Genotypic variation in morphological traits, yield, essential oil profiles, and mineral composition of fennel (Foeniculum vulgare L.) across two growing seasons

Gulsum Yaldiz; Mahmut Camlica; Hakan Apaydın

doi:10.1038/s41598-025-18991-y

. 2025 Oct 7;15:34989. doi: 10.1038/s41598-025-18991-y

Genotypic variation in morphological traits, yield, essential oil profiles, and mineral composition of fennel (Foeniculum vulgare L.) across two growing seasons

Gulsum Yaldiz ^1,^✉, Mahmut Camlica ¹, Hakan Apaydın ²

PMCID: PMC12504647 PMID: 41057429

Abstract

Foeniculum vulgare L. (fennel), a member of the Apiaceae family, is a widely cultivated spice plant valued for its aromatic fruits and medicinal properties. This study aimed to evaluate the agro-morphological characteristics, yield potential, essential oil content and components, as well as elemental profiles of twenty genetically diverse fennel genotypes under identical agro-climatic conditions during the 2019 and 2020 growing seasons. Significant phenotypic variation was observed among the genotypes, with fruit yields ranging from 183.78 to 1682.77 kg/ha. Essential oil content varied between 1.80% and 4.11%, with Ames23130 and Ames30693 genotypes exhibiting the highest oil yields. Also, essential oil yield values were found between 3.92 and 55.74 L/ha, and Ames23130 genotype had the highest essential oil yield. Gas chromatography-mass spectrometry (GC-MS) analysis identified 17 essential oil components, five of which trans-anethole (54.14–90.44%), estragole (2.38–28.75%), p-cymene (0.10-39.63%), limonene (0.13–7.94%), and α-fenchone (0.47–8.44%) were classified as major components. Among these, trans-anethole consistently dominated across all genotypes and both years, reflecting a stable chemotypic profile. Elemental analysis performed via inductively coupled plasma optical emission spectrometry (ICP-OES) revealed that fennel fruits are rich in potassium, calcium and magnesium, with negligible levels of toxic metals such as cadmium and lead, affirming the samples’ nutritional quality and food safety. Cluster analysis grouped the genotypes based on integrated yield, phytochemical, and mineral traits, with Ames23130 emerging as the most promising genotype for both fruit and essential oil production. Additionally, PI649471 and NSL6409 stood out for their distinct essential oil profiles, while PI414189 was notable for its superior potassium accumulation. The PCA analysis showed 42.9% of total variation, and correlation analysis revealed that highly significant positive correlation was found between Mn and Ca mineral contents with r = 0.749** These findings provide valuable insights for fennel breeding programs and support the selection of elite genotypes for both commercial cultivation and functional food applications.

Supplementary Information

The online version contains supplementary material available at 10.1038/s41598-025-18991-y.

Keywords: Foeniculum vulgare L., Genotype selection, Essential oil component, Mineral content

Subject terms: Biochemistry, Biotechnology, Plant sciences

Introduction

In recent years, data on the trade of medicinal and aromatic plants and their derived products derived have demonstrated significant potential for economic development. The global herbal medicine industry is growing rapidly, driven by increasing consumer demand for natural and alternative healthcare options. This rising demand is partly attributable to the pharmaceutical industry’s incorporation of medicinal herbs and their metabolites into products for human consumption, such as tablets, capsules, and syrups¹. The determination of the elemental composition of plant materials has become increasingly important, given the critical roles that trace elements play in plant metabolism and their subsequent impact on human nutrition. All elements required by plants for vital functions are also essential for human health and must be present in appropriate amounts. Since nearly all nutrients are acquired through the diet, determining the elemental composition of foodstuffs is necessary to estimate dietary intake. Additionally, the FAO and WHO emphasize the importance of evaluating not only the energy and protein content but also the micronutrient density of diets².

Fennel (Foeniculum vulgare L.) is a valuable spice plant from the Apiaceae family, widely used in the food, pharmaceutical, and perfume industries³. Its essential oil content varies depending on the part of the plant used for the extraction, ranging from 0.21% in stems to 0.83% in leaves and 3.5-6% in fruits. In addition, essential oils contribute to both their flavor and therapeutic properties⁴. Fennel fruits may contain up to 6% essential oil, primarily composed of trans-anethole, methyl chavicol, fenchone, and limonene^5,6. Therefore, both essential oil content and fruit yield are critical commercial traits^7,8. Reported fruit yields of fennel vary greatly, ranging from as low as 130 kg/ha to as high as 4140 kg/ha^9–12. Global production of fennel fruit is estimated at 842,000 tons per year, while Türkiye produced only 1,125 tons in 2024¹³. Unfortunately, fennel production in Türkiye has been declining annually. The primary reason for this decline is the widespread use of genetically diverse population-type fruits in cultivation, which prevents the achievement of standardized yield and quality. To enhance fennel production in Türkiye, the development of well-defined cultivars is essential. As global demand for fennel fruits increases, breeders must prioritize this crop¹⁴. Genetic variability and heritability studies in fennel suggest that selection can be an effective method for yield improvement. Furthermore, it is important to identify suitable regions for cultivation based on agrotechnical requirements as well as soil and climate characteristics. The increasing frequency of droughts due to global climate change, shifts in cropping patterns, and the need to develop new crop alternatives for dryland agriculture have drawn attention to fennel. Fennel landraces are known to exhibit substantial diversity in ripening time, fatty acid composition, and essential oil content¹⁵. This genetic diversity offers an opportunity for breeders to develop high-yielding, biotic and abiotic stress-tolerant cultivars¹⁶. Utilizing such cultivars is necessary to meet the growing global demand. In fennel, both additive and non-additive genetic variation components play significant roles in trait development.

Our previous studies on Turkish fennel landraces demonstrated significant genetic and agro-morphological diversity^3,17. Likewise, identifying genetic variation among plant genotypes of different origins is crucial for selecting high-performing lines with desirable traits¹⁸. Therefore, this study aimed to evaluate variations in yield and quality traits by growing foreign and local fennel genotypes under the same ecological conditions. Our selection program, initiated in 2016, represents the first comprehensive study of its kind in Türkiye. A total of 43 genotypes were selected following the 2016 vegetation period, and 37 genotypes were re-evaluated under augmented trial design conditions during the 2017 and 2018 growing seasons.

In this study, we aimed to comprehensively evaluate fruit yield and both the quality and quantity of essential oil components in 20 selected fennel genotypes of diverse origins. The selected genotypes were also evaluated as advanced selection materials for breeding programs. Top-performing genotypes were identified and proposed for further development. Our findings provide valuable insights into the performance of both domestic and foreign-origin genotypes, particularly for crops such as fennel. Furthermore, predicting the effects of interannual variability on the interactions among fennel genotypes requires a comprehensive understanding of the temporal distribution of environmental factors and their ecological impacts during the growing periods. Therefore, this study presents experimental results examining how genetic variation among different fennel genotypes influences competitive interactions under varying ecological conditions, and how these effects vary in response to year-specific environmental factors.

Materials and methods

Plant material and growing conditions

This study was conducted during the 2019–2020 growing seasons at Bolu Abant İzzet Baysal University, located in Bolu, Türkiye. The experimental field was situated within the Research and Application Area of the Faculty of Agriculture, at 40°44′45″ N latitude and 31°37′46″ E longitude, with an elevation of 752 m above sea level. The experimental material consisted of fennel genotypes sourced from various geographical regions worldwide. In 2016, a total of 46 genotypes were cultivated, including 32 fennel genotypes obtained from the United States Department of Agriculture (USDA) and 14 local genotypes collected from different regions of Türkiye (e.g., Erzurum, Aydın, Denizli, Kırşehir, Burdur, and Antalya). These genotypes were developed through single-plant selection, had resistance to various diseases, and were evaluated using an augmented trial design. Based on the evaluations, 37 promising genotypes were selected and re-evaluated using an augmented trial design during the 2017 and 2018 growing seasons. The fennel genotypes included in the present study (used during 2019 and 2020) were selected from among these previously grown genotypes¹⁷. A total of 20 fennel genotypes were selected and evaluated in the 2019–2020 field trials (Table 1).

Table 1.

Plant name and origin of fennel genotypes used in the study.

No	Accession number	Plant name	Origin	Improvement level	Gene bank	Coordinate
1	Ames23130	FOE 24/92	Basilicata, Italy	Cultivated material	NC 7	40°30′N/16°00′E
2	Ames27588	N.6 Marco	Italy	Cultivar	NC7	42° 50’ N/12° 50’ E
3	Ames30289	Tun258	Tunisia, Sfax	Landrace	NC7	34° 44’ 42.57” N/10° 45’ 40.68” E
4	Ames30290	Tun259	Tunisia, Sfax	Landrace	NC7	34° 44’ 42.57” N/10° 45’ 40.68” E
5	Ames30693	Ames30693	Oregon, United States	Wild material	NC7	44° 07′ 48.00′′ N/120° 35′ 24.00′′ W
6	Ames7551	Ames7551	Illinois, United States	Uncertain improvement status	NC7	41° 16’ 41.58” N/-88° 22’ 48.86” W
7	Antalya3	Antalya3	Antalya, Türkiye*	Local genotype	Farmer	36° 53′ 15″ N/30° 42′ 27″ E
8	Burdur1	Burdur1	Burdur, Türkiye*	Local genotype	Farmer	37° 43′ 10″ N/30° 17′ 00″ E
9	Burdur2	Burdur2	Burdur, Türkiye*	Local genotype	Farmer	37° 43′ 10″ N/30° 17′ 00″ E
10	Burdur5	Burdur5	Burdur, Türkiye*	Local genotype	Farmer	37° 43′ 10″ N/30° 17′ 00″ E
11	Denizli	Denizli	Denizli, Türkiye*	Local genotype	Farmer	38° 12’ N/28°30’ E
12	Erzurum	Erzurum	Erzurum, Türkiye*	Local genotype	Farmer	39° 56’ 46” N/41° 06′ 17″ E
13	NSL6409	Sweet fennel	California, United States	Cultivated material	NC7	37 °03′ 00″ N/119° 37′ 48″ W
14	PI194892	9382	Ethiopia	-	NC7	9.1450° N/40.4897° E
15	PI414189	B-51,657	Al Qāhirah, Egypt	-	NC7	30° 2’ 39” N/31° 14’ 8” E
16	PI414191	Dulce	Maryland, United States	Cultivated material	NC7	39° 2’ 44.718’’ N/-76° 38’ 28.576” E
17	PI649465	VIR 38	Uzbekistan	-	NC7	41° 18’ N/64° 56’ E.
18	PI649466	IS-035-NAT-96	Pays-de-la-Loire, France	Wild material	NC7	47° 25′ 03″ N/00° 51′ 18″ W
19	PI649469	S009	Syria	Landrace	NC7	35° 00’ N/38° 00’ E
20	PI649471	Nafaa	Morocco	Cultivated material	NC7	32° 00’ N/ 05° 00’ W

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*Local genotypes.

Mean climatic data were recorded 13.95 °C for temperature; 82.1 mm for precipitation; 75.75% for relative humidity during the vegetation period for 2019, and 15.25 °C for temperature; 71.30 mm for precipitation; 66.40% for relative humidity during the vegetation period for 2020¹⁸. The experimental area soil properties were found as clayey, pH 7.56, 3.71% organic matter, 0.52 kg/ha phosphorus, 1083.08 kg/ha potassium, and 0.0383% salty¹⁹. The experimental design was a completely randomized block with three replications in both years. Each experimental plot consisted of five 4-m-long rows, with a distance of 0.3 m between each row and 0.25 m between each plant; the total number of plants in each plot was 80. The fruits of fennel genotypes were sown in field conditions at Bolu Abant İzzet Baysal University, Research and Application Area of the Faculty of Agriculture, on 15 April 2019 and on 10 April 2020. Diammonium phosphate (DAP) fertilizer was applied at a rate of 60 kg/ha at sowing, providing 18% nitrogen (N) and 46% phosphorus (P2O5). Later, a topdressing application of 40 kg/ha ammonium sulfate (AS), containing 21% nitrogen and 24% sulfur, was split between sowing time and the period before flowering. The necessary irrigation and weed control were carried out during the vegetation periods.

Determination of morphological features and yield values

Field data were collected by cutting randomly 10 plants from each plot, and the yield traits of each plant were considered as the mean for each plot in 2019 and 2020. Plants were harvested by hand when the plants reached at the fully ripe fruits. Harvest were made at above the ground, and fennel genotypes were harvested in warm and sunny weather to allow high essential oil yield. After sowing of the fennel fruits, the 50% seedling, flowering and fruit linking days were determined. Before harvest, the height of plant, the number of branching, number of umbel, number of umbellet and stem diameter values were measured. After harvest, biological yield (kg/ha), and fruit weight (kg/ha) values were determined. For the fruit weight, the fruits were dried in a thermal drying compartment at a temperature of 35 °C. The morphological and yield values were determined as follows:

Plant height (cm): Distance from the soil surface to the tip of the main stem, measured with a measuring tape.

