1 Introduction
The fast-paced urban lifestyle has significantly reduced opportunities for people to engage and interact with nature, which has negatively affected human physical and mental health, well-being, and social cohesion
[1]. In recent years, sub-health conditions have become increasingly prevalent, especially among young people, including university students. Studies show that university students are prone to health issues such as sleep disorders and deteriorating physical fitness
[2]. Being in a critical period of psychological development, they face multiple pressures from family, academics, interpersonal relationships, and future employment
[3].
The 2016 National Health and Wellness Conference of China outlined key environmental health goals, emphasizing the urgent need to address pressing environmental issues affecting public health
[4]. According to the World Health Organization, health encompasses three dimensions: physical, mental, and social well-being, meaning that good physical function, sound psychological health, and harmonious social relationships are essential
[5]. Therefore, creating environments that provide continuous positive interventions is crucial. Existing research has demonstrated that natural environments positively affect human physiology, emotions, and attention
[6] [7].
Green spaces, as a type of natural environment, offer a wide range of health benefits related to recreational and ecological well-being
[8]. Plants, the most important component of green spaces, significantly promote human health—for example, exposure to flowers has been shown to foster positive emotions, alleviate stress, and aid in attentional restoration
[9]. During the COVID-19 pandemic, close contact with plants provided therapeutic effects
[10].
Rosa chinensis (commonly known as "Chinese rose, " referred to as "rose" hereafter) is widely used in landscape design due to its rich variety of colors and fragrant scents. Its volatile compounds have high therapeutic value, making it an important resource for aromatherapy and healthcare.
[11]~
[13] Thus, exploring the health intervention effects of rose landscapes, as well as their variability, is critical for creating healthy living environments.
2 Literature Review
2.1 Landscape Perception
Perception forms the foundation for human interaction with the environment, and landscape experiences involve the coordination of multisensory modalities
[14]. Plants, as a key medium for human interaction with the natural environment, provide rich sensory stimuli. For instance, the color and shape of plant organs provide visual stimuli, the scent of flowers, leaves, and fruits generate olfactory stimuli, while the sounds produced by wind or rain on leaves offer auditory stimuli. In some cases, edible plants may even evoke taste stimuli.
Visual perception, one of the most significant human sensory modalities, offers abundant environmental cues
[15] [16]. The visual characteristics of a landscape typically include color, shape, size, as well as horizontal and vertical structures
[17]. For plant visual perception, users primarily process physical information such as shape, size, color, and posture. Studies have pointed out that plant color has the most profound visual impact, often being the first feature to attract attention, followed by growth form and size
[18]. Human sensitivity to different plant colors also varies
[19], and plant colors directly affect sensory experiences, eliciting both physiological and emotional responses
[20]. In contrast, olfactory perception is often underappreciated. Unlike other sensory pathways, olfactory sensory neurons are directly connected to the central nervous system, which controls language, memory, and emotions. Therefore, compared with other senses, olfaction can more directly evoke deep emotional responses, and scents can significantly influence emotions, cognition, and behaviors
[21].
Moreover, interactions between sensory modalities can influence landscape perception. Studies indicate that visual stimuli can enhance olfactory perception
[22], and olfactory input can alter perceptions of environmental atmosphere
[23]. The involvement of olfactory perception significantly enhances individuals' awareness of environmental biodiversity, amplifying the restorative effects of the environment on health
[24]. The distinct qualities of olfactory stimuli can also modulate visual attention
[25]; for instance, certain scents may heighten attention to visually congruent objects
[26], and a higher consistency between modalities enhances the overall pleasantness of the environment
[27]. Research on forest landscape perception has demonstrated that combined visual and olfactory stimuli produce significantly greater physiological and psychological relaxation compared with single sensory stimulation
[28], and that the congruence between visual and olfactory inputs can improve evaluations of plant landscapes
[29].
Human perception also affects landscape preference, satisfaction, and pleasure
[30]. Preferences arise from individuals' evaluations on landscape through sensory perception and cognitive processing
[31]. These preferences are linked not only to psychological states induced by cognitive and emotional responses to the environment
[32], but also to the restorative benefits the environment provides for physical and mental well-being
[33]. Research has shown that plant landscape preferences significantly aid psychological recovery
[34]. The presence of trees and flowers enhances landscape ratings and reduces mental stress
[35].
