Phytotoxic Effects and Mechanism of Action of Essential Oils and Terpenoids

[EN] Weeds are one of the major constraints in crop production affecting both yield and quality. The excessive and exclusive use of synthetic herbicides for their management is increasing the development of herbicide-resistant weeds and is provoking risks for the environment and human health. Therefore, the development of new herbicides with multitarget-site activity, new modes of action and low impact on the environment and health are badly needed. The study of plant-plant interactions through the release of secondary metabolites could be a starting point for the identification of new molecules with herbicidal activity. Essential oils (EOs) and their components, mainly terpenoids, as pure natural compounds or in mixtures, because of their structural diversity and strong phytotoxic activity, could be good candidates for the development of new bioherbicides or could serve as a basis for the development of new natural-like low impact synthetic herbicides. EOs and terpenoids have been largely studied for their phytotoxicity and several evidences on their modes of action have been highlighted in the last decades through the use of integrated approaches. The review is focused on the knowledge concerning the phytotoxicity of these molecules, their putative target, as well as their potential mode of action.This research was supported by the Ministerio de Ciencia, Innovacion y Universidades RTI2018-094716-B-100 and by the Italian Ministry of Education, University and Research (MIUR), project SIR-2014 cod. RBSI14L9CE (MEDANAT).Verdeguer Sancho, MM.; Sánchez-Moreiras, AM.; Araniti, F. (2020). Phytotoxic Effects and Mechanism of Action of Essential Oils and Terpenoids. Plants. 9(11):1-52. https://doi.org/10.3390/plants9111571S15291

Application of indole-alkaloid harmaline induces physical damage to photosystem II antenna complexes in adult plants of Arabidopsis thaliana (L.) Heynh

Finding herbicides with new and multiple modes of action is a solution to stop the increase in resistant weed species. Harmaline, a natural alkaloid with proven phytotoxic potential, was tested on Arabidopsis adult plants by watering and spraying; watering resulted as the more effective treatment. Harmaline altered several photosynthetic parameters, reducing the efficiency of the light- (ΦII) and dark-adapted (Fv/Fm) PSII, suggesting physical damages in photosystem II, although dissipation of the energy in excess under the form of heat was not compromised as demonstrated by the significant increase in ΦNPQ. Metabolomic alterations, such as osmoprotectant accumulation and reduction in sugars’ content, also indicate a reduction of photosynthetic efficiency and suggest early senescence and water status alteration induced by harmaline. Data suggest that harmaline might be considered a new phytotoxic molecule interesting for further studies.Ministerio de Ciencia e Innovación | Ref. RTI2018-094716-B-100Universidade de Vigo/CISU

Control of Problematic Weeds in Mediterranean Vineyards with the Bioherbicide Pelargonic Acid

[EN] Pelargonic acid (PA) is the only natural herbicide authorized for professional use in Spain. Incorporating PA into an integrated weed management strategy in vineyards may enable a more sustainable production method for grapes. In this work, PA of 55% concentration, formulated by a commercial company (PSEI), was evaluated and applied at 8, 10, 12, and 15 L/ha for weed control in Mediterranean vineyards during 2020 and 2021. A total of 22 different weed species, 16 dicotyledonous and 6 monocotyledonous, were identified in the experimental areas. Previously, greenhouse assays were performed against Avena fatua L. and Chenopodium album L. to determine the dose/response curves. PSEI proved to be a viable post-emergence herbicide with an efficacy of 40.79¿80.90%, depending on the applied dose (higher doses were the most effective). Broader herbicidal activity (20% or more) was obtained against dicotyledonous weeds compared with monocotyledonous. The PA formulation was remarkable in achieving PSEI-similar effects as compared to the market reference but at lower concentrations (around 13% less PA) and doses (1¿8 less L/ha). PA has proved to be a good candidate to control weeds in Mediterranean vineyards when used as a post-emergence broad-spectrum herbicide in the first stages of weed development.This research was funded by SEIPASA.Muñoz, M.; Torres-Pagán, N.; Jouini, A.; Araniti, F.; Sánchez-Moreiras, AM.; Verdeguer Sancho, MM. (2022). Control of Problematic Weeds in Mediterranean Vineyards with the Bioherbicide Pelargonic Acid. Agronomy. 12(10):1-18. https://doi.org/10.3390/agronomy12102476118121

Effect of different parameters (treatment administration mode, concentration and phenological weed stage) on Thymbra capitata L. essential oil herbicidal activity

