Allelopathic plant extracts have been proposed as natural herbicides, and as an alternative to synthetic herbicides. However, further studies are still required on the active principles of these extracts as well as on their soil dynamics and weed control effects in the field. We carried out the bioguided isolation of active compounds of EtOH extract of the ornamental plant, Cortaderia speciosa, with biodegradation and field trial experiments. Six phenolic acids were found to be responsible for herbicidal activity against Solanum lycopersicum: ferulic acid, p-coumaric acid, caffeic acid, vanillic acid, p-hydroxybenzoic acid and gallic acid. The effective concentrations for 50% inhibition of germination (ECg₅₀) were determined for each of these compounds in tomato (S. lycopersicum), and for mixtures of them in radish (Raphanus sativus), lettuce (Lactuca sativa), tomato (Solanum lycopersicum), onion (Allium cepa) and alfalfa (Medicago sativa). p-Coumaric acid was the most active in inhibiting the germination of S. lycopersicum (ECg₅₀ = 0.31 mg/mL), followed by ferulic acid (0.39 mg/mL), vanillic acid (0.51 mg/mL), caffeic acid (0.73 mg/mL), p-hydroxybenzoic acid (0.79 mg/mL), and gallic acid (1.67 mg/mL). Some equimolar mixtures of phenolic acids showed synergistic effects on germination, the best combination being ferulic acid with p-coumaric acid (5:2 molar ratio), with an EC₅₀ = 0.06 mg/mL. Biodegradation studies of C. speciosa extract in soil showed a half-life of 31.08 (± 0.90) h, according to HPLC quantification of phenolic acids in samples taken on different days. In field trials of C. speciosa extract, the weed cover area was significantly different from the control from Day 9 until the end of the experiment (Day 43). At concentrations of 50, 100 and 200 kg of C. speciosa extract/ha, weed suppression was 7%, 18% and 24% with respect to control at Day 43, indicating inhibition of the germination of spontaneous weeds. A treatment with a combination of phenolic acids (ferulic acid, p-coumaric acid, caffeic acid, vanillic acid, p-hydroxybenzoic acid and gallic acid, molar ratio 5:2:1:3:3:0.1) at 2.8 kg/ha strongly inhibited the appearance of weed, showing a surface cover 60% smaller than that of control at the end of the experiment. Weed biomass was reduced by 47%, 64%, 78% and 91% with respect to control by 50, 100, 200 kg of extract/ha and the 2.8 kg/ha mixture of phenolic acids, respectively. Biodegradation and field studies revealed that, despite degrading in a few hours, the phenolic acids inhibited weed emergence in the field.

中文翻译：

---

Cortaderia speciosa提取物的植物毒性，有效成分，土壤降解和现场试验的有效性

已提出化感植物提取物作为天然除草剂，并替代合成除草剂。但是，仍需要对这些提取物的活性成分及其在田间的土壤动力学和杂草控制效果进行进一步研究。我们进行了生物降解和现场试验实验，对观赏植物Cortaderia speciosa的EtOH提取物的活性化合物进行了生物引导分离。发现六种酚酸对番茄茄有除草活性：阿魏酸，对香豆酸，咖啡酸，香草酸，对羟基苯甲酸和没食子酸。50％抑制发芽的有效浓度（ECg ₅₀）在番茄（S. lycopersicum）中以及萝卜（Raphanus sativus），生菜（Lactuca sativa），番茄（Solanum lycopersicum），洋葱（Allium cepa）和苜蓿（Medicago sativa）中的每种化合物的含量）。p香豆酸为最活跃的抑制萌发番茄（ECG ₅₀  = 0.31毫克/毫升），随后阿魏酸（0.39毫克/毫升），香草酸（0.51毫克/毫升），咖啡酸（0.73毫克/毫升），p-羟基苯甲酸（0.79 mg / mL）和没食子酸（1.67 mg / mL）。某些等摩尔浓度的酚酸混合物对发芽具有协同作用，最佳组合是阿魏酸与对香豆酸（摩尔比为5：2），EC ₅₀  = 0.06 mg / mL。的生物降解研究皱皮木瓜在土壤提取物显示出31.08（±0.90）h的半衰期，根据在不同的日子取出的样品的酚酸HPLC定量。在C. speciosa提取物的田间试验中，从第9天到实验结束（第43天），杂草覆盖面积与对照显着不同。浓度为50、100和200 kg的C. speciosa提取物/公顷，在第43天，相对于对照，杂草抑制率为7％，18％和24％，表明抑制了自发杂草的发芽。以2.8 kg / ha的酚酸（阿魏酸，对香豆酸，咖啡酸，香草酸，对羟基苯甲酸和没食子酸的摩尔比5：2：1：3：3：0.1）的组合进行处理强烈抑制杂草的出现，在实验结束时，其表面覆盖率比对照小60％。与对照相比，杂草生物量分别减少了50％，100kg，200kg的提取物/公顷和2.8kg / ha的酚酸混合物，分别比对照减少了47％，64％，78％和91％。生物降解和田间研究表明，尽管在几个小时内降解，但酚酸仍能抑制田间杂草的出现。