Effect of dazomet fumigation on nitrogen uptake and utilization in tobacco
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.
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