生長素類型(auxins) 除草劑是農業上最早使用之選擇性除草劑，可以有效的控制穀類作物田間的雙子葉雜草及闊葉性雜草。生長素類除草劑乃是模擬高等植物中生長素的作用，而過量的生長素會誘導ACC 合成晦的活性，促進乙:時合成，乙:時則會造成葉的上偏生長、老化及促進離層酸(ABA) 的形成。而離層酸則會抑制植株生長、促進老化、氣孔關閉、蒸散作用及CO2同化作用降低，因而導致植物死亡。

Auxin-type herbicides were among the first selective herbicides to be developed for agricultural use. This kind of herbicides e旺\"ectively controls dicotyledonous and broadleaf weeds in cultivation of cereal crops. The action mode of these herbicides is rrurruc endogeneous auxin in higher plant. The stimulation of ethylene biosynthesis through the induction of l-aminocyclopropane-l-carboxylic (ACC) synthase is observed in most of plants suffered from auxin-type herbicides. Consequently, increased ethylene elicits the leaf epinasty and stimulates abscisic acid (ABA) biosynthesis. It is well known that ABA inhibits plant growth indirectly by stomata closure and senescence, which may limit carbon assimilation and subsequent biomass production, leading to plants death eventually.