Although some studies have explored the combined effects of visual and olfactory stimuli on health, or how visual-olfactory perceptions influence public landscape experiences, research on the health benefits of plant landscapes from a multisensory interaction perspective remains limited.
2.2 Plant Landscapes and Physical and Mental Health
Physiological assessments, utilizing EEG, blood pressure, heart rate variability, etc., along with psychological assessment tools like the Profile of Mood States (POMS), are commonly used to explore the relationship between plant landscapes and human physical and mental health.
[36]~
[38] For example, one study employing eye-tracking technology and semantic differential scales found that yellow-green and bright green leaves attract more attention than other colors, inducing feelings of pleasure and relaxation. In contrast, green-and-white mixed leaves often evoke negative emotions
[39]. Another study analyzed the impact of plant community images with varying colors and proportions on relaxation. Its results showed that green and yellow plant communities were found to be more relaxing than the red ones, with the best relaxation effect achieved at a color ratio of 55% green, 25% yellow, and 20% red
[40].
Furthermore, numerous physiological and psychological experiments confirmed the health benefits of inhaling plant fragrances. For example, Hexian Jin et al. reported that the scents of
Prunus mume and
Osmanthus fragrans could reduce muscle electrical activity and body temperature, while improving attention and memory after exposure to the Osmanthus fragrance
[41]. Other studies have shown that inhaling
Perilla frutescens for a period of time can relax university students and alleviate negative emotions
[42], while
Gardenia jasminoides fragrance reduces stress and improves mood
[43]. The scent of
Gelsemium sempervirens helps relieve anxiety, enhance attention, and regulate blood pressure
[44]. The plant
Jasminum polyanthum triggers positive emotions and relaxation at different times of day, with evening exposure particularly effective in alleviating depression
[45].
2.3 Rose Landscape
The Rosa genus, a member of the Rosaceae family, includes perennial evergreen or deciduous shrubs with a variety of flower colors, forms, and extended flowering periods, and is renowned for its rich fragrance and cultural significance
[46]. As one of the Ten Famous Traditional Flowers in China, roses are widely applied in landscape greening and home gardening. Their growth forms include shrub, tree, and climbing vine. Shrub roses are typically used for ground cover or in flower beds, often planted in clusters or patches. Tree-type roses, through a unique triple-grafting technique, are ornamental flower trees commonly seen in parks and gardens. Compared with shrub-type roses, tree roses are closer to human olfactory senses and emit more intense, lasting fragrances. The climbing vine type is ideal for vertical landscaping, and can be used in flower trellises and other structures to create floral walls, hedges, arches, pergolas, and gates
[47], creating romantic spatial atmospheres.
Most studies on roses have focused on their environmental resilience and ornamental value. For example, some proposed landscape configuration strategies based on regional characteristics
[48], or used analytic hierarchy process to evaluate rose varieties suitable for specific regions
[49]. Other studies employed scenic beauty estimation method and network analytic hierarchy process to assess rose landscapes in specialized gardens, providing insights into community configuration models of roses
[50] [51]. Meanwhile, with the continuous development and popularization of horticultural therapy
[52], the therapeutic potential of rose landscapes is gaining recognition. However, the therapeutic benefits of rose color and fragrance have not been fully explored. Previous studies have found that rose essential oils can modulate sympathetic activity, thereby exerting calming and anti-anxiety effects
[53] [54]. But the specific factors in rose landscapes that contribute to these therapeutic effects and their mechanisms of action and pathways for promoting human health remain unclear.
Thus, this study raises the following questions. 1) Can rose landscapes, through visual and olfactory perception, generate restorative benefits for the human health? 2) Which visual and olfactory factors yield the most significant restorative effects? And 3) is there an interaction between visual and olfactory perceptions? If so, which interaction model maximizes health benefits?
