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近地层臭氧(O_3)浓度升高作为全球气候变化的重要因素之一,对土壤生态环境和农作物生长发育造成了很大影响。本研究采用开顶式气室(OTCs)法,探究臭氧浓度升高对小麦不同生育期(分蘖期、拔节期、孕穗期和成熟期)根际土壤酶活性(过氧化氢酶、多酚氧化酶、脱氢酶和转化酶)和有机酸含量(草酸、柠檬酸和苹果酸)的影响规律,并结合根际土壤理化性质、植株根系生长状况等分析其产生影响的原因。结果表明:O_3浓度升高不同程度地提高了小麦成熟期土壤过氧化氢酶、多酚氧化酶、脱氢酶和转化酶活性,其中过氧化氢酶和多酚氧化酶活性提高达显著水平;在抽穗期,脱氢酶和转化酶活性因臭氧浓度升高而显著提高,增幅最高可达76.7%。在成熟期,O_3浓度升高显著提高了根际土壤中柠檬酸和苹果酸含量;显著降低了根际土壤pH、电导率、总碳和总氮含量,增加了土壤氧化还原电位(Eh);显著降低了小麦根系生物量、总根长和根总表面积,而增加了根平均直径。
Ozone (O 3) concentration in the near-surface layer is one of the important factors of global climate change, which has a great impact on soil ecological environment and crop growth and development. In this study, OTCs were used to investigate the effects of elevated ozone on rhizosphere soil enzyme activities (catalase, polyphenol oxidase activities at different growth stages (tillering, jointing, booting and maturing) Enzyme, dehydrogenase and invertase) and organic acids (oxalic acid, citric acid and malic acid), and analyzed the reasons for their influence on the physical and chemical properties of rhizosphere soil and the growth of plant roots. The results showed that the increase of O_3 increased the activity of catalase, polyphenol oxidase, dehydrogenase and invertase in wheat at different stages, and the activities of catalase and polyphenol oxidase increased significantly at the same time. At heading stage, the activity of dehydrogenase and invertase increased significantly due to the increase of ozone concentration, up to 76.7%. At the mature stage, the increase of O 3 significantly increased the content of citric acid and malic acid in the rhizosphere soil; decreased the pH, conductivity, total carbon and total nitrogen in the rhizosphere soil and increased the soil redox potential (Eh); Significantly reduced the wheat root biomass, total root length and total root surface area, while increasing the root mean diameter.