Abstract: With simulation test and plastic greenhouse experiment, this paper studied the effects of urea and minerals-coated urea on the soil pH and harmful gases concentrations in plastic greenhouse. The results showed that under simulated condition, the application of these two N fertilizers led to an initial increase of soil pH, which reached the maximum (an increment of ＞50%) within the first week and dropped to the initial level by the end of the fifth week. In plastic greenhouse, applying urea and coated urea resulted in the increase of NH₃, NO₂ and O₃ concentrations. The daily volatilization amount of NH₃ and NO₂ was higher in urea treatment than in coated urea treatment, and the highest value in urea treatment was 42.36μg·m^-3·d^-1 for NH₃ , 41.95 μg·m^-3·d^-1 for NO₂, and 86.00μg·m^-3·d^-1 for O₃. The volatilization intensity of NH₃ and NO₂ was influenced by temperature and sunlight, while the O₃ concentration was influenced by sunlight.

Key words: Sinopodophyllum hexandrum, Population, Seed production, Seed set ratio