保護劑能選擇性保護作物，可降低除草劑在田間防除雜草時之傷害。目前了解保護劑能提高作物對除草劑之耐性，主要是誘導作物體中之解毒酵素如細胞色素P-450單加氧酶(cytochrome P450 monooxygenase)及穀胱苷肽轉移酶(glutathione S-transferases)而促進對除草劑之代謝。由於目前廣泛地使用保護劑，因此在考慮如何有效利用保護劑以提高除草劑之選擇性方面，對於保護劑作用機制之了解相當重要。

Herbicide safeners can protect crops from herbicidal injury caused by herbicides. As we know, the primary mechanism of action for herbicide safener is to promote herbicide metabolism by virtue of the induction of detoxifying enzyme system, such as cytochrome P-450 monooxygenase and glutathione S-transferases. In the future more detailed knowledge of safener action is required to improve the effective use of safener in weed control.