Phytotoxic Potential and Phenolic Profile of Extracts from Scrophularia striata

Abstract

A large number of plants produce secondary metabolites known as allelochemicals that are capable of inhibiting the germination of competitive species. This process is known as allelopathy and is mediated by several classes of chemicals, among which phenolic compounds are the most frequent. Thus, plant allelochemicals can be used to control weeds in agricultural systems. In the present work, we analyzed the phenolic profile and phytotoxic potential of different extracts (pure water or water: ethanol 50:50) from Scrophulariastriata plants that were collected from two ecological regions in Iran (Pahleh and Lizan). The total polyphenolic content (TPC), as evaluated by the Folin-Ciocolteau method, ranged from 28.3 mg/g in the aqueous extract obtained from the Lizan ecotype to 39.6 mg/g in the hydroalcoholic extract obtained from the Pahleh ecotype. Moreover, HPLC analysis was aimed at determining the content of eight phenolic compounds, namely eugenol, rosmarinic acid, hesperetin, hesperedin, trans-ferulic acid, vanillin, and caffeic acid. According to the results, rosmarinic acid appeared to be the most abundant component. The phytotoxic activities of S.striata extracts were examined on the seed germination of a crop species, Lepidium sativum, and two weeds, Chenopodium album and Malva sylvestris. All extracts showed inhibitory effects on these species. The efficiency of these inhibitory effects depended on the type of plant species, origin, and concentration of extract. The highest phytotoxic activity was caused by approximately 1% concentration of extract. The most susceptible weed was M. sylvestris. The extracts that were obtained from the Pahleh ecotype, notably the hydroalcoholic ones, showed higher phytotoxicity against L. sativum, C. album and M. sylvestris. These results encourage further studies to support the use of S. striata as a source of bioherbicides.

Bioherbicidal Properties of Parthenium hysterophorus, Cleome rutidosperma and Borreria alata Extracts on Selected Crop and Weed Species

“…The highest reduction of 100% was observed from the maximum concentration (100 g L −1 ) of P. hysterophorus extract at the mature stage of A. conyzoides. This type of dose-dependent inhibitory activity was reported by many researchers around the globe [19,34,37,38]. A greater decrease in plant height was recorded in A. conyzoides compared to other species.…”

Phytochemical Constituents and Allelopathic Potential of Parthenium hysterophorus L. in Comparison to Commercial Herbicides to Control Weeds

“…At the mature stage of C. iria , the maximum concentration (100 g L −1 ) of P. hysterophorus extract resulted in the greatest decrease. Many researchers from all around the world have demonstrated dose-dependent inhibitory activity [ 21 , 27 , 30 , 31 ]. Only untreated C. iria continued flowering 21 days after spray, indicating that allelochemicals stress may have suppressed the other treated plants.…”

Phytotoxic Activity of Melia Azedarach(l.) Aqueous Leaf Extracts on Germination and Seedling Development of Abelmoschus Esculantus (L.) and Sesamum Indicum (L.)

“…Phytochemicals are thought to hinder seed germination by disrupting mitochondrial respiration and oxidative pentose phosphate pathways, according to a previous study 24 . Furthermore, the synergistic effect of multiple phenolic compounds contained in the extract may increase phytotoxicity 25 . The inhibitory activity on germination was, however, depending on the test plant species and concentration.…”

“…When it came to the growth of herbal species, differences were depending on inhibitory effects on some plants (e.g., Dactylis hispanica Roth) and stimulatory effects on others (e.g., Aegilops geniculate Roth) 30 . The leaf extracts of Gliricidia sepium inhibited the growth of lettuce radicles due to the presence of coumarins 31 .…”

“…Different plant parts, including flowers, leaves, leaf litter, and leaf mulch, stems, bark, roots, soil, and soil leachates and their derived compounds, can have an allelopathic activity that varies over a growing season. Various plant species produce phytochemicals, and their anti-weed and anti-crop activities have been widely established 10,11 .…”