鲁西北平原冬小麦田臭氧浓度变化特征及对产量的潜在影响和机理分析

Variation of ozone concentration of winter wheat field and mechanistic analysis of its possible effect on wheat yield in Northwest-Shandong Plain of China

近地层高浓度臭氧(O3)对农作物生长和产量形成有明显的影响。利用在中国科学院禹城综合试验站(山东省)冬小麦(Triticum aestivum)农田生态系统上观测的O3浓度及微气象资料,分析了鲁西北平原冬小麦农田生态系统O3浓度的日变化和季节变化规律,在此基础上初步分析了O3浓度与CO2通量(Fc)的关系,并用欧洲和美国科学家在实验室得到的O3浓度-冬小麦产量关系模型估算了O3对冬小麦产量的潜在影响。结果表明:O3浓度存在明显的日变化规律,日最小值和最大值分别出现在7:00和16:00左右。整个观测期间(2011年3-5月)平均O3浓度为(30.4±20.1)nL·L-1(平均值±标准误差);30min平均浓度的最大值为93.1nL·L-1。在冬小麦春季生长季节,O3浓度日平均值呈现逐步增加的趋势,O3浓度日均增加约为0.17nL·L-1·d-1;白天7h和12h平均浓度(M7和M12)分别为45.7和43.1nL·L-1;O3浓度超过40nL·L-1的3个月累积值(AOT40)为9.8μL·L-1·h;超过60nL·L-1的O3浓度累积值(SUM06)为12.6μL·L-1·h;经过权重修正的O3污染指标W126为10.1μL·L-1·h。在高浓度O3(>60nL·L-1)情况下,CO2通量与O3浓度呈现负相关关系,鲁西北平原O3对冬小麦光合作用影响的阈值取60nL·L-1比较合适,该值高于欧洲国家普遍采用的40nL·L-1。基于以上结果,初步估算得出:在目前的O3浓度水平下,鲁西北平原近地层O3可能会使冬小麦产量减少5.2%-8.8%。

Aims High near-surface ozone （O3） has adverse effects on crop growth and yield.Our objective was to analyze the potential impact of O3 concentration on winter wheat yield,the magnitude and change characteristic of O3 concentration over a winter wheat field and the relationship between CO2 flux and O3 concentration.Methods The research site was a winter wheat field at the Yucheng Experimental Station （Shandong Province） of the Chinese Academy of Sciences.We observed O3 concentration with a portable ozone analyzer.We simulta-neously measured micrometeorological and radiation factors such as air temperature,humidity,wind speed and global and net radiation.All data were recorded with a high frequency data-logger and averaged every 30 min.Important findings There was a diurnal change pattern in O3 concentration,with low and high mean O3 concen-trations at about 7：00 and 16：00,respectively.Mean O3 concentration was （30.4 ± 20.1） nL·L-1 （mean ± SE）,and the maximum of the 30 min-averaged O3 concentration was 93.1 nL·L-1.During wheat spring growing season （1 March to 31 May,2011）,mean O3 concentration increased 0.17 nL·L-1·d-1.Daytime 7-hour and 12-hour mean O3 concentration （M7 and M12） were 45.7 and 43.1 nL·L-1,respectively.Accumulated O3 concentration above the threshold of 40 nL·L-1 （AOT40） was 9.8 μL·L-1·h.Accumulated O3 concentration above 60 nL·L-1 （SUM06） was 12.6 μL·L-1·h.Weight-corrected O3 concentration accumulation （W126） was 10.1 μL·L-1·h.When O3 concentra-tion is high （i.e.,60 nL·L-1）,there is an inverse relationship between CO2 flux and O3 concentration.It implied that the threshold of O3 concentration should be about 60 nL·L-1,which is higher than the 40 nL·L-1 threshold widely applied by European scientists.By using yield-response models to O3 concentration obtained in open-top chambers （OTC） by European and USA scientists,winter wheat yield is potentially decreased about 5.2%-8.8% at the current O3 level in Northwest-Shandong Plain.