苗期玉米、大豆在土壤-植物系统N_2O排放中的贡献

The Contribution of Maize and Soybean to N_2O Emission from the Soil-Plant System During Seedling Stage

为区分植物在土壤 植物系统N2 O排放中的贡献 ,用封闭式箱法对在温室内砂培和土培的玉米、大豆幼苗及砂、土、砂 植物系统、土壤 植物系统的N2 O排放进行了测定 ,同时对植物N2 O排放与植物叶片中的硝酸还原酶 (NR)活性及NO- 3 N、NO- 2 N含量的关系进行了分析 .结果表明 :在 5 3d的观测期内 ,玉米、大豆幼苗本身均可排放N2 O ,且在土壤 (砂 ) 植物系统的N2 O排放中占有很大份额 (79 1 8%～ 1 0 0 % ) ;植物N2 O的排放与植物叶片的硝酸还原酶活性和NO- 3 N、NO- 2 N的含量显著正相关 (R2 ≥ 0 97,n =6 ) .

To fractionate the contribution of plant to N 2O emission from soil-plant system, the N 2O emissions from soybean seedling, maize seedling, sand, soil, sand-plant system and soil-plant system were measured by closed chamber method in greenhouse. At the same time the correlation of plant N 2O emission with nitrate reductase activity, nitrate content and nitrite content of the plant leaves was also analyzed. The results clearly indicated that N 2O could be a by-product of plant metabolism. The emissions of N 2O from maize and soybean accounted for 93%～100% of the total N 2O emissions in the sand-plant systems, and 79.18%～92% in the soil-plant systems. The flux of plant N 2O emission was significantly correlated(R 2≥0.97,n=6) with the nitrate reductase activities, nitrate content and nitrite content of the maize and soybean leaves.