Translocation and recovery of 15N-labeled N derived from the foliar uptake of 15NH3 by the greenhouse tomato(Lycopersicon esculentum Mill.)

摘要

cqvip:In order to completely evaluate ammonia emission from greenhouse vegetable fields,crop canopy absorption should not be neglected.The foliar uptake of NH3 applied at two growth stages and the subsequent 15N-labeled N translocation to other plant components were investigated under greenhouse conditions using chambers covered with the soil of a tomato field.Treatments comprised three NH3-N application rates(70,140,and 210 mg/plot) using 15N-labeled ammonium sulfate.Plants were harvested immediately after exposure for 24 h,and the total N concentrations and 15N/14 N ratios were determined.With increased NH3 concentration,total 15NH3-N absorption increased considerably,whereas the applied 15NH3-N uptake decreased gradually.The tomato plants absorbed 33-38% and 24-31% of the 15NH3-N generated at the anthesis and fruit growth stages,respectively.A total of 71-80% of the recovered NH3 was observed in the leaves and 20-30% of the recovered NH3 was remobilized to other components.Among them,an average of 10% of the absorbed 15NH3-N was transferred into the tomato fruits.All these results indicated the potential of the tested tomatoes for the foliar uptake of atmospheric 15NH3 and the distribution of 15N-labeled vegetative N among different plant components.The results are of great importance for the complete evaluation of nitrogen use efficiency in the greenhouse tomato fields.