The essential oil (EO) of Thymbra capitata has been demonstrated to possess herbicidal activity and could be used as an alternative to synthetic herbicides with reduced persistence in soil and new mode of action. Nevertheless, it is necessary to determine the adequate doses for its use, the proper way for its application and the best phenological stage of weeds and crops in which the EO should be applied to obtain maximum efficacy against weeds without compromising crop production. In this work, T. capitata EO was tested at three different concentrations against weeds grown from a citrus orchard soil seedbank untreated with herbicides and against three important weed species grown in substrate to determine the efficacy of the concentrations on different weed species. All experiments were carried out under greenhouse conditions. To find out the best way for applying the EO, it was applied by irrigation and by spraying on the targeted weeds, and to verify the influence of timing, it was tested on Lolium rigidum at two different phenological stages and on wheat at a later phenological stage than weeds. The highest concentration tested (12 µL·mL−1) showed the best performance to control weeds. The more effective mode of application was by spraying on dicotyledons and by irrigation on monocotyledons at the earliest phenological stage. T. capitata EO was phytotoxic for wheat. More trials in different crops are needed to determine the best conditions for its use.Spanish Society of Weed Scienc

Cellular and ultrastructural alterations of Arabidopsis thaliana roots in response to exogenous trans-aconitic acid

In this work, the responses of Arabidopsis thaliana (L.) Heynh to trans-aconitic acid (TAA) were investigated. A. thaliana was grown in the presence of TAA in a concentration range of 400–1200 µM for 7 or 15 days. Changes in the morphoanatomy, cellular ultrastructure, and micromorphology of the roots were evaluated by light and transmission electron (TEM) microscopy. At concentrations below 1000 µM, TAA reduced the length of the primary roots, but induced an early appearance of lateral roots and root hairs. At a concentration of 1200 µM, TAA suppressed the growth of seedlings. The images of longitudinal sections of root tips of seedlings treated with IC50 of TAA (684 µM) revealed a reduced elongation zone with an increased differentiation zone. TEM images showed an increase in the number and volume of vacuoles, an increase in vesicles containing electron-dense material derived from plasmalemma, and electron-dense granules attached to the cell wall. Trans-aconitic acid induced an early differentiation of A. thaliana seedlings suggesting an interference in the auxin action. Changes in the cellular ultrastructure may represent vacuolar and extracellular accumulation of TAA, to remove excess TAA in the cytosol and mitochondria. An inhibition of aconitase and the chelation of intracellular cations may have contributed to cytotoxicity of TAA at 1200 µM concentration.Ministerio de Economía y Competitividad | Ref. AGL2013-41281-RUniversidade de Vigo/CISU

Phytotoxic Effects of Three Natural Compounds: Pelargonic Acid, Carvacrol, and Cinnamic Aldehyde, against Problematic Weeds in Mediterranean Crops

