abscission
noun [ U ] biology specialized uk/æbˈsɪʃ.ən/ us/æbˈsɪʃ.ən/
（植物的）切除，截去;脱落
the separation or falling off of part of a plant
The flower buds and immature fruit frequently drop off; researchers have tried to determine the role growth hormones play in this abscission. 花蕾和未成熟的果实频频掉落;研究人员已经试图从生长激素方面寻找脱落原因。