Carum carvi L. essential oil: A promising candidate for botanical herbicide against Echinochloa crus-galli (L.) P. Beauv. in maize cultivation

Abstract

In this study we tested the possibility that foliar-applied caraway or peppermint essential oils (EOs) can selectively inhibit the growth of Echinochloa crus-galli (a typical maize weed) but not that of maize plants, attempting to develop an eco-friendly botanical herbicide.We tested the phytotoxic potential of oil-in-water emulsions of each EO with addition of commercial adjuvant mainly composed of fatty acids methyl esters, studying their effect on 2 visible plants injuries, biomass accumulation, chlorophyll a fluorescence and changes to biochemical patterns of both the main crop (maize) and the weed (E. crus-galli) via an untargeted metabolomic approach. We found that oil-in-water emulsion containing 2.5% of adjuvant and of caraway EO did not affect significantly the growth of maize plants, did not induce foliar symptoms and did not alter the status of the photosynthetic apparatus, as revealed by chlorophyll a fluorescence. On the contrary, this emulsion exerted significantly negative effects against E. crus-galli growth, inducing foliar injuries and reducing the photosynthetic efficiency of photosystem II. We also found that the studied emulsions caused a series of biochemical changes in the plant tissues, with caraway emulsion being more phytotoxic, as compared to the peppermint EO-emulsion. We conclude that oil-in-water emulsion containing 2.5% of caraway EO could be used in future as a foliar-applied botanical herbicide against E. crus-galli in maize cultivation.

Phytotoxicity of Essential Oils: Opportunities and Constraints for the Development of Biopesticides. A Review

“…EOs physiological impacts have been and can be studied at the metabolomic [113], proteomic [114] and transcriptomic [115] levels and large amounts of untargeted data will emerge by grouping these techniques of research together. As phytotoxicity is either a goal (herbicide) or a constraint (other biopesticidal application or biostimulation), both parts will be discussed separately.…”

“…Phytotoxicity towards weeds without affecting the crop is essential to develop selective bio-herbicides. In this regard, the identification of other molecular mechanisms such as sugar and amino acid accumulation to prevent EOs stress seems promising as demonstrated in maize [113].…”

Biopesticide Trunk Injection Into Apple Trees: A Proof of Concept for the Systemic Movement of Mint and Cinnamon Essential Oils

“…For a healthy sample, this ratio is around 0.83 and lowers as plant stress increases, reaching 0.3 at the end of senescence ( Bresson et al, 2018 ). Moreover, the maximum quantum yield of photosystem II has been used to evaluate foliar response after EO application ( Synowiec et al, 2015 , 2019 ). Measurements were performed at the same time of day for each time considered ( t = 0, 24, 48, 72, and 96 h for each modality tested).…”

Phytotoxic Effects and Mechanism of Action of Essential Oils and Terpenoids

“…Concerning the selectivity of the EOs, Synowiec et al [ 93 ] reported that caraway EO emulsion was a good candidate for weed management in corn crops. This EO was selective, severely affecting the physiology and metabolism of E. crus-galli without damaging the corn.…”