Studies On BVOCs Emission Of Garden Broadleaf Tree Species In Eastern Subtropical Region

Garden plants are an indispensable part of the urban ecological environment and play an important role in improving the environment,purifying the air and maintaining the ecological balance.In order to clarify the emission characteristics and composition of BVOCs in common broad-leaved landscaping tree species in the eastern subtropical region,and combining the BVOCs emissions of tree species after mechanical damage to explore the relationship between plant BVOCs emissions and biological characteristics,habitat adaptability and photosynthetic productivity for tree species,which provided a theoretical basis for the complex evolution of garden tree species BVOCs and provided data support for future scientific research.In this study,gas adsorption sampling was used to determine 45 common landscaping trees in Zhejiang Province by TD-GC-MS mass spectrometry.The following conclusions were obtained:（1）The emission of BVOCs from the common broad-leaved landscaping tree species in the eastern part of the northern subtropical region is mainly composed of isoprenoids,and its emissions have obvious regional characteristics.The more type of BVOCs emitted by plants,the higher its emission rate.After mechanical damage,the emission rate of plant BVOCs generally increased.Among them,the relative emission ratio of BVOCs of Cinnamomum camphora reached the maximum of all species,which was 84.02%.GLVs increased significantly,accounting for 55.97%of BVOCs composition.（2）Monoterpenes and aroma emissions have similar changes with leaf water content（LWC）,single leaf area（A_L）and leaf dry mass per unit area（LMA）.Correlation analysis showed that the isoprenoid emission rate was linearly correlated with LWC and LMA,respectively.Aromatic compounds are accompanied by monoterpenes and are linear positive correlations.The evergreen leathery tree species are mainly composed of aromatic compounds and monoterpenes,and the papery leaf tree species are the main isoprene emitters.From the habitat adaptability of tree species,the light species,thermophilic species and drought-tolerant species mainly emit isoprene,and the moisture-resistant species and shade-tolerant tree species are the main sources of aromatic compounds.（3）Different isoprenoids emission tree species have different photosynthetic parameters.From a single species,the net photosynthetic rate（P_n）was linearly positively correlated with the emission rates of isoprene（Chimonanthus praecox）,monoterpene（Michelia chapensis）and sesquiterpenes（Machilus pauhoi）,respectively.Machilus pauhoi has higher maximum net photosynthetic rate（P_n）,transpiration rate（T_r）,dark respiration rate（R_d）,and maximum carboxylation rate(V_cmax)of Rubisco enzyme.Koelreuteria bipinnata var.integrifoliola has the highest light saturation point（LSP）and low light compensation point（LCP）,therefore,Koelreuteria bipinnata var.integrifoliola has a wide light environment adaptability.Michelia chapensis has the highest maximum electron transfer rate(J_max),and it J_max/V_cmax ratio is the highest,which indicates that Michelia chapensis V_cmax is limited,and its light energy utilization rate is the lowest.Combined with Michelia chapensis LSP,we speculate that it may be as the optical system is suppressed,resulting in its carbon assimilation efficiency is too low.（4）Cluster analysis showed that BVOCs emissions of different tree species showed obvious classification signals,and species characteristics also had partial effects.Although this relationship is weak,it has an impact on the evolution of plant BVOCs.We suspect that plants have produced a degree of differentiation during long-term evolution.In summary,the emission capacity and species of plant BOVCs have undergone a certain degree of differentiation.The factors affecting the emission of BVOCs in plants are not single,but from the perspective of plant kinship,the influence of external factors on plant BVOCs emissions seems to be greater than the plant itself.Regardless of the changes in the emission capacity and species of plant BVOCs,there are certain commonalities in the defense strategies of plants against external damage.