Branch number: Count of primary branches emerging from the main stem on each sampled plant.

Umbels: Total number of umbels bearing fruits per plant.

Umbellets: Total number of umbellets across all umbels on the same plant (summed per plant).

Stem diameter (mm): Measured on the main stem 5 cm above the soil surface using a digital caliper; the mean of two perpendicular readings per plant was recorded.

Phenology (days after sowing, DAS):

50% seedling days: Days from sowing until ≥ 50% of plants in the plot had emerged.

50% flowering days: Days from sowing until ≥ 50% of plants showed open flowers on the primary umbel.

50% fruit linking days: Days from sowing until ≥ 50% of plants had visible developing seeds on the primary umbel.

Extraction of essential oil

Essential oils were extracted from fully ripe fruits, and for this purpose, twenty g of fruit from each genotype were milled to a fine powder and then mixed with 500 mL of deionized water and heated to 100 °C. Subsequently, the oil was collected using a Clevenger-type apparatus for 4 h. Each extraction was performed in triplicate. The amount obtained was recorded (in mL) from the graduated section of the flask, and the weights were then used to calculate percentage essential oil yields. Later on, essential oil content was calculated using the following formula:

Essential oil content (%) = [mass of oil obtained (g)/Weight of dry fruits (g)] × 100.

The yield of essential oil yield (L/ha) was determined for each genotype on the basis of calculating essential oil content multiplying by dry fruit yield per hectare and dividing by 100.

GC-MS analysis of essential oils

Essential oils were analyzed using gas chromatography combined with mass spectrometry (GC/MS) with a Varian CP-3800 instrument and a VF-5 column (30 m in length, 0.25 mm inner diameter, 0.25-µm film thickness). The carrier gas was helium, flowing at a rate of 1 ml/min. The ionization energy used by the mass spectrometer was 70 electron volts. The injector and detector temperatures were kept at 250 °C, and the oven temperature was programmed to ramp up from 60 to 250 °C at a rate of 3 °C per minute. The injection volume was 1 µL in the split mode. By calculating the retention indices of the essential oil at certain temperature settings and using n-alkanes with a range of C6 to C24 as benchmarks, the component of the oil was evaluated. Utilizing a VF-5 column and the same chromatographic parameters, the oils were examined. The chemicals were identified by comparing their mass spectra to those in the internal reference mass spectra library (Wiley 7) or those of authentic compounds. Additionally, the retention indices of the chemicals were compared to either recognized compounds or values listed in the published literature to confirm their identity. Relative area percentages discovered via Flame Ionization Detection (FID) were used for quantification without the need for correction factors²⁰.

Elemental analysis

Elemental analysis of fennel fruit samples was carried out using inductively coupled plasma optical emission spectrometry (ICP-OES). All reagents used were of analytical grade and applied without any further purification. For the digestion process, concentrated HNO₃ (65% v/v, Sigma-Aldrich, St. Louis, MO, USA) and H₂O₂ (30% m/v, Merck, Darmstadt, Germany) were utilized. Calibration standards for Al, Ca, Cd, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, Pb and Zn were prepared from a multi-element solution (Merck, Item No: 1.11355, Darmstadt, Germany). Sample digestion was conducted using a microwave digestion system (Speedwave, Berghof Instruments, Germany). Precisely 0.4 g of each powdered fennel sample was weighed into Teflon digestion vessels. To each sample, 7 mL of HNO₃ (65%) and 1 mL of H₂O₂ (35%) were added. The digestion program followed the manufacturer’s instructions, consisting of three steps: heating at 145 °C for 5 min, 200 °C for 10 min, and a final cooling step at 50 °C for 10 min. After cooling, clear digests were transferred to 25 mL volumetric flasks and diluted to volume with ultrapure deionized water²¹. Elemental concentrations of elements were quantified using an ICP-OES instrument (iCAP 6000 Dual View, Thermo Scientific, Cambridge, UK). Calibration was performed using appropriate standard solutions for each element. The wavelengths used for detection were as follows: Al (167.08 nm), Ca (317.9 nm), Cd (228.8 nm), Cr (283.5 nm), Cu (324.7 nm), Fe (259.9 nm), K (766.5 nm), Mg (279.5 nm), Mn (257.6 nm), Na (588.9 nm), Ni (221.65 nm), P (177.4 nm), Pb (220.3 nm) and Zn (213.8 nm).

Statistical analysis

The statistical analysis was conducted using one-way analysis of variance (ANOVA) using JMP statistical software. The significance of the examined traits results (p < 0.05) was determined using the LSD test. The cluster analysis was determined by using JMP statistical software. Principal Component Analysis (PCA) was performed on the fruit yield values, major essential oil components and major mineral contents using the JMP 13 statistical software (SAS Institute Inc., Cary, NC, USA). In addition, the correlation analysis was conducted to determine the relationship between essential oil content and its major components and all mineral matter contents by using Avci statistical program (https://yeniavciistatistik.blogspot.com/2024).

Results

Variation in the morphological and yield parameters of fennel genotypes

Since genotype by year interactions were statistically significant (p < 0.05), separate yearly analyses were performed to capture genotype-specific responses to differing climatic and soil conditions across years. Aggregating the data could obscure genotype performance variation under different environmental pressures, especially for traits such as essential oil content and mineral accumulation, which are sensitive to abiotic factors. The data were presented separately for each year due to a significant year-genotype interaction (p < 0.05). Pooling data across years could mask these genotype-specific responses by averaging out the effects of annual environmental factors. The interactions between genotypes and the ecological conditions of each year may be obscured, leading to misleading or generalized conclusions based on the combined data from multiple years. In some cases, pooling might also diminish significant differences that would be detected in separate analyses, ultimately reducing the ability to discern how different genotypes respond to varying environmental conditions over time. Thus, separate analyses are crucial for obtaining a clear and accurate understanding of genotype-environment interactions. Significant differences were found for plant height values among the fennel genotypes in both years and their means (p < 0.05). The mean plant height ranged from 61.47 to 86.85 cm in 2019 and from 54.77 to 90.50 cm in 2020 (Table 2). Among the genotypes, the NSL6409, Ames27588, and PI194892 exhibited the greatest plant heights in 2019, measuring 86.85, 82.86, and 82.37 cm, respectively. In 2020, the NSL6409 and Ames27588 again showed high values, with plant heights of 90.50 and 85.16 cm, respectively. When considering the two-year mean, the NSL6409 and Ames27588 emerged as superior genotypes in terms of plant height. So, these genotypes consistently exhibited plant heights greater than 80 cm in both years, suggesting a higher tolerance to variable environmental conditions relative to the other genotypes. Conversely, Antalya3 and Erzurum consistently recorded the shortest plants across both years.

Table 2.

Plant height and branch number values of fennel genotypes.

No	Genotypes	Plant height (cm)			Branch number (number/plant)
No	Genotypes	2019	2020	Mean	2019	2020	Mean
1	Ames23130	81.87^ab	76.00^bcd	78.94^abc	7.77^ab	7.40^abc	7.59^ab
2	Ames27588	82.86^ab	85.16^ab	84.01^ab	7.03^ab	7.53^ab	7.28^ab
3	Ames30289	80.70^ab	68.97^c − g	74.83^a − e	6.97^ab	5.90^e − h	6.44^bcd
4	Ames30290	67.23^ab	61.57^e − h	64.40^def	7.60^ab	6.10^c − h	6.85^a − d
5	Ames30693	76.75^ab	78.98^bc	77.86^a − d	7.37^ab	8.47^a	7.92^a
6	Ames7551	69.51^ab	72.43^cde	70.97^b − f	5.89^ab	7.13^a − f	6.51^bcd
7	Antalya3	61.47^b	54.77^h	58.12^f	6.97^ab	6.70^b − g	6.84^a − d
8	Burdur1	68.98^ab	62.00^e − h	65.49^c − f	8.03^a	6.00^d − h	7.02^a − d
9	Burdur2	72.22^ab	60.43^fgh	66.33^c − f	6.90^ab	6.27^b − h	6.58^bcd
10	Burdur5	77.65^ab	55.53^h	66.59^c − f	7.50^ab	5.30^h	6.40^bcd
11	Denizli	74.06^ab	56.87^h	65.46^c − f	7.47^ab	5.87^fgh	6.67^a − d
12	Erzurum	69.56^ab	56.10^h	62.83^ef	6.73^ab	6.07^c − h	6.40^bcd
13	NSL6409	86.85^a	90.50^a	88.67^a	7.43^ab	6.13^c − h	6.78^a − d
14	PI194892	82.37^ab	59.33^gh	70.85^b − f	7.06^ab	7.37^a − d	7.21^abc
15	PI414189	67.32^ab	65.07^d − h	66.20^c − f	6.37^ab	5.67^gh	6.02^cd
16	PI414191	68.35^ab	63.17^e − h	65.76^c − f	5.95^ab	5.73^gh	5.84^d
17	PI649465	71.70^ab	70.93^c − f	71.32^b − f	7.21^ab	6.47^b − h	6.84^a − d
18	PI649466	73.68^ab	65.10^d − h	69.39^c − f	5.83^b	5.87^fgh	5.85^d
19	PI649469	65.30^ab	58.00^gh	61.65^ef	6.60^ab	8.10^a	7.35^ab
20	PI649471	81.27^ab	65.40^d − h	73.34^b − e	7.00^ab	7.27^a − e	7.13^abc
Mean		73.98	66.32	70.15	6.98	6.57	6.78
LSD (5%)		24.36	11.15	14.46	2.17	1.37	1.26
CV (%)		19.92	10.17	12.47	18.82	12.61	11.23

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*Within a column, means followed by different letters differ significantly at p < 0.05 (LSD). LSD: Least Significant Difference, CV: Coefficient of Variation.

The mean number of branches per plant among the examined genotypes ranged from 5.85 to 8.03 across the two years (Table 2). In 2019, the Burdur1 (8.03) and Ames23130 (7.77) genotypes recorded the highest number of branches, while in 2020, the Ames30693 (7.92) and Ames23130 (7.59) exhibited the highest values. Considering both years, the Ames30693, Ames23130, and PI649469 consistently demonstrated the highest number of branches per plant, with values of 7.92, 7.59, and 7.35, respectively. The lowest branch number was recorded in the PI649466 genotype (5.85 branches/plant). In general, in terms of branch number values, the Burdur1 genotype had the highest value in the first year, while the Ames30693 genotype had the highest value in the second year. The PI414191 and PI649466 genotypes had lower branch number than compared to other genotypes.

Overall, the mean number of branches per plant was higher in 2019 compared to 2020, likely due to differences in plant height and growing conditions. Additionally, across both years, the highest branch numbers were typically observed during the first harvest.

Among the genotypes, the Erzurum and Ames30289 exhibited higher umbel numbers in the first year, with values of 32.87 and 31.72 umbels per plant, respectively. In the second year, the PI649469, PI194892, and Ames23130 demonstrated relatively high umbel numbers, recording 28.86, 27.47, and 27.30 umbels per plant, respectively (Table 3). Overall, the mean number of umbels per plant across the two experimental years ranged from approximately 11.30 to 25.05 number. Based on the two-year mean, the Ames30290 genotype emerged as the most productive in terms of umbel number, meaning 25.05 umbels per plant.

Table 3.

Data for number of umbel and umbellets among the fennel genotypes.

