Comparison Of A Diurnal Vs Steady-state Ozone Exposure Profile On Growth And Yield Of Oilseed Rape (brassica Napus L.) In Open-top Chambers In The Yangtze Delta, China

摘要

Most available exposure-response relationships for assessing crop loss due to elevated ozone (O_3) have been established using data from chamber and open-top chamber experiments, using a simulated constant O_3 concentration exposure (square wave), which is not consistent with the diurnal variation of O_3 concentration that occurs in nature. We investigated the response of oilseed rape (Brassica napus L.) to O_3 as affected by two exposure regimes: one with a diurnal variation (CF100D) and another with a constant concentration (CF100). Although the two exposure regimes have the same mean O_3 concentration and accumulated O_3 concentration above 40 ppb (AOT40), our results show that O_3 at CF100D reduced biomass and number of pods/plant more than O_3 at CF100. Both O_3 exposures resulted in larger seed weights/ 100 pods compared to CF. Numbers of seeds/100 pods were reduced by CFI00, while numbers of seeds/100 pods in the CF100D chambers were comparable to those in CF. Our results suggest that chamber experiments that use a constant O_3 exposure may underestimate O_3 effects on biomass and yields.