Abstract: Static chamber-GC technique was employed to study the effects of different treatment winter cover crops, including no-tillage and directly sowing ryegrass (T₁), no0tillage and directly sowing Chinese milk vetch (T₂), tillage and transplanting rape (T₃), notillage and directly sowing rape (T₄), and fallowing (CK), on the CH₄ and N₂Oemission from double cropping rice paddy field. During the growth period of test winter cover crops, the CH₄ and N₂O emission in treatments T₁-T₄ was significantly higher than that in CK (P<0.01). Treatments T₁and T₃not only had the largest CH₄ emission(0.60 and 0.88 g·m^-2), but also had the largest N₂O emission (0.20 and 0.23 g·m^-2, respectively). After the winter cover crops returned to field, the CH₄ emission from early and late rice fields in treatments T₁、T₂、T₃, andT₄was larger than that in CK. In early rice field, treatments T₁ and T₂had the largest CH₄emission (21.70 and 20.75 g·m^-2); while in late rice field, treatments T₃ and T₄had the largest one (58.90 and 54.51 g·m^-2, respectively). Treatments T₁-T₄also had larger N₂O emission from early and late rice fields than the CK did. The N₂Oemission from early rice field in treatments T₁, T₂, T₃, andT₄ was increased by 53.7%, 12.2%, 46.3%, and 29.3%, and that from late rice field in corresponding treatments was increased by 28.6%, 3.8%, 34.3%, and 27.6%, respectively, compared with CK.

Key words: winter cover crop, rice field, CH₄, N₂O, emission, Laodelphax striatellus, buprofezin, resistance screening, risk assessment, cross-resistance, biochemical resistance mechanism.