The Sustainability of Rosa rugosa Thunb. Under Climate Change Conditions: A Study of Morphological Variability in Urban Areas

Abstract

Urban stressors intensified by climate change affect plants in terms of growth, vitality, and ornamental value. This study examines how different light availability (full sun, partial shade, and shade) affect the development, fruit morphology, and planting suitability of Rosa rugosa Thunb. in urban environments. A total of 360 shrub individuals were analyzed in a linear formation along a riverbank in Novi Sad, Serbia, linking climatic parameters with the bioecological characteristics of the investigated plants. Comparison of the groups was performed using the multivariate methods and Principal Component Analysis (PCA). Furthermore, 13 morphological parameters were analyzed on a sample of 100 fruits per group. There were no significant deviations in fruiting patterns, but the fruit parameters, even though showing high yield and favorable fruit size, indicated that light variation affects morphology. These findings confirm the species’ resilience and adaptability to urban environments, capable of withstanding various challenges, including proximity to paved surfaces, heavy traffic, and diverse light conditions. R. rugosa proves to be an ideal choice for urban planting and nature-based solutions that enhance human well-being.

1. Introduction

Rosa rugosa Thunb. (commonly known as Rugosa rose, Beach rose, Japanese rose, or Ramanas rose) is a shrub species belonging to the genus Rosa L. and the family Rosaceae Juss. Native to eastern Asia—including China, Japan, Korea, and Southeastern Siberia (Kamchatka)—it has a rich history of use in traditional medicine and the food industry [1,2]. Introduced to Europe in the 19th century for ornamental purposes, R. rugosa is now considered an invasive species in northwestern Europe [3], where it occupies sandy beaches and sand dunes along the Baltic and North Seas [4] and suppresses native vegetation [5]. However, in other parts of Europe, it is naturalized, not posing a threat and remaining underutilized in urban greening, becoming a landscape component that enhances environmental conditions [6].

Rugosa rose is a deciduous shrub reaching 1.5–2 m in height, with fragrant, nectarless flowers (6–8 cm) that bloom from May to August and sometimes into autumn. These flowers occur singly or in small clusters. Cultivated varieties display a diverse range of colors and forms [2,7,8,9]. Its brick-red, globular hips (up to 2.5 cm) ripen from August to October, containing numerous nutlets, with flowers and fruits often present simultaneously on the shrub [7,9].

The Rugosa rose is known for its strong tolerance to drought and heat, its adaptability to sandy soils [10], and its high resistance to pests and diseases, especially to Black Spot and Powdery Mildew [11]. These favorable traits make it an excellent choice for urban street greening. It thrives in both full sun and partial shade but is sensitive to flooding [2]. R. rugosa L. does not accumulate heavy metals [12] and it has been recognized as a dual-purpose crop for ecological restoration and fragrance production in Cd-impacted areas [13], indicating its potential for planting on soils potentially contaminated with heavy metals, such as urbisol. Being both entomophilous and ornithochorous, R. rugosa plays a vital role in supporting fauna, contributing significantly to biodiversity in urban environments.

In addition to its ornamental and ecological value, the genus Rosa has significant economic potential due to the rich biochemical composition of fruits and flowers and wide application in medicine, pharmacy, and the food industry. The fruits are abundant in bioactive compounds such as polyphenols, triterpenic acids, essential fatty acids, galactolipids, vitamins (A, B1, B2, C, E, K), minerals, sugars, and phenolic compounds including tannins, flavonoids, phenolic acids, and anthocyanins [14,15,16,17,18,19]; they also contain terpenoids (including β-carotene and lycopene), essential oils, pigments, organic acids, polysaccharides (e.g., pectins), and amino acids [20,21,22]. Flowers also contribute to the plant’s pharmacological and economic potential. They are rich in flavonoids, anthocyanins, tannins, and essential oils like geraniol, citronellol, and nerol [23]; these compounds contribute to antimicrobial, anticancer, antidiabetic, and anti-inflammatory effects documented in ethnopharmacology [10,24,25].

The fresh fruits of Rugosa rose are highly valued in the food industry, particularly for the production of jams, juices, sauces, syrups, wines, and jellies. In Europe, rose hips, including rugose hips, have been widely utilized in the food industry [26]. The fruits are not only edible [10] but also offer significant economic opportunities, making Rugosa rose an ideal candidate for small-scale agricultural enterprises and family farms as the species provides consistent and regular yields [2]. The petals of Rugosa rose are used to extract essential oils, which are employed in the production of perfumes, cosmetics, aromatherapy products, spices, and nutritional supplements [10,23]. Additionally, dried buds and petals are commonly utilized in the production of herbal teas [23].

To achieve its full potential, fulfill its ecological role, and provide ecosystem services, R. rugosa requires optimal conditions in urban environments. Sun exposure significantly influences the growth, flowering, and fruiting of ornamental plants [27,28]. In shaded environments, plants often experience delayed flowering, reduced flower weight, and faded flower color due to lower anthocyanin and flavonoid content [29,30]. Shade also declines overall performance, including photosynthetic capacity [29]. On the other side, sun exposure significantly enhances growth and flowering, particularly in full sun or light shade conditions [31], affecting plant height, leaf number, stem diameter, branch number, and crown width [29,31]. Additionally, light exposure significantly influences fruit quality in ornamental plants, improving fruit coloration and overall quality when plants receive higher light levels [32].

Despite the well-documented ecological and economic value of R. rugosa, there is a lack of comprehensive research on how varying urban light conditions influence its morphological traits, especially in secondary populations established outside its native or invasive ranges. Most previous studies have focused on natural or coastal habitats, while the performance of R. rugosa in structured urban settings remains underexplored. This study addresses that gap by analyzing how different light regimes—full sun, partial shade, and full shade—affect the species’ growth habit and fruit morphology in urban environments. Unlike previous studies, it also examines the role of spatial positioning relative to trees and paved areas, providing new insights into the species’ adaptability, suitability for combined or solitary planting, and potential for urban greening and landscape resilience. To our knowledge, no prior studies have systematically examined the combined effects of light regime and spatial context on R. rugosa within urban landscapes, which positions this research as a novel contribution to climate-adaptive urban horticulture.

