Research Article |
Corresponding author: Mima Todorova ( minatodor@abv.bg ) Academic editor: Kalina Danova
© 2022 Mima Todorova, Ana Dobreva, Nadezhda Petkova, Neli Grozeva, Mariya Gerdzhikova, Petya Veleva.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Todorova M, Dobreva A, Petkova N, Grozeva N, Gerdzhikova M, Veleva P (2022) Organic vs conventional farming of oil-bearing rose: Effect on essential oil and antioxidant activity. In: Chankova S, Peneva V, Metcheva R, Beltcheva M, Vassilev K, Radeva G, Danova K (Eds) Current trends of ecology. BioRisk 17: 271-285. https://doi.org/10.3897/biorisk.17.77488
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The aim of this study was to establish whether the type of the agricultural system has any influence on the essential oil production and antioxidant activity of industrial cultivated Rosa damascena Mill. in the Rose valley, Bulgaria. Six private farms from Kazanlak (Rose) Valley, Southern Bulgaria were included in the study conducted in the period 2019–2020. The first three selected farms are designated within the conventional farming and the other three are certificated as organic farms. GC/FID and GC/MS analyses were performed; the contents of total polyphenols and flavonoids in the methanol extracts from rose petals were determined. Additionally, the antioxidant activity of rose extracts was evaluated by four reliable methods: 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2´-azino-bis-3-ethylbenzthiazoline-6-sulphonic acid (ABTS), ferric reducing antioxidant power (FRAP), and cupric reducing antioxidant capacity (CUPRAC) assays. The impact of the agricultural system on the essential oil composition and antioxidant activity was evaluated by ANOVA statistical analysis. The results obtained showed that organic farming produced essential oil with a higher linalool and geraniol content and lower β-citronellol + nerol concentrations than conventional farming. It was found that organic farming production demonstrated a better antioxidant activity evaluated by the three DPPH, ABTS, and CUPRAC methods according to the averaged data for two years, 806.82, 797.66 and 1534.40 mM TE/g dw versus 510.34, 521.94 and 917.48 mM TE/g dw for CF, respectively, with high statistical significance for the DPPH and ABTS analyses. Consequentially, the rose extracts from the organic farming accumulated more phenolic compounds that corresponded to the higher antioxidant potential of the organic roses.
cv. Raduga, DPPH, Rosa damascena Mill., rose oil composition, total phenol
Globally, the oil-bearing rose, for the production of essential oil, is industrially grown mainly in Bulgaria, Turkey, Iran, India, Pakistan, China, Morocco, Egypt, France, and Russia. However, Bulgaria is the leading producer of the main genotype oil-bearing rose (Rosa damascena Mill.) (
The field study was conducted in private farms, located in the northwest part of the Kazanlak Rose valley, Bulgaria, in the two-year period of 2019–2020. The valley is situated at 400–500 m altitude, in the middle of the country between the Balkan range in the north and Sredna Gora mountain to the south. The climate is continental, the winters are generally cold and wet, and the summers cooler than in other parts of Bulgaria. January is the coldest month of the year with a -1.1 °C average temperature. July is the warmest month in Kazanlak with an average temperature of 21.2 °C. Spring in Kazanlak has the feel of winter, with late snowfalls. The annual precipitation rates range from 500 to 650 mm in the Kazanlak valley, with heaviest precipitation between April and June (
The field study was conducted in six private farms, as three of the oil rose private plantations are certified as organic farms whereas they apply an organic agricultural system and the rest of them are designated within the conventional farming. The farms are located close to each other and the dominant soil type is fluvisols. Fluvisols (Deluvial soils) are formed by downhill creep, where the sorting of materials comes about through gravity. Creep is the slow movement of soil masses down slopes that are usually steep. The process takes place in response to gravity where there is a pronounced water saturation (
Detailed characterization of the agricultural practices of the studied farms is presented in Table
Farming system, geographical data, variety with general agricultural practices in the studied farms.