3 Research Materials and Methods
3.1 Preliminary Research
Given the representativeness of rose landscapes, the preliminary research of this study selected rose landscape sites in Hangzhou and Ningbo, China including the Rose Garden in the Flower Square of Hangzhou Flower Nursery, the Rose Garden in Baima Lake Park, Daguan Park, and the Rose Garden in Ningbo Botanical Garden, known for their diverse rose varieties and landscaping styles. To investigate the public's visual and olfactory perceptions of rose landscapes, questionnaires and semi-structured interviews were conducted at each site. The questionnaires were distributed on April 22 ~ 23, 2023, with 20 for each site, totaling 80 responses. Respondents included university students, office workers, and retirees aged 17 to 65 years, comprising 32 males and 48 females.
According to the survey results (Fig.1), flower color and fragrance type in rose landscapes were identified as the primary factors influencing visual and olfactory perception (as over 80% participants perceived). Therefore, this study selected color and fragrance type as visual and olfactory variables, respectively. In terms of visual traits, previous studies have categorized roses into ten primary color series: red, scarlet, white, yellow, orange, pink, blue-violet, green, multicolored, and bicolor
[55]. For fragrance types, the Rose Fragrance Institute Corp. in Japan used gas chromatography-mass spectrometry (GC-MS) to analyze the fragrance components of roses and classified them into several categories, including Fragrance of Damask Classic (classic rose scent), Fragrance of Damask Modern (modern rose scent), Fragrance of Tea, Fragrance of Fruity, Fragrance of Spicy, Fragrance of Myrrh, and Fragrance of Blue. Based on field surveys, this study found that white, orange, pink, red, yellow, and blue-violet roses were more commonly observed. Therefore, the visual variables in this research were defined as six color series, including white, orange, pink, red, yellow, and blue-violet. Semi-structured interviews conducted after the questionnaire survey revealed that the classic and modern rose scents were observed similar, while these two rose fragrances ("Fragrance of Rose" hereafter) and the Fragrance of Fruity were easily identifiable. Thus, the olfactory variables in this study were the Fragrance of Rose (FR) and Fragrance of Fruity (FF).
3.2 Experimental Material Collection and Processing
Visual landscape stimuli can be presented through real environmental experiences or simulated images. Since the latter is often conducted in controlled laboratory settings, it is more suitable for exploring interaction mechanisms between complex variables
[36]. In this study, the research team visited the study sites from April 25 to 30, 2023 (peak bloom time for roses), during clear weather conditions, specifically at 10:00 ~ 11:00 and 13:00 ~ 14:00. Using a Sony A6000 camera, photos of various colored rose landscapes were taken at a shooting height of around 1.6 m (close to typical human visual level) with a front-lit angle to minimize the impact of lighting. Each color series included three growth forms: shrub, tree, and climbing vine. To eliminate the interference of unrelated factors, such as differences in growth status, the colors of rose landscapes captured in photos were processed using ColorImpact and Photoshop software. This ensured consistency within each color series across different growth forms, and the color ratios for each series were standardized. As a result, six color series were processed into a total of 18 simulated rose landscape images, each with dimensions of 5, 650 × 3, 809 pixels (Tab.1).
For olfactory materials, based on relevant research
[56], the following were selected: Rosa 'Crimson Glory, ' a small climbing vine with dark red flowers and a cup-shaped bloom, for FR type; Rosa 'Golden Celebration, ' a shrub with golden-yellow flowers and a cup-shaped bloom, for FF type.
The main compounds responsible for the rose fragrances were found in the petals and pollen
[57] [58]. Therefore, fresh petals were collected as the olfactory source material. A pre-experiment was conducted to determine the optimal fragrance concentration. To ensure that the fragrance concentration approximated the actual scent experienced in the environment, fresh petals were placed in 500 ml sealed opaque, odorless, cylindrical polyethylene (PE) containers, with an opening on one side to allow olfactory testing. This method effectively simulated the natural volatile effect of the fragrance
[59], while preventing visual interference during the olfactory evaluation. Six different weights (120 g, 100 g, 80 g, 60 g, 40 g, and 20 g) were tested to evaluate the perceived fragrance concentration. The results indicated the highest perception scores at 60 g and 40 g, for which an average value of 50 g was chosen for the olfactory concentration. For accuracy concern, rose petals were collected half or an hour before the experiment, with equal weights prepared for both fragrance types.
