No abstract

The aim of the present study was to evaluate the effect of different levels of mineral nutrient availability on development and physiological performance of several common indoor ornamental plant species (Anthurium sp., Chlorophytum comosum, Epipremnum aureum, Plectranthus fruticosus, Spathiphyllum sp., and Tradescantia pallida) cultivated in hydroponics with potential use in active botanical biofilter systems. Plants were grown in expanded clay granules at four levels of mineral nutrient availability provided by two types of commercial mineral fertiliser. The growth stimulative effect of increased mineral nutrient availability depended on plant growth rate, with a lower effect on slower growing species. The need for nutrients increased in the order Anthurium < Spathiphyllum < Epipremnum < Chlorophytum < Tradescantia < Plectranthus. Tissue water content showed pronounced differences between various plant species as well as between plant organs. For several species, increase in mineral nutrient availability resulted in a significant increase in tissue water content. Chlorophyll fluorescence analysis showed that indoor plants can successfully adapt to low and moderate mineral fertiliser levels with balanced individual nutrient rates, without negative consequences to photochemistry of photosynthesis. Consequently, indoor plants can be cultivated at a relatively low concentration of mineral nutrients for optimum utilisation in active botanical biofilter systems.

Recently the modern green wall (GW) systems with active air circulation, higher plants and optimized growth media are becoming increasingly more efficient for indoor air biofiltration. However, the functioning mechanisms of these complex systems are still poorly investigated. This study was focused on the activity of biofilm on the ceramic granules, which has been developed in the experimental GW within four months under realistic office conditions. Microbial abundance on the surface of ceramic granules has been evaluated by the number of culturable heterotrophic bacteria, as well as enzyme activity, i.e., fluorescein diacetate (FDA) hydrolysis and potential ammonium oxidation (PAO). Different pre-treatment types of granules, i.e., grinding and sonication, showed significant (p<0.05) differences in FDA and PAO activities. The microbial activity of biofilm derived from the surface of ceramic granules in pots with Epipremnum aureum placed on the 1 st , 3 rd , 5 th , 7 th and 9 th height levels, did not exhibit a linear dependence on the height. Particularly, the FDA hydrolysis on the granule surface varied in the range from 167.4 µg/g on the 3 rd level up to 463.9 µg/g on the 1 st level. Contribution of the GW to the concentration of airborne microorganisms in the air was found to be negligible. Further experiments will be focused on the GW performance in terms of biodegradation of volatile organic compounds.