英语释义
1. any of various usually acidic organic substances that promote cell elongation in plant shoots and usually regulate other growth processes (such as root initiation): such as
2. indoleacetic acid
3. any of various synthetic substances (such as 2,4-D) resembling indoleacetic acid in activity and used especially in research and agriculture
4. plant hormone
5. an organic substance that is able in low concentrations to promote elongation of plant shoots and usually to control other specific growth effects broadly plant hormone