Farm’s number | Area | GPS coordinates | Variety | Agricultural practices | Drip irrigation |
---|---|---|---|---|---|
Conventional Farming (CF) | |||||
01 | Koprinka | 42°38'10.74"N, 25°19'29.496"E | R. × damascena f. trigintipetala Dieck | Soil tillage, mineral fertilization, foliar feeding with NPK + microelements during vegetation, pesticides | - |
02 | Damascena 1 | 42°40'11.6"N, 25°11'50.1"E | R. × damascena f. trigintipetala Dieck | Turf surface as mulching, mineral fertilization, foliar feeding with NPK + microelements during vegetation, pesticides | yes |
03 | Damascena 2 | 42°40'6.60"N, 25°11'53.40"E | R. × damascena f. trigintipetala Dieck | Turf surface as mulching, mineral fertilization, foliar feeding with NPK + microelements during vegetation, pesticides | yes |
Organic Farming (OF) | |||||
04 | Yasenovo | 42°41'36.0"N, 25°16'39.8"E | R. × damascena f. trigintipetala Dieck | Soil tillage, manure application, bio pesticides | - |
05 | Asen | 42°38'35.8"N, 25°10'30.0"E | cv. Raduga Rosa damascena × Rosa gallica | Turf surface as mulching, manure application, bio pesticides | yes |
06 | Skobelevo | 42°40'16.5"N, 25°10'36.5"E | cv. Raduga Rosa damascena × Rosa gallica | Turf surface as mulching, manure application, bio pesticides | yes |
Farm 1 is characterized as typical conventional farming with soil tillage, mineral fertilization, foliar feeding with NPK + microelements during vegetation. The soil tillage included 3–4 hoeing with a cultivator between the rows.
Farms 2 and 3 are conventional with combined good agricultural practices, in our case - turf surface as mulching, drip irrigation, mineral fertilization, foliar feeding with NPK + microelements during vegetation.
Farm 4 is certified as organic farming with manure fertilization 2–3 t/dka (20–30 t/ha), applied every 3–4 years before vegetation. Before and after flowering – several times foliar application of organic fertilizer containing macro-, micronutrients, and amino acids. Only soil tillage was carried out to control weeds. The soil tillage included 3–4 hoeing with a cultivator or manually between the rows, with biopesticides application.
Farms 5 and 6 are also certified as organic farming, with manure fertilization, foliar application of organic fertilizer containing macro-, micronutrients, and amino acids, with a turf surface as mulching between the rows and drip irrigation.
We surveyed farms growing oil-bearing roses - R. damascena f. trigintipetala Dieck and cultivar Raduga [(Rosa damascena Mill. × Rosa gallica subsp. Eryosyla Kell var. Austriaca Br.) × Rosa gallica L.] (
The essential oil content in the blossoms was determined after steam distillation in the Clevenger-type micro apparatus. The essential oil was measured to the graduated part of the apparatus in milliliters and was calculated as a percentage by volume (v/w). For higher accuracy, a relative density recalculation was made and was presented as a percentage by weight (w/w). After collection, the oil was treated with anhydrous Na2SO4 and stored in tightly closed vials at 4 °C till analysis. The analysis was performed on an Agilent 7820A GC System coupled with a flame ionization detector and 5977B MS detector. The protocol was made according to ISO 9842 for gas chromatographic analysis of rose oil. Two capillary columns: non-polar EconoCapTM ECTM (30 m × 0.32 mm ID, 0.25 µm film thickness) and polar HP-20M (50 m × 0.32 mm ID, 0.30 µm film thickness) were used. The first one was operated with an oven program from 80 °C (2.5 min held) to 320 °C at a rate of 10 °C/min; with 10 min held at the final temperature was applied. Hydrogen (99.999%) was used as a carrier gas at a constant flow rate of 20 ml/min. The split ratio was 1:10, the inlet temperature was set to 250 °C and the FID temperature was set to 300 °C. The non-polar column reveals a much richer spectrum of compounds and better presentation of paraffins, but it is not suitable for dividing the main terpene alcohols citronellol and nerol. They have very similar retention times and could not be split and calculated. For this reason the polar column was used for better separation. Due to the character of the HP-20M, the oven temperature program was the following: 65 °C for 0 min, then 2 °C/min to 220 °C for 10 min.
The GC/MS analysis was performed under all conditions, described above.
The ingredients were quantified by the area of FID peaks without any correction factor. The oil constituents were identified by their mass spectra, matching with the NIST and MS library, as well as whenever possible, the authentic substances were used.
Rose petals were subject to extraction in duplicate with 80% methanol in 1:15 solid to solvent ratio. The extraction was conducted in an ultrasonic bath (SIEL, Gabrovo, Bulgaria, 35 kHz, and 300 W) for 20 mins, at 65 °C. The combined extracts were used for further analysis.
The total phenolic content was measured using a Folin-Ciocalteu reagent with slight modification (
The total flavonoids content was analyzed using Al(NO3)3 reagent (
The rose petal water extract (0.15 mL) was mixed with 2.85 mL 0.1 mM methanol solution DPPH. After 15 min at 37 °C, the reduction of absorbance was measured at 517 nm against methanol used as a blank sample (
The rose petal extract (0.15 mL) was mixed with 2.85 ml of the ABTS solution. After 15 min at 37 °C in darkness, the absorbance was measured at 734 nm (
The assay was performed according to Benzie and Strain (1996).
