Laboratory experiments and quasi-experimental field studies have documented beneficial effects of indoor plants on outcomes such as psychophysiological stress, task performance, and symptoms of ill health. Such studies have taken an interest in the value of indoor plants in work settings, but they typically have not considered how the effects of plants might compare with effects of other workplace characteristics. The present study makes an initial attempt to situate the potential benefits of indoor plants in a broader workplace context. With cross-sectional survey data from 385 Norwegian office workers, we used hierarchical regression analyses to estimate the associations that plants and several often-studied workplace factors have with perceived stress, sick leave, and productivity. Other variables included in our models were gender, age, physical workplace factors (e.g., noise, temperature, lighting, air quality), and psychosocial workplace factors (demands, control, social support). After controlling for these variables, the number of indoor plants proximal to a worker's desk had small but statistically reliable associations with sick leave and productivity. Although small, such associations can have substantial practical significance given aggregation over the large number of office workers over time.
Effects of an indoor plant intervention in a Norwegian rehabilitation center were assessed in a quasi-experiment. During a 2-year period, coronary and pulmonary patients (N = 282) completed self-report measures of health, subjective well-being, and emotion on arrival, after 2 weeks, and at the end of a 4-week program. The intervention involved the addition of indoor plants for the second year. On average, patient physical and mental health improved during the program, but the addition of plants did not increase the degree of improvement. Subjective well-being did, however, increase more in patients who went through their program after the addition of plants, although the effect was only apparent in the pulmonary patients. The patients reported more satisfaction with indoor plants and the interior generally after the intervention. Room for the intervention to affect outcomes may have been limited by the well-designed interior and the center's location in a scenic mountain area, but these favorable features of the context apparently did not negate the potential for indoor plants to contribute to patient well-being.
The role of phytochrome in control of stem elongation by daily temperature alternations is unclear. The aim of this work was to study the involvement of phytochrome B in thermoperiodism in cucumber (Cucumis sativus L.), and the interaction with gibberellin (GA). The wild type and the phytochrome B deficient, long-hypocotyl (lh) cucumber mutant were grown under alternating day (DT) and night temperature (NT) and either with or without an exposure to end-of-day far-red light (EOD-FR). Without EOD-FR, hypocotyl and internodes of the wild type plants were shorter under a low DT (19 °C)/high NT (25 °C) (negative DIF) compared with a high DT/low NT regime (positive DIF), while the number of leaves was reduced by 12%. EOD-FR enhanced elongation of hypocotyl and internodes. However, EOD-FR reduced the effect of alternating temperature on hypocotyl elongation. The lh cucumber mutant did not respond to EOD-FR treatments, but internode length was slightly increased by positive compared with negative DIF. The results suggest that phytochrome B is required for a maximum effect of daily temperature alternations on stem elongation in cucumber. Additional GA4 reduced the difference between positive and negative DIF, but it had a minor effect only on the difference between EOD-FR and EOD red light (EOD-R) in the wild type. Plants depleted for endogenous GA by the GA biosynthesis inhibitor paclobutrazol, did not respond at all to DIF or EOD treatments. When seedlings were treated with prohexadione-calcium, which blocks both biosynthesis and inactivation of GA4, response to applied GA4 was enhanced by EOD-FR. The present results suggest that, in cucumber, EOD-FR, and probably also positive DIF, enhances tissue sensitivity to GA4. In addition, catabolism of GA4 can be enhanced by negative DIF.