嘉磷塞對野茼蒿(Conyza sumatrensis) 葉片葉綠素螢光及抗氧化狀態之影響

Abstract

嘉磷塞是被廣泛使用的除草劑，屬於非選擇性及系統型之萌後藥劑，世界上已有約42種雜草具有抗性。野茼蒿(Conyza sumatrensis)為旱田常見雜草，台灣在2006年已發現抗嘉磷塞之族群。本試驗擬比較四個地區野茼蒿族群，包含台大、桃園及對嘉磷塞敏感性及具有耐性之族群，以植株葉圓片處理不同濃度嘉磷塞對葉綠素螢光及抗氧化物質狀態之影響。由結果得知，隨著嘉磷塞濃度提高會造成Fo和Qn上升、Fv/Fm、ΦPSII、Qp及ETR的下降，而耐性跟敏感性族群在螢光指標中具有顯著的差異。在光合色素含量的結果中，嘉磷塞處理會造成兩個地區及敏感性族群的葉綠素、類胡蘿蔔素含量下降，耐性地區僅在高濃度處理下出現葉綠素含量下降。在氧化逆境方面，不論哪個地區的材料在嘉磷塞400及1000 µM處理第3日後，MDA含量皆上升，並誘導DPPH清除力、還原力提升，在抗氧化物質中也出現花青素含量的增加。本實驗以葉圓片系統結合葉綠素螢光儀，提供一個快速簡易的方法來篩選野茼蒿的抗性，以Fv/Fm作為指標，在濃度400至1000 µM處理3日至7日分出抗性差異；另外在抗氧化系統中，也確認本次實驗中使用的四個族群皆受嘉磷塞間接導致氧化逆境，且族群皆會提升抗氧化能力，但並無出現此方面之非標靶抗性。

Glyphosate, widely-used herbicide in the world, is a non-selective and systemic post-emergence herbicide. There are about 42 species of weeds developing the resistance to glyphosate in the world, including Conyza sumatrensis confirmed in Taiwan in 2006. This experiment is intended to compare the effects of different concentrations of glyphosate in the four regions of broadleaf fleabane, including NTU, TY, sensitive and tolerant to glyphosate populations. The effects of glyphosate are determined by the chlorophyll fluorescence and antioxidant status of the leaves. The result showed that Fo and Qn increased but Fv/Fm, ΦPSII, Qp and ETR decreased as the concentration of glyphosate increased while sensitive and tolerant groups had significant differences in chlorophyll fluorescence indices. The content of chlorophyll and carotenoids in the two regions and sensitive population decreased under the treatment of glyphosate. On the other hand, the chlorophyll content decreased in the tolerant population only under high concentration treatment. In terms of oxidative stress, MDA content of all region increased after glyphosate treatment; DPPH scavenging, reducing power and anthocyanin content increased after treating three consecutive days with 400 and 1000 μM glyphosate. However, the results were not consistent in the total phenolic content. The combination of the leaf disc system and the chlorophyll fluorescence provided a quick and easy method to screen the resistance of Conyza sumatrensis in this experiment. After treatment for three to seven days at the concentration of 400 to 1000 μM glyphosate, there was difference in resistance between sensitive and tolerant populations by using Fv/Fm as an indicator. The antioxidant capacity of the four populations was also enhanced due to oxidative stress caused indirectly by glyphosate, but there was no non-target-site based resistance in tolerant population of this study.