The rose petal extract (0.1 mL) was mixed with 1 mL CuCl2.2H2O, 1 mL Neocuproine (7.5 mL in methanol), 1 mL 0.1 M ammonium acetate buffer and 1 mL distilled water. After 20 min at 50 °C, the absorbance was measured at 450 nm (
The data were expressed as a mean ± standard deviation (SD) from three replicates for each sample. All the results from the determination of antioxidant activity were performed in triplicates and expressed as mM Trolox equivalents (mM TE) by dry weight. To establish the influence of the agricultural practices in the studied farms on the essential rose oil composition and antioxidant activity, ANOVA statistical analysis was performed. The significant differences were tested and the P values < 0.05 were considered statistically significant. The impact of the factors was evaluated via the Coefficients of determination R2. The IBM SPSS Statistics 26.0, Copyright 1989, 2019 statistical package was used to process the data.
The climate data for the 2019–2020 period showed that the temperatures were much higher than the average rates for the winter season (especially 2019). This is the dormancy period for the plants. During the spring months, the temperatures were normal and higher in June, particularly in 2019. Regarding precipitation, it is obvious that in both years they were below normal. The second year of the study is characterized as wetter with more rainfall than in 2019, especially during the spring.
The chemical composition of the essential oil of rose flowers under conventionally and organically grown roses is presented in Table
Biochemical composition of the essential oil of rose flowers under conventionally and organically grown roses for the two years period of study.
Type of farming | Conventional farming - CF | Organic farming - OF | R2 | ||||||
---|---|---|---|---|---|---|---|---|---|
Biochemical component | min | max | average | SD | min | max | average | SD | |
Rose oil,% | 0.03 | 0.05 | 0.04 ns | 0.01 | 0.02 | 0.05 | 0.03 ns | 0.01 | 0.229 |
Ethanol | 0.00 | 0.92 | 0.19 ns | 0.36 | 0.01 | 0.92 | 0.21 ns | 0.31 | 0.025 |
Linalool | 0.38 | 0.71 | 0.54 a | 0.11 | 0.52 | 0.93 | 0.61a | 0.22 | 0.569 |
cis –Rose oxide | 0.15 | 0.27 | 0.22 a | 0.05 | 0.00 | 0.27 | 0.16 a | 0.10 | 0.521 |
trans –Rose oxide | 0.08 | 0.14 | 0.12 a | 0.02 | 0.00 | 0.14 | 0.08 a | 0.05 | 0.532 |
Phenylethyl alcohol | 0.33 | 1.33 | 0.83 ns | 0.37 | 0.34 | 1.33 | 0.80 ns | 0.34 | 0.000 |
β-Citronellol and Nerol | 25.48 | 33.60 | 29.47 a | 3.18 | 17.86 | 33.60 | 25.08 a | 7.91 | 0.450 |
Geraniol | 23.11 | 26.13 | 24.33 a | 1.18 | 20.91 | 35.81 | 25.42 a | 8.03 | 0.427 |
Eugenol | 0.38 | 1.35 | 0.70 ns | 0.35 | 0.00 | 1.35 | 0.56 ns | 0.46 | 0.185 |
Methyleugenol | 0.46 | 0.72 | 0.60 ns | 0.10 | 0.00 | 1.32 | 0.50 ns | 0.36 | 0.055 |
Heptadecane (C17) | 0.85 | 2.47 | 1.96 ns | 0.60 | 0.98 | 2.69 | 1.83 ns | 0.68 | 0.000 |
Farnesol | 0.19 | 3.37 | 1.51 ns | 1.43 | 0.32 | 3.37 | 1.59 ns | 1.32 | 0.003 |
Nonadecene (C19:1) + Nonadecane (C19) | 14.37 | 18.62 | 17.29 a | 1.65 | 11.36 | 18.62 | 15.09 a | 4.30 | 0.367 |
Eicosane (C20) | 0.98 | 1.76 | 1.33 ns | 0.27 | 0.52 | 1.77 | 1.11 ns | 0.46 | 0.261 |
Heneicosane (C21) | 4.56 | 8.56 | 6.00 ns | 1.37 | 2.71 | 10.14 | 5.43 ns | 2.26 | 0.053 |
Tricosane (C23) | 0.90 | 2.06 | 1.36 ns | 0.43 | 1.06 | 3.01 | 1.50 ns | 0.70 | 0.139 |
Pentacosane (C25) | 0.27 | 0.80 | 0.50 ns | 0.19 | 0.36 | 1.16 | 0.56 ns | 0.28 | 0.118 |
Heptacosane (C27) | 0.16 | 0.64 | 0.38 ns | 0.16 | 0.19 | 0.92 | 0.38 ns | 0.21 | 0.013 |
The total phenols, total flavonoids, and antioxidant activity in methanol extracts from conventionally and organically grown roses are presented in Table
The total phenols, total flavonoids and antioxidant activity in methanol extracts from conventionally and organically grown roses.