This study aims to perform the following:

• Investigate the impact of different light conditions (full sun, partial shade, and shade) on the growth habit and fruit morphology of R. rugosa in urban environments.
• Analyze the adaptability of R. rugosa in different spatial contexts—beneath tree canopies, near trees, and in open spaces—focusing on morphological and bioecological characteristics.
• Assess its suitability for solitary versus combined planting with trees, considering light availability and spatial positioning.

2. Materials and Methods

2.1. Study Area

The studied groups of R. rugosa are located in a linear planting extending in an east–west direction between the following coordinates: 1. Shrub group in shade (A) (45°15′4.34″ N; 19°51′20.72″ E). 2. Shrub group in partial shade (B) (45°15′9.74″ N; 19°51’20.05″ E). 3. Shrub group in sunny exposure (full sunlight) (C) (45°15′12.00″ N; 19°51′19.65″ E), at an elevation of 77 m on an exposed terrain near a major river in the urban area of Novi Sad, Serbia (Figure 1). The soil is anthropogenic alluvial sand [33] and the distance from the left bank of the Danube is 24.17 m. The soil is of the urbisol type, compacted, polluted, and structurally deteriorated, which may be classified as highly degraded, mostly under anthropogenic influence [34].

2.2. Climatic Data

Following the WMO recommendations for deviations in climatic parameters [35] during the research period of 2024, the cultivation period of R. rugosa (2010–2024), compared to the reference period 1991–2020, as well as only the insolation for older time series 1961–1991, 1971–2001, and 1981–2011, data from the Republic Hydrometeorological Institute of Serbia (RHMS) were used [36]. Data were collected from the main meteorological station (MMS) Rimski Šančevi (45°19′19.97″ N; 19°49′48.01″ E; altitude: 86 m).

2.3. Plant Material

The observed Rugosa rose groups are situated near a heavily trafficked roadway on one side and a cycle path on the other. The research area belongs to green space of the sports and recreational type, with exceptionally high user frequency throughout the day. This area was redeveloped in 2010, when the observed R. rugosa groups were planted. The quay is situated in an area where the natural potential vegetation would be fresh willow and poplar (Salicion albae Soo) [37].

The R. rugosa groups were planted as part of the existing dendroflora of the quay and can be divided into three categories: the group growing in the shade—A (specifically, the shade is provided by tall deciduous vegetation, in this case by specimens of white poplar (Populus alba L.) at the observed site); the group existing under partial shade—B; and the group located in a fully sunlit exposure—C. During 2010, at the investigated site, an initial planting of 120 individuals of R. rugosa was carried out per research group (Figure 2). Although located in the same climatic area, with a distance of 165.67 m between A and B groups and 71.95 m between B and C, these habitats provide different ecological conditions for the development of the investigated groups of R. rugosa, taking into account different light conditions. The maintenance of the studied R. rugosa groups includes pruning as a regular care measure—once during the dormancy period and a second time after the flowering period. Usual rose pruning back to 2–3 buds is applied at the end of each season, providing the same starting point for the vegetative growth of individuals each spring. Pruning also removes damaged and dry shoots after flowering, to rejuvenate and clean the shrubs.

Both quantitative and qualitative analyses were performed as part of the biometrical analysis of the investigated plants at the group level. Quantitative analyses included measurements of bioecological characteristics [38,39] such as the number of plants per group (NP), shrub area (SA), and shrub height (SH) with a Vertex V altimeter. Qualitative analysis included the degree of damage (DD), vitality (V), and decorativeness (D) according to [40]. Additional spatial characteristics such as the distance from the nearest paved surface (DNPS), distance from the bicycle path (DBP), distance from the nearest tree (DNT), and width of the green belt (WGB) were measured. Near the shrub groups in shade and partial shade, tree features of Populus alba L. individuals, such as height (TH), height to the first branches (HFB), diameter at breast height (DBH), and crown width (CW), were also measured according to the same methodologies [38,39,40]. Qualitative vegetative traits were investigated in three mentioned R. rugosa shrub groups following the UPOV protocol [41] for roses (

Table 1. Qualitative vegetative characteristics investigated in R. rugosa shrub groups following the UPOV protocol for roses (Rosa L.).

Characteristics	Abbreviations	Scores
Plant: growth type	GT	1—miniature, 2—dwarf, 3—bed, 4—shrub, 5—climber, 6—ground cover
Plant: growth habit	GH	1—upright, 2—semi-upright, 3—intermediate, 4—moderately spreading, 5—strongly spreading
Plant: height	H	1—very short, 2—short, 3—medium, 4—tall, 5—very tall
Stem: number of prickles	NP	1—absent or very few, 2—few, 3—medium, 4—many, 5—very many
Prickles: predominant color	PC	1—greenish, 2—yellowish, 3—reddish, 4—purplish

).

Fruit yield was evaluated according to [42] by quantifying phenological observations on a five-point Kaper scale, where 0 is a shrub without fruit (0% of branches bearing fruit); 1. is a small number of fruits (≤20%); 2. is a low number of fruits (>20–≤40%); 3. is a moderate number of fruits (>40–≤60%); 4. are the abundant fruits (>60–≤90%); and 5. is the maximum number of fruits (>90%). Fruits were collected in the physiological stage of maturity in November 2024.

