Effects of indoor CO2 concentration, temperature, humidity and light variation on volatile organic compounds released by Plectranthus hadiensis var. tomentosus

The aromatic odor of Plectranthus hadiensis var. tomentosus has been found to have the potential to improve physical and mental health of people in indoor environment, but its effectivess is reduced for that the release of volatile organic compounds from plants is susceptible to indoor environmental changes. The purpose of this study was to investigate the response of volatile organic compounds released by P. hadiensis var. tomentosus to common indoor environmental changes, and to provide a scientific basis for its efficient and sustainable application in building a comfortable pro-biotic environment to improve the physical and mental health of indoor personnel. Thus, the effects of four typical indoor environmental factors, such as air temperature, air relative humidity, CO2 concentration and light variation, on the release of volatile organic compounds from P. hadiensis var. tomentosus were investigated in this study. And the dynamic headspace and gas chromatography-mass spectrometry techniques were used to analyze the volatile organic compounds in different indoor environments with an environmental control device based on mixed-level orthogonal array design. The results were as follows: (1) Among the four typical indoor environmental factors of air temperature, air relative humidity, CO2 concentration and light condition, CO2 concentration and air temperature had greater effects on the release of volatile organic compounds from P. hadiensis var. tomentosus, while the effects of air relative humidity and light were weak. (2) For P. hadiensis var. tomentosus cultivated under normal photoperiod, an environmental condition with CO2 concentration of 500 μmol·mol-1, air temperature of 25℃ and air relative humidity of 60% was the most suitable for releasing volatile organic compounds from P. hadiensis var. tomentosus in the absence of light. Under this environmental condition, the total amount of volatile organic compounds released by P. hadiensis var. tomentosus was 86.23 μg·L-1·kg-1, and the content of biological active components with potentials for the positive intervention of physical and mental health was 78.03 μg·L-1·kg-1. In summary, the results suggest that when the aroma plant P. hadiensis var. tomentosus is used to build an indoor pro-biotic environment to maintain or improve the physical and mental health of people in indoor, the environmental conditions should be controlled properly, especially CO2 concentration and air temperature, so as to fully and efficiently produce the positive health benefits from P. hadiensis var. tomentosus.