3.3 Experiment Location and Timing
The experiment was conducted in the engineering laboratory at the Donghu Campus of Zhejiang A & F University. During the experiment, doors and windows were closed, and the curtains were drawn to eliminate the impact of noise and lighting differences. The experiment was carried out from May 10 to 24, 2023, during specific periods of 8:30 ~ 11:30, 13:30 ~ 16:30, and 18:30 ~ 21:30. The indoor temperature and humidity were maintained at around 26℃ and 55%, respectively.
3.4 Participants
A total of 240 university student volunteers were recruited via campus posters. Participants were aged between 18 and 25, with normal body mass index, olfactory and visual abilities, and none had taken hormonal medications in the past six months. They were instructed to get sufficient sleep 24 hours before the experiment and to avoid consuming alcohol, tobacco, or coffee. Before the experiment, the staff explained the procedure and equipment usage in detail, and all participants signed an informed consent form.
3.5 Experiment Procedure
Previous research has indicated that exposure to natural environments for 3 ~ 5 min can yield better restorative effects
[60]. This experiment consisted of two phases: a pre-test stress phase and a post-test recovery phase, each lasting 3 min, with a total experiment duration of 20 min. The 240 participants were randomly assigned to 12 sensory groups combining the six color series with the two fragrance types (20 participants per group). Before the experiment, participants wore the EMOTIV EPOC-X device to collect EEG data and sat quietly for 5 min. The experiment began with a series of arithmetic tasks designed to induce stress while EEG data was collected. After the pre-test phase, participants completed the POMS to assess their emotional state. During the post-test recovery phase, participants viewed rose images (three images for each color series, with each displayed for 1 min) on a screen while smelling rose materials placed in the opaque containers. EEG data continued to be collected during this phase. Afterward, participants removed the EEG devices and completed the POMS scale (Fig.2). Between each session, the room was ventilated for 5 min to remove residual odors.
3.6 Physiological and Psychological Data Collection
Physiological indicators were analyzed using EEG data collected from the EMOTIV EPOC-X device. The device's 14 electrodes cover four brain regions: the parietal lobe, responsible for sensory processing and language function; the occipital lobe, which processes visual information; the frontal lobe, reflecting emotions, language, cognition, and behavior; and the temporal lobe, supporting auditory processing and language functions
[61]. Different EEG frequency bands reflect specific states: Alpha waves (8 ~ 13 Hz) represent relaxation and are highly associated with pleasure; Beta waves (14 ~ 30 Hz) reflect mental alertness and attention, as well as emotions such as anxiety, anger, tension, focus, and excitement
[62]; Theta waves (4 ~ 7 Hz) indicate low physiological arousal (fatigue, lack of vitality). The β/α ratio describes the impact of stress on the nervous system
[63], with a higher ratio indicating higher stress or alertness. The θ/β ratio assesses attention-related neural performance
[64], with a lower ratio indicating better focus. Thus, this study used the β/α ratio to assess stress levels and the θ/β ratio to evaluate attention levels.
Psychological indicators were primarily assessed using the POMS to evaluate emotional states. This study employed a simplified version of the POMS
[65], which includes 7 emotional states (40 feelings) rated on a 5-point scale (1 = very little, 5 = very much). These emotional states, i.e. tension, anger, fatigue, depression, energy, panic, and self-esteem
①, were further combined into three indicators: positive emotion score, negative emotion score, and total mood disturbance score (Tab.2).
① Detailed content of the POMS used in this study is provided in the supplementary materials.
3.7 Statistical Analysis
Data analysis was conducted using SPSS 26.0 software. Firstly, paired sample t-tests were performed to analyze changes in the β/α and θ/β ratios and POMS emotional states during the stress and recovery phases. Then, a covariance analysis was conducted on the physiological and psychological indicators of the 12 groups, using corresponding indicators from the stress phase as a covariate to eliminate baseline differences and to assess the main effects of the visual and olfactory variables. Simple effects analysis was performed for significant interactions observed between visual and olfactory variables.