No	Genotypes	Umbel number per plant			Number of umbellets per plant
No	Genotypes	2019	2020	Mean	2019	2020	Mean
1	Ames23130	20.07^ef	27.30^a	23.68^ab	217.57^a − d	203.50^b	210.53^bc
2	Ames27588	17.59^ef	5.16^f	11.37^k	115.70^d	58.29^f	86.99^e
3	Ames30289	31.72^ab	12.27^e	21.99^b − e	319.47^ab	100.50^def	209.98^bc
4	Ames30290	31.60^abc	18.50^bcd	25.05^a	269.20^a − d	125.83^de	197.52^bc
5	Ames30693	21.68^def	20.38^b	21.03^de	258.07^a − d	216.36^b	237.21^b
6	Ames7551	18.00^ef	14.13^de	16.07^hı	154.56^cd	119.23^de	136.89^cde
7	Antalya3	16.97^ef	19.97^bc	18.47^g	179.83^bcd	122.53^de	151.18^cde
8	Burdur1	29.13^a − d	13.87^de	21.50^cde	295.27^abc	124.07^de	209.67^bc
9	Burdur2	23.27^cde	18.60^bcd	20.93^de	229.42^a − d	111.23^def	170.33^bcd
10	Burdur5	22.97^def	11.83^e	17.40^gh	205.77^a − d	83.83^ef	144.80^cde
11	Denizli	22.05^def	14.57^cde	18.31^g	183.10^bcd	102.97^def	143.03^cde
12	Erzurum	32.87^a	13.13^de	23.00^bc	319.13^ab	98.77^def	208.95^bc
13	NSL6409	14.73^f	12.27^e	13.50^j	165.40^bcd	107.63^def	136.52^cde
14	PI194892	18.10^ef	27.47^a	22.78^bcd	197.62^a − d	196.27^bc	196.95^bc
15	PI414189	18.20^ef	16.97^b − e	17.58^gh	202.80^a − d	141.53^cde	172.17^bcd
16	PI414191	23.73^b − e	13.67^de	18.70^fg	247.03^a − d	99.40^def	173.22^bcd
17	PI649465	17.50^ef	12.47^e	14.99^ıj	142.76^cd	90.27^ef	116.51^de
18	PI649466	28.87^a − d	11.83^e	20.35^ef	284.00^abc	99.27^def	191.63^bcd
19	PI649469	17.34^ef	28.86^a	23.10^bc	350.13^a	345.53^a	347.83^a
20	PI649471	15.90^ef	20.50^b	18.20^g	175.30^bcd	157.70^bcd	166.50^b − e
Mean		22.11	16.69	19.40	225.61	135.24	180.42
LSD (5%)		8.43	5.74	4.79	154.33	59.31	79.68
CV (%)		23.05	20.80	14.95	41.39	26.53	26.72

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*Statistically significant differences were found any means in the same column followed by different letters by Significant Difference test (LSD) at p < 0.05. LSD: Least Significant Difference, CV: Coefficient of Variation.

According to our experimental results, the increase in temperature and rainfall observed during the second year had a positive effect on umbel production. Significant differences were also found among the genotypes regarding the number of umbellets per umbel (Table 3). Specifically, the PI649469 exhibited the highest mean number of umbellets (350.13), followed by the Ames30289 (319.47) and Erzurum (319.13) in the first year. In the second year, the PI649469 and Ames30693 were the best genotypes with 345.53 and 216.36 umbellets per plant, respectively. Over the two years, the PI649469 consistently produced the highest number of umbellets, followed by the Ames30693 and Ames23130, while the Ames27588 recorded the lowest umbellet number.

The 50% seedling days of the different fennel genotypes were found between 31.00 and 46.67 days for the first year, and between 28.67 and 45.00 days for the second year (Table 4). The earliest 50% seedling day was observed in the Burdur5, PI649466, and Ames30289 genotypes over two consecutive years. In contrast, the latest 50% seedling emergence was recorded in the PI649469 genotype in both years (Table 4). Analysis of variance for flowering days revealed a wide range of variation and statistically significant differences among all evaluated fennel genotypes. This trait varied from 86.67 to 124 days in 2019 and from 85.00 to 124.33 days in 2020. The earliest flowering was observed in the PI649466, while the latest flowering was recorded in the Ames27588 in both years. Significant differences were also observed among the genotypes for fruit setting days (p < 0.05). Fruit setting ranged from 121.67 to 147.67 days in 2019 and from 120.67 to 144.00 days in 2020. The earliest fruit setting was recorded in the Ames30290, while the latest fruit setting occurred in the Ames7551 and Ames30693 genotypes across both years (Table 4).

Table 4.

Seedling, flowering and fruit linking days of the fennel genotypes.

No	Genotypes	50% seedling days			50% flowering days			50% fruit linking days
No	Genotypes	2019-SD	2020-SD	Mean	2019-FD	2020-FD	Mean	2019-FLD	2020-FLD	Mean
1	Ames23130	40.67^a − e	39.67abc	40.17^a − e	98.33^b	95.00^bc	96.67^bc	139.00^a − d	136.67^ab	137.83^abc
2	Ames27588	40.67^a − e	43.00ab	41.83^a − d	124.00^a	124.33^a	124.17^a	132.67^d − g	133.00^bc	132.83^cde
3	Ames30289	31.33^g	28.67e	30.00^h	91.00^c − g	90.67^c − h	90.83^e−ı	124.33^gh	125.67^cde	125.00^def
4	Ames30290	40.33^a − e	39.33abc	39.83^a − e	91.33^c − g	85.67^hı	88.50^ghı	121.67^h	120.67^e	121.17^f
5	Ames30693	44.33^ab	41.33abc	42.83^abc	96.00^bc	93.67^cd	94.83^b − e	147.67^a	144.00^a	145.83^a
6	Ames7551	43.00^abc	45.00^a	44.00^ab	100.00^b	99.67^b	99.83^b	147.00^ab	145.67^a	146.33^a
7	Antalya3	39.33^a − f	37.33^bcd	38.33^b − f	94.00^b − f	90.00^c−ı	92.00^c − h	124.67^fgh	124.00^cde	124.33^def
8	Burdur1	36.00^c − g	35.33^cde	35.67^d − h	90.67^c − g	87.67^e−ı	89.17^f−ı	124.33^gh	120.33^e	122.33^f
9	Burdur2	32.00^fg	30.33^de	31.17^gh	90.00^c − g	87.00^f−ı	88.50^ghı	126.33^e − h	122.33^de	124.33^def
10	Burdur5	31.00^g	29.00^e	30.00^h	88.67^efg	87.67^e−ı	88.17^ghı	124.33^gh	122.67^cde	123.50^ef
11	Denizli	42.00^a − d	43.67^ab	42.83^abc	95.33^bcd	91.67^c − g	93.50^c − g	126.00^e − h	124.67^cde	125.33^def
12	Erzurum	35.00^d − g	32.00^de	33.50^e − h	91.33^c − g	88.33^d−ı	89.83^e−ı	123.67^gh	122.00^de	122.83^ef
13	Nsl6409	33.33^efg	31.67^de	32.50^fgh	98.00^b	95.00^bc	96.50^bcd	144.67^abc	144.00^a	144.33^ab
14	PI194892	42.67^abc	42.33^abc	42.50^a − d	91.00^c − g	91.33^c − g	91.17^d−ı	128.67^d − h	123.33^cde	126.00^def
15	PI414189	33.33^efg	29.67^e	31.50^fgh	89.33^d − g	85.00^ı	87.17^hı	122.67^gh	121.33^e	122.00^f
16	PI414191	34.67^d − g	31.00^de	32.83^fgh	88.33^fg	89.00^d−ı	88.67^ghı	128.33^d − h	126.00^cde	127.17^def
17	PI649465	34.33^efg	31.33^de	32.83^fgh	95.33^bcd	93.00^cde	94.17^c − f	135.33^c − f	133.00^bc	134.17^bcd
18	PI649466	31.00^g	29.00^e	30.00^h	86.67^g	86.33^ghı	86.50^ı	128.67^d − h	126.67^b − e	127.67^c − f
19	PI649469	46.67^a	45.00^a	45.83^a	95.00^b − e	92.00^c − f	93.50^c − g	136.67^b − e	132.33^bcd	134.50^bcd
20	PI649471	38.33^b − g	35.67^cde	37.00^c − g	88.33^fg	86.33^ghı	87.33^hı	128.00^e − h	123.67^cde	125.83^def
Mean		37.50	36.02	36.76	94.13	91.97	93.05	130.73	128.60	129.67
LSD (5%)		7.64	7.00	6.90	6.52	5.62	5.47	10.74	10.59	10.21
CV (%)		12.33	11.76	11.36	4.19	3.70	3.56	4.97	4.98	4.76

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* Within a column, means followed by different letters differ significantly at p < 0.05 (LSD). LSD: Least Significant Difference, CV: Coefficient of Variation.

The mean stem diameter ranged from 4.85 to 11.08 mm in 2018 and from 10.47 to 5.03 mm in 2019 (Table 5). The stem diameter was widest for the Ames27588 genotype in the two successive years. The PI414189 (4.94 mm) and Erzurum (4.99 mm) genotypes had the smallest stem diameter in two experimental years. As seen in Table 5, the fennel genotypes showed significant differences based on the biological yield. The PI414191 genotype exhibited the highest mean biological yield (20371.69 kg/ha), followed by the PI649471 (18152.98 kg/ha), and Ames27588 genotypes (17452.94 kg/ha) in 2019. In addition, the NSL6409 genotype had the highest biological yield with 32964.07 kg/ha, and followed by the Ames30693 (25065.79 kg/ha) and Burdur2 (21110.74 kg/ha) genotypes. Overall, the NSL6409 and PI414191 were superior genotypes in the two successive years on mean.

Table 5.

Values of stem diameter and biological yield of the fennel genotypes.

No	Genotypes	Stem diameter (mm)			Biological yield (kg/ha)
No	Genotypes	2019	2020	Mean	2019	2020	Mean
1	Ames23130	8.49^bcd	8.57^abc	8.53^b	12901.96^c − f	16772.50^de	14837.23^d − g
2	Ames27588	11.08^a	10.47^a	10.77^a	17452.94^ab	13745.93^e − h	15599.44d^ef
3	Ames30289	9.14^b	6.20^def	7.67^bcd	17394.86^ab	17274.26^cde	17334.56^bcd
4	Ames30290	7.81^bcd	6.26^def	7.04^b − f	8062.30^g	16726.11^de	12394.21^gh
5	Ames30693	6.15^efg	10.43^a	8.29^bc	8890.78^fg	25065.79^b	16978.28^cd
6	Ames7551	7.83^bcd	8.82^ab	8.32^bc	9770.41^efg	15605.74^ef	12688.07^fgh
7	Antalya3	5.83^fg	6.34^def	6.09^d − g	11120.19^d − g	10930.74^hı	11025.47^h
8	Burdur1	7.48^cde	5.80^ef	6.64^c − g	14040.81^b − e	12535.00^fgh	13287.91^e − h
9	Burdur2	6.95^def	6.18^def	6.56^c − g	16770.98^abc	21110.74^bc	18940.86^bc
10	Burdur5	7.59^b − e	4.67^f	6.13^d − g	10510.89^efg	12168.15^f−ı	11339.52^h
11	Denizli	5.20^g	6.86^b − e	6.03^d − g	7937.76^g	8092.04^ı	8014.90^ı
12	Erzurum	4.95^g	5.03^ef	4.99^g	9397.52^fg	14580.00^e − h	11988.76^gh
13	NSL6409	6.93^def	7.91^bcd	7.42^b − e	16456.04^abc	32964.07^a	24710.06^a
14	PI194892	8.23^bcd	6.97^b − e	7.60^bcd	9376.98^fg	15567.87^efg	12472.43^gh
15	PI414189	4.85^g	5.03^ef	4.94^g	10285.76^efg	13996.85^e − h	12141.31^gh
16	PI414191	5.59^fg	5.66^ef	5.63^fg	20371.69^a	20012.22^cd	20191.96^b
17	PI649465	8.70^bc	5.77^ef	7.24^b − f	11121.81^d − g	15085.00^efg	13103.40^fgh
18	PI649466	5.30^g	6.12^def	5.71^efg	15060.43^bcd	17091.30^cde	16075.86^cde
19	PI649469	8.45^bcd	6.30^def	7.37^b − f	3389.39^h	11453.32^ghı	7421.36^ı
20	PI649471	4.96^g	6.63^c − f	5.80^efg	18152.98^ab	15346.11^efg	16749.55^cd
Mean		7.08	6.80	6.94	12423.3	16306.20	14364.80
LSD (5%)		1.60	1.99	1.79	4341.5	4123.10	2951.00
CV (%)		13.71	17.72	15.62	21.14	15.30	12.43

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* Within a column, means followed by different letters differ significantly at p < 0.05 (LSD). LSD: Least Significant Difference, CV: Coefficient of Variation.

Fruit weight, essential oil content and essential oil yield

Statistical significant differences were found among the fennel genotypes in both years (p < 0.05). The fruit weight values of the fennel genotypes showed high variability from 183.78 kg/ha to 1867.40 kg/ha in the first year. Similarly fruit weight values showed variability in the second year ranged from 343.22 kg/ha to 1468.48 kg/ha. Compared to mean values of the years (Table 6), it is evident that in the first year, the Ames30290 and Ames23130 genotypes exhibited notably higher fruit yields, measuring 1867.40 and 1682.77 kg/ha, respectively. In the second year, the Ames23130 and Ames30290 again demonstrated the highest fruit yields, recording 1468.48 and 1228.70 kg/ha, respectively (Table 6). Considering the cumulative fruit yield over the two years, the Ames23130 and Ames30290 genotypes stood out with the highest yields, reaching 1575.62 and 1547.85 kg/ha, respectively, whereas the PI649469 genotype displayed the lowest fruit yield at 393.33 kg/ha (Table 6).

Table 6.

Fruit weight, essential oil content and essential oil yield of fennel genotypes.

