摘要：
Environmental simulation system is an effective way to study the response of agro-ecological system to global change.However,current atmospheric carbon dioxide (CO2) enrichment simulation systems have some limitations,including excessive CO2 gas consumption,high experimental cost,disparity between the simulated and the natural environments,space limitation,lack of replications.To address these problems,we upgraded the hardware and improved the design of the CO2 concentration and temperature gradient chambers (CTGCs) that control CO2 gas to release accurately and cost-effectively to improve the simulation of future elevated CO2 concentration environment.Besides,the improved CTGCs was more spacious,which allowed the growth of more crop species simultaneously.In this system we used a set of electromagnetic valves and an individual CO2 concentration infrared sensor to constitute a multi-passageway CO2 concentration monitoring system for real-time monitoring of the change in CO2 concentration.A proportional pressure reducing regulator valve was also deployed at the source of CO2 gas emission.This effectively reduced the pressure storing in the gas pipeline when CO2 was compressed and released from the gasholder,which resulted in accurate CO2 gas emission.The pipeline consisted of head and peripheral branch tubes which were connected to the flux regulating valve.The equipment changed the CO2 gas emission from longitudinal to lateral emission.The above changes form an evenly-distributed CO2 gas released area in the improved CTGC system.The improved CTGC system achieved CO2 concentrations of 387±4.5,441±13.4,490±20.9,534±24.3 and 567±28.9μmol·mo1-1.The system improved effectively the response to environmental change,performed accurately real-time monitoring the change in CO2 concentration in every treatment of the chamber,and released precisely CO2 gas to maintain the targeted CO2 concentration gradient in a stable and continuously manner.In summary,the improved CTGC system would be a better system for studying the responses of plants to CO2 enrichment.%环境控制模拟系统,是开展农田生态系统对全球气候变化响应研究的有效手段,但目前应用于试验中的模拟系统均存在一定局限,如CO2气体过量消耗、试验成本较高、模拟的试验环境与真实的自然环境差异较大、试验空间有限、不易重复等.针对这些问题,本研究对半开放式CO2浓度和温度递增模拟系统(CTGC)进行了硬件升级和设计改进,针对其CO2浓度的控制效果包括CO2浓度监测、CO2气体释放两大系统进行改进,使其能达到精准控制CO2气体释放,降低试验成本,精确模拟未来高CO2浓度的生产环境,其空间面积较大,适合多种作物同时试验.改进后的系统利用电磁阀组和CO2浓度检测传感器组成的多通道监测系统,实时检测各处理区域内的CO2浓度,实现精准监测.在CO2气体释放源端,采用比例调节式减压器,有效减少了CO2从储气罐中被减压后在气体管路中的压力积蓄,控制CO2气体精量释放;系统将CO2释放方式由纵向改为横向,释放管道由主管加支管组成,由控制流量调节阀将主管与支管相连接,使气室内形成均匀的CO2释放区域,从而达到CO2浓度梯度升高的模拟效果.试运行结果表明,改进后的CTGC系统可以实现CO2浓度387±4.5、441±13.4、490土20.9、534±24.3和567±28.9μmol.mo1-1的梯度递增,系统对环境变化的响应速度加快,能够精确实时监测气室内各处理区域CO2浓度的变化,并实现CO2气体的精量释放;系统内的CO2浓度梯度递增趋于稳定,从而更好地模拟大气CO2浓度逐渐升高的过程,满足作物对气候变化响应研究的需要.
