锰胁迫对酸性土壤氮素转化及酶活性和甘蔗氮吸收的影响

Effects of Manganese Stress on Nitrogen Conversion and Enzyme Activity in Acidic Soil and Sugarcane Nitrogen Absorption

【目的】探究锰胁迫对酸性土壤氮素转化、酶活性及甘蔗氮素吸收利用的影响,为酸性土壤上甘蔗的合理施肥提供参考依据。【方法】在室内开展模拟酸性土壤锰胁迫培养试验,在玻璃温室中进行甘蔗盆栽试验,测定、分析锰胁迫下土壤氮素组分含量、pH和土壤酶活性的差异及其与甘蔗氮素吸收累积的关系。【结果】锰胁迫可使土壤铵态氮含量和净氨化速率显著提高(P<0.05,下同),土壤硝态氮含量和净硝化速率显著降低,并显著提高土壤净矿化速率;同时,锰胁迫显著降低土壤脲酶活性和显著提高土壤转化酶活性,但对土壤蛋白酶活性无显著影响(P>0.05)。相关分析结果表明,土壤脲酶活性与土壤铵态氮含量和pH分别呈显著和极显著(P<0.01,下同)正相关;土壤蛋白酶活性与土壤铵态氮含量呈显著正相关,与土壤硝态氮含量和净硝化速率分别呈极显著和显著负相关。在锰胁迫下,甘蔗的株高、生物量、植株氮素累积量和氮素吸收效率均显著降低。【结论】锰胁迫能抑制酸性土壤的硝化作用,减少铵态氮向硝态氮转化,同时使土壤脲酶活性降低,土壤转化酶活性升高,从而减少酸性土壤中甘蔗可利用氮素含量,使甘蔗对氮的吸收利用减少。

【Objective】The present paper aimed to explore the effects of manganese stress on acid soil nitrogen conversion,enzyme activity and sugarcane nitrogen absorption and utilization,and provide a reference for the rational fertilization of sugarcane on acid soil.【Method】Simulated acidic soil manganese stress cultivation experiment in the indoor,and the sugarcane pot experiment in the glasshouse were carried out,and the difference of soil nitrogen component content,pH and soil enzyme activity under manganese stress and its relationship with sugarcane nitrogen absorption and accumulation relationship were measyured and analyed.【Result】Manganese stress significantly increased soil ammonium nitrogen content and net ammonification rate(P<0.05,the same as below),significantly reduced soil nitrate nitrogen content and net nitrification rate,and significantly increased soil net mineralization rate.At the same time,manganese stress significantly reduced soil urease activity and significantly increased soil invertase activity,but had no significant effect on soil protease activity(P>0.05).The results of correlation analysis showed that soil urease activity was significantly and extremely(P<0.01,the same as below)positively correlated with soil ammonium nitrogen content and pH,soil protease activity was significantly positively correlated with soil ammonium nitrogen content,and extremely and significantly negatively correlated with soil nitrate nitrogen content and net nitrification rate respectively.Under manganese stress,sugarcane plant height,biomass,plant nitrogen accumulation and nitrogen absorption efficiency were significantly reduced.【Conclusion】Manganese stress can inhibit the nitrification of acid soils,reduce the conversion of ammonium nitrogen to nitrate nitrogen,and at the same time reduce the activity of soil urease and increase the activity of soil invertase,thereby reducing the available nitrogen content of sugarcane in acid soil,reducing the absorption and utilization of nitrogen by sugarcane.