Visual characteristics (e.g., the color and shape) of ornamental plants can significantly affect their beneficial influence on humans. Prior research, however, has largely focused on the effects of the color or shape of flowers and the impact of differences in the visual appearance of foliage plants and plants with ornamental stalks has not yet been fully explored. This study examined the psychophysiological effects of urban ornamental bamboos that expressed different colors on different organs. Three hundred Chinese college students participated in the experiment. They were randomly assigned to view images of five ornamental bamboo landscapes with the following different visual characteristics: green stalks (GS) non-green stalks (NGS) multicolored stalks (MS) green leaves (GL) and multicolored leaves (ML). Before and after viewing the images, their EEG, blood pressure, pulse, profile of mood states (POMS) score, and state-trait anxiety inventory (STAI) score were measured. The results showed that ornamental bamboo landscapes have extremely significant beneficial psychophysiological effects as compared to urban landscapes. After viewing landscapes in the NGS and MS groups, EEG, blood pressure, and pulse rate of subjects showed more beneficial changes. Significant gender differences were observed only in systolic blood pressure and in the vigor score. In addition, an extremely significant interaction between color and organ of color expression was observed on systolic and diastolic blood pressure. Organ of expression had significant main effects on all the physiological indicators and the fatigue, vigor, and irritability scores, while color only had a main effect on systolic blood pressure. Our study concluded that viewing urban ornamental bamboo landscapes with different visual characteristics has different effects on humans. With regards to ornamental bamboo, the organ expressing the color had a greater impact on psychophysiological responses than did the type of color itself. These study results can provide guidance for landscape construction of urban greening.
Keywords: color variation; organ expression; ornamental plants; physiological and psychological responses; urban greening.