Cover crops provide many agroecosystem services, including weed suppression, which is partially exerted through release of allelopathic benzoxazinoid (BX) compounds. This research (1) characterizes changes in concentrations of BX compounds in shoots, roots, and soil at three growth stages (GS) of cereal rye (Secale cereale L.), and (2) their degradation in soil over time following termination. Concentrations of shoot dominant BX compounds, DIBOA-glc and DIBOA were lowest at GS 83 (boot). The root dominant BX compound, HMBOA-glc, concentration was least at GS 54 (elongation). Rhizosphere soil BX concentrations were 1000 times smaller than in root tissues. Dominant compounds in soil were HMBOA-glc and HMBOA. Soil BX compound concentrations were similar near root crowns and between-rows. Soil BX concentrations following cereal rye termination declined exponentially over time in three of four treatments: incorporated shoots (S) and roots (R), no-till S + R (cereal rye rolled flat), and no-till R (shoots removed); no-till S had consistently low concentrations. In treatments showing changes, soil concentrations of HMBOA-glc and HMBOA increased above initial concentrations on the day following cereal rye termination. Concentrations of these two compounds decreased more rapidly than the other compounds. Placement of shoots on the surface of an area where cereal rye had not grown (no-till S) did not increase soil concentrations of BX compounds. The short duration and complex dynamics of BX compounds in soil prior to and following termination illustrate the limited window for enhancing weed suppression directly by cereal rye allelochemicals; valuable information for programs breeding for enhanced weed suppression.

覆盖作物提供许多农业生态系统服务，包括杂草抑制，这部分是通过释放化感作用的苯并恶嗪 (BX) 化合物来发挥的。本研究 (1) 描述了谷物黑麦 ( Secale graine ) 三个生长阶段 (GS) 中芽、根和土壤中 BX 化合物浓度的变化。L.）和（2）它们在终止后随时间在土壤中的降解。在 GS 83 (boot) 时，芽优势 BX 化合物、DIBOA-glc 和 DIBOA 的浓度最低。根占优势的 BX 化合物 HMBOA-glc 浓度在 GS 54（伸长率）时最少。根际土壤 BX 浓度比根组织小 1000 倍。土壤中的主要化合物是 HMBOA-glc 和 HMBOA。根冠附近和行间土壤 BX 化合物浓度相似。在四种处理中的三种处理中，谷物黑麦终止后的土壤 BX 浓度随时间呈指数下降：合并枝条 (S) 和根部 (R)、免耕 S + R（谷物黑麦轧平）和免耕 R（去除枝条） ; 免耕 S 的浓度一直很低。在显示变化的治疗中，在谷物黑麦终止后的第二天，土壤中 HMBOA-glc 和 HMBOA 的浓度高于初始浓度。这两种化合物的浓度比其他化合物下降得更快。在谷物黑麦未生长的区域（免耕 S）表面放置新芽不会增加 BX 化合物的土壤浓度。终止前后土壤中 BX 化合物的持续时间短且动态复杂，说明谷物黑麦化感物质直接增强杂草抑制作用的窗口有限；为增强杂草抑制的育种计划提供有价值的信息。在谷物黑麦未生长的区域（免耕 S）表面放置新芽不会增加 BX 化合物的土壤浓度。终止前后土壤中 BX 化合物的持续时间短且动态复杂，说明谷物黑麦化感物质直接增强杂草抑制作用的窗口有限；为增强杂草抑制的育种计划提供有价值的信息。在谷物黑麦未生长的区域（免耕 S）表面放置新芽不会增加 BX 化合物的土壤浓度。终止前后土壤中 BX 化合物的持续时间短且动态复杂，说明谷物黑麦化感物质直接增强杂草抑制作用的窗口有限；为增强杂草抑制的育种计划提供有价值的信息。