单 位：
Qingdao Agr Univ, Coll Resources & Environm Sci, Qingdao 266109, Peoples R China
摘 要：
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 N-15-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 N-15-labeled ammonium sulfate. Plants were harvested immediately after exposure for 24 h, and the total N concentrations and N-15/N-14 ratios were determined. With increased NH3 concentration, total (NH3)-N-15-N absorption increased considerably, whereas the applied (NH3)-N-15-N uptake decreased gradually. The tomato plants absorbed 33-38% and 24-31% of the (NH3)-N-15-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 (NH3)-N-15-N was transferred into the tomato fruits. All these results indicated the potential of the tested tomatoes for the foliar uptake of atmospheric (NH3)-N-15 and the distribution of N-15-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.