Morphometric analysis of fruits was performed on a sample of 100 aggregate fruit per group, measuring the following traits, fruit weight (FWE) with a laboratory scale Kern 572 with a precision of 0.01, fruit length (FL), fruit width (FWI), petiole length (PL), and sepal length (SL), using a digital caliper with an accuracy of 0.01 mm, the number of sepals (NS), number of achenes in the hypanthium (NAH), extent of trichomes (ET), and color of trichomes (CT). The number of sepals (NS), number of achenes in the hypanthium (NAH), extent of trichomes (ET), and color of trichomes (CT) were recorded for each fruit (Figure 3). The extent of trichomes was determined using a visual method with a scale from 1 to 3 for their presence in the fruit. After measuring the aggregate fruits, individual achene fruits were measured. On a sample of 100 individual achene fruits, their length, width, and the weight were recorded.

2.4. Processing of Data

The characteristics of the investigated fruits were analyzed using descriptive statistics and analysis of variance (ANOVA). Data processing was performed using the software packages Google Earth Pro (7.3.6.10201), XLSTAT2022, and STATISTICA 13 (TIBCO Software Inc., Palo Alto, CA, USA, 2020). Principal Component Analysis (PCA) was carried out using the SRplot statistical program [43]. Photographic material was collected during the field research.

3. Results

3.1. Climatic Predictors

Average seasonal temperatures are important for the growth and development of Rosa rugosa, as well as for its physiological functions and fruiting phenophase. Based on the presented seasonal temperatures (

Table 2. Seasonal climatic variables for the reference period (1991–2020), the period 2010–2023, and the year of the study (2024), based on data from the Rimski Šančevi meteorological station (MMS).

Average Air Temperatures (°C)
Season	Spring	Summer	Autumn	Winter
Months Period	3–5	6–8	9–11	12–2
$\overline{x}$ 91/2020	12.2	21.9	12.0	1.6
$\overline{x}$ 10/2023	12.5	22.9	12.9	2.6
$\overline{x}$ 2024	15.3	26.2	12.7	5.9
Average maximum air temperatures (°C)
$\overline{x}$ 91/2020	18.1	28.2	17.9	5.4
$\overline{x}$ 10/2023	18.3	29.2	18.9	6.5
$\overline{x}$ 2024	21.7	33.1	18.9	11.0
Average minimum air temperatures (°C)
$\overline{x}$ 91/2020	6.6	15.7	7.4	−1.8
$\overline{x}$ 10/2023	6.8	16.4	8.2	−0.8
$\overline{x}$ 2024	8.8	18.7	7.5	1.7
Total and average precipitation amounts (mm)
$\overline{x}$ 91/2020	163.4	222.3	169.0	125.4
$\overline{x}$ 10/2023	186.2	204.3	156.5	137.5
$\overline{x}$ 2024	114.5	87.9	237.9	79.7
Total and average sunshine duration (h)
$\overline{x}$ 91/2020	627.2	900.3	463.0	228.1
$\overline{x}$ 10/2023	627.3	935.5	475.2	228.7
$\overline{x}$ 2024	726.9	1011.3	521.2	318.2
Number of summer days (Tmax ≥ 25 °C)
$\overline{x}$ 91/2020	14.9	71.7	16.8	0.0
$\overline{x}$ 10/2023	15.0	76.5	20.9	0.0
$\overline{x}$ 2024	32	87	21	0
Number of tropical days (Tmax ≥ 30 °C)
$\overline{x}$ 91/2020	1.6	33.6	3.2	0.0
$\overline{x}$ 10/2023	1.4	41.0	5.7	0.0
$\overline{x}$ 2024	1	77	10	0

, Figures S1–S3), a trend of their increase is observed in the period from 2010 to 2023, and in the year of the study (2024), compared to the reference period. Sharp winters alternate with hot summers and mild winters with cool summers in a cyclical pattern [36]. The largest deviation was recorded in 2024 for winter and summer, when the average temperatures were higher by 4.3 °C compared to the reference period and by 3.3 °C compared to the 2010–2023 period. The smallest deviation was observed in autumn 2024, with temperatures higher by 0.7 °C compared to 1991–2020, but lower by 0.2 °C compared to the 2010–2023 period.

Therefore, the average monthly air temperatures and precipitation amounts for September, October, and November in the period 1991–2024 are presented in relation to their norms for the reference period 1991–2020 in Figure 4, Figure 5 and Figure 6. It is noticeable that September 2024 had both air temperatures and precipitation significantly above the upper tercile (Figure 4), while in October, temperatures were slightly above the upper tercile, and precipitation fell between the normal and the lower tercile (Figure 5). In November, temperatures were significantly below the lower tercile, and precipitation was in the upper tercile (Figure 6). November 2024, based on achieved temperatures, was 37.5% below the lower tercile, while 29% of the time, precipitation was in the upper tercile. The average seasonal maximum and minimum temperatures (Table 2) show a linear upward trend. The largest deviation was recorded in 2024 for winter, when the average temperatures were higher by (a) maximum temperatures by 5.6 °C compared to the reference period and by 4.5 °C compared to the 2010–2023 period, and (b) minimum temperatures by 3.5 °C compared to the reference period and by 2.5 °C compared to the 2010–2023 period. Precipitation was variable and in a deficit in all seasons except autumn, where a surplus was recorded in 2024. The difference, expressed as percentages, was 48.2% and 52.0% compared to the reference period and the 2010–2023 period, respectively. The number of sunshine hours in all seasons also shows a linear upward trend (Table 2, Figure 7), which is best illustrated by the annual totals of sunshine hours, which were 2533.3 h in 2024, 2218.4 h on average for 1991–2020, and 2270.5 h on average for 2010–2023 [40].

3.2. Bioecological Parameters of R. rugosa. Groups

The three examined groups of R. rugosa individuals located within the green area of the quay in Novi Sad comprise a total of 360 individuals, distributed as 120 individuals per group (Figure 8). The surface areas occupied by the observed plants are proportional to the number of individuals, amounting to 52.5 m² for area A (shade), 13.5 m² for area B (partial shade), and 10.5 m² for area C (full sunlight).

Following the UPOV protocol [41] for roses (Rosa L.), the growth type was uniform across all investigated R. rugosa groups and was recorded as shrub. The growth habit is semi-upright, and the plant height is classified as medium.