No	Genotypes	Fruit weight (kg/ha)			Essential oil content (%)			Essential oil yield (L/ha)
No	Genotypes	2019	2020	Mean	2019	2020	Mean	2019	2020	Mean
1	Ames23130	1682.77^a	1468.48^a	1575.62^a	3.16^b − e	3.80^a	3.48^ab	52.95^a	55.74^a	54.70^a
2	Ames27588	1169.87^b	343.32^g	756.59^d	2.25^gh	3.48^a − d	2.86^cde	26.38^cde	11.62^ı	21.46^efg
3	Ames30289	1058.00^b	865.19^cd	961.59^c	3.05^b − f	2.43^efg	2.74^c − f	32.29^bc	21.46^e − h	26.48^cde
4	Ames30290	1867.40^a	1228.70^ab	1547.85^a	2.60^c − g	3.55^abc	3.07^bcd	48.61^a	41.57^b	47.23^b
5	Ames30693	390.54^e − h	644.54^def	517.54^fgh	4.11^a	3.71^ab	3.91^a	16.44^ghı	22.51^e − h	20.07^fgh
6	Ames7551	444.87^d − g	515.16^fg	480.01^gh	2.71^b − g	2.67^c − g	2.69^def	11.86^h − k	13.78^hı	12.90^ıjk
7	Antalya3	264.50^gh	566.85^efg	415.68^h	2.19^gh	2.99^a − g	2.59^d − g	5.79^kl	17.06^f−ı	10.80^jk
8	Burdur1	625.13^cde	847.96^d	736.55^d	1.98^gh	2.04^g	2.01^h	12.39^g − k	16.80^ghı	14.90^h − k
9	Burdur2	730.79^c	1207.96^b	969.37^c	3.30^bcd	3.29^a − e	3.29^bc	24.08^def	39.48^bc	31.88^c
10	Burdur5	629.00^cde	807.96^de	718.48^d	2.58^c − g	2.62^c − g	2.60^def	16.24^ghı	21.29^e − h	18.71^ghı
11	Denizli	584.93^cde	503.70^fg	544.32^e − h	3.32^bc	2.73^c − g	3.03^bcd	19.42^efg	13.72^hı	16.45^g − j
12	Erzurum	507.19^c − f	789.81^de	648.50^def	3.45^ab	2.69^c − g	3.07^bcd	17.52^fgh	21.21^e − h	19.93^fgh
13	NSL6409	1081.00^b	1147.04^b	1114.02^bc	1.80^h	2.76^b − g	2.28^fgh	19.61^efg	31.75^cd	25.52^def
14	PI194892	183.78^h	1099.26^bc	641.52^d − g	2.15^gh	2.72^c − g	2.43^e − h	3.92^l	29.95^de	15.63^g − j
15	PI414189	499.61^c − g	842.04^d	670.82^def	2.17^gh	3.00^a − f	2.59^d − g	9.43^ı−l	26.14^def	17.47^ghı
16	PI414191	1221.96^b	1113.33^b	1167.64^b	2.76^b − g	2.43^efg	2.60^def	33.70^b	27.35^de	30.35^cd
17	PI649465	1227.40^b	778.52^de	1002.96^c	2.47^e − h	2.79^b − g	2.63^def	30.27^bcd	20.87^e − h	26.25^cde
18	PI649466	637.32^cd	781.48^de	709.40^d	2.03^gh	2.05^fg	2.04^gh	12.94^g − k	16.00^ghı	14.47^h − k
19	PI649469	336.48^fgh	450.19^fg	393.33^h	2.33^fgh	2.52^d − g	2.43^e − h	7.83^jkl	11.35^ı	9.54^k
20	PI649471	531.30^c − f	842.96^d	687.13^de	2.52^d − h	2.85^a − g	2.69^def	13.28^g − j	23.91^d − g	18.33^ghı
Mean		783.67	842.22	812.95	2.65	2.86	2.75	20.75	24.18	22.65
LSD (5%)		238.56	244.41	162.50	0.78	0.96	0.56	7.25	9.11	5.85
CV (%)		18.42	17.56	12.09	17.90	20.27	12.24	21.13	22.81	15.63

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* Within a column, means followed by different letters differ significantly at p < 0.05 (LSD). LSD: Least Significant Difference, CV: Coefficient of Variation.

Significant differences were noted among the fennel genotypes for the essential oil contents depending on the experimental years (p < 0.05). As shown in Table 6, the essential oil contents of the twenty studied fennel genotypes ranged from 1.80 to 4.11% in the first year and from 2.04 to 3.80% in the second year. The variation in essential oil content between the highest and lowest values was approximately 2.28-fold in the first year and 1.86-fold in the second year. In terms of essential oil content, the Ames30693 and Erzurum genotypes exhibited the highest levels at 4.11% and 3.45%, respectively, in the first year. In the second year, the top-performing genotypes were Ames23130 and Ames30693, with 3.80% and 3.71% essential oil content, respectively.

Essential oil yield showed statistically significant among the fennel genotypes in both experimental years and mean values of the years. Essential oil yield values of fennel genotypes showed high variability and ranged from 3.92 L/ha to 52.74 L/ha in the first year (Table 6). The highest essential oil yield was found in the Ames23130 (52.95 L/ha), and followed by the Ames30290 (48.61 L/ha) genotype. The lowest essential oil yield values were observed from the PI194892 (3.92 L/ha) and Antalya3 (5.79 L/ha) genotypes. In the second year, the Ames23130 and Ames30290 genotypes had the highest essential oil yield values with 55.74 L/ha and 41.57 L/ha, respectively. The lowest essential oil yield values were noted in the PI649469 (11.35 L/ha) and Ames27588 (11.62 L/ha) genotypes. It was clearly observed that the essential oil yield of the fennel genotypes was related to their fruit weight. The mean essential oil values of the years showed high variability, and the Ames23130 (54.70 L/ha) and PI649469 (9.54 L/ha) genotypes had the highest and lowest values compared to other fennel genotypes, respectively.

Essential oil components of fennel genotypes

The essential oil components of different fennel genotypes fruits showed statistically significant differences in the vegetation periods of 2019 and 2020 years. A total of 17 components were identified by GC-MS from the essential oil of fennel at full ripening stage which represented between 83.74 and 100% of the total essential oil components. Analysis of variance revealed significant differences (p < 0.05) among the fennel genotypes for both years, as well as for the mean values across years, with respect to their major and minor essential oil components.

The main essential oil components were determined as trans-anethole (54.14–90.44%), estragole (2.38–28.75%), p-cymene (0.10-39.63%), limonene (0.13–7.94%) and α-fenchone (0.47–8.44%) among the all essential oil components (Table 7). The percentage components of the remaining 12 compounds ranged from 0.03 to 3.21% (supplementary Table 1). The total essential oil content of the five major components ranged from 92.70 to 97.86% in the first year, from 67.57 to 100.00% in the second year, and from 80.79 to 97.13% when averaged over the two years. Only one genotype (PI649465) had the 100% total variations based on the five essential oil components in the second year (Table 7). The genotypes PI649469 and PI649465 had the highest total essential oil components. The content of trans-anethole, the first major component of the essential oil, showed high variability among the genotypes and vegetation periods and ranged from 54.14 to 88.52% and 57.64–90.44% in the first and second years, respectively. As depicted in Table 7, the highest percentage of trans-anethole belonged to local fennel genotypes as Burdur1, and Burdur5 (88.52 and 87.42%, respectively) in the first year. The lowest trans-anethole percentage was obtained in the PI649469 (54.14%) originated from Syria and the Ames7551 (58.52%) originated from Illinois, United States. In the second year, the Denizli (90.44%) originated from Türkiye and Ames27588 (90.35%) originated from Italy fennel genotypes had the highest concentration of trans-anethole, and the Ames30290 and Ames30693 genotypes had the minimum trans-anethole concentrations among the fennel genotypes with 57.64% and 71.36%, respectively. The trans-anethole concentrations ranged from 68.49 to 88.30%. among the mean values of the years. The highest and lowest trans-anethole values were obtained from the Burdur5 and PI649469 genotypes. Among the local genotypes, the trans-anethole concentrations of the Antalya3, Burdur1, Burdur2 and Burdur5 had the higher values compared to mean of the all genotypes from the first year (77.58%), second year (81.70%) and mean values of the years (79.64%).

Table 7.

Variability of major five essential oil components of fennel genotypes.

No	Genotypes	Limonene					α-fenchone					p-cymene					Estragole					Trans-anethole					Total
No	Genotypes	2019		2020		Mean	2019		2020		Mean	2019		2020		Mean	2019		2020		Mean	2019		2020		Mean	2019		2020		Mean
1	Ames23130	6.06^d		5.42^a		5.74^a	6.28^b		4.33^b		5.30^a	3.72^h		nd		1.86^q	nd		7.71^c		3.86^l	77.84^ı		76.14^p		76.99^ı	93.89^jk		93.60^l		93.75^j
2	Ames27588	5.14^f		1.96^ı		3.55^h	1.07^k		0.47^o		0.77ⁿ	nd		4.38^l		2.19^o	9.68^d		nd		4.84^ı	79.06^h		90.35^b		84.70^d	94.95^h		97.16^ef		96.06^f
3	Ames30289	3.57^k		1.46^j		2.51^j	nd		1.16^j		0.58^o	0.14^k		nd		0.07^r	4.21^l		15.88^a		10.05^b	84.56^d		78.13ⁿ		81.34^f	92.49^m		96.62^g		94.56^ı
4	Ames30290	4.26^ı		0.25^p		2.26^k	1.87^h		1.40^h		1.63^jk	0.37^ı		4.32^m		2.35ⁿ	4.49^ı		3.96^f		4.23^k	83.00^f		57.64^s		70.32ⁿ	94.00^ıj		67.57^o		80.79^m
5	Ames30693	4.42^h		0.13^q		2.27^k	3.34^e		0.60ⁿ		1.97^ı	6.53^c		4.26ⁿ		5.39^f	4.42j		5.36^d		4.89^h	77.49^ı		71.36^r		74.43^l	96.20^cd		81.71ⁿ		88.95^l
6	Ames7551	7.94^a		0.71ⁿ		4.32^d	nd		0.96^l		0.48^o	0.32^ıj		4.92^ı		2.62^k	28.75^a		2.38^h		15.56^a	58.52^o		88.38^d		73.45^m	95.52^fg		97.35^cde		96.44^de
7	Antalya3	5.87^e		3.05^f		4.46^c	3.76^d		0.87^m		2.32^fg	5.44^e		nd		2.72^j	nd		4.46^e		2.23ⁿ	78.61^h		88.36^d		83.48^e	93.68^kl		96.74^g		95.21^h
8	Burdur1	2.36ⁿ		2.21^h		2.28^k	0.97^k		5.92^a		3.44^c	nd		5.36^g		2.68^j	4.30^k		nd		2.15^o	88.52^a		83.63^ı		86.07^c	96.14^d		97.13^f		96.63^c
9	Burdur2	7.27^c		3.70^d		5.48^b	1.20^ıjk		0.98^l		1.09^m	4.52^f		4.77^j		4.64^h	nd		nd		nd	80.50^g		86.30^g		83.40^e	93.49^l		95.75^ı		94.62^ı
10	Burdur5	3.10^m		1.96ı		2.53^j	1.16^jk		2.37^e		1.76^j	0.10^k		3.90^o		2.00^p	4.02^m		nd		2.01^p	87.42^b		89.17^c		88.30^a	95.79^e		97.40^cd		96.60^cd
11	Denizli	7.50^b		0.80^m		4.15^f	3.27^e		1.07^k		2.17^gh	0.11^k		4.88^ı		2.49^m	8.58^f		nd		4.29^j	76.17^k		90.44^a		83.31^e	95.63^ef		97.20^def		96.41e
12	Erzurum	4.08^j		0.39^o		2.23^k	1.42^ıj		1.76^g		1.59^k	0.29^j		11.56^c		5.93^e	4.57^h		nd		2.29^m	83.80^e		78.28^m		81.04^g	94.16^ı		91.99^m		93.08k
13	NSL6409	5.00^g		2.26^gh		3.63^g	2.52^g		2.19^f		2.36^f	nd		13.62^b		6.81^d	13.60^b		nd		6.80^d	75.02^l		79.69^l		77.36^h	96.14^d		97.76^b		96.95b
14	PI194892	4.11^j		4.38^c		4.24^e	1.11^k		3.60^d		2.35^f	6.30^d		nd		3.15^ı	nd		10.01^b		5.00^g	84.69^d		77.97^o		81.33^f	96.21^cd		95.96^h		96.08f
15	PI414189	7.59^b		1.02^l		4.30^de	8.44^a		1.24^ı		4.84^b	nd		10.35^d		5.17^g	10.79^c		nd		5.40^f	68.62ⁿ		84.89^h		76.76^ıj	95.44^fg		97.50^c		96.47de
16	PI414191	4.17^ıj		4.58^b		4.37^d	5.22^c		0.85^m		3.03^d	16.67^b		6.61^f		11.64^c	nd		nd		nd	70.34^m		83.00^j		76.67^j	96.40^c		95.03^k		95.72 g
17	PI649465	1.33^o		1.11^k		1.22^m	1.46^ı		1.38^h		1.42^l	4.08^g		19.46^a		11.77^b	8.36^g		5.36^d		6.86^c	76.84^j		72.69^q		74.77^k	92.07ⁿ		100.00^a		96.04f
18	PI649466	3.12^m		0.84^m		1.98^l	1.95^h		3.70^c		2.83^e	nd		5.10^h		2.55^l	4.28^k		nd		2.14^o	86.02^c		88.16^e		87.09^b	95.38^g		97.80^b		96.59 cd
19	PI649469	1.19^p		3.36^e		2.28^k	2.90^f		0.64ⁿ		1.77^j	39.63^a		8.59^e		24.11^a	nd		nd		nd	54.14^p		82.84^k		68.49^o	97.86^a		95.44^j		96.65c
20	PI649471	3.36^l		2.31^g		2.83^ı	3.71^d		0.48^o		2.09^hı	nd		4.62^k		2.31ⁿ	9.54^e		3.32^g		6.43^e	80.46^g		86.47^f		83.47^e	97.07^b		97.19^ef		97.13a
Mean		4.57	2.09		3.33		2.87	1.80		2.19		6.30	7.29		5.12		8.54	6.49		5.24		77.58	81.70		79.64		95.13	94.34		94.74
LSD (5%)		0.13	0.05		0.07		0.30	0.05		0.15		0.06	0.04		0.04		0.06	0.04		0.04		0.52	0.05		0.26		0.23	0.21		0.16
CV (%)		1.67	1.44		1.25		6.93	1.75		4.14		0.89	0.44		0.46		0.65	0.81		0.52		0.40	0.04		0.20		0.14	0.13		0.10

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* Within a column, means followed by different letters differ significantly at p < 0.05 (LSD). LSD: Least Significant Difference, CV: Coefficient of Variation, nd: Not detected.

