基于气孔导度和臭氧吸收模型的冬小麦干物质累积损失评估

为深入了解地表臭氧(O3)增加对冬小麦的伤害,利用开顶式气室(OTC)开展了大田试验,综合分析了不同生育期温度、光照、水汽压差等环境变量的变化,以及生育期差异和O3胁迫的影响,利用Pleijel等2007年修正的Jarvis型气孔导度阶乘模型,计算了冬小麦气孔导度的变化,并与冬小麦扬花期测定的日气孔导度变化进行了比较,表明该模型适用于本地O3增加对冬小麦影响的评估。同时,根据O3吸收通量模型,计算冬小麦的O3日吸收通量大于6nmol.m-2全生育期的累积吸收通量AFst06,并建立其与冬小麦全生育期干物质累积损失响应的关系模型,分析结果表明,在整个O3熏期期间的150nL.L-1和100 nL.L-1处理的AFst06与冬小麦不同生育期的干物质累积相对值的决定系数分别为0.91和0.93(P0.01),存在显著的相关关系,当AFst06增加10mmol.m-2,150nL.L-1和100nL.L-1处理组与对照相比,其干物质累积分别损失16.41%和13.23%。此外,讨论了O3胁迫下不同评估方法的优劣和通量响应评估模型的优势,以及不同水汽压差(VPD)等环境条件对气孔导度和O3吸收通量的影响。

Assessment of loss of accumulated dry matter in winter wheat based on stomatal conductance and ozone uptake model

To in-depth understand the injury of increased ozone concentration at surface to winter wheat, the Open-Top Chamber(OTC) is used to make field experiment, in which investigated are temperature, sunshine duration and vapor pressure difference (VPD) in various phases of growth, together with their difference in stages and impacts of ozone stress explored. Change in stomatal conductance are calculated by means of the Jarvis-type factorial model of stomatal conductance improved by Pleijel et al.(2007) and the calculation if compared with the daily variation in conductance in the flowing stage. Results show that the model is applicable to the assessment of the effects of local ozone increase upon winter wheat. Besides, the model of ozone absorption flux is utilized to compute the accumulative uptake flux AFst06 for the whole growth periods at daily ozone absorption flux higher than 6nmol·m-2, which is used to construct its relationship with the response to the loss of dry matter accumulated during the entire growth/development stage. Analysis suggests that the coefficient of determination is 0.91and 0.93(P<0.01) between AFst06 treated by 150nL·L-1 and 100nL·L-1 during the O3 smudging and the relative value of dry matter accumulation in winter wheat in different stages, respectively, both figures in high correlation. For the increase in AFst06 by 10mmol·m-2, the treatments of 150nL·L-1 and 100nL·L-1 compared to CK show the loss of dry matter to be 16.41% and 13.23%, respectively. Also, discussion if made of merits and demerits of different assessment methods and the strength of with the flux response assessment model under O3 stress as well as the effect of vapour pressure differences(VPD) and other upon stomatal conductance and O3 uptake flux. This research provides a new means for comprehensive evaluation of surface ozone increase influencing photosynthesis productivity of winter wheat and its yield formation conducted in China, and it thus of practical significance to the assessment of the intensification of surface ozone concentration impacting on food crop security in our country.