Plant height ranges from 0.5 m (group C) to 0.8 m (group B), although it should be noted that the plants were pruned twice during the growing season (

Table 3. Bioecological characteristics of investigated R. rugosa shrubs.

Sun Exposure	Area (m2)	Number of Individuals	Height (m)	Degree of Damage	Vitality	Decorativeness	DNPS (m)	DPB (m)	WGB (m)	DNT (m)	Fruit Yield (1–5)
A	52.5	116	0.6	*	5	5	0.5	2.5	4.5	0.3	5
B	13.5	15	0.8	/	5	5	0.5	0.5–3	2–2.5	4.2	5
C	10.5	14	0.5	/	5	5	0.5	2–3	3.5–4	/	5

Legend: Degree of damage: * low.

). No significant damage was observed on the studied groups, as indicated by the recorded vitality and ornamental value ratings, both of which reached maximum values. The DNPS was relatively uniform at 0.5 m, which is extremely close to the paved area, whereas in group B (partial shade), the distance from the road varied between 1.5 m and 3 m. The DBP ranged from 0.5 m to 3 m, which is considered a close proximity to the cycle path. The width of the green belt where the observed R. rugosa groups are located ranges from 2 m (B) to 4.5 m (A), which is favorable for the normal growth and development of R. rugosa plants.

In the vicinity of R. rugosa groups A and B, there are mature white poplar (Populus alba L.) trees, with TH ranging from 13.77 m to 12.15 m, HFB from 1.2 m to 2 m, and DBH varying from 54.14 cm to 88.53 cm. The crowns of the observed Populus alba L. individuals near the studied Rugosa rose groups are well developed, with CW ranging from 14 m to 16 m and crown volume ranging from 2084.74 m³ to 3001.35 m³. This indicates that they create a shaded area above the R. rugosa individuals, influencing both the microclimate and the light conditions of the site.

3.3. Morphometric Characteristics of R. rugosa Fruits

The species R. rugosa produces an aggregate fruit, the hypanthium, commonly known as rose hip, which contains a large number of individual achenes. The average values of the measured morphometric parameters for the studied R. rugosa groups growing under different ambient light conditions—sunlight, partial shade, and shade—are 1.5 g for FWE, 1.55 cm for FL, and 2.17 cm for FWI (

Table 4. Descriptive statistics of morphometric parameters of aggregate and individual fruits of R. rugosa and ANOVA analysis.

Exposure	A			B			C			ANOVA
Traits	Mean ± Se	SD	Cv (%)	Mean ± Se	SD	Cv (%)	Mean ± Se	SD	Cv (%)	F	p **
FWE	1.41 ± 0.26	0.81	47.34	1.71 ± 0.11	0.37	25.98	1.38 ± 0.12	0.39	27.97	215.42	0.00 *
FL	1.44 ± 0.12	0.40	27.62	1.56 ± 0.07	0.24	15.47	1.66 ± 0.07	0.24	14.26	797.06	0.00 *
FWI	2.22 ± 0.11	0.35	15.72	2.27 ± 0.08	0.26	11.38	2.34 ± 0.09	0.29	14.28	1559.4	0.00 *
PL	1.03 ± 0.08	0.27	25.91	1.1 ± 0.09	0.30	27.10	1.2 ± 0.15	0.49	40.45	280.26	0.00 *
SL	1.65 ± 0.17	0.53	32.10	1.77 ± 0.10	0.33	18.46	1.3 ± 0.11	0.36	27.38	433.43	0.00 *
NS	4.6 ± 0.22	0.70	15.20	4.7 ± 0.15	0.48	10.28	4.7 ± 0.15	0.48	10.28	2051.16	0.00 *
NAH	74.7 ± 6.03	19.06	25.52	64.40 ± 4.75	15.04	23.36	64.8 ± 7.99	25.27	39.00	338.56	0.00 *
AHL	4.80 ± 0.33	1.03	21.51	4.25 ± 0.27	0.85	20.18	5.05 ± 0.29	0.93	18.34	7.47	0.00 *
AHWI	2.17 ± 0.21	0.66	30.67	2.2 ± 0.15	0.46	21.29	2.27 ± 0.20	0.63	27.63	4.17	0.00 *
AHWE	0.17 ± 0.03	0.09	51.92	0.12 ± 0.05	0.01	15.21	0.11 ± 0.01	0.03	30.74	1.76	0.00 *

* Abbreviations: A—full shade; B—partial shade; C—full sun; FWE—fruit weight; FL—fruit length; FWI—fruit width; PL—petiole length; SL—sepal length; NS—number of sepals; NAH—number of achenes in the hypanthium; AHL—length of achenes (mm); AHWI—width of achenes (mm); AHWE—weight of achenes. ** statistically significant differences at p < 0.05.

). The highest values of these parameters were recorded in groups B (FWE of 1.71 g) and C (FL of 1.66 cm and FWI of 2.34 cm), indicating that optimal fruit development requires greater light availability, i.e., partial shade or full sun exposure. The range of values for the observed parameters was from 2.85 to 5.2 g for FWE, from 1 to 2.4 cm for FL, and from 1.6 to 2.8 cm for FWI.

The average PL of the analyzed fruits was 1.11 cm, while the recorded average SL was 1.57 cm. Individuals from group C exhibited the highest average PL values (1.2 cm), whereas individuals from group B showed the highest average values for SL (1.77 cm) and NS (4.7). Inside the aggregate fruit, trichomes of varying intensity and coloration were observed. In specimens growing in shaded conditions (A and B), a greater presence of yellow trichomes was recorded (60%), while fruits from group C predominantly exhibited white and gray trichomes (50%) of lower density.