The second major essential oil component was estragole (methyl chavicol) which varied from 4.21 to 28.75% in the first year and varied from 2.38 to 15.88% in the second year (Table 7). In the first year, the estragole concentrations were not detected in six genotypes (Ames23130, Antalya3, Burdur2, PI194892, PI414191 and PI649469) among the fennel genotypes. In the first year, the Ames7551 originated from Illinois, United States and the NSL6409 originated from California, United States had the highest concentrations of estragole (28.75 and 13.60%). In the second year, the highest estragole concentration was found in the Ames30289 (15.88%) originated from Sfax, Tunisia and followed by the PI194892 (10.01%) originated from Ethiopia genotypes. The genotypes Ames7551 (2.38%) originated from Illinois, United states and PI649471 (3.32%) originated from Morocco had the minimum estragole concentrations among the fennel genotypes. Four local fennel genotypes (Burdur1, Burdur5, Denizli and Erzurum) had the estragole values in the first year, and Antalya3 local genotype had the estragole value in the second year. It was determined that two genotypes of Tunisian origin had estragole values in both vegetation periods. The estragole values in the means of the years changed between 2.01 and 15.56%, and the highest and lowest estragole values were obtained from the Ames7551 (15.56%) and Burdur5 (2.015) genotypes. The mean estragole contents of the local genotypes (ranging from 2.01 to 4.29%) was found to be lower than the overall mean value observed across all fennel genotypes (5.24%).

The third major essential oil component was identified as p-cymene, which exhibited a high degree of variability among the fennel genotypes (Table 7). The p-cymene concentrations ranged from 0.10 to 39.63% in the first year. Essential oil contents of six fennel genotypes (Ames27588, Burdur1, NSL6409, PI414189, PI649466 and PI649471) had no p-cymene concentrations. Among the included p-cymene concentrations, the PI649469 (originated from Syria) genotype had the highest value with 39.63% and followed by the PI414191 (originated from Maryland, United States) genotype with 16.67% in the first year. However, the local genotypes the Burdur5 (0.10%) and Denizli (0.11%) with Ames30289 (0.14%) (originated from Sfax, Tunisia) genotype revealed the lowest values compared to other genotypes in the first year. In the second year, p-cymene values ranged from 3.90 to 19.46% among the different origin fennel genotypes (Table 7). The high concentration of p-cymene was obtained from the PI649465 (originated from Uzbekistan) genotype with 19.46%, followed by the NSL6409 (originated from California, United States) genotype with 13.62%, whereas the minimum concentration of p-cymene was obtained from the Burdur5 local genotype (3.90%) and followed by the Ames30693 (Oregon, United States) genotype (4.26%). The contents of p-cymene in five fennel genotypes (PI649465, NSL6409, Erzurum, PI414189 and PI649469) originated from different countries (Uzbekistan, United states, Türkiye, Egypt and Syria) were found higher than means of all fennel genotypes. Among the local genotypes, the Erzurum genotype had the highest p-cymene value with 11.56% in the second year, and it has an approximately 54% higher p-cymene concentration compared to the Burdur1 genotype, which contains 5.36% p-cymene. The two-year mean values showed that p-cymene values ranged from 0.07 to 24.11%, and the PI649469 (24.11%) and Ames30289 (0.07%) genotypes had the maximum and minimum values, respectively.

Limonene was determined as forth major essential oil component in the fennel genotypes depending on the vegetation periods. Statistically significant results were found among the fennel genotypes for the limonene (p < 0.05) in two experimental years (Table 7). In the first vegetation period, the limonene values varied from 1.19 to 7.94%, and the Ames7551 (originated from Illinois, United States) with 7.94%, the PI414189 (originated from Cairo, Egypt) with 7.59% had the highest limonene values. The genotypes PI649469 (1.19%) originated from the Syria and PI649465 (1.33%) originated from Uzbekistan had the lowest limonene values among the different fennel genotypes. In the second vegetation period, the limonene values changed between 0.13 and 5.42% among the fennel genotypes (Table 7). The Ames23130 (5.42%) genotypes originated from Italy had the highest limonene value and followed by the PI414191 (4.58%) originated from Maryland, United States and the PI194892 (4.38%) originated from Ethiopia genotypes. The lowest limonene values were found from the Ames30693 (0.13%) originated from Oregon, United States and the Ames30290 (0.25%) originated from Sfax, Tunisia (0.25%) in the second year. According to means of the two vegetation periods, the limonene values ranged from 1.22 to 5.74% among the fennel genotypes.

The last major essential oil component was α-fenchone which concentrations ranged from 0.97 to 8.44% in the first year, changed between 0.47 and 5.92% in the second year (Table 7). The PI414189 (originated from Cairo, Egypt) with 8.44% and Ames23130 (originated from Italy) with 6.28% genotypes had the highest α-fenchone values, while the genotypes Burdur1 genotype with 0.97% and Ames27588 with 1.07% (originated from Italy) had the lowest values in the first year. Among the twenty fennel genotypes, two genotypes (Ames30289 and Ames7551) had no α-fenchone values. In the second year, the highest α-fenchone value was found in the Burdur1 (5.92%) genotype and followed by the Ames23130 (4.33%) and PI649466 (3.70%) genotypes. The lowest α-fenchone values were determined in the Ames27588 (0.47%) and PI649471 (0.48%) genotypes. The two-years mean α-fenchone values ranged from 0.48 to 5.30%, and the Ames23130 (5.30%) and Ames7551 (0.48%) genotypes had the highest and lowest values, respectively. It was clearly noted that α-fenchone concentrations of the Burdur1 genotype revealed the lowest value in the first year and the highest value in the second year. Twelve minor essential oil components were identified in different fennel genotypes, ranging from 0.03 to 3.21% (Supplementary Table 1). These minor components included α-pinene, sabinene, myrcene, 1,8-cineole, γ-terpinene, δ-terpinolene, β-cymene, camphor, α-cubebene, fenchyl acetate, anethole, and p-anisaldehyde. Statistically significant differences (P < 0.05) were observed among the fennel genotypes across the two growing years and in their mean values. Based on the mean values across years, the highest proportion among the minor essential oil components was α-pinene (2.49%) in the Ames23130 genotype, followed by p-anisaldehyde (1.83%) in the Ames30693 genotype.

The twelve minor essential oil components of the fennel essential oil were identified as α-pinene, sabinene, myrcene, 1,8 cineol (eucalyptol), γ-terpinene, δ-terpinolene, β-cymene, α-cubebene, camphor, fenchyl acetate, anethole, and p-anisaldehyde. The highest values of α-pinene and δ-terpinolene were consistently observed in both the first and second years, whereas the other components exhibited variability between years.

Mineral matter contents of the fennel genotypes

The elemental compositions of 20 fennel fruit samples were analyzed using ICP-OES during the two vegetation periods (Tables 8 and 9). Among the macronutrients during the two vegetation periods, K was the most abundant element, with concentrations ranging from approximately 6822.25 to over 10906.20 mg/kg in the first year. The highest K content was detected in the PI414189 genotype (10906.20 mg/kg). In the second year, the K values ranged from 7425.24 mg/kg to 10.420.24 mg/kg, and the highest and lowest K values were found in PI649469 and PI649466 genotypes. Ca values were found between 1417.99 and 2646.18 mg/kg in the first year, and between 1817.52 and 2715.30 mg/kg in the second year. Ca was also present in considerable quantities, with the PI649466 and Antalya3 genotypes showing the highest Ca content with 2646.18 mg/kg in the first year and 2715.30 mg/kg in the second year, respectively. Mg was the third most abundant macronutrient, showing substantial variability among the samples. The maximum Mg content was found in the Antalya3 with 583.66 mg/kg in the first year and with the PI141189 genotype with 580.87 mg/kg in the second year. In terms of trace elements during the two vegetation periods, iron (Fe) and zinc (Zn) exhibited noteworthy concentrations. Iron content is 279.74 mg/kg, with the highest level observed in the Burdur5. Also, the Ames30289 genotype exhibited the highest Zn content at 51.71 mg/kg. While the Pb and Ni mineral matters were not found in fennel genotypes in both years, Cd element was found in the PI414189 genotypes in the first year, and the Ames23130 and Denizli genotypes in the second year with lower values < 0.04 mg/kg.

Table 8.

Mineral matter contents of fennel genotypes growing in 2019 year.