Compound, % | Region | Year | Total phenols, mg GAE/g dw | Total flavonoids, mg QE/g dw | Antioxidant activity, mM TE/g | |||
---|---|---|---|---|---|---|---|---|
DPPH | ABTS | FRAP | CUPRAC | |||||
Conventional farming | Koprinka | 2019 | 49.01±0.22 | 11.07±0.23 | 524.32±39.89 | 522.74±65.06 | 3235.01±27.85 | 1713.83±147.19 |
Koprinka | 2020 | 40.60±13.30 | 9.38±1.12 | 596.61±128.1 | 544.50±111.18 | 955.50±333.31 | 456.79±52.22 | |
Damas 1 | 2019 | 41.14±0.23 | 11.49±1.44 | 509.57±34.58 | 571.33±96.56 | 2309.14±227.49 | 1128.14±77.45 | |
Damas 1 | 2020 | 39.50±7.3 | 11.13±1.30 | 639.64±127.62 | 578.43±77.21 | 1602.74±316.61 | 723.13±193.31 | |
Damas 2 | 2019 | 41.74±0.07 | 11.59±0.64 | 476.75±41.83 | 607.67±79.99 | 2744.97±189.04 | 1176.25±145.31 | |
Damas 2 | 2020 | 23.1±3.2 | 7.46±0.56 | 315.143±89.74 | 306.99±82.78 | 1062.2±326.452 | 306.76±44.27 | |
min | 23.10 | 7.46 | 315.14 | 306.99 | 955.50 | 306.76 | ||
max | 49.01 | 11.59 | 639.64 | 607.67 | 3235.01 | 1713.83 | ||
average | 39.18 ns | 10.35 ns | 510.34 a | 521.94 a | 1984.93 ns | 917.48 ns | ||
SD | 8.58 | 1.63 | 112.77 | 109.26 | 927.65 | 523.16 | ||
Organic farming | Yasenovo | 2019 | 63.45±0.05 | 12.36±0.50 | 1033.06±30.57 | 793.72±63.72 | 3141.96±29.02 | 2687.07±121.83 |
Yasenovo | 2020 | 36.30±4.9 | 8.89±2.27 | 592.86±64.63 | 604.33±78.95 | 1418.70±362.67 | 537.34±107.42 | |
Asen | 2019 | 73.23±0.99 | 11.32±0.68 | 839.96±12.47 | 1033.31±84.04 | 746.41±90.16 | 2658.17±242.94 | |
Asen | 2020 | 41.8±12.8 | 13.02±2.46 | 675.69±179.13 | 676.23±178.20 | 1301.9±609.73 | 687.46±169.86 | |
Skobelevo | 2019 | 69.83±4.58 | 11.55±1.0 | 754.32±29.86 | 1026.13±21.60 | 721.49±44.06 | 1760.29±112.99 | |
Skobelevo | 2020 | 41.3±3.3 | 13.03±1.56 | 945.04±326.25 | 652.21±45.17 | 3648.3±1951.29 | 876.06±107.71 | |
min | 36.30 | 8.89 | 592.86 | 604.33 | 721.49 | 537.34 | ||
max | 73.23 | 13.03 | 1033.06 | 1033.31 | 3648.30 | 2687.07 | ||
average | 54.32 ns | 11.70ns | 806.82 a | 797.66 a | 1829.79 ns | 1534.40 ns | ||
SD | 16.32 | 1.55 | 165.60 | 190.27 | 1255.27 | 978.51 | ||
R2 | 0.288 | 0.176 | 0.568 | 0.486 | 0.006 | 0.156 |
The phenolic compounds, even if not directly related to the food nutritional quality, have been receiving increasing attention as a result of their specific biological activity. Higher values of the total phenols were found in the methanol extract of rose petals from OF between (36.30–73.23) mg GAE/g dw, with a mean value of 54.32 mg GAE/g dw and a lower concentration for CF between (23.10–49.01) mg GAE/g dw with a mean value of 39.18 mg GAE/g. The values of total flavonoids varied between 8.89 and 13.03 mg QE/g dw with a mean value of 11.70 mg QE/g dw for OF and (7.46–11.59) QE/g dw with a mean value of 10.35 QE/g dw for CF. An interaction was found between the impact of the agricultural system and annual conditions in the study period on the total phenol and total flavonoids content, but a statistically significant difference was not found with regards to the agricultural system. The antioxidant activity of the rose petal extracts was evaluated by four methods based on the different mechanisms (DPPH, ABTS, FRAP, and CUPRAC). It was found that organic farming production (Table
The impact of climate conditions in 2019 and 2020, irrigation practice and the variety types on the essential oil composition and the antioxidant activity of rose petals was also studied. The results are presented in Table
Impact of the climate condition in 2019 and 2020 years, irrigation practice and variety on the rose oil composition and the antioxidant activity of rose petals.