Given that the fruit of R. rugosa is aggregate, it contains a varying number of individual nutlet-type fruits (achenes), with individuals from group A standing out with the highest average number of achenes per aggregate fruit at 74.7. The number of achenes within the observed population ranged from 31 to 120. The measured morphometric parameters for individual fruits showed that AHL and AHWI values ranged from 0.2 to 0.7 cm (2 to 7 mm), and from 0.1 to 0.5 cm (1 to 5 mm), respectively. The average values of these parameters at the population level were 4.7 cm and 2.2 cm, respectively, while the highest AHL and AHWI values were recorded in specimens from the full sun group (C). The measured weight of 10 individual fruits ranged from 0.07 to 0.37 g, with an average value of 0.13 g. Fruits sampled from individuals in the full sun group (C) had the highest average AHWE value of 0.17 g.

Out of the 12 analyzed morphometric characteristics of aggregate and individual fruits at the level of the entire observed secondary R. rugosa population, the greatest variability was recorded for the parameters FWE (CV 37.42%), PL (CV 32.20%), ET (CV 38.26%), CT (CV 38.40%), and AHWE (CV 43.90%), which is confirmed by the large differences between the minimum and maximum values of these parameters. Significant variability was also observed in SL and the number of achenes per aggregate fruit (NAH). The remaining parameters showed moderate variability.

When viewed by group, it is evident that in the full shade group (A), the coefficient of variation was highest for FWE (CV 47.34%) and AHWE (CV 51.92%); in the partial shade group (B), the highest CV was recorded for ET (CV 46.08%); while in the full sun group (C), the greatest variability was observed in PL (CV 40.45%) and NAH (CV 39.00%).

In Table 4 and Figure S4, the results of descriptive statistics for the measured parameters of morphological parameters and ANOVA analysis are presented, where statistically significant differences at the population level were recorded for all the measured parameters (p < 0.05).

Based on the ANOVA results, and for a more precise definition,

Table 5. Results of the Duncan test for the investigated parameters.

Contrast	Difference *	Standardized Difference	Critical Value	Pr > Diff	Alpha (Modified)	Significant	Lower Bound (95%)	Upper Bound (95%)	Lower Bound (95%)	Upper Bound (95%)
FWE (g)
A vs. C **	0.329	1.300	2.159	0.408	0.098	No	−0.218	0.876
A vs. B	0.265	1.018	2.056	0.318	0.050	No	−0.270	0.799
B vs. C	0.064	0.247	2.056	0.807	0.050	No	−0.470	0.599
FL (cm)
C vs. A	0.220	1.603	2.159	0.262	0.098	No	−0.076	0.516
C vs. B	0.093	0.662	2.056	0.514	0.050	No	−0.196	0.383
B vs. A	0.127	0.898	2.056	0.377	0.050	No	−0.163	0.416
PL (cm)
C vs. A	0.170	1.042	2.159	0.558	0.098	No	−0.182	0.522
C vs. B	0.067	0.398	2.056	0.694	0.050	No	−0.278	0.411
B vs. A	0.103	0.616	2.056	0.543	0.050	No	−0.241	0.448
FWI (cm)
B vs. C	0.227	1.604	2.159	0.262	0.098	No	−0.079	0.532
B vs. A	0.047	0.330	2.056	0.744	0.050	No	−0.244	0.337
A vs. C	0.180	1.309	2.056	0.202	0.050	No	−0.103	0.463
SL (cm)
B vs. C	0.444	2.308	2.159	0.072	0.098	Yes	0.029	0.860
B vs. A	0.094	0.490	2.056	0.628	0.050	No	−0.301	0.490
A vs. C	0.350	1.867	2.056	0.073	0.050	No	−0.035	0.735
NS
B vs. A	0.100	0.391	2.159	0.919	0.098	No	−0.452	0.652
B vs. C	0.033	0.127	2.056	0.900	0.050	No	−0.507	0.573
B vs. A	0.067	0.254	2.056	0.802	0.050	No	−0.473	0.607
NAH
A vs. C	9.900	1.102	2.159	0.521	0.098	No	−9.502	29.302
A vs. B	7.811	0.846	2.056	0.405	0.050	No	−11.164	26.786
B vs. C	2.089	0.226	2.056	0.823	0.050	No	−16.886	21.064
AHWE
A vs. C	0.057	2.189	2.056	0.038	0.098	Yes	0.003	0.110
A vs. B	0.049	1.941	2.056	0.063	0.050	No	−0.003	0.101
B vs. C	0.008	0.300	2.056	0.767	0.050	No	−0.046	0.061
AHL (mm)
C vs. B	0.430	2.772	2.072	0.016	0.098	Yes	0.109	0.751
C vs. A	0.214	1.376	1.968	0.170	0.050	No	−0.092	0.520
A vs. B	0.216	1.389	1.968	0.166	0.050	No	−0.090	0.522
AHWI (mm)
A vs. C	0.052	0.496	2.072	0.873	0.098	No	−0.166	0.271
A vs. B	0.042	0.401	1.968	0.689	0.050	No	−0.165	0.250
B vs. C	0.010	0.095	1.968	0.924	0.050	No	−0.197	0.217

* Analysis of the differences between the categories with a confidence interval of 95%. ** Abbreviations: A—full shade; B—partial shade; C—full sun; FWE—fruit weight; FL—fruit length; FWI—fruit width; PL—petiole length; SL—sepal length; NS—number of sepals; NAH—number of achenes in the hypanthium; AHL—length of achenes (mm); AHWI—width of achenes (mm); AHWE—weight of achenes.

presents the results of the Duncan test (least significant differences), which indicate the significant variations in the morphometric characteristics of the hypanthium and achenes for SL (sepal length) and AHL (achenes length) between groups B (semi-shade) and C (sunlit area), and for AHWE (weight of 10 achenes) between groups A (shade) and C (sunlit area). For the other parameters, no statistically significant differences were found between the groups.