No	Genotypes	Al	Cu	Zn	Fe	Cd	Ca	Cr	Pb	Mg	Mn	Ni	K	Na
1	Ames23130	50.78 ± 3.96	6.79 ± 0.15	36.28 ± 0.92	219.14 ± 2.86	nd	2152.52 ± 107.36	0.677 ± 0.017	nd	481.99 ± 18.18	42.39 ± 1.77	nd	9695.36 ± 857.05	1.553 ± 0.221
2	Ames27588	49.51 ± 4.63	6.98 ± 0.08	39.88 ± 1.47	249.23 ± 15.54	nd	2203.82 ± 92.13	0.735 ± 0.037	nd	386.67 ± 14.33	41.26 ± 0.67	nd	9221.29 ± 156.17	1.497 ± 0.278
3	Ames30289	40.98 ± 1.74	5.66 ± 0.37	51.71 ± 0.68	255.17 ± 4.38	nd	2139.76 ± 94.15	0.768 ± 0.028	nd	364.6 ± 28.01	48.83 ± 4.15	nd	9431.29 ± 9.95	1.321 ± 0.24
4	Ames30290	48.37 ± 2.42	6.31 ± 0.03	36.78 ± 1.56	242.48 ± 6.25	nd	1940.81 ± 183.97	0.800 ± 0.027	nd	466.82 ± 10.35	40.61 ± 4.99	nd	9502.16 ± 266.46	1.408 ± 0.146
5	Ames30693	41.4 ± 3.01	7.48 ± 0.5	41.99 ± 0.06	233.53 ± 21.44	nd	2387.5 ± 239.81	0.714 ± 0.084	nd	384.36 ± 32.05	46.55 ± 5.77	nd	7715.78 ± 585.13	1.278 ± 0.104
6	Ames7551	36.5 ± 2.87	6.6 ± 0.17	41.22 ± 0.46	236.02 ± 17.93	nd	2348.57 ± 245.65	0.702 ± 0.014	nd	422.35 ± 40.30	47.71 ± 0.19	nd	8227.96 ± 419.47	1.151 ± 0.133
7	Antalya3	49.12 ± 0.06	8.6 ± 0.77	33.16 ± 0.95	255.17 ± 7.00	nd	1417.99 ± 119.7	0.645 ± 0.045	nd	583.66 ± 33.36	33.57 ± 2.42	nd	9280.31 ± 719.64	0.868 ± 0.117
8	Burdur1	47.13 ± 3.68	6.17 ± 0.12	31.5 ± 0.95	220.85 ± 7.57	nd	1988.12 ± 80.93	0.797 ± 0.038	nd	395.11 ± 9.39	34.04 ± 1.40	nd	9213.49 ± 1053.05	1.387 ± 0.084
9	Burdur2	39.66 ± 3.36	7.02 ± 0.72	40.65 ± 0.88	245.76 ± 15.28	nd	2188.95 ± 43.51	0.752 ± 0.023	nd	377.87 ± 39.18	45.96 ± 3.87	nd	8946.51 ± 126.65	1.366 ± 0.116
10	Burdur5	40.04 ± 0.45	5.89 ± 0.29	37.16 ± 4.39	230.28 ± 12.61	nd	2020.18 ± 161.46	0.69 ± 0.01	nd	499.08 ± 38.08	31.21 ± 1.95	nd	8369.65 ± 139.84	1.489 ± 0.235
11	Denizli	50.52 ± 4.14	9.26 ± 1.24	38.96 ± 0.53	226.95 ± 13.22	nd	1431.88 ± 67.56	0.697 ± 0.027	nd	560.1 ± 7.26	40.9 ± 2.91	nd	10120.06 ± 310.37	1.224 ± 0.165
12	Erzurum	34.37 ± 2.22	7.43 ± 0.52	42.82 ± 1.8	229.95 ± 9.3	nd	2563.32 ± 34.48	0.713 ± 0.053	nd	444.86 ± 33.89	44.11 ± 4.22	nd	8221.71 ± 1064.97	1.096 ± 0.134
13	NSL6409	35.02 ± 1.04	5.55 ± 0.25	42.25 ± 0.6	259.06 ± 18.91	nd	2547.14 ± 51.39	0.784 ± 0.044	nd	357.9 ± 30.49	52.24 ± 1.43	nd	9241.38 ± 61.76	1.042 ± 0.126
14	PI194892	49.81 ± 0.16	10.5 ± 0.8	31.19 ± 1.34	207.65 ± 20.66	nd	1489.55 ± 191.16	0.56 ± 0.028	nd	486.48 ± 16.86	29.96 ± 2.03	nd	9354.30 ± 428.79	1.183 ± 0.198
15	PI414189	49 ± 3.34	11.5 ± 0.98	37.52 ± 2.2	226.26 ± 18.93	0.033 ± 0.009	1445.14 ± 13.2	0.626 ± 0.02	nd	542.78 ± 62.17	35.55 ± 1.44	nd	10906.20 ± 373.44	1.04 ± 0.107
16	PI414191	38.25 ± 0.21	6.81 ± 0.58	44.62 ± 3.66	223.05 ± 24.15	nd	2561.06 ± 30.29	0.724 ± 0.097	nd	454.66 ± 48.22	48.43 ± 1.88	nd	7149.80 ± 225.44	1.185 ± 0.148
17	PI649465	52.08 ± 0.08	7.56 ± 0.54	34.92 ± 1.86	249.42 ± 7.96	nd	1861.35 ± 34.99	0.753 ± 0.096	nd	509.78 ± 35.58	39.25 ± 5.76	nd	9415.32 ± 495.51	1.437 ± 0.109
18	PI649466	39.62 ± 2.93	6.27 ± 0.3	43.64 ± 3.19	230.09 ± 11.82	nd	2646.18 ± 63.38	0.799 ± 0.007	nd	349.31 ± 23.9	47.62 ± 5.06	nd	8648.01 ± 36.13	1.292 ± 0.095
19	PI649469	43.68 ± 0.12	5.61 ± 0.36	43.42 ± 1.59	261.63 ± 10.49	nd	2506.62 ± 9.05	0.63 ± 0.003	nd	340.84 ± 18.29	52.05 ± 4.07	nd	9443.66 ± 517.05	1.197 ± 0.085
20	PI649471	49.99 ± 5.42	9.22 ± 0.64	38.42 ± 2.09	221.26 ± 9.35	nd	1636.37 ± 4.86	0.648 ± 0.007	nd	462.42 ± 37.58	34.21 ± 3.25	nd	9691.13 ± 761.04	1.215 ± 0.178

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*Values represent means ± standard deviation. nd: Not detected.

Table 9.

Mineral matter contents of fennel genotypes growing in 2020 year.

No	Genotypes	Al	Cu	Zn	Fe	Cd	Ca	Cr	Pb	Mg	Mn	Ni	K	Na
1	Ames23130	45.49 ± 2.29	6.03 ± 0.37	42.50 ± 0.98	240.96 ± 27.52	0.037 ± 0.014	2129.02 ± 201.41	0.819 ± 0.006	nd	435.83 ± 36.88	39.72 ± 2.05	nd	7895.05 ± 47.82	1.325 ± 0.159
2	Ames27588	33.26 ± 0.48	7.39 ± 0.43	40.14 ± 1.73	232.56 ± 0.80	nd	2574.23 ± 7.13	0.864 ± 0.021	nd	495.23 ± 64.89	34.65 ± 0.26	nd	7546.38 ± 202.78	1.041 ± 0.197
3	Ames30289	45.77 ± 1.6	8.13 ± 0.68	34.67 ± 3.31	250.48 ± 20.37	nd	1990.57 ± 167.03	0.755 ± 0.016	nd	399.13 ± 2.2	34.17 ± 1.81	nd	9486.9 ± 83.40	1.293 ± 0.189
4	Ames30290	47.54 ± 4.66	7.47 ± 1.11	39.00 ± 0.69	261.49 ± 19.89	nd	1817.52 ± 36.13	0.754 ± 0.003	nd	418.06 ± 14.43	33.86 ± 2.81	nd	9706.38 ± 808.61	1.289 ± 0.056
5	Ames30693	49.99 ± 4.78	6.79 ± 1.04	38.12 ± 0.14	251.75 ± 36.12	nd	1908.07 ± 119.98	0.813 ± 0.004	nd	470.4 ± 27.14	36.2 ± 3.6	nd	9747.77 ± 123.38	1.405 ± 0.152
6	Ames7551	38.16 ± 1.18	6.75 ± 0.35	41.03 ± 0.96	220.29 ± 9.07	nd	2688.43 ± 35.34	0.914 ± 0.063	nd	543.26 ± 9.11	40.67 ± 5.79	nd	6822.25 ± 401.99	0.982 ± 0.14
7	Antalya3	40.10 ± 1.36	7.44 ± 0.71	46.56 ± 1.08	195.10 ± 1.80	nd	2715.30 ± 12.95	0.987 ± 0.082	nd	514.06 ± 56.55	41.98 ± 4.1	nd	8709.86 ± 660.17	1.059 ± 0.058
8	Burdur1	54.22 ± 1.26	6.15 ± 0.28	39.47 ± 3.67	262.60 ± 24.23	nd	2158.54 ± 14.29	0.708 ± 0.074	nd	487.12 ± 50.59	40.72 ± 4.99	nd	10186.7 ± 306.46	1.243 ± 0.182
9	Burdur2	47.63 ± 3.91	7.23 ± 0.48	34.30 ± 1.44	240.17 ± 26.07	nd	2035.72 ± 66.43	0.754 ± 0.019	nd	420.18 ± 30.27	37.28 ± 1.36	nd	8351.35 ± 890.38	1.503 ± 0.201
10	Burdur5	55.1 ± 1.6	7.21 ± 0.28	36.30 ± 1.69	279.74 ± 10.97	nd	1996.76 ± 118.92	0.858 ± 0.019	nd	443.28 ± 55.65	34.12 ± 2.62	nd	9257.96 ± 189.34	1.185 ± 0.177
11	Denizli	40.18 ± 2.77	6.36 ± 0.84	36.44 ± 0.09	231.88 ± 10.60	0.028 ± 0.007	2431.45 ± 68.86	0.822 ± 0.021	nd	502.95 ± 4.73	37.17 ± 3.2	nd	7898.31 ± 373.5	1.116 ± 0.238
12	Erzurum	41.44 ± 1.56	7.02 ± 0.84	36.19 ± 1.95	237.97 ± 6.51	nd	1862.47 ± 65.66	0.648 ± 0.002	nd	464.78 ± 46.84	35.25 ± 3.07	nd	7788.83 ± 159.52	1.235 ± 0.105
13	NSL6409	36.21 ± 0.23	7.33 ± 0.39	37.99 ± 2.03	226.20 ± 13.17	nd	2369.1 ± 238.69	0.919 ± 0.047	nd	517.78 ± 21.09	43.78 ± 2.8	nd	9330 ± 193.02	1.171 ± 0.206
14	PI194892	45.56 ± 0.83	7.03 ± 0.81	42.08 ± 2.20	240.03 ± 35.13	nd	1864.63 ± 33	0.644 ± 0.007	nd	431.19 ± 14.33	37.07 ± 4.98	nd	8134.07 ± 5.08	1.363 ± 0.241
15	PI414189	39.56 ± 3.14	7.31 ± 0.41	46.95 ± 0.54	219.47 ± 6.76	nd	2500.35 ± 139.97	0.837 ± 0.044	nd	580.87 ± 72.73	35.84 ± 1.8	nd	8065.95 ± 180.35	1.15 ± 0.229
16	PI414191	47.56 ± 3.09	7.67 ± 0.35	37.82 ± 1.82	215.45 ± 18.28	nd	2068.26 ± 104.59	0.831 ± 0.024	nd	437.37 ± 63.55	35.17 ± 0.39	nd	8158.59 ± 747.62	1.318 ± 0.191
17	PI649465	51.4 ± 0.17	7.24 ± 0.47	42.35 ± 0.99	244.43 ± 36.68	nd	2061.25 ± 162.93	0.775 ± 0.009	nd	385.48 ± 16.34	39.74 ± 5.95	nd	9797.02 ± 18.28	1.387 ± 0.158
18	PI649466	36.07 ± 1.78	5.68 ± 0.19	41.92 ± 3.98	227.65 ± 1.18	nd	2277.34 ± 182.77	0.765 ± 0.026	nd	478.63 ± 14.23	37.36 ± 0.94	nd	7475.24 ± 218.54	1.191 ± 0.134
19	PI649469	52.57 ± 0.08	7.79 ± 0.63	40.55 ± 0.77	264.96 ± 19.94	nd	2054.98 ± 96.67	0.705 ± 0.033	nd	422.42 ± 0.92	41.33 ± 4.04	nd	10420.24 ± 245.36	1.525 ± 0.202
20	PI649471	53.07 ± 0.28	8.06 ± 0.58	34.61 ± 1.22	234.03 ± 13.5	nd	2101.34 ± 57.81	0.67 ± 0.003	nd	440.22 ± 15.72	36.54 ± 0.54	nd	8161.44 ± 278.11	1.594 ± 0.235

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* Values represent means ± standard deviation. nd: Not detected.

Cluster analysis

Cluster analysis was performed to classify and group the genotypes based on the variation observed in the examined traits in this study. In this study, 20 genotypes were analyzed and clustering was performed based on 10 traits, including fruit yield, essential oil content, five major essential oil components and the contents of potassium (K), calcium (Ca) and magnesium (Mg). The K, Ca, and Mg elements were selected for the cluster analysis due to containing highest values compared to other elements. The cluster analysis grouped these genotypes into four clusters and two main groups as A and B. The main group A was separated from main group B with the traits of trans-anethole, magnesium and fruit weight values. In addition, the group A had the most of the genotypes, however most of the local genotypes were found in the group B (Fig. 1). According to results, cluster 1 contained seven genotypes and the local genotypes Erzurum and Burdur2 took place in this cluster. The cluster 1 was separated from clusters depending on the calcium and estragole contents. Five genotypes were grouped in cluster 2 and the genotypes originated from Tunisia were found in this cluster. The main traits of the cluster 2 separated from others clusters were α-fenchone and potassium content. The local genotypes Antalya3 and Denizli with PI414189 genotype (originated from Egypt) were grouped in cluster 3. This cluster was grouped depending on the magnesium and limonene contents. The cluster 4 contained five genotypes; the local genotypes Burdur1 and Burdur5 with PI649466, PI649471 and PI194892 genotypes. The cluster 4 separated from other clusters based on the fruit yield and p-cymene values.

Fig. 1 — Cluster analysis results of the examined traits for the fennel genotypes.

Principal component analysis (PCA)

PCA was performed to identify grouping patterns among the genotypes based on the examined traits (Fig. 2). The first two principal components (PCs) explained 25.6% and 17.3% of the total variance, respectively. In total, the first five PCs with Eigenvalues greater than 1 accounted for 82.96% of the variability. The PCs were uncorrelated with one another, indicating that different PCs accounted for variability in distinct sets of variables. PC1 represented variation among fennel genotypes for estragole, trans-anethole, p-cymene and magnesium contents, whereas PC2 accounted for potassium, calcium, α-fenchone and fruit weight. The most representative variables for PC1 and PC2 were estragole (23.34%) and potassium (39.77%), respectively. The PCA results showed no distinct clustering of fennel genotypes based on their geographical origin. Specifically, the local genotypes Burdur5, Erzurum, and Antalya3 were located on the same side of the PCA plot, whereas the Burdur1 and Burdur2 were positioned on the opposite side. This pattern could be attributed to the fact that the PCA was based on the measured traits (PC1 and PC2) rather than geographical differences among genotypes. Additionally, most of the USA genotypes were grouped on the same side of the PCA plot.

