Deep application of controlled-release urea increases the yield and saponin content of Panax notoginseng by regulating soil nitrate distribution - Su, Yun-xia; Zhao, Ping; Jia, Li-jie; Cao, Yuan-feng; Liu, Guan-ze; Chen, Jun-wen; Yang, Sheng-chao; Zhou, Yan-li; Long, Guang-qiang (Frontiers in Plant Science, 2025)