C源与NP添加对Cd胁迫下林地土壤呼吸作用的影响

Effects of C,N and P additions on soil respiration in woodland under Cd stress

【目的】研究C源与矿质营养氮磷(NP)添加对土壤呼吸作用毒物兴奋效应(Hormesis)的影响。【方法】以模式土壤为对象,接种杨树林地土壤微生物,设置单独添加葡萄糖(GC)、单独添加矿质营养NP(NP)、同时添加葡萄糖和NP(GC+NP),以及二者均无添加的对照(CK)4个处理,研究Cd胁迫下土壤呼吸作用潜在的Hormesis效应。【结果】(1)NP和GC+NP处理,林地土壤呼吸速率在Cd剂量为0.02、0.10、0.40、2.50、13.00 mg/kg时均显著高于对照,且表现出显著的多重Hormesis效应交替出现的现象,刺激幅度变化在66.6%~262.6%。(2)土壤中不添加Cd时,GC与NP处理土壤呼吸速率之和大于GC+NP处理,土壤呼吸对二者的添加表现为拮抗效应;当Cd剂量在0.01~0.20 mg/kg区间时,GC与NP处理土壤呼吸速率之和小于GC+NP处理,C源与NP添加对土壤呼吸的影响表现为协同效应;Cd剂量>0.20 mg/kg时,二者之间表现为协同与拮抗效应的交替出现。【结论】外源添加N、P条件下,Cd诱导林地土壤呼吸表现出显著的Hormesis效应。当面临逐渐增加的Cd胁迫时,C源与NP添加对土壤呼吸的交互作用表现为由拮抗向协同效应转变。

【Objective】Artificial standard soil was used to investigate the potential stimulatory effects of low-dose C,N,and P additions on soil respiration and Hormesis under heavy metal stress.【Method】The four treatments were:GC(glucose),NP(nitrogen and phosphorus),GC+NP(glucose,nitrogen and phosphorus),and,no additions(CK).The soil samples were inoculated with soil microorganisms from forest land to determine the potential Hormesis effect of exogenous addition of glucose,N and P on soil respiration under Cd stress.【Result】In the case of the NP and GC+NP treatments,the soil respiration rate was significantly higher than that of the control at Cd doses of 0.02,0.10,0.40,2.50,and 13.00 mg/kg,respectively.There was a significant alternating phenomenon of multiple hormetic effects with stimulation amplitudes between 66.6%and 262.6%.When there was no Cd added to the soil,the sum of the soil respiration rates in the GC and NP treatments was greater than that in the GC+NP treatment.The interaction between C source and NP addition on soil respiration showed an antagonistic effect.When the Cd dose was 0.01 to 0.20 mg/kg,the sum of soil respiration rates in GC and NP treatments was lower than the corresponding rates in GC+NP treatments,and the effects of C source and NP additions on soil respiration showed a synergistic effect.Synergistic and antagonistic effects appeared alternately when the Cd dose was over 0.20 mg/kg.【Conclusion】The Cd-induced soil respiration rate had a significant Hormesis effect under exogenous NP addition.With increasing Cd stress,the interaction between the C source and NP addition on soil respiration changed from antagonistic to synergistic effects.