively affect insidious flower bugs.

Early infestations by arthropod pests induce unique changes in plant compositional traits and leaf reflectance.

BACKGROUNDWith steadily growing interest in the use of remote‐sensing technologies to detect and diagnose pest infestations in crops, it is important to investigate and characterize possible associations between crop leaf reflectance and unique pest‐induced changes in plant compositional traits. Accordingly, we compiled plant compositional traits from chrysanthemum and gerbera plants in four treatments: non‐infested, or infested with mites, thrips or whiteflies, and we acquired hyperspectral leaf reflectance data from the same plants over time (0–14 days).RESULTSPlant compositional traits changed significantly in response to arthropod infestations, and individual chrysanthemum and gerbera plants were classified with 78% and 80% accuracy, respectively. Based on leaf reflectance, individual plants from the four treatments were classified with moderate accuracy levels of 76% (gerbera) and 73% (chrysanthemum) but with a clear distinction between non‐infested and infested plants. Accurate and consistent diagnosis of biotic stressors was not achieved.CONCLUSIONTo our knowledge, this is the first study in which infestations by multiple economically important arthropod pests are directly compared and associated with leaf reflectance responses and changes in plant compositional traits. It is important to highlight that imposed stress levels were low, period of infestation was short, and hyperspectral remote‐sensing data were acquired at four time points with analyses based on large data sets (3826 leaf reflectance profiles for chrysanthemum and 4041 for gerbera). This study provides novel insight into crop responses to different biotic stressors and into possible associations between plant compositional traits and hyperspectral leaf reflectance data acquired from crop leaves.

Effects of exogenous melatonin on photosynthesis and physiological characteristics of chry-santhemum seedlings under high temperature stress.

We examined the effects of exogenous melatonin (MT) on the resistance of Chrysanthemum morifolium 'Jinba' to high temperature stress. Chrysanthemum leaves were sprayed with 200 μmol·L-1MT, and then subjected to high temperature stress at 40 ℃ (day)/ 35 ℃ (night). The ultrastructure of chloroplast and thylakoid of chrysanthemum leaves were observed, and the photosynthetic and physiological indices were measured. The results showed that the chloroplast and thyla-koid structures of chrysanthemum were damaged under high temperature stress. The chlorophyll contents and maximum fluorescence (Fm) were significantly reduced, while the OJIP curve changed with the fluorescence of K and J points increased. The net photosynthetic rate (Pn), transpiration rate (Tr) and stomatal conductance (gs) were significantly decreased, while the internal CO2 concentration (Ci) was significantly increased. The relative conductivity (REC), malondialdehyde (MDA), reactive oxygen species (ROS), osmotic adjustment substances content and antioxidant enzyme activity all increased significantly. Spraying exogenous MT onto leaves could maintain the integrity of chloroplast and thylakoid structure under high temperature in chrysanthemum and significantly decrease the increment in the K and J points of OJIP curve. Exogenous application of MT alleviated the inhibition of high temperature stress on photosynthesis and fluorescence of chrysanthemum, as indicated by significantly higher Fm, Pn, gs, Tr and photosynthetic pigment contents and lower Ci. Exogenous MT also significantly reduced the REC, MDA and ROS contents of chrysanthemum under high temperature stress, and enhanced the osmotic adjustment substances content and antioxidant enzyme activity in chrysanthemum leaves. It suggested that exogenous MT could protect the integrity of chloroplast structure of chrysanthemum leaves, enhance photosynthesis, inhibit the excessive production of ROS in the plants under high temperature stress, improve the activity of antioxidant enzyme system, reduce the level of membrane peroxidation and keep the integrity of lipid membrane, and thus improve the ability of chrysanthemum plants to resist high temperature stress.

THE USE OF SMALL-FLOWERED CHRYSANTHEMUMS IN THE EXPANSION OF GREEN AREAS OF THE URBAN ENVIRONMENT IN THE CONTEXT OF CLIMATE CHANGE

Gardeners delight in hundreds of different types of chrysanthemums, often classified by criteria such as bloom time, shape, color, size and arrangement of petals. To simplify the process for home gardeners, plants are often divided into eight distinct chrysanthemum plant types. The results of the research on the application methods of small-flowered chrysanthemum varieties in landscaping of garden and park objects of Vinnytsia region are presented and the indicators of adaptation to growing conditions are determined. A decorative assessment of the varieties of the botanical species Chrysanthemum indicum L. grown in the conditions of the architectural and exposition area of Vinnytsia National Agrarian University was carried out. Peculiarities of phenological development of the studied varieties of small-flowered chrysanthemums such as Amiko violet, Axima yellow, Rowan improved, Camina red, Bigli pink, Tricky white, Elissa have been established. According to the results of phenological observations, the plants were grouped according to the timing of flowering. The morphological indicators of the studied varieties of small-flowered chrysanthemums are analyzed in order to establish the peculiarities of growth processes in the conditions of the architectural-exposition site of VNAU. The characteristics of varieties that are representative of a set of such indicators as plant height, shape of the bush and its foliage are described. Variants of using small-flowered chrysanthemum varieties for creating garden compositions and landscaping of garden and park objects of Vinnytsia region have been identified. The ability of small-flowered chrysanthemum plants to form shoots after overwintering has been established. The evaluation of varieties makes it possible to determine the main ways of future targeted creation and filling of the collection of garden chrysanthemums. It is established that due to the high intensity of flowering and the long flowering period in general, the studied varieties are highly decorative and are in demand in both industrial and amateur floriculture.

Provision of astigmatid mites as supplementary food increases the density of the predatory mite Amblyseius swirskii in greenhouse crops, but does not support the omnivorous pest, western flower thrips

Astigmatid mites can be used as prey for mass rearing of phytoseiid predators, but also as a supplemental food source to support predator populations in crops. Here we evaluated the potential of six species of astigmatid mites (living or frozen) as alternative food for the predatory mite Amblyseius swirskii Athias-Henriot in greenhouse crops. All prey mites tested were suitable for predator oviposition. In general, oviposition was greater when prey mites were reared on dog food with yeast than when they were reared on wheat bran with yeast. Amongst prey items provided as frozen diet, larvae of Thyreophagus entomophagus (Laboulbene), Acarus siro L. and Lepidoglyphus destructor (Schrank) that had been reared on dog food with yeast, resulted in the highest oviposition rates of A. swirskii. T. entomophagus larvae as frozen diet resulted in the shortest preimaginal developmental time of A. swirskii. On chrysanthemum plants, we found that the greatest increase in predator density occurred when living mites of T. entomophagous were used as a food source. This increase was greater than when predators were fed cattail pollen, a commonly used supplemental food. Effects on predators of providing living A. siro and L. destructor, or frozen larvae of T. entomophagous as food, were comparable with provision of pollen. Use of supplemental food in crops can be a risk if it is also consumed by omnivorous pests such as western flower thrips, Frankliniella occidentalis Pergande. However, we showed that both frozen and living mites of T. entomophagous were unsuitable for thrips oviposition. Hence, we believe that provision of prey mite species increases A. swirskii density, supporting biological control of thrips and other pests in greenhouse crops.