[EN] Weeds and herbicides are important stress factors for crops. Weeds are responsible for great losses in crop yields, more than 50% in some crops if left uncontrolled. Herbicides have been used as the main method for weed control since their development after the Second World War. It is necessary to find alternatives to synthetic herbicides that can be incorporated in an Integrated Weed Management Program, to produce crops subjected to less stress in a more sustainable way. In this work, three natural products: pelargonic acid (PA), carvacrol (CV), and cinnamic aldehyde (CA) were evaluated, under greenhouse conditions in postemergence assays, against problematic weeds in Mediterranean cropsAmaranthus retroflexus,Avena fatua,Portulaca oleracea,andErigeron bonariensis, to determine their phytotoxic potential. The three products showed a potent herbicidal activity, reaching high efficacy (plant death) and damage level in all species, being PA the most effective at all doses applied, followed by CA and CV. These products could be good candidates for bioherbicides formulations.This research was funded by SEIPASA.Muñoz, M.; Torres-Pagán, N.; Peiró Barber, RM.; Guijarro, R.; Sánchez-Moreiras, AM.; Verdeguer Sancho, MM. (2020). Phytotoxic Effects of Three Natural Compounds: Pelargonic Acid, Carvacrol, and Cinnamic Aldehyde, against Problematic Weeds in Mediterranean Crops. Agronomy. 10(6):1-20. https://doi.org/10.3390/agronomy10060791S120106Vos, R., & Bellù, L. G. (2019). Global Trends and Challenges to Food and Agriculture into the 21st Century. Sustainable Food and Agriculture, 11-30. doi:10.1016/b978-0-12-812134-4.00002-9Vats, S. (2014). Herbicides: History, Classification and Genetic Manipulation of Plants for Herbicide Resistance. Sustainable Agriculture Reviews, 153-192. doi:10.1007/978-3-319-09132-7_3Bagavathiannan, M., Singh, V., Govindasamy, P., Abugho, S. B., & Liu, R. (2017). Impact of Concurrent Weed or Herbicide Stress with Other Biotic and Abiotic Stressors on Crop Production. Plant Tolerance to Individual and Concurrent Stresses, 33-45. doi:10.1007/978-81-322-3706-8_3The International Code of Conduct on Pesticide Management. Rome http://www.fao.org/agriculture/crops/thematic-sitemap/theme/pests/code/en/Villa, F., Cappitelli, F., Cortesi, P., & Kunova, A. (2017). Fungal Biofilms: Targets for the Development of Novel Strategies in Plant Disease Management. Frontiers in Microbiology, 8. doi:10.3389/fmicb.2017.00654Da Mastro, G., Fracchiolla, M., Verdini, L., & Montemurro, P. (2006). OREGANO AND ITS POTENTIAL USE AS BIOHERBICIDE. Acta Horticulturae, (723), 335-346. doi:10.17660/actahortic.2006.723.46Seiber, J. N., Coats, J., Duke, S. O., & Gross, A. D. (2014). Biopesticides: State of the Art and Future Opportunities. Journal of Agricultural and Food Chemistry, 62(48), 11613-11619. doi:10.1021/jf504252nDahiya, A., Sharma, R., Sindhu, S., & Sindhu, S. S. (2019). Resource partitioning in the rhizosphere by inoculated Bacillus spp. towards growth stimulation of wheat and suppression of wild oat (Avena fatua L.) weed. Physiology and Molecular Biology of Plants, 25(6), 1483-1495. doi:10.1007/s12298-019-00710-3The International Herbicide-Resistant Weed Database www.weedscience.orgHazrati, H., Saharkhiz, M. J., Moein, M., & Khoshghalb, H. (2018). Phytotoxic effects of several essential oils on two weed species and Tomato. Biocatalysis and Agricultural Biotechnology, 13, 204-212. doi:10.1016/j.bcab.2017.12.014Bajwa, A. A., Sadia, S., Ali, H. H., Jabran, K., Peerzada, A. M., & Chauhan, B. S. (2016). Biology and management of two important Conyza weeds: a global review. Environmental Science and Pollution Research, 23(24), 24694-24710. doi:10.1007/s11356-016-7794-7Graziani, F., Onofri, A., Pannacci, E., Tei, F., & Guiducci, M. (2012). Size and composition of weed seedbank in long-term organic and conventional low-input cropping systems. European Journal of Agronomy, 39, 52-61. doi:10.1016/j.eja.2012.01.008Benbrook, C. M. (2016). Trends in glyphosate herbicide use in the United States and globally. Environmental Sciences Europe, 28(1). doi:10.1186/s12302-016-0070-0Salamci, E., Kordali, S., Kotan, R., Cakir, A., & Kaya, Y. (2007). Chemical compositions, antimicrobial and herbicidal effects of essential oils isolated from Turkish Tanacetum aucheranum and Tanacetum chiliophyllum var. chiliophyllum. Biochemical Systematics and Ecology, 35(9), 569-581. doi:10.1016/j.bse.2007.03.012Synowiec, A., Kalemba, D., Drozdek, E., & Bocianowski, J. (2016). Phytotoxic potential of essential oils from temperate climate plants against the germination of selected weeds and crops. Journal of Pest Science, 90(1), 407-419. doi:10.1007/s10340-016-0759-2Hazrati, H., Saharkhiz, M. J., Niakousari, M., & Moein, M. (2017). Natural herbicide activity of Satureja hortensis L. essential oil nanoemulsion on the seed germination and morphophysiological features of two important weed species. Ecotoxicology and Environmental Safety, 142, 423-430. doi:10.1016/j.ecoenv.2017.04.041Verdeguer, M., Blázquez, M. A., & Boira, H. (2009). Phytotoxic effects of Lantana camara, Eucalyptus camaldulensis and Eriocephalus africanus essential oils in weeds of Mediterranean summer crops. Biochemical Systematics and Ecology, 37(4), 362-369. doi:10.1016/j.bse.2009.06.003Benarab, H., Fenni, M., Louadj, Y., Boukhabti, H., & Ramdani, M. (2020). Allelopathic activity of essential oil extracts from Artemisia herba-alba Asso. on seed and seedling germination of weed and wheat crops. Acta Scientifica Naturalis, 7(1), 86-97. doi:10.2478/asn-2020-0009Benchaa, S., Hazzit, M., & Abdelkrim, H. (2018). Allelopathic Effect ofEucalyptus citriodoraEssential Oil and Its Potential Use as Bioherbicide. Chemistry & Biodiversity, 15(8), e1800202. doi:10.1002/cbdv.201800202Verdeguer, M., Castañeda, L. G