4 Research Results
4.1 Physiological Recovery Benefits of Visual-Olfactory Perception
The results of the paired sample t-test② revealed significant differences in the β/α and θ/β ratios across four brain regions during the stress (p = 0.015)③ and recovery (p = 0.021) phases (Fig.3). During the recovery phase, following exposure to the 12 combinations of different rose-colored and scented landscapes, the β/α and θ/β ratios significantly decreased compared with the stress phase. This indicates a marked improvement in participants' stress levels and a notable increase in their attention levels.
② In the paired sample t-test analysis results, letters a and b indicate statistical significance—same letters between groups indicate no significant difference (p > 0.05), while different letters indicate significant difference (p < 0.05).
③ The significance values used in this study were based on the median.
4.1.1 Stress-Related Indicators
Covariance analysis of the β/α ratios in the four brain regions showed a significant main effect④ of color in the parietal (p = 0.011), occipital (p = 0.023), and frontal (p = 0.026) regions, but no significant effect in the temporal region (p = 0.080). Specifically, the orange series exhibited the highest β/α ratios in the parietal (M = 0.687), occipital (M = 0.705), and frontal (M = 0.738) regions, while the white color had the lowest β/α ratios in the occipital (M = 0.501) and frontal (M = 0.559) regions. The blue-violet color also displayed lower β/α ratios in the occipital (M = 0.523) and frontal (M = 0.567) regions (Fig.4). These results suggest that white and blue-violet roses are more effective in alleviating stress. However, the main effect of fragrance was not significant in the occipital, frontal, or temporal brain regions (p > 0.05), with only a significant main effect found in the parietal region (p = 0.031). In particular, FR (M = 0.621) had a significantly higher β/α ratio than FF (M = 0.548) (Fig.4), suggesting that the latter fragrance is more effective in relieving stress. Furthermore, no significant interaction effects were found between color and fragrance type in any brain regions (p > 0.05), indicating no notable interaction between these factors in terms of stress indicators.
④ In the main effect analysis results, letters a and b indicate statistical significance—same letters between groups indicate no significant difference (p > 0.05), while different letters indicate significant difference (p < 0.05).
4.1.2 Attention-Related Indicators
Covariance analysis of the θ/β ratios showed no significant main effect of fragrance in any of the four brain regions (p > 0.05), but a significant main effect of color was found in all regions (p = 0.029, p = 0.014, p = 0.021, and p = 0.017, respectively). Interaction effects between color and fragrance were significant in the occipital (p = 0.010) and temporal (p = 0.036) regions. The color analysis showed that the red color had the lowest θ/β ratios across all regions, while the blue-violet color had the highest (Fig.5), indicating that red roses are most effective in restoring attention. Simple effects analysis⑤ of the significant interactions revealed the following results: 1) In the occipital region, FR with the orange color had significantly higher θ/β ratios than FF, with no significant difference between the two fragrances in other colors (Fig.6). In the FR condition, the blue-violet color had the highest θ/β ratios, but the red color had the lowest; while under FF, the blue-violet color had the highest and the yellow had the lowest (Fig.6). In the temporal region, FR with the orange color had significantly higher θ/β ratios than FF (Fig.7). Under FR, the orange color had the highest θ/β ratios, but the red had the lowest; while under FF, the blue-violet color had the highest and the orange had the lowest (Fig.7). These results suggest that yellow and orange colors with FF, and red color with FR, are more effective in enhancing attention.
⑤ In the simple effects analysis results, letters a and b indicate statistical significance—same letters between groups indicate no significant difference (p > 0.05), while different letters indicate significant difference (p < 0.05).
4.2 Psychological Recovery Benefits of Visual-Olfactory Perception
The paired t-test results for the POMS indicators during the stress and recovery phases showed significant changes in tension (p = 0.025), anger (p = 0.015), fatigue (p = 0.011), depression (p = 0.035), energy (p = 0.042), panic (p = 0.033), self-esteem (p = 0.036), as well as positive emotion score (p = 0.039), negative emotion score (p = 0.022), and total mood disturbance score (p = 0.019) before and after the experiment (Fig.8). During the recovery phase, following visual-olfactory stimulation with rose-colored and scented landscapes, participants exhibited a significant increase in positive emotions, while negative emotions and total mood disturbance showed a decreasing trend.
