增施氮肥能够缓解麦田土壤线虫群落对O_3浓度升高的响应

N fertilization regulates the response of soil nematode communities to elevated O_3 in a wheat field

在辽宁沈阳农田生态系统国家野外科学观测研究站,利用运行2a的开顶式气室,研究了臭氧(O3)浓度升高和不同氮肥施用水平对土壤线虫群落的影响。结果表明:(1)O3浓度升高降低了成熟期小麦根生物量。O3浓度升高和不同氮肥施用水平的交互作用改变了小麦成熟期土壤微生物生物量碳、氮和水溶性有机碳的含量。低氮条件下,O3浓度升高降低了土壤微生物生物量碳、氮和水溶性有机碳的含量;而高氮条件下则表现出相反的趋势。(2)O3浓度升高和不同氮肥施用水平对土壤线虫总数没有产生显著影响,而在灌浆期,食细菌线虫和食真菌线虫中c-p值为4(Ba4 and Fu4)的功能团对O3浓度升高和不同氮肥施用水平的响应敏感;与对照相比,不同氮处理中,O3浓度升高均降低了灌浆期Ba4功能团线虫的数量。灌浆期,O3浓度升高条件下,与对照相比Fu4功能团线虫数量在高氮条件下表现出增加的趋势,而在低氮条件表现出降低的趋势。(3)O3浓度升高和不同氮肥施用水平的交互作用显著影响了小麦灌浆期线虫的成熟度指数(MI)和结构指数(SI)。与对照相比,线虫成熟度指数和结构指数在低氮条件下随O3浓度升高而降低;而在高氮条件下随O3浓度升高而升高。上述结果表明,氮肥的施用能够缓解O3浓度升高对土壤食物网的扰动。

We evaluated the effects of elevated O3 and different N fertilization on soil nematode communities in a wheat field using the open top chambers （OTC） in National Field Research Station of Shenyang Agroecosystems. The results showed that （ 1 ） elevated O3 decreased the root biomass at wheat ripening stage. The interactive effects between elevated O3 and N fertilization changed soil microbial biomass carbon （ MBC ）, microbial biomass nitrogen （MBN） and dissolved organic carbon （DOC） at ripening stage, which were decreased by the elevated O3 under low nitrogen treatment and increased under high nitrogen treatment. （2） Elevated O3 and N fertilization did not affect the total nematode abundance. While at wheat filling stage, nematode functional guilds belonging to baetefivores and fungivores with c-p 4 values （ Ba 4 and Fu 4） were sensitive to elevated O3 and N fertilization. At wheat filling stage, the numbers of Ba4 were decreased in the elevated O3 treatments in comparison with control, this trend regardless of N conditions. Following the elevated O3 , the functional guilds of Fu4 were increased in high nitrogen treatment, while decreased under low nitrogen treatment at filling stage. （3） Analysis of the ecological indices indicated that effects of elevated O3 and N fertilization might change the structure of soil micro-food web. Following elevated O3, nematode maturity and structural indices were decreased under low nitrogen treatment and increased under high nitrogen treatment, which suggest that high nitrogen fertilization may relieve the disturbance of elevated O3 on soil micro-food web.