棉隆熏蒸对烟草氮素吸收利用的影响

Effect of dazomet fumigation on nitrogen uptake and utilization in tobacco

为探究棉隆熏蒸对烟草氮素吸收转化利用的影响,本试验选取云南酸性红壤、北京碱性潮土2种中国典型土壤,以本氏烟Nicotiana benthamiana为对象,研究了棉隆熏蒸对土传病原菌防效、土壤氮素转换、根系氮素供应、植株氮空间分布及氮代谢关键酶活性的影响。结果显示,棉隆熏蒸对2种供试土壤中土传病原菌镰孢属Fusarium spp.、疫霉属Phytophthora spp.真菌的抑制率均超过89%,棉隆熏蒸显著增加了土壤铵态氮含量,减少了硝态氮含量,抑制了土壤硝化速率及根系硝态氮供应速率,而促进了土壤反硝化速率及根系铵态氮供应速率。棉隆熏蒸显著降低了烟草组织总氮含量,但增加了根、茎、叶各部位铵态氮含量,减少了硝态氮含量,且在酸性红壤土中更明显。棉隆熏蒸后硝酸还原酶、亚硝酸还原酶、谷氨酰胺合成酶和谷氨酸合成酶活性有不同程度增加。试验结果表明,棉隆熏蒸通过改变根际氮素形态及含量,进而影响根际氮素供应速率及氮代谢关键酶活性,促进烟草根茎叶各部位硝态氮的代谢,促进烟草生长。研究结果为棉隆的科学应用提供了理论支撑。

In order to explore the effects of dazomet fumigation on nitrogen uptake,conversion,and utilization,two typical Chinese soils,acidic red soil in Yunnan and alkaline tidal soil in Beijing were selected for this experiment.The effects of dazomet fumigation on soil-borne pathogens,soil nitrogen conversion,root nitrogen supply,plant nitrogen spatial distribution,and the activities of key nitrogen metabolism enzymes were studied.The results showed that the control efficacies of dazomet fumigation against the soil-borne pathogens,Fusarium spp.and Phytophthora spp.in both test soils,exceeded 89%.The fumigation significantly increased soil ammonium nitrogen content,reduced nitrate nitrogen content,inhibited soil nitrification rates,and root nitrate nitrogen supply rates,and promoted soil denitrification rates and root ammonium nitrogen supply rates.Dazomet fumigation significantly decreased the total nitrogen content in the leaf tissues,increased ammonium nitrogen content in the roots,stems,and leaves and reduced nitrate nitrogen content,especially in the acidic red loam.Following dazomet fumigation,the activities of nitrate reductase,nitrite reductase activities glutamine synthase and glutamate synthase in tobacco tissues increased to some extent.The experimental results showed that dazomet fumigation changed the morphology and content of rhizosphere nitrogen.This,in turn,affected the rhizosphere nitrogen supply rate and the activities of key enzymes in nitrogen metabolism,promoted the metabolism of nitrate nitrogen in various parts of tobacco rhizomes and leaves,ultimately promoting tobacco growth.These results provide theoretical support for the scientific application of dazomet.