本研究探討外加藥劑是否能提高水稻對巴拉刈(paraquat)的抗性，試驗分別外加抗壞血酸(ascorbic acid)及多胺(polyamines)於感性水稻突變體分蘗期葉片，發現其中多胺較能有效提高水稻對巴拉刈之抗性，其中又以5 mM 精胺(spermine, Spm)較10 mM 有效。外加Spm 雖然僅略提高ascorbate peroxidase 活性，但H2O2 顯著下降，故推測外加Spm 可能誘導感性水稻突變體之抗氧化系統活性，降低巴拉刈對水稻造成的氧化傷害，以提高感性水稻對巴拉刈之抗性。

Ascorbic acid and polyamines were tested on a paraquat-susceptible rice mutant to evaluate the effect of exogenously applied chemicals on its susceptibility to this herbicide. The results showed that polyamines, especially spermine at 5 mM, could improve rice tolerance to paraquat. Although the ascorbate peroxidase activity was only slightly increased by spermine, a significant decrease of H2O2 suggested that this polyamine effectively improved paraquat resistance of rice plant through enhanced activity of antioxidative system.