Herbicidal activity of kidney leaf mud plantain leaves extracts on the germination of four species

Abstract Background: Plants synthesize compounds of specialized metabolism to defend themselves against biotic and abiotic stresses. These compounds could be used as models for pesticide development. Among the species that have not yet been studied for the potential to produce active compounds is the kidney leaf mud plantain (Heteranthera reniformis). Objective: The goal was to evaluate the effect of hexanic, ethyl acetate and methanolic extracts of H. reniformis leaves on cress (Lepidium sativum) seed germination to determine which one have the highest biological activity; and to evaluate different concentrations of extract with the highest biological activity on lettuce (Lactuca sativa), barnyard grass (Echinochloasp.) and giant arrowhead (Sagittaria montevidensis) germination. Methods: The seeds were placed on petri dishes containing two sheets of germitest paper, and after the application of the extract, they were sealed and placed in growth chambers with controlled temperature and photoperiod. The variables analyzed were 1st and 2nd germination count, germination speed index and length of the aerial part and roots. Results: The ethyl acetate extract provided greater phytotoxicity on cress than the other extracts. In general, the highest concentration of ethyl acetate extract was the most efficient in reducing variables for all species. Conclusions: The ethyl acetate extract of H. reniformis presents inhibitory activity on the seeds of cress, lettuce, giant arrowhead and barnyard grass, but this activity was dependent on the concentration of the extract and the species studied. H. reniformis synthesizes compounds with phytotoxic activity and purification of extracts is required to isolate, identify and characterize the action mechanism of the compounds with herbicide activity, so that in the future these can be used as models for the development of herbicides.

摘要 背景：植物通过合成特化代谢产物以抵御生物与非生物胁迫，此类化合物可作为农药开发的候选模型。目前，肾叶水兰（Heteranthera reniformis）仍是尚未被探究活性化合物生产潜力的物种之一。
目的：本研究目标分为两点：其一，评估肾叶水兰（Heteranthera reniformis）叶片的正己烷提取物、乙酸乙酯提取物与甲醇提取物对独行菜（Lepidium sativum）种子萌发的影响，以筛选出生物活性最强的提取物；其二，探究活性最强的提取物的不同浓度对生菜（Lactuca sativa）、稗草（Echinochloa sp.）及大慈姑（Sagittaria montevidensis）种子萌发的作用。
方法：将种子置于铺有两张发芽测试纸的培养皿中，施加提取物后密封培养皿，随后移入温度与光周期均可控的生长箱中培养。本研究观测的指标包括第1次发芽计数、第2次发芽计数、发芽速率指数，以及地上部分与根系的长度。
结果：相较于其他两类提取物，乙酸乙酯提取物对独行菜的植物毒性更强。总体而言，最高浓度的乙酸乙酯提取物对所有受试物种的各项观测指标均表现出最显著的抑制效果。
结论：肾叶水兰的乙酸乙酯提取物对独行菜、生菜、大慈姑及稗草的种子均具有萌发抑制活性，且该活性依赖于提取物浓度与受试物种种类。肾叶水兰可合成具有植物毒性的化合物，后续需对提取物进行纯化，以分离、鉴定并表征具有除草剂活性的化合物的作用机制，进而为未来开发除草剂候选模型奠定基础。