Covariance analysis of the POMS emotional indicators across different visual-olfactory interaction groups revealed no significant differences between the FR and FF types for three emotional indicators (p > 0.05). However, a significant main effect of color was found for self-esteem and energy (p = 0.010), along with a significant interaction effect between color and fragrance type (p = 0.013). As shown in Fig.9, the blue-violet color induced the lowest positive emotion scores, while the red and yellow colors induced the highest positive emotion scores. Simple effects analysis of the significant interaction effect for positive emotions revealed the following results. 1) In the orange color, FF induced significantly higher positive emotion scores than FR, whereas the reverse was observed in the red color. No significant differences were found between the two fragrance types in other colors (Fig.10). 2) In the FR type, the red color induced the highest positive emotion scores, while the orange color induced the lowest. In the FF type, the yellow color induced the highest positive emotion scores, while the white and blue-violet colors induced the lowest.
In conclusion, different colors, fragrance types, and their interactions had varying degrees of impact on participants' mental and physical health indicators, including stress, attention, and emotional states.
5 Conclusions and Discussion
This study, based on the perspective of visual-olfactory interactive perception, explored the restorative benefits and differences experienced by participants when exposed to different color and fragrance combinations of rose landscapes. The findings provide scientific evidence on how the appropriate pairing of colors and fragrances in rose landscapes can maximize the health benefits. The results showed significant differences in stress reduction, attention recovery, and improvement of emotional health among various combinations. The main conclusions are as follows.
1) Visual-olfactory perception of rose landscapes generates positive restorative effects. The experimental results demonstrated positive changes in participants' mental health indicators when exposed to different color and fragrance combinations in rose landscapes. Specifically, the β/α ratio, which represents stress levels, significantly decreased, and the θ/β ratio, representing attention levels, also showed a significant reduction. The POMS results revealed a significant increase in positive emotions and a decrease in negative emotions. According to the Stress Reduction Theory, humans have evolved with a long-term dependence on natural environments, and a pleasant natural setting (such as beautiful plant landscapes) can activate parasympathetic nervous activity, significantly relieving mental stress and promoting emotional relaxation
[61]. The Attention Restoration Theory suggests that natural environments, characterized by features such as "being away, " "fascination, " "extent, " and "compatibility, " help enhance cognitive function and attention levels
[66]. Previous research has also confirmed the positive health benefits of flowering plants
[67]. Therefore, the visual stimulation from the rich colors of roses, combined with the olfactory stimulation from their pleasing fragrances, can improve well-being, reduce sympathetic nervous activity, alleviate stress, and promote attention recovery.
2) Cool-toned and fruity-scented roses relieve physiological stress more effectively. The findings showed that white and blue-violet roses induced lower β/α ratios in the parietal, occipital, and frontal lobes, suggesting that these colors, compared with warmer colors like red and orange, are more effective in improving the brain's stress response. Similarly, roses with FF showed a lower β/α ratio in the parietal region compared to those with FR, demonstrating stronger stress relief effects. Existing studies have also found that white and blue flowers are most effective in relieving tension and stress
[68], which aligns with the results of this study. Additionally, research on the effects of rose essential oils on emotions showed that rose oils can effectively reduce anxiety and improve sleep quality among healthcare workers
[69]. In this study, FF roses were found to alleviate stress more effectively than FR roses, possibly due to the presence of volatile substances like hexyl acetate, which have a calming effect and significantly promote relaxation
[70].
3) Warm-toned roses and their combinations with both fragrances enhance attention recovery and positive emotions
. According to the results of this study, the red color generated the lowest θ/β ratio across four brain regions, indicating that red roses are the most effective for attention recovery. Moreover, interaction results revealed that combinations such as red–FR, yellow–FF, and orange–FF significantly enhance attention recovery. Relevant studies suggest that red plants can activate brain regions that control attention and focus, making them particularly effective for improving attention levels
[71] [72]. Yellow flowers, by enhancing relative Theta power spectrum in the occipital region, can also effectively improve attention and boost pleasant feelings
[71]. Additionally, the fragrance of roses contributes to the enhancement of Beta waves, creating an environment conducive to concentration and calmness
[73]. As previously mentioned, the interaction between visual and olfactory stimuli affects perceptual preferences and attention, which explains the outstanding performance of the red-FR combination in attention recovery.
