臭氧胁迫对两种榕树幼苗BVOCs释放的短期影响

Short-term effects of ozone stress on BVOCs emissions from two Ficus seedlings

为探究短期臭氧胁迫对植物源挥发性有机物(BVOCs)释放的影响,以一年生黄葛树(Ficus virens)和雅榕(Ficus concinna)幼苗为对象,通过开顶式气室(OTC)进行3种处理:对照组(常规大气O_(3)浓度)、低浓度组(常规大气O_(3)浓度加40 nmol·mol^(-1))和高浓度组(常规大气O_(3)浓度加80 nmol·mol^(-1))。运用热脱附与气质联用技术对榕树幼苗释放的BVOC进行分离鉴定,并使用单因素方差分析和Pearson相关系数等进行数据统计与分析。结果表明:除低浓度O_(3)对两种榕树幼苗地上和地下含氧单萜(OTs)的释放有显著促进外,其他各类BVOCs释放速率在受到短期O_(3)胁迫后均显著降低;光合参数与各组分BVOCs释放速率相关性各异,净光合速率(Pn)、气孔导度(Gs)等是影响地上BVOCs释放的主要影响因子,Pn与土壤呼吸速率(Rs)则是地下BVOCs释放的主要影响因子;在大部分处理时,以BVOCs形式排放的碳与光合作用同化的碳的比例(BVOC-C损失比)显著降低,仅在低浓度O_(3)胁迫后黄葛树幼苗地上BVOC-C损失比例升高。本研究结果可以揭示两种榕树幼苗对O_(3)胁迫的响应和BVOCs释放的变化规律,对了解环境空气质量变化下榕树BVOCs释放的变化特征和响应机制,评估城市重点区域绿地环境空气质量具有重要意义。

Biogenic volatile organic compounds(BVOCs)play crucial roles in atmospheric chemistry and biosphere-atmosphere interaction.They will be affected by various environmental factors including ozone.Changes in tropospheric O_(3) concentration caused by global climate change will lead to unknown changes in BVOCs emissions.In order to reveal the short-term effect of O_(3) concentration change on BVOCs emissions and explore the relationship between BVOCs emissions and photosynthetic parameters,1-year-old seedlings of Ficus virens and Ficus concinna were treated through open top chamber(OTC)with O_(3) at three atmospheric concentrations in an ozone fumigation experiment,including normal atmospheric concentration of O_(3) as control group,normal atmospheric concentration plus 40 nmol·mol^(-1) of O_(3) as low concentration group,and normal atmospheric concentration plus 80 nmol·mol^(-1) of O_(3) as high concentration group.The BVOCs emissions from Ficus seedlings were isolated and identified by thermal desorption and GC-MS,and the data were statistically analyzed by one-way ANOVA and Pearson correlation coefficient.The results showed except that the oxygenated monoterpenes(OTs)emissions were significantly promoted by the low O_(3) concentration group in the above and under the ground of the seedlings of two Ficus species,the other components of BVOCs emissions significantly decreased after the short-term O_(3) stress.Photosynthetic parameters had different correlations with the emission rates of each component of BVOCs.Net photosynthetic rate(Pn)and stomatal conductance(Gs)were significantly positively correlated with the above ground BVOCs emissions,while Pn and soil respiration rate(Rs)were the major factors affecting the underground BVOCs emissions.In most cases,the ratio of carbon emitted as BVOCs to that assimilated by photosynthesis(the ratio of BVOC-C loss)of the seedlings of two Ficus species were significantly reduced.Only after low concentration of O_(3) stress,the ratio of BVOC-C loss of the above ground F.virens seedlings increased.This experiment revealed the response of Ficus seedlings under O_(3) stress and the changing rules of BVOCs emissions,which is of great significance to understand the change characteristics and response mechanisms of BVOCs emissions from Ficus seedlings under changes of environmental air quality,and to evaluate the change characteristics in the environmental quality of green spaces in key urban areas.