Assessing the effects of ambient ozone in China on snap bean genotypes by using ethylenediurea (EDU)

Moderate drought did not affect the effectiveness of ethylenediurea (EDU) in protecting Populus cathayana from ambient ozone

“…However, EDU can be toxic at higher concentration (Agathokleous et al, 2016). This study showed that 450 ppm EDU applied as foliar spray is better than other concentrations to protect the poplar against O 3 , which is consistent with snap bean (Yuan et al, 2015). EDU increased A sat by sustaining higher V cmax , J max , and fluorescence parameters in the light, and chlorophyll and carotenoids contents.…”

“…Higher chlorophyll content in EDU compared with non-EDU-treated plants suggests that EDU delayed foliar senescence by reducing oxidative stress. Similar results were also found in soybean and snap bean (Rai et al, 2015;Yuan et al, 2015). By maintaining higher carotenoids concentration, chlorophyll damage due to O 3 is also avoided because carotenoids provide photoprotection and are antioxidant molecules (Demmig-Adams and Adams, 1996).…”

“…Also, it has exceeded the O 3 threshold of 12 ppm h for poplar species defined by Hu et al (2015). High O 3 concentration also occurred in 2014 (Yuan et al, 2015), suggesting that Beijing has been a hotspot of O 3 pollution. And this situation cannot be changed in the short term because O 3 precursors (mainly NOx) are currently increasing in China at an annual rate of 5% .…”

“…In China, O 3 concentration is rising at a higher rate than in other countries because O 3 precursors (mainly NO 2 ) have steadily increased at annual growth rate of 5% caused by its fast industrialization and urbanization . At Changping site, downwind of Beijing city, the AOT40 (accumulated hourly O 3 concentration over a threshold of 40 ppb during daytime) from June to August was 29 ppm h in 2014 (Yuan et al, 2015). More than 28 species and cultivars in the open field showed the typical O 3 symptoms around Beijing (Feng et al, 2014).…”

“…It has been shown that most hybrid poplar species are sensitive to O 3 with respect to visible leaf injury (Ryan et al, 2009;Hoshika et al, 2013), damaged photosystems (CO 2 assimilation and chlorophyll fluorescence) (Novak et al, 2005), and reduced growth (Bortier et al, 2000;Hoshika et al, 2013). As the representative deciduous tree species in Northern China, Populus trees are facing the risk of O 3 damage due to high ground-level O 3 pollution in China Yuan et al, 2015).…”