Given that the Duncan test generally shows consistent patterns of homogeneous groups for testing mean differences between independent samples, and that the observed differences may be conditioned by genotype rather than solely by sunlight exposure, the significance of the identified differences was further confirmed by performing a multivariate statistical analysis using Principal Component Analysis (PCA). PCA reveals overlaps between groups based on observations from seven characteristics of the hypanthium, fruit weight, fruit length, fruit width, petiole length, sepal length, number of sepals, and number of achenes in the hypanthium, as well as three characteristics of the achenes: length, width, and weight of 10 fruits. The scatter plot visually displays the traits influencing the separation and overlap (Figure 9). Overlap of the hypanthium morphological characteristics within the groups is observed, with PC1 explaining 25.7% and PC2 explaining 21.8% of the variance, totaling 47.5% (Figure 9a). Principal Component 1 (PC1) likely reflects a balance among the variables. The confidence ellipses significantly overlap, particularly between the group existing under partial shade (B) and the group located in a fully sunlit exposure (C), indicating no statistically significant differences, except for sepal length. The group growing in shade (A) shows the highest variability, while the group under partial shade (B) is the most consistent, with groups showing partial separation. Due to the significant overlap and low variance, PC1 and PC2 did not fully distinguish the groups. The vectors of hypanthium morphological characteristics (NAH, FWE, FWI, FL, SL, NS) show diverse directions, indicating that the original variables capture different aspects of the data. The variability of the achene samples could be separated, with the first two axes describing 85.1% of the variability, which indicates that the plot captures most of the data’s structure. Significant differences (Figure 9b) are highlighted by PCA for the morphological characteristics of achene length, width, and weight, with very high variations (PC1 51.8% and PC2 33.3%).

Within the group growing in shade (A), points are widely scattered and the confidence ellipse is large, indicating high variability in this group. Greater homogeneity and the lowest variability are observed in the group under partial shade (B). Based on the group located in full sun (C), which has scattered points and an ellipse that significantly overlaps with groups A and B, a similarity among them can be observed. The groups are not fully distinct, and based on the substantial overlap of all groups regarding achene characteristics, it can be concluded that there is still similarity among the groups based on the principal components PC1 and PC2.

PCA grouped the morphometric characteristics of SL (sepal length), AHL (achenes length), and AHWE (weight of 10 achenes), as well as the width of the achene, as indicators of the impact of light, consistent with the results of the Duncan test.

To further identify the impact of light on the analyzed hypanthium and achene parameters, and given the observed differences in previous tests, the LS means (Least Squares Means) test was also applied. LS values estimate the means that would be observed if the data were balanced and indicate the significance of the response for the analyzed parameter. Based on the LS means results for the investigated parameters, only the significance of the differences for the AHL parameter between the groups was confirmed (

Table 6. LS means results of the examined parameters for the groups at the significance level of p < 0.05.

Group	FWE (g)	FL (cm)	PL (cm)	FWI (cm)	SL (cm)	NS	NAH	AHWE (g)	AHL (mm)	AHWI (mm)
B	1.718 a*	1.567 a	1.133 a	2.267 a	1.744 a	4.667 a	66.889 a	0.120 ab	4.390 b	2.190 a
A	1.453 a	1.440 a	1.030 a	2.220 a	1.650 ab	4.600 a	74.700 a	0.169 a	4.606 ab	2.232 a
C	1.389 a	1.660 a	1.200 a	2.040 a	1.300 b	4.700 a	64.800 a	0.112 b	4.820 a	2.180 a
Pr > F (Model)	0.403	0.291	0.583	0.249	0.066	0.924	0.520	0.073	0.023 **	0.871
Significant	No	No	No	No	No	No	No	No	Yes	No
Pr > F (Group)	0.403	0.291	0.583	0.249	0.066	0.924	0.520	0.073	0.023	0.871
Significant	No	No	No	No	No	No	No	No	Yes	No

Abbreviations: A—full shade; B—partial shade; C—full sun; FWE—fruit weight; FL—fruit length; FWI—fruit width; PL—petiole length; SL—sepal length; NS—number of sepals; NAH—number of achenes in the hypanthium; AHL—length of achenes (mm); AHWI—width of achenes (mm); AHWE—weight of achenes. * The labels a, b, and ab represent the groups to which the LS means values of the investigated parameters belong. ** Bolded values indicate statistically significant values.

).

The patterns of morphological variability in the hypanthium and achenes suggest phenotypic changes, as well as adaptation to different light conditions of the habitat, and may serve as a starting point for conservation programs for R. rugosa in light of climate change projections.

3.4. Multivariate Cluster Analysis

The multivariate cluster analysis (Figure 10) indicates a distinct separation of the R. rugosa group growing under full shade conditions (A), while individuals from groups B and C are grouped in a second sub-cluster. Group A is distinguished by the highest average values for NAH and AHWE, whereas individuals from groups B and C were clustered based on similar values for FL, FWI, PL, NS, ET, AHL, and AHWI.

Based on the results of the cluster analysis, it can be presumed that the grouping was influenced by micro-locational conditions, particularly the varying levels (intensity) of light at the sites where the observed Rugosa rose groups are located, as well as by genetic predispositions and the origin of the planting material, since the plants were grown from seed. Potential genetic variability might have contributed to the observed differences in fruit morphological parameters among Rosa rugosa groups exposed to different levels of sunlight.