Correlation analysis

Correlation analysis was performed to assess the relationships between essential oil content, its major components, and mineral element contents, based on the mean values across the two growing years (Table 10). A total of 26 significant correlations were identified among the examined traits, most of which were negative. The strongest positive correlation was observed between Ca and Mn (r = 0.749**, p < 0.01). Other notable positive correlations included Al with K and Na; Cu with Mg; Zn with Ca and Mn; Fe with K; and Ca with Cr. In addition, p-cymene showed positive associations with Mn, Fe, and Na. The strongest negative correlation was between Al and Ca (r = − 0.743**, p < 0.01). Other strong negative correlations were found between p-cymene and trans-anethole, Al and Ca, Cu and Ca, Fe and Mg, and Mg and Na. Eleven additional significant negative correlations were detected, most frequently involving Mn (four correlations) and Fe (three correlations). Notably, essential oil content itself showed no significant correlation with any of the examined traits.

Table 10.

Correlation coefficients among essential oil components and mineral element contents of fennel genotypes.

Traits	Mean limonene	Mean α-fenchone	Mean p-cymene	Mean estragole	Mean Trans-anethole	Mean Al	Mean Cu	Mean Zn	Mean Fe	Mean Ca	Mean Cr	Mean Mg	Mean Mn	Mean K	Mean Na
Mean EOC	0.25	-0.071	-0.151	0.016	-0.268	0.085	0.072	-0.061	0.056	-0.139	-0.006	-0.016	0.002	-0.145	0.299
Mean limonene		0.334	-0.228	-0.016	0.059	-0.185	0.256	-0.021	-0.537*	0.032	0.085	0.373	0.03	-0.314	-0.222
Mean α-fenchone			-0.022	-0.327	0.008	0.211	0.159	-0.003	-0.447*	-0.147	-0.108	0.388	-0.148	0.147	-0.019
Mean p-cymene				-0.342	-0.589**	0.127	-0.062	0.274	0.331	0.208	-0.229	-0.297	0.479*	0.241	0.15
Mean estragole					-0.221	-0.225	0.074	0.205	-0.085	0.115	0.198	0.119	0.124	-0.111	-0.26
Mean Trans-anethole						-0.062	-0.003	-0.34	-0.227	-0.098	0.04	0.129	-0.468*	-0.218	-0.064
Mean Al							0.26	-0.557*	0.225	-0.743**	-0.446*	0.009	-0.525*	0.586**	0.61**
Mean Cu								-0.121	-0.488*	-0.61**	-0.473*	0.577**	-0.533*	0.104	-0.232
Mean Zn									-0.028	0.589**	0.275	-0.122	0.576**	-0.173	-0.343
Mean Fe										0.02	0.073	-0.595**	0.207	0.561**	0.467*
Mean Ca											0.561*	-0.267	0.749**	-0.479*	-0.296
Mean Cr												0.128	0.366	-0.13	-0.357
Mean Mg													-0.446*	-0.061	-0.644**
Mean Mn														-0.088	-0.105
Mean K															0.258

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*: Significant at 5%, **: Significant at 1%, EOC: Essential oil content.

Discussion

Climate change is expected to exert both direct and indirect physiological impacts on plants, including significant alterations in secondary metabolism. Plant secondary metabolites are a diverse group of organic compounds synthesized by plants that play essential roles in the plant’s interaction with its environment. These compounds function as key elements in plant defense mechanisms, serve as important signaling molecules under abiotic and biotic stress conditions, and contribute significantly to plant adaptation in extreme environments. In addition, environmental factors such as temperature fluctuations, light intensity, ultraviolet-B radiation, tropospheric ozone (O₃), salinity and soil water availability can also influence the biosynthesis and accumulation of secondary metabolites. Understanding how these factors interact with plant metabolic pathways is essential for predicting plant responses to climate change and for developing strategies to enhance plant resilience under future environmental scenarios²². The responses of secondary metabolites to climate change are influenced by both the types of metabolites and the specific climatic factors involved. However, additional variables, such as plant functional types and the specific organs analyzed, may also affect secondary metabolite responses due to underlying genetic and physiological differences²³. For example, studies on Panax ginseng have shown that moderate changes in temperature or precipitation can enhance ginsenoside accumulation, whereas extreme alterations in these factors tend to have detrimental effects^24,25. The duration of exposure to climate change is also critical, as it has been demonstrated to either intensify or mitigate impacts on plant growth and physiological processes under various global change factors^26,27. Moreover, several studies investigating plant responses to a simulated nitrogen deposition have emphasized the importance of mean annual temperature and mean annual precipitation in shaping plant performance^28,29. Soil organic carbon and total nitrogen are crucial for improving soil quality, supporting vegetation growth, and promoting carbon sequestration, influencing climate change^30,31. Therefore, different fennel genotypes showed differences for the morphological, yield and essential oil content and its components during the two success growing seasons. Plant height values of fennel genotypes in 2019 (between 61.47 and 86.50 cm) were generally higher than those observed in 2020 (between 54.77 and 90.50 cm), except four genotypes (Ames27588, Ames30693, Ames7551 and NSL6409). This difference is likely attributable to more favorable weather conditions in 2019, including higher temperatures during the vegetative growth period and lower rainfall compared to the 2020 season¹⁹. Previous studies have reported similar variation in plant height among fennel genotypes. For instance, Yaldız and Çamlıca³² found plant heights ranging between 59.73 and 73.97 cm under organic and inorganic fertilizer treatments, while Yaldiz and Camlica¹⁷ observed a broader range of 39.22–129.60 cm in genotypes of various geographic origins. Yadav et al.³³ also reported that plant heights ranged from 86.67 to 151.34 cm among 25 different fennel genotypes. The plant height values obtained in the current study are consistent with those reported by Yaldız and Çamlıca³²and partially align with the results of Yaldiz and Camlica¹⁷and Yadav et al.³³. These variations can be attributed to genotypic differences, cultivation conditions, ecological variability, and soil properties.

Branch number values have been reported to range between 4.64 and 10.80 per plant among different fennel genotypes³³. In another study, Telugu et al.³⁴ reported that the branch number in fifty fennel genotypes ranged from 5.08 to 12.70 per plant. The mean branch number values (5.84–7.92) observed in the current study are in agreement with those reported in previous studies. The number of umbels per plant and the number of umbellets per plant varied among fennel genotypes based on the experimental years. Yadav et al.³³ reported that the number of umbels per plant ranged from 26.79 to 99.93, while Telugu et al.³⁴ noted that the umbel number of fifty fennel genotypes ranged from 23.67 to 71.40 per plant. The results regarding umbel and umbellet numbers in this study were found to be similar to those reported by Yaldız and Çamlıca³²who observed umbel numbers ranging from 15.20 to 18.73, and umbellet numbers per plant ranging from 176.57 to 192.17 under organic manures and inorganic fertilizers.

The results obtained from this study for the 50% flowering days were comparable to those reported in previous studies. Specifically, Yadav et al.³³ reported a range of 87.00-100.33 days, Telugu et al.³⁴ observed between 107.03 and 125.80 days, and Kumar et al.³⁵ documented between 102 and 132 days in fifty fennel germplasms. So, the results of the 50% flowering days (85.00-124.33 days) from this study were found similar with the previous studies^33–35.

Fruit yield was positively influenced by the number of fruits and umbellets; an increase in these traits led to higher yields among the fennel genotypes³⁵. Differences in fruit yield across studies may be attributed to genotypic variability, environmental conditions, and cultivation practices. The fruit yields observed in the present study (393.33 to 1575.62 kg/ha) were found higher than reported by previous researchers, which ranged from 0.015 to 10.7 tons/ha/year³⁶.

Previous studies have demonstrated significant variability among genotypes and across years in economically important traits of fennel^5,37. Likewise, Hawkins et al.³⁸ argued that the water-energy dynamics hypothesis plays a key role in shaping plant traits, which aligns with the results of this study. According to Ehsanipour et al.⁹the fruit yields of four fennel genotypes without fertilizer application ranged from 44 to 105 g/m². Shojaiefar et al.⁵ reported fruit yields of eighteen fennel genotypes under fertilizer treatment ranging from 40 to 390 g/m² in the first year and from 24 to 420 g/m² in the second year. Similarly, Yaldız and Çamlıca³² reported fennel fruit yields between 901.4 and 1127.2 kg/ha under organic manure and inorganic fertilizer application.

Fennel essential oils and mature fruits are widely utilized in pharmaceutical, cosmetic, and food industries, and are also consumed as functional foods due to their bioactive properties^17,39. According to Bahmani et al.³⁶the essential oil content of fennel populations ranged between 0.9% and 5.1%. Also it was reported that the essential oil content of eighteen fennel genotypes varied from 1.5 to 4.7% in the first year and from 2.0 to 3.7% in the second year (Bahmani et al., 2024)³⁶. Shojaiefar et al.⁵ noted that essential oil content in the first year was approximately 12% higher than in the second year.

In support of these findings, Šunić et al.⁴⁰ reported an essential oil content of 3.49% in fruits of wild fennel plants from the Montenegro coast. Kalleli et al.⁴¹ found that fennel fruit essential oil contents ranged from 3.24 to 5.26% in Tunisian samples and from 3.81 to 4.12% in French samples. Similarly, Yaldiz and Camlica⁴² reported that the fruit essential oil content of fennel grown under various organic and inorganic fertilization regimes ranged from 2.40 to 3.35%. In contrast, Ehsanipour et al.⁹ found lower essential oil contents in four studied fennel genotypes, ranging from 1.20 to 1.62%.

The present study found that the genotype effect on essential oil yield was significant at the 5% level (Table 6). The differences among the essential oil yield values of different fennel fruit genotypes used in the study can be attributed to variations in the genetic makeup differences of the genotypes, as well as changing climatic conditions during the two experimental years²³. These results of essential oil yield (3.92–55.74 L/ha) were found partly similar with the findings of Gedik and Kuş⁴³ who reported 46.55 L/ha yield of fennel fruit essential oil in Tokat 1 population. Likewise, Ehsanipour et al.⁹ reported that the essential oil yields of different fennel populations ranged from 7.25 to 25.55 L/ha. Otherwise, Bahmani et al.³⁶ reported that the essential oil yield ranged from 10.1 to 152.2 L/ha in intermediate-maturing fennels. These disparities can be ascribed to genetic, geographic and environmental factors⁶phenological stage³⁶distillation time⁴⁴ and cultivation practices³.

Fennel essential oils have been associated with various pharmacological activities, including hepatoprotective, acaricidal, anti-inflammatory, antioxidant, antifungal, antithrombotic, anti-tumor, antidiabetic and antibacterial effects⁴⁵. These activities were linked to the essential oil components in of fennel essential oil⁴⁵. Estragole is one of the important essential oil components of the plants⁴⁶. It is used as a food flavoring agent and in specific liqueurs. In addition, it was reported that the high estragole dose may cause the carcinogen⁴⁶. Paini et al.⁴⁷ noted that estragole has positive effect on growth of malignant tumors in rodents. For these properties, the European Union Scientific Committee on Food (SCF) has established a new legal limit (10 mg/kg) for estragole in soft drinks⁴⁷. In this study, five essential oil components within the 17 components were found as predominant components among the fennel genotypes in the vegetation periods. Saharkhiz and Tarakeme⁴⁸ reported that trans-anethol (84.1–86.1%), fenchone (7.13–8.86%), limonene (3.0-3.3%), and methyl chavicol (2.5–2.7%) were the main components of fennel at different fruit maturity stages. Similary, Yaldiz and Camlica³ revealed that trans-anethole (18.43–69.69%) and estragole (0.27–29.55%) were found as first and second most important components in different origin fennel genotypes. In a study, it was reported the essential oil of fennel contains lower than 10% estragole or 7.5% fenchone for the quality of fennel essential oil⁴⁹. From this context, all studied genotypes had quality essential oil contents except the PI414189 genotype in the first year for fenchone (8.44%), and the Ames7551 (28.75%), NSL6409 (13.60%) and PI414189 (10.79%) genotypes in the first year and Ames30289 (15.88%) genotype in the second year for estragole. Wild fennel plant parts (leaves and stems) had the two major essential oil components as (E)-anethole (51.4%) and estragole (9.3%)⁵⁰. Bowes et al.⁵¹ reported that anethole (47-80.2%), fenchone (9.83%) and estragole (4.46%) were the main essential oil components of the grown in Nova Scotia. In another study, Bozovic et al.⁵² identified 18 chemical components in wild fennel fruit collected from three locations of Monte Negro and reported four main essential components as anethole, estragole, terpineol and fenchone. The main essential oil components were noted estragole (60.01%-35.33%), anethole (22.15%-52.27%) and fenchone (6.50%-4.32%) in the both wild and cultivated fennel³⁸. Hosseini et al.⁵³ reported that the main essential oil components were determined as trans anethole (22.37–86.47%), estragole (2.47–25.86%), fenchone (4.96–19.79%), and limonene (0.53–11.87%) in 20 fennel genotypes from 17 countries. In another study, major essential oil components of 64 fennel genotypes were found as trans-anethole (22.4–90.6%), estragole (2.1–25.8%), fenchone (4.9–19.8%), and limonene (0.5–11.9%) from different 23 countries⁵⁴. Similarly, total essential oil components of fennel fruits were reported between 84.46 and 93.36%, and the major essential oil components were found as trans-anethole (35.08–44.68%), camphor (16.98–20.49%), limonene (4.35–16.91%), p-anisaldehyde (1.83–13.13%) and terpinene (5.37–9.13%). Also, major essential oil components were noted between 77.29 and 86.56% of the total essential oil content grown under different organic manures and inorganic fertilizer⁴². When the obtained results for the essential oil components were compared to previous studies, in general, similar results were found, although there were some differences. The differences could be attributed mainly to the biosynthesis of the main components, in addition to the effect of genotypic differences, climatic (yearly rainfall, temperature and humidity or etc.) and geographic conditions (altitude (752 m in growing site)³. The major essential oil components were found similar with previous studies. Similarly, the minor essential oil components were found partly similar with previous studies^3,55,56.

