School of Agriculture, Yangtze University, Jingmi Road 88, Jingzhou 434025, China.
School of Agriculture, Yangtze University, Jingmi Road 88, Jingzhou 434025, China; Institute of Pesticides, Yangtze University, Jingmi Road 88, Jingzhou 434025, China.
Pestic Biochem Physiol. 2022 May;183:105086. doi: 10.1016/j.pestbp.2022.105086. Epub 2022 Mar 25.
To improve the selectivity of the fenoxaprop herbicide to rice and barnyard grass, a series of fenoxaprop-P-ethyl-amino acid ester conjugates were designed and synthesized, and tested for biological activity as well as their phloem mobility. The bioassay results indicated that the target compounds possessed better activity against barnyard grass (Echinochloa crusgalli) than rape (Brassica campestris L.) at the concentration of 0.5 mmol/L. Compounds 3h and 3i, showed more than 70% control efficiency against barnyard grass, while less than 30% for rape. The compounds showed less impact on rice after spray treatment than in the germination test. Compounds 3i, 3j, and 3k showed excellently herbicidal activities against barnyard grass and low phytotoxicity to rice. Compound 3k showed 6.1% phytotoxicity to rice at a spray concentration of 0.25 mmol/L, better than fenoxaprop-P-ethyl (61.6%) at the same concentration. The selectivity results of the target compounds revealed that most of compounds obviously reduced phytotoxicity to rice while retaining herbicidal activity of barnyard grass. The herbicidal activity of compound 3d compared to FPE was increased by 50%, while its safety on rice was also increased by 50%. The concentration of the compounds in barnyard grass roots was higher than in rice roots, showing greater phloem mobility. In particular, the concentration of compound 3d on barnyard grass exhibited 142.72 mg/kg which was 3 times as much as Fenoxaprop, while its concentration on rice exhibited 3.65 mg/kg, the results revealed that the difference of phloem mobility might be the important reason for causing the selectivity.
为提高苯氧羧酸类除草剂精恶唑禾草灵对水稻和稗草的选择性，设计并合成了一系列精恶唑禾草灵-P-乙基-氨基酸酯轭合物，测试了其生物活性及韧皮部传导性。生测结果表明，在 0.5mmol/L 浓度下，目标化合物对稗草的活性明显优于油菜，化合物 3h 和 3i 对稗草的防效均在 70%以上，而对油菜的防效均在 30%以下。喷雾处理后，化合物对水稻的影响小于发芽试验。化合物 3i、3j 和 3k 对稗草表现出优异的除草活性，对水稻的低毒性。化合物 3k 在 0.25mmol/L 的喷雾浓度下对水稻的毒性为 6.1%，优于相同浓度下的精恶唑禾草灵-P-乙基（61.6%）。目标化合物的选择性结果表明，大多数化合物明显降低了对水稻的毒性，同时保留了对稗草的除草活性。化合物 3d 的除草活性比 FPE 提高了 50%，同时对水稻的安全性也提高了 50%。化合物在稗草根中的浓度高于水稻根中的浓度，表现出较大的韧皮部移动性。特别是化合物 3d 在稗草上的浓度为 142.72mg/kg，是精恶唑禾草灵的 3 倍，而在水稻上的浓度为 3.65mg/kg，结果表明韧皮部移动性的差异可能是导致选择性的重要原因。