4. Discussion

The research encompassed three groups of 360 R. rugosa shrubs, distributed across three different exposures, full shade, partial shade, and full sunlight, situated within a linear green space along the bank of a major river in the urban core. The objectives were focused on examining the impact of different light conditions on the bioecological characteristics of secondary populations of the investigated shrubs, as well as the morphological variations in their fruits. In addition, the study assessed how the proximity of trees affects the growth and adaptability of Rugosa rose compared to its performance in open spaces. The suitability of R. rugosa for solitary planting versus planting in combination with trees was also evaluated, considering its adaptability to different spatial and light conditions in urban environments. This research is relevant in the context of the rapid expansion of cities, which leads to increased air temperatures and changes in urban ecosystems, negatively affecting the comfort and well-being of both residents and plants. This study is in agreement with the statements of [44] who noted that growth and increased temperatures significantly affect morphological and phenological changes, as confirmed by both satellite and ground-based evidence over recent decades. It is also noteworthy that the impact of heat on plants was observed as early as the 18th century by [45], who introduced the concept of heat units (temperature sums) to predict plant development, linking growth, development, and maturity to accumulated air temperatures. Even then, Réaumur pointed out that plant development is proportional to the sum of air temperatures, to which extremely warm winters—such as that of 2024—make a considerable contribution. Explanations of morphological variability and phenological monitoring are not possible without climate data, as the spatial distribution of the onset dates or duration of phenological events reflects the spatial variation in the climate and microclimate [46]. Earlier onsets and later endings of the growing season—implying extended vegetation periods—have also been reported in studies by [47,48]. Delays or earlier occurrences of phenophases, as well as morphological variability, support the conclusion by [49] that climate variables at or before those times differed from established climatic norms. The significance of the findings in this study, conducted in 2024—the warmest year on record globally (WMO)—is further supported by the results of [50], who emphasized that understanding the complex relationships between phenology and climate contributes to a better understanding of vegetation productivity, and in this case, the productivity of R. rugosa in the context of global warming and extreme climatic events [51,52,53]. Rugosa rose is a widely used species in landscape design due to its notable tolerance to environmental stress [24], making it a frequent choice for urban greening. In this context, we can recommend guidelines for the application of Rosa rugosa across different categories of green spaces. When planted as a pure, linear hedge—typically along roadsides, cycling paths, or pedestrian walkways, which is the most common use for this species—a planting distance of 0.3–0.5 m is recommended. In group plantings with irregular, organic forms, usually found in park areas, a minimum spacing of 0.5 m between plants is advised to allow them to reach their full potential, receive sufficient light, and flower abundantly. For mixed plantings, considering the entomophilous nature of this species, it is recommended to combine Rugosa rose with other woody shrubs and perennials of striking color such as Lavandula angustifolia L., Photinia sp., and Euonymus sp., or those with a more uniform coloration such as Pinus mugo Turra, Juniperus horizontalis Moench., and Juniperus squamata Buch.—Ham. ex D. Don. It is also an important horticultural and ornamental plant with high commercial value, especially in the pharmaceutical [54] and food [26,55] industries. In medicine, the fruits of Rugosa rose are used in the prevention of cancer [55,56,57]. Due to its ornamental value, R. rugosa has been widely traded and introduced to many countries worldwide, and in favorable conditions, it has become naturalized [3]. The study may serve as a guideline for policy makers dealing with urban greenery. Rosa rugosa is recommended due to its low maintenance requirements, suitability for both solitary and mixed planting across various exposures and forms, and its ability to provide a wide range of ecosystem services. Notably, these include serving as a food source for birds and small mammals, as well as supporting pollination.

According to the UPOV protocol [41] for roses (Rosa L.), all investigated R. rugosa groups were classified as shrubs with a semi-upright growth habit and medium plant height. It should be noted that the plants were pruned twice during the growing season. Consequently, the measured plant heights were lower than those reported by [7,8,9], who recorded heights for R. rugosa ranging from 1.5 to 2 m. The DNPS was fairly consistent at 0.5 m, which is considered extremely close to a paved surface. In group B (partial shade), the distance from the road varied between 1.5 m and 3 m, but from the nearest paved surface it was also 0.5 m. Such close proximity to paved areas can negatively affect plants by altering phenology [58,59] inducing osmotic stress [60], raising rhizospheric temperatures [61] and reducing nutrient availability [29,62]. Extensive paving also indirectly contributes to the urban heat island effect [63], increasing ground temperatures and potentially affecting the growth, size, flowering, fruiting, and yield quality of woody species [64]. In this study, no significant deviations were observed in typical annual growth patterns, suggesting that Rugosa rose is a highly resilient species capable of tolerating the stressful conditions associated with close proximity to paved surfaces and roads. Furthermore, the short distance to the bicycle path (DBP), which ranged from 0.5 m to 3 m, was positively evaluated in this study. Shrub groups such as Rugosa rose contribute to the enhancement of recreational green spaces, as their foliage and flowering improve the aesthetic quality of urban green areas and provide positive psychological and mental health benefits [65,66,67]. In addition, vegetation lowers surrounding temperatures through shading, improving the comfort of cycle path users during the summer months [68] and enhancing overall human thermal comfort [69].

Regarding the morphological variability of R. rugosa fruits under different light conditions, our study yielded significant results. Rugosa rose produces an accessory fruit, the hypanthium, commonly known as rose hip, which contains a large number of individual nut-like fruits, or achenes [4]. The fruit represents a valuable raw material for the food industry due to its wide range of bioactive compounds and secondary metabolites [16,19,21]. Moreover, R. rugosa fruit is an important resource for the pharmaceutical industry [54] which highlights the importance of understanding the fruiting potential of individuals in secondary urban populations, as well as the influence of microclimatic conditions on fruit development, dimensions, and yield. Future research could be directed toward analyzing the biochemical composition of fruits from secondary Rugosa rose populations. Additionally, the skin color and size of the fruit may enhance the visual appeal of urban green spaces, thereby contributing to improved user experience and aesthetic value [70].

Taking all of the above into consideration, and by comparing our results on the morphometric parameters of fruits with those reported by other authors, the R. rugosa groups in our study exhibited average values that slightly deviate from published data. A study that examined the morphological characteristics of fruits from four R. rugosa genotypes in an arboretum in Slovakia, reported fruit lengths ranging from 16.10 to 18.13 mm [2]. In comparison, our values for fruit length were slightly lower, while our values for fruit width were somewhat higher than those reported in that study, which ranged from 21.38 to 22.46 mm. On the other hand, our results aligned with reported fruit sizes in the literature, with lengths of 1.5–2 cm and widths of 2–2.5 cm [7], and widths of 2–3 cm [71]. In terms of fruit weight, values ranging from 5.14 to 5.46 g have been reported [2], which are higher than our averages due to the late November harvest when fruits were drying. Conversely, slightly lower average values of 1.58 g were reported in another study [16]. It can be assumed that the difference in fruit weight values is influenced by the varying latitudes of the studied areas. It may also be assumed that local cultivation conditions had an impact, considering that in the studies by authors [16,23], the study area was an arboretum, where conditions differ significantly from those in our research. Fruit weight represents a highly important economic trait, particularly in relation to the practical utilization of the fruit.

