Allelopathic and Herbicidal Effects of Crude Extract from Chromolaena odorata (L.) R.M.King and H.Rob. on Echinochloa crus-galli and Amaranthus viridis.

Thanatsan Poonpaiboonpipat,Hisashi Kato-Noguchi,Ramida Krumsri

doi:10.3390/plants10081609

Thanatsan Poonpaiboonpipat, Hisashi Kato-Noguchi + Show 1 more

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https://doi.org/10.3390/plants10081609

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Abstract

The present study was aimed at investigating the allelopathic effects of a crude extract from Chromolaena odorata (L.) R.M.King and H.Rob. (Siam weed). The effects of 70% crude ethanol extract from the whole plant, leaf, stem, and root on the germination and growth of Echinochloa crus-galli and Amaranthus viridis seedlings were evaluated using Petri-dish tests under laboratory conditions. Crude extracts from the leaf showed the highest inhibitory activity. The leaf extract (OR) was further separated by sequential solvent extraction to provide hexane (HX), ethyl acetate (ET), and butanol (BU) fractions, which were also evaluated using Petri-dish tests. The hexane fraction was significantly the most active; therefore, it was selected for formulation in a concentrated suspension and tested for its herbicidal characteristics. The formulation showed greater early post-emergence than post- and pre-emergence activities, respectively. The physiological mechanism of the formulation was tested against E. crus-galli and showed that chlorophyll a and b and the carotenoid contents of the leaf dramatically decreased when the concentration was increased, suggesting its ability to disrupt the process of photosynthesis. As thiobarbituric acid reactive substances also occurred in the leaf of E. crus-galli, this suggests lipid peroxidation and cell disruption. These results represent the possibility that C. odorata extract contains inhibitory compounds with herbicidal activity and could be used as an early post-emergence herbicide for weed control.

Highlights

Published: 5 August 2021Many plant species, including crop plants, can produce and release biologically active compounds, termed allelopathic compounds, allelochemicals, or allelochemics [1], which affect the growth and development of surrounding organisms
Amaranthus viridis seemed to be more susceptible to C. odorata extracts than E. crus-galli
Our results showed that the contents of chlorophyll a, b, and carotenoid were reduced with increasing times of application, indicating that the crude hexane (CH) product interfered with photosynthetic metabolism (Figure 6)

Summary

Introduction

Many plant species, including crop plants, can produce and release biologically active compounds, termed allelopathic compounds, allelochemicals, or allelochemics [1], which affect the growth and development of surrounding organisms. Allelochemicals have been proven to affect other plant species through different pathways, such as disturbing mitotic activity in the roots or seedling growth; the ion uptake rate; photosynthesis; respiration; protein formation; the permeability of cell membranes; and changing or inactivating the functions of certain hormones and enzymes [2,3,4]. Various allelochemicals can be stimulatory or inhibitory, depending on the type of active compounds or the static and dynamic availability and the target species [5]. Numerous allelopathic compounds have been successfully identified in and isolated from plants or plant extracts worldwide. Benzoxazoline (BOA) exuded from the roots of several grass species; sarmentine extracted from the fruits of the long pepper (Piper longum L.); fatty

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