Quantifying variabilities in monoterpene emission among natural individuals of an urban-greening species (Quercus phylliraeoides) using a rapid measuring method

Abstract

Quercus phillyraeoides, a strong monoterpene-emitting species, is widely planted in urban and suburban areas in Japan. Urban-greening plants with terpenoid emission may affect air quality by increasing photochemical oxidants through the reaction between their terpenoid emissions and urban gases. In mitigating this issue, replacing the original plants with low-emitting variants can be a workable approach without substantially altering the original landscapes and ecotopes. This study aimed to identify the low- or non-emitting variants among Q. phillyraeoides. To deal with a large number of Q. phillyraeoides samples, a method using detached leaves was adopted and optimized for observation of terpenoid emission rates from Q. phillyraeoides. The testing showed that the emission rate would be relatively stable at approximately 40 min of incubation under a photosynthetic photon flux density of ∼1000 μmol m–2 s–1 and a surrounding temperature of 30°C. Although the emission rates were different from those derived using the conventional method (i.e., the leaf cuvette method), they were well calibrated, with a regression line between the datasets of the two methods. We used this method to inspect the monoterpene emission rate from Q. phillyraeoides in multiple locations in Shizuoka Prefecture and detected a variability in the monoterpene emission rate (no detection to 14.8 nmol m–2 s–1), which were independent of environmental effects for each location. The Q. phillyraeoides individuals with no emission of monoterpenes are expected to be suitable for propagation as non-terpenoid-emitting greening materials.