丛枝菌根真菌和不同形态氮对杉木幼苗根际土壤氮磷养分含量及其相关酶化学计量比的影响

Effects of Arbuscular Mycorrhizal Fungi Inoculation and Different Forms of Nitrogen Addition on Soil Nitrogen and Phosphorus Contents and Enzyme Stoichiometry in the Rhizosphere of Chinese Fir Seedlings

[目的]探究丛枝菌根真菌(AMF)和不同形态氮(NH_(4)^(+)-N、NO_(3)^(-)-N)对杉木根际土壤氮(N)与磷(P)养分含量、相关酶活性及其化学计量比的影响,为杉木人工林的可持续经营管理提供理论依据与数据支持。[方法]本研究以1年生杉木幼苗为研究对象,采用盆栽实验,研究杉木幼苗在接种摩西球囊霉(G.mosseae,Gm)和添加不同形态N(NH_(4)^(+)-N、NO_(3)^(-)-N)后根际土壤N、P养分含量及其相关酶活性与化学计量比的变化。[结果](1)AMF接种提高了土壤有效P含量,降低了土壤中硝态氮、铵态氮、可溶性有机氮以及全P含量,与NH_(4)^(+)-N处理相比,NO_(3)^(-)-N处理下AMF对土壤N、P养分的调节作用更显著(p<0.05);(2)AMF和不同形态N添加提高了土壤中酸性磷酸酶(AP)、脲酶(URE)、N-乙酰-β-D葡萄糖苷酶(NAG)活性,其中,NH_(4)^(+)-N处理下AMF更有利于提高URE活性,NO_(3)^(-)-N处理下AMF更有利于提高NAG活性。(3)接种AMF降低了土壤URE:AP、PRO:AP以及NAG:AP的比值(p<0.05),且在NO_(3)^(-)-N处理下土壤URE:AP、PRO:AP的化学计量比的下降幅度高于NH_(4)^(+)-N处理。[结论]AMF接种通过提高土壤中氮磷相关转化酶的活性,降低氮磷转化酶的化学计量比来提高杉木土壤P有效性,促进土壤中有效N、P向植物体内的转移,维持土壤N、P平衡,且NO_(3)^(-)-N处理下AMF对土壤N、P平衡的调节效果强于NH_(4)^(+)-N处理。

[Objective]To understand the influences of arbuscular mycorrhizal fungi(AMF)inoculation and different forms of nitrogen(N)addition on soil nitrogen(N)and phosphorus(P)nutrients,soil N and P enzyme activities and their enzyme stoichiometry in the rhizosphere of Chinese fir(Cunninghamia lanceolata)for providing theoretical basis of sustainable management of Chinese fir plantations.[Method]In the present study,a pot experiments were carried out to investigate the AMF inoculation(G.mosseae,Gm)and different forms of N(NH_(4)^(+)-N,NO_(3)^(-)-N)addition on soil N and P nutrients,related enzyme activities and their stoichiometry of one-year-old Chinese fir seedlings.[Result]The results showed that:(1)AMF inoculation increased soil available P content,but decreased the NO_(3)^(-)-N,NH_(4)^(+)-N,DON and total P content.Compared with NH_(4)^(+)-N treatment,AMF under NO_(3)^(-)-N treatment had more significant effect on soil N and P nutrients(P<0.05).(2)AMF inoculation and different forms of N addition increased the activities of soil acid phosphatase(AP),urease(URE),and N-acetyl-β-D glucosidase(NAG).Inoculation of AMF under NH_(4)^(+)-N treatment was more conducive to improve urease activity,and inoculation of AMF under NO_(3)^(-)-N treatment was more conducive to improve N-acetyl-β-D glucosidase activity.(3)AMF inoculation reduced the ratios of soil URE:AP,PRO:AP and NAG:AP(p<0.05),and the decrease of soil URE:AP,PRO:AP stoichiometry under NO_(3)^(-)N treatment was higher than that under NH4-N treatment.[Conclusion]AMF inoculation can improve soil P availability,and increase the transfer of soil available N to the plants by increasing the activities of nitrogen and phosphorus-related enzyme in the soil and reducing the stoichiometry of nitrogen and phosphorus-related enzyme to maintain soil N and P balance.Moreover,the effects of NO_(3)^(-)-N treatment on soil nitrogen and phosphorus balance is larger than that under NH_(4)^(+)-N treatment.