资源环境科技发展态势分析平台

Ozone (O-3) pollution and drought are frequent in summer, which adversely affects plant growth. In this study, we investigated the interactive effects of O-3 and water deficit on growth parameters, and carbon (C) and nitrogen (N) stocks and their allocation to different organs in poplar saplings in the summer of 2017. The saplings were subjected singularly and in combination to two chronic O-3 treatments (charcoal-filtered air [CF] and ambient air + 40 ppb of O-3 [E-O-3]) and two watering regimens (well-watered [WW] and reduced watering [RW]). The results showed that both O-3 and drought inhibited poplar growth, whereas the effects of drought were greater than those of O-3. Moreover, drought stress protected the saplings from O-3 damage, suggesting that some previous studies on well-watered plants might have overestimated the damage caused by O-3 . Inconsistent with the general trend, RW significantly increased the light-saturated rate of CO2 assimilation (A(sat)) in this study, whereas it reduced the total leaf area. E-O-3 significantly increased the N concentration and reduced the C/N ratio of each organ as well as the total C stock (CStotal), while it did not significantly affect the total N stock (NStotal). Drought significantly increased the C and N concentrations and reduced the C/N ratio in most organs, and significantly reduced the C stock of each organ, CStotal and NStotal CStotal was positively correlated with the total leaf area and the photosynthetic rate of the whole plants (A(plant)). However, there was no significant relationship between CS(total )and A(sat,) suggesting that A(plant) can better reflect the growth of the whole plant than A(sat). In addition, NStotal was positively correlated with the root biomass. Both O-3 and drought had no significant effect on the ratio between the root and shoot N stocks, and there were also no interactive effects of O-3 and drought on most C and N parameters. These findings will facilitate better understandings of C and N metabolisms future environment with higher O-3 and more frequent droughts.