| This study was based on Ozone Free-air Concentration Enrichment (O3-FACE) system in Jiangdu County, Jiangsu Province. Our objective is to investigate the effects of atmospheric elevated O3(target at50%above ambient) on N、P、K、Fe、Mn、Cu、Zn content in soil and wheat in2009-2010and2011(stop the supply of O3). In the wheat crop ecological system, we analyzed the cycles ofN、P、K、Fe、Mn、Cu and Zn changing in different wheat growth stages. We aimed to provide a basis for rational farming of wheat crops in the future under environmental conditions of climate change. The main results are as follows:(1) In the whole growth season, elevated O3reduces the concentrations of soil NH4+-N、 NO3-N and available K, decreased by5.7%,3.6%、3.0%, respectively; while the soil available P concent increased by26.3%which indicated significant differences among the all stage (p=0.015).After gas supply stoped, the soil available N、 K concentrations still kept the pattern that the content was lower than the control treatment, the soil available P concent was higher than the control treatment, but the effect was slowed down.(2) Under FACE treatment, N concentrations in wheat plant at jointing stagen heading stage、filling stage increased by6.4%、8.2%、5.2%respectively; K concentrations in wheat plant at jointing stage increased28.4%,and reached significant(p=0.01); the P concentrations in wheat plant at jointing stage increased by6.3%, at filling stage and heading stage reduced by14.7%and5.3%; the N concentrations at different organs at maturing stage all reduced, while the K and P concentrations in wheat grain increased by6.5%and4.2%. Elevated atmospheric3could promote the N and K uptake by wheat plant in its whole growth period, increase the K and P concentrations in wheat grain, but reduce N concentration in wheat plant at maturing stage.(3) Elevated O3affected the concentrations of DTPA-extractable microelements in wheat soil significantly, which were different with growth stage and soil depth. Elevated O3has increased the concentrations of DTPA-extractable Fe and Mn, but reduced DTPA-extractable Zn and Cu. In the whole wheat season, the concentrations of DTPA-extractable Zn decreased to reach significant levels in the5-10cm and10-15cm soil layer. FACE effective state of trace elements in the cultivated soil is mainly concentrated in the5-10cm soil layer (p-value is minimum).After stoped O3supply, the effective trace element content difference remains the same as during the gas woking stage, and the concentrations of DTPA-extractable Fe and Mn have a higher difference at some growth stage and soil depth, the concentrations of DTPA-extractable Fe in5-10cm at the heading stage and the concentrations of DTPA-extractable Mn in5-15cm at the silling stage increase that all reach significant, this may be associated with high ozone effected on the soil elements in rice growing season and the different climatic conditions in this tow years.(4) Elevated O3limiled Cun Zn content in wheat straw, the concentrations of Mn increased before the maturing stage, while the concentrations of Fe had different changes at different wheat growing stage. Elevated O3reduced the concentrations of Fe、 MnO、Cu、Zn at the maturing stage, and significantly reduced the concentrations of Cu in the wheat grain. After stoping gas, affected by the effective content of microelements in soil and plants absorb, the concentrations of Fe、Mn increase and Cu、Zn reduce.(5)Elevated O3reduced wheat plant biomass and the accumulation of nutrition elements (N、 P、K、Fe、Cu、Zn、Mn), and significantly affected the concentrations of N、P、Cu、P、Cu. This effect still existed after the stop gas, both N and P fond sifnificant change. |
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