The observed calyx leaf number, ranging from four to six in our study, aligns with the value of five reported in the literature [23]. Sepal length (SL) averaged between 0.5 and 2.2 cm, which is slightly below the 2 to 3 cm reported in other studies [7,23]. This further suggests that higher latitude, i.e., a colder climate, has an influence on the fruit size of R. rugosa. The fruit of Rugosa rose is aggregate, containing a variable number of individual fruits (achenes). In our study, the number of achenes ranged from 31 to 120 across the observed population. The fruits from group A, growing in full shade, had the highest average number of achenes (74.7), exceeding previously reported averages ranging from 48.45 to 71.05 [2]. The measured morphometric values for individual fruits—(AHL and AHWI)—were consistent with values reported in the literature, ranging from 4 to 6 mm for AHL and 2 to 6 mm for AHWI [7].

Although light intensity and the duration of light exposure throughout the day have a significant effect on several aspects of plant growth—particularly flowering and fruiting [72,73]—no significant reduction in flowering or fruiting abundance was observed in our study, nor were there notable differences in the morphological characteristics of the investigated R. rugosa fruits.

There is a notable lack of studies specifically addressing the effects of light conditions on the growth and phenology of Rosa rugosa. To provide context, we compared our findings with research on other woody shrub species that share a similar habitus, ecological function, and ornamental value, such as Paeonia lactiflora Pall., Rosa hybrida, Spiraea alba Du Roi, and Spiraea tomentosa L. In Paeonia lactiflora Pall. [29] morphological parameters such as plant height, leaf number, stem diameter, branch number, node number, and crown width were all greater in sun-exposed plants compared to those grown in shaded conditions. Studies on Rosa hybrida [30] indicate that shade delays the onset of flowering but also extends its duration; however, key physiological indicators were reduced under low light. Research on Spiraea species [31] showed differences in plant height, flowering intensity, and leaf greenness, with light exposure influencing overall growth, canopy density, and reproductive performance. These findings suggest that reduced light availability can affect both vegetative and reproductive traits across a range of ornamental shrub species, supporting our interpretation of the patterns observed in Rosa rugosa. Large, dense, vertical tree structures are known to restrict light interception, negatively affecting fruit quality characteristics such as yield, fruit weight, color, soluble solids content, and acidity [74]. The white poplar trees (Populus alba L.) present at the study site indeed create such environmental conditions, given their dimensions (TH ranging from 13.77 to 12.15 m and CW ranging from 14 to 16 m); however, they did not appear to impact the growth or fruiting of the examined Rugosa rose groups. Application in shaded conditions does not reduce plant growth; however, smaller fruit size and reduced flowering intensity were observed in the groups under full shade. Therefore, the use of Rosa rugosa is recommended in fully sunlight exposures and partial shade.

This study has several limitations. First, it was conducted over a single season in a single city, which limits the ability to capture interannual and geographical variability in morphological traits and environmental responses. Additionally, fruit sampling was performed in November, although the full ripeness was reached in September. As a result, the fruits were partially dehydrated, which may have affected the weight and prevented the measurement of certain traits, such as mesocarp thickness or internal fruit layers that are more accessible when the fruit is fully ripe and juicy.

Furthermore, the study did not quantify some environmental factors—such as soil characteristics, microclimatic conditions, or potential urban pollutants—which may have influenced the observed morphological differences. Lastly, possible genetic variability among the examined R. rugosa individuals was not evaluated, which could also have contributed to the differences recorded between groups. However, they are rarely planted as solitary shrub, and are generally always of a generative origin, so our findings are applicable in the similar environments. Although the study has certain limitations, it offers a solid foundation for future research on the adaptability and bioecological performance of R. rugosa in urban environments. Building on the current findings, future studies should prioritize controlled, multi-year monitoring to account for seasonal variation and to gain deeper insight into the stability of observed traits over time. This approach would provide a solid base for the selection of the most promising genotypes and their usage as mother plants for future vegetative propagation and rapid multiplication. Additional directions include integrating genetic analyses to better understand the variability among populations, as well as systematically assessing environmental variables such as soil quality, microclimate, and urban stressors, which were not quantified in this study but could significantly affect plant performance.

5. Conclusions

The study examined the adaptability and morphological variability of R. rugosa in urban environments under varying light exposures. The findings confirmed that R. rugosa exhibits strong resilience to stressful urban settings—such as close proximity to paved roads and varying light exposures—demonstrating uniform growth type, high ornamental value, and stable performance across different spatial contexts. Statistically significant differences in fruit morphology between light exposure groups further highlight the influence of light on reproductive traits. The most significant differences were observed in sepal length and achene length between the partial shade (B) and full sun (C) groups, as well as in achene weight between the shade (A) and full sun (C) groups.

Although limited to a single season, location, and without detailed environmental or genetic data, the study provides a valuable baseline for understanding the ecological role of R. rugosa in urban green infrastructure. Future research should expand to multi-year, multi-site studies, incorporate genetic analyses, and quantify environmental variables such as soil conditions and urban microclimates. Such approaches will enhance understanding of long-term adaptability and support the evidence-based use of R. rugosa in sustainable urban greening and nature-based solutions, especially under climate change conditions. The patterns of morphological variability in the hypanthium and achenes suggest phenotypic changes, as well as adaptation to different light conditions of the habitat, and may serve as a starting point for conservation programs for R. rugosa in light of climate change projections.