The POMS results showed that red and yellow roses produced the highest scores for positive emotions. Interaction results indicated that the red–FR and yellow–FF combinations produced higher positive emotion scores than other combinations. This is consistent with many studies. For example, an experiment on the association between emotional words and colors found that the color of yellow was most frequently linked to positive emotions, while red was associated with passion
[74]. Another study on the effects of different colored cut flowers on psychological states reported that red flowers elicited feelings of "intensity" and "vitality, " while yellow flowers were associated with "warmth" and "energy"
[75]. After exposure to red and yellow flowers, participants showed a significant increase in parasympathetic nervous activity and positive emotional states such as energy
[76]. Furthermore, a study found that after 4 min of exposure to pink roses, the high-frequency components of participants' heart rate variability significantly increased, and their comfort levels noticeably improved
[77], which aligns with the findings of this study. Some scholars have pointed out that color not only influences the pleasantness of a fragrance but also activates corresponding olfactory images, often involving a blend of all scents associated with that color. For example, yellow is commonly associated with the scent of lemon, i.e. the fragrance that matches this color the most dominates the perception, while combinations that contradict sensory expectations are less pleasant
[78]. Therefore, color and fragrance combinations that align with sensory expectations tend to elicit positive emotional responses.
4) Color has a greater effect on attention and positive emotions than fragrance. In this study, the main effects of colors on the θ/β ratios and positive emotion scores were significant, while those of fragrance were not. This suggests that in rose landscapes, color has a much greater impact on attention and positive emotions than fragrance. Related studies have found that visual stimuli from Osmanthus landscapes have a more pronounced effect on sympathetic nervous activity than olfactory stimuli, meaning that viewing Osmanthus flowers is more effective in promoting attention recovery and arousing emotions than smelling the flowers
[79]. This difference supports the view that vision is the primary sensory channel for receiving environmental information
[80].
In planning and designing rose landscapes, it is recommended to prioritize sensory experiences, including visual and olfactory perceptions, and tailor designs to specific health needs to maximize the therapeutic value of rose gardens. Based on the analysis results of main and interaction effects together with practical applications of roses, it is suggested to increase the proportion of white, blue-violet, and FF roses in spaces for rest and meditation, while strategically incorporating yellow–FF roses to create floral corridors, pergolas, and archways that help relieve stress and soothe emotions. Alternatively, rose pathways can be designed through patch or mass planting, with seating provided for meditation and relaxation. For spaces requiring focus, vitality, and creativity, red and yellow roses should dominate, where the FR and FF varieties should be appropriately combined. These can be used to create flowerbeds and borders. Another option is to plant tree-shaped roses in rows to form a fragrant plant barrier, fully utilizing the attention-enhancing and emotional awakening benefits of such landscapes. Additionally, fountains and other dynamic water features can be added to these spaces to diffuse fragrances across a broader area through evaporation, thus enhancing the aromatherapy effects.
6 Limitations and Future Directions
Despite the valuable findings, this study has several limitations. Firstly, regarding the experimental design, landscape images combined with fresh flowers were used to simulate the environment, which may differ from real-world experiences. Therefore, future research could consider using virtual reality technology to create more realistic landscape experiences. Secondly, this study focused on university students as participants, lacking a comparative study of different age groups. Future research should evaluate individuals from various age groups, educational backgrounds, and cultural contexts to broaden the applicability of the results. Previous research has pointed out that the intensity of visual and olfactory stimuli varies with the duration of exposure: initially, vision predominates, while the olfactory effect is weaker; but as exposure time increases, the impact of olfaction gradually strengthens
[28]. This study only examined the immediate effects during the stress and recovery phases (both lasting 3 min), for which future studies can explore the long-term restorative effects or the sustained recovery processes. Finally, this study only observed the immediate effects of roses during their peak blooming period. Given that the flower shapes, colors, and fragrance compositions of roses differ at various growth stages, further research should focus on their long-term restorative effects across different growth cycles, and delve deeper into the mediating effects and interaction mechanisms to derive conclusions that are more widely applicable.
PDF
(4711KB)
