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

Abstract

Most available exposureeresponse 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 CF100, 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.

Contrasting effects of water salinity and ozone concentration on two cultivars of durum wheat ( Triticum durum Desf.) in Mediterranean conditions

“…In fact, although the total number of ears was significantly reduced, the total grain yield remained almost unchanged, as well as the hectoliter weight. Because this result was related to a decrease in the number of empty ears and to a significant increase in the specific grain yield per ear, it reveals that the salt stress induced in Virgilio a greater investment in the reproductive efficiency, a plant response which has been generally reported for other abiotic stresses, such as O 3 (Gerosa et al, 2009b;Black et al, 2007;Wang et al, 2008) .…”

Diurnal Variations in Physiological Characteristics, Photoassimilates, and Total Ascorbate in Early and Late Sown Indian Wheat Cultivars under Exposure to Elevated Ozone

“…If precursor gases of O 3 are produced nearby, peaks generally occur around noon, but at more distance, the peaks of O 3 occur in the late afternoon [5]. Many researchers have developed exposure regimes where ambient O 3 concentration reaches its highest level diurnally in mid-to late-afternoon [6]. The concentration of tropospheric O 3 is increasing rapidly in the Asian countries since 1990 due to rising O 3 precursors [3,7].…”

Impact of Elevated Ozone on Growth, Yield and Nutritional Quality of Two Wheat Species in Northern India

“…Impacts of tropospheric O 3 on crop plants are reported from many developing countries, which are rapidly industrializing like China (Wang et al, 2007(Wang et al, , 2008, India (Bhatia et al, 2011) and Pakistan (Wahid, 2006;Rai et al, 2007;Wahid et al, 2012). O 3 impairs plant metabolism leading to yield reduction in agricultural crops and its influence is dependent on dose, genetic background and the developmental phase of plants and varies between species and cultivars (Fiscus, 2005;Rai et al, 2010).…”