Abstract

Greenhouse gas (GHG) emitted from agricultural field was received considerable attention worldwide, depending on differed land use and cropping system. An innovative strategy to mitigate agricultural N₂O by intercropping traditional Chinese medicinal herb Isatis indigotica in winter wheat field was assessed. By exogenously applying root exudates of I. indigotica in a lab incubation study, we testify and quantify whether N₂O emission was inhibited.

Results demonstrated great reduction of N₂O emission from winter field soil intercropping I. indigotica (NPKWR-N+P+K+wheat+I. indigotica) compared to CK (NPKW-N+P+K+wheat but no I. Indigotica) was found. N₂O emission in treatment of NPKWR was decreased by 32% than that in CK during the whole winter wheat growth season, among which the best decreasing N₂O emission was obtained in the stage of grain filling of winter wheat, N₂O emitting from NPKWR was reduced by 60% than that in CK. The N₂O emission intensity per kg of harvested wheat grain treated with I. indigotica was declined to 0.15 g N₂O/kg grain from 0.24 g N₂O/kg grain in CK.

qPCR (quantitative fluorescent polymerase chain reaction) analysis indicated nitrifying microbial population in wheat soil was severely suppressed by I. indigotica. The number of qPCR gene copy in both soil intercropping I. indigotica and exogenously applying root exudates of I. indigotica was lower than in CK. Such trend of decreased microbial population number was in agreement with that of N₂O emission from winter wheat field. This suggested that intercropping I. indigotica was a practical and simple technique to reduce N₂O emission from winter wheat field which was an effective strategy for mitigating and adapting global change worldwide in agriculture.

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