Biochemical component of rose oil/rose flower | min | max | mean | SD | min | max | mean | SD | R2 |
---|---|---|---|---|---|---|---|---|---|
2019 Year | 2020 Year | ||||||||
Essential oil, % | 0.02 | 0.04 | 0.03ns | 0.01 | 0.03 | 0.05 | 0.04ns | 0.00 | 0.01 |
Farnesol | 0.19 | 3.37 | 0.28a | 0.67 | 2.43 | 3.37 | 2.88a | 0.34 | 0.97 |
Tricosane (C23) | 1.30 | 3.01 | 2.09a | 0.68 | 0.90 | 1.31 | 1.18a | 0.17 | 0.54 |
Pentacosane (C25) | 0.45 | 1.16 | 0.77a | 0.30 | 0.27 | 0.53 | 0.42a | 0.98 | 0.44 |
Heptacosane (C27) | 0.26 | 0.92 | 0.52a | 0.24 | 0.16 | 0.38 | 0.28a | 0.08 | 0.35 |
Total phenols, mg GAE/g dw | 41.14 | 73.23 | 56.40 a | 14.25 | 23.10 | 41.80 | 37.10 a | 7.13 | 0.47 |
CUPRAC,mM TE/g | 1128.14 | 2687.14 | 1853.96 a | 686.34 | 306.76 | 876.06 | 597.92 a | 204.66 | 0.65 |
Irrigation | Non irrigation | ||||||||
Methyleugenol | 0.00 | 0.67 | 0.31 a | 0.27 | 0.67 | 1.32 | 0.92 a | 0.30 | 0.56 |
Heptadecane (C17) | 1.76 | 2.69 | 2.22 a | 0.29 | 0.85 | 2.36 | 1.40 a | 0.68 | 0.47 |
R. Damascena | cv. Raduga | ||||||||
Linalool | 0.38 | 0.83 | 0.57 a | 0.14 | 0.81 | 0.93 | 0.87 a | 0.56 | 0.62 |
cis –Rose oxide | 0.15 | 0.27 | 0.22 a | 0.43 | 0.00 | 0.04 | 0.02 a | 0.21 | 0.88 |
trans –Rose oxide | 0.08 | 0.14 | 0.12 a | 0.23 | 0.00 | 0.03 | 0.01 a | 0.02 | 0.87 |
β-Citronellol and Nerol | 25.48 | 33.60 | 29.29 a | 3.05 | 17.86 | 20.02 | 18.80 a | 0.96 | 0.81 |
Geraniol | 20.91 | 27.24 | 24.27 a | 1.97 | 32.36 | 35.81 | 34.46 a | 1.64 | 0.89 |
Methyleugenol | 0.46 | 1.32 | 0.74 a | 0.28 | 0.00 | 0.14 | 0.06 a | 0.07 | 0.68 |
Eicosane (C20) | 0.98 | 1.77 | 1.35 a | 0.30 | 0.52 | 0.89 | 0.66 a | 0.17 | 0.64 |
ABTS, mM TE/g | 306.99 | 793.70 | 566.21 a | 133.45 | 652.21 | 1033.31 | 846.97 | 211.27 | 0.45 |
According to
The conventional or organic agricultural type of system is a question of choice for every farmer, based on the benefits and challenges in the agricultural sector. In the medical plants cultivation, including oil bearing rose production, the choice of the system and the application of agricultural practices could have an enormous effect on the quality of cosmetic rose products and food supplements. Our results show that the application of combined eco-friendly agricultural practices in organic private farms in R. damascena cultivation gives a better quality of the rose flowers with higher values of antioxidant activity in comparison with the conventional agricultural system.
This work was supported by the Bulgarian Ministry of Education and Science under the National Research Programme “Healthy Foods for a Strong Bio-Economy and Quality of Life” approved by DCM Nº 577/17.08.2018.