Maize shading inhibited the growth of soybean at the seedling stage, reduced the number of soybean flowers and pods, and decreased the yield of soybean under maize-soybean relay strip intercropping system. To explore the effect of exogenous plant growth regulators (PGRs) on flowering, pod setting, and yield of soybean is important for relay strip intercropping soybean production. Field experiments were used one-factor randomized block design to investigate the effect of foliage spraying 6-Benzylaminopurine (6-BA), diethyl aminoethyl hexanoate (DTA-6) and uniconazole (S3307) at the beginning of flowering stage on abscission of flowers and pods, leaf carbon and nitrogen metabolism, and yield formation in relay strip intercropping soybean. The results demonstrated that spraying PRGs improved the sucrose synthetase (SS), sucrose phosphate synthetase (SPS) and invertase (Inv) activities in soybean leaves. Exogenous PGRs increased soluble sugar content in stems, leaves, and pods of soybean at the beginning of grain-filling stage, promoted soluble sugar transport from stem and leaves to pods. Exogenous PGRs increased carbon and nitrogen content and decreased the C:N ratio in soybean leaves at the beginning of podding stage. PGRs increased the carbon content, decreased nitrogen content, and increased the C:N ratio in soybean leaves at beginning of grain-filling stage. Foliar spraying PGRs increased the number of flowers and pods, reduced the abscission pod number, and 第 4 期 罗凯等: 外源喷施植物生长调节剂对套作大豆碳氮代谢和花荚脱落的影响 753 decreased the ratio of pods abscission and flowers-pods abscission, the effect of DTA-6 treatments was better than others. The pods per plant and yield of soybean in 2018 and 2019 under DTA-6 treatment were increased by 25.4%, 41.3% and 32.9%, 37.6% as compared with CK, respectively. Foliar spraying PGRs increased the activities of SPS, SS, and Inv enzymes in soybean leaves, coordinated the carbon-nitrogen metabolism in soybean organs, promoted the soybean flowering and pod-setting, decreased the abscission of pods, increased the pods per plant and yield of relay strip intercropping soybean, the production increasing effect of DTA-6 were better than others.