In the first year, most of the essential oil component values were found to be above 58%. The minor components (α-pinene, sabinene, myrcene, 1,8 cineole, γ-terpinene, δ-terpinolene, β-cymene, camphor, α-cubebene, fenchyl acetate, anethole, and p-anisaldehyde) identified in this study were consistent with those reported in previous studies^3,48,50,57.

The maturity stage of fennel plants significantly affects their essential oil content and components. Anwar et al.⁵⁸ reported that the limonene content (3.52–7.81%) of fennel decreased as plants reached maturity. In addition to maturity stage, geographic origin also influences the variability of the chemical properties of fennel genotypes. For example, Ahmed et al.⁵⁹ reported significant differences in the chemical profiles of fennel essential oils originating from China and Egypt, particularly in their main components. Harvest time and temperature are also important factors in fennel cultivation, as early harvesting and higher temperatures can markedly affect essential oil and trans-anethole contents. It has been reported that high temperatures can promote trans-anethole accumulation while reducing the total essential oil content⁶⁰. Consequently, some genotypes exhibited high essential oil and trans-anethole contents depending on the temperature conditions during the experimental years. In addition, growing conditions, such as the application of organic manures and chemical or biological fertilizers, as well as ecological factors (soil type and structure, and climatic conditions), can exert positive or negative effects on fennel production and its chemical properties. It has been reported that the application of 10 t/ha sheep manure increased fruit yield, essential oil content, and component, particularly for compounds such as camphor and p-anisaldehyde^32,42. The variations between the current and previous studies in essential oil component can be attributed to factors such as the plant chemotypes, plant part used, harvest time, geographical origin, environmental factors (including climatic conditions), and agronomic practices, as all of these can influence essential oil component and structure^6,61.

The uptake and utilization of essential nutrients such as calcium (Ca), potassium (K), and magnesium (Mg) can vary significantly among different fennel genotypes. These macronutrients are crucial for various physiological processes in fennel, including cell wall integrity (Ca), osmotic balance and stomatal regulation (K), and chlorophyll synthesis and photosynthesis (Mg). Genotypic differences in fennel can influence the efficiency of nutrient absorption and their subsequent metabolic utilization, particularly under different environmental conditions. For example, some fennel genotypes may be more efficient at acquiring calcium, while others might show higher potassium uptake, affecting their growth and stress resilience. Understanding these genotype-specific nutrient requirements is essential for optimizing fennel cultivation, improving yield stability, and enhancing tolerance to abiotic stresses, such as drought or salinity^3,62–64. Moreover, mineral nutrients in plants are essential for human nutrition. Fennel fruits can be consumed as a condiment due to their unique flavor and abundant nutritional profile⁶⁵. In addition, it was reported that fennel is an excellent plant-based source of potassium, sodium, phosphorus, and calcium⁶⁶. Farajpour et al.⁶⁷ indicated that Mg and K including high contents as important mineral matters were suitable for medicinal applications. It was also reported that different plant genotypes had different genetic makeup and influenced from mineral uptake and distribution within the genotypes. The variabilities among the plants were based on the genetic factors, interaction between genetics and environmental conditions. In a study noted that the fruit mineral contents significantly increased the antioxidant activity, revealing the non-linear and interdependent nature of biochemical interactions within the fruit matrix. In addition, the opposite relationship between the fruit potassium content and antioxidant activity were found. This relationship may be explained that excessive K accumulation in fruits can suppress antioxidant mechanisms and that moderate increases in Mg and Cu can synergistically enhance both DPPH and FRAP responses⁶⁸. Therefore, these mineral elements were included in the PCA and hierarchical cluster analysis to evaluate the mineral composition of different fennel genotypes. One of the most important minerals is potassium (K), which plays key roles in several biological processes such as muscle function, nerve impulse transmission, and regulation of osmotic pressure³. In this study, the K content values (7149.80-10906 mg/kg) showed high variabilities, and the obtained K value results in both years were in agreement with previous findings indicating that fennel fruits can accumulate K at levels exceeding 18000 mg/kg, highlighting its nutritional richness⁶⁹. These values are slightly higher than those reported by⁷⁰where calcium concentrations in fennel fruits were recorded in the range of 2000–2600 mg/kg. The high accumulation of Ca and K in certain samples underscores the potential of specific genotypes for enhanced mineral density³. The findings for Fe (195.10-279.74 mg/kg) and Zn (31.19–51.71 mg/kg) are almost in line with the literature, where Fe levels in fennel fruits are generally reported between 150 and 250 mg/kg and zinc levels around 35–45 mg/kg⁷⁰. The presence of these essential micronutrients reinforces the value of fennel as a dietary component with functional properties. The observed variation in elemental concentrations across samples can be attributed to genotypic differences and environmental factors such as soil composition, cultivation practices and climate conditions^3,71. For example, some genotypes demonstrated consistently higher mineral accumulation (e.g., Ames30289, Burdur5 and Antalya3 genotypes), suggesting underlying genetic traits influencing nutrient uptake. For example, certain genotypes, such as Ames30289 (51.71 mg/kg Zn), Burdur5 (490.08 mg/kg Mg), and Antalya3 (2715.30 mg/kg Ca) consistently exhibited higher mineral accumulation, suggesting the presence of genetic factors that influence nutrient uptake efficiency. Similar genotype related mineral variation has been reported in other medicinal and aromatic plants⁶⁹. The results confirm that fennel fruits can be an excellent source of K, Ca, Mg, Fe, and Zn, all of which play critical roles in human metabolism and health⁷². Recent advances in integrative plant phenotyping and ionomics have clarified the regulation of mineral dynamics in crops. For example, genome-wide association and QTL mapping studies have identified both species-specific and conserved loci controlling K, Ca, and Mg homeostasis, including transporters such as the HAK/KUP/KT, CAX, and NHX families, whose activity is often modulated by environmental factors^73–75. In fennel and related Apiaceae crops, multi-season phenotyping has shown that inter-annual environmental variation can substantially alter essential-oil chemotypes, with morphological traits such as plant height and umbel number correlating with major volatiles like trans-anethole and fenchone⁷⁶. In light of these findings, testing correlations between mineral concentrations and essential oil components in our dataset could illuminate biochemical linkages between nutritional and phytochemical traits and their modulation by genotype-environment interactions. Regarding potentially toxic elements, the findings were reassuring. Cadmium (Cd) was either undetected or present at trace levels far below the safety threshold of 1.0 mg/kg as specified by the European Pharmacopoeia^69,77. Cd was quantifiable only in a limited number of genotypes (genotypes PI414189 (0.033 mg/kg in 2019), Ames23130 (0.037 mg/kg in 2020) and Denizli (0.028 mg/kg in 2020), and even in those, levels remained below 0.05 mg/kg. Lead and nickel were not detected in any genotype, and chromium concentrations were low across all genotypes, generally below 0.8 mg/kg. Previous studies have conducted PCA on different fennel genotypes. Akbari et al.⁷⁸ reported that, in 11 fennel populations, the first two principal components (PC1 and PC2) accounted for 86.8% of the phenotypic variation. Similarly, Kadoglidou et al.⁷⁹ found that PC1 and PC2 explained 68.4% of the variation in morpho-agronomical traits of 12 Greek fennel genotypes. In another analysis, the same authors reported that PC1 and PC2, based on 23 essential oil components, cumulatively accounted for more than 73% of the total variance. The PCA results obtained in the present study differed from those in previous research due to variations in genotype number, origin, and the traits examined.

Correlation analysis in this study revealed 26 significant positive or negative correlations among the examined traits in 20 fennel genotypes. Positive correlations suggest that the paired elements may share a common source, whereas negative correlations imply that their sources are likely independent⁸⁰. Such strong correlations, whether positive or negative, can facilitate the prediction of one element from another using simple regression models⁶⁸.

Conclusion

This study provides a comprehensive evaluation of twenty fennel genotypes originating from diverse geographical regions, focusing on morphological traits, yield parameters, essential oil component, and mineral content under uniform agro-ecological conditions. Significant genetic variability was observed among the genotypes across both experimental years, particularly in terms of plant height, umbel development, fruit yield, and essential oil characteristics. The essential oil profile revealed five major components, with trans-anethole emerging as the dominant compound across all genotypes and seasons, thereby identifying a shared chemotype among the examined materials. The relative abundance of estragole, p-cymene, limonene and α-fenchone varied among genotypes, indicating the potential for targeted selection based on desired phytochemical profiles. Elemental analysis demonstrated that fennel fruits are a rich source of macro- and micronutrients, particularly potassium, calcium, magnesium, iron and zinc. Several genotypes including the Ames30289, Burdur5, and Ames27588, exhibited elevated mineral concentrations, highlighting their suitability for nutritional enhancement and biofortification strategies. The absence or minimal presence of toxic elements such as cadmium and lead confirmed the safety of these genotypes for use in food and nutraceutical formulations. Cluster analysis based on key agronomic, phytochemical, and nutritional traits enabled the grouping of genotypes with similar performance profiles, offering practical insights for breeding and cultivar development. Notably, the Ames23130 genotype demonstrated superior performance in both fruit yield and essential oil content, making it a strong candidate for future cultivar release or integration into breeding programs aiming to improve both yield and phytochemical quality. In summary, the evaluated fennel genotypes present valuable genetic resources for the development of high-yielding, nutritionally rich, and phytochemically potent cultivars suitable for sustainable agricultural systems and functional food applications.

Supplementary Information

Below is the link to the electronic supplementary material.

Supplementary Material 1^{(33KB, docx)}

Author contributions

G. Y. and M. C. conceived this project and designed the research. G. Y. and M. C. performed most of the experiments as field study and laboratory analysis. H. A. analyzed the mineral matter content. G. Y. and M. C. analyzed the data. G. Y., M. C. and H. A. wrote the article, revised the article and approved the manuscript in final form prior to submission.

Data availability

Data will be made available on request by corresponding author.

Declarations

Competing interests

The authors declare no competing interests.

Footnotes

Publisher’s note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

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Supplementary Materials

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Data Availability Statement

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[CR36] 36.Bahmani, K., Akbari, A., Darbandi, A. I. & Ghamari, T. Phenological traits, seed yield, and essential oil yield of Fifty populations of bitter fennel (Foeniculum vulgare). Int. J. Hortic. Sci. Technol.11 (3), 391–410 (2024). [Google Scholar]

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Genotypic variation in morphological traits, yield, essential oil profiles, and mineral composition of fennel (Foeniculum vulgare L.) across two growing seasons

Gulsum Yaldiz

Mahmut Camlica

Hakan Apaydın

Abstract

Supplementary Information

Introduction

Materials and methods

Plant material and growing conditions

Table 1.

Determination of morphological features and yield values

Extraction of essential oil

GC-MS analysis of essential oils

Elemental analysis

Statistical analysis

Results

Variation in the morphological and yield parameters of fennel genotypes

Table 2.

Table 3.

Table 4.

Table 5.

Fruit weight, essential oil content and essential oil yield

Table 6.

Essential oil components of fennel genotypes

Table 7.

Mineral matter contents of the fennel genotypes

Table 8.

Table 9.

Cluster analysis

Fig. 1.

Principal component analysis (PCA)

Fig. 2.

Correlation analysis

Table 10.

Discussion

Conclusion

Supplementary Information

Author contributions

Data availability

Declarations

Competing interests

Footnotes

References

Associated Data

Supplementary Materials

Data Availability Statement

ACTIONS

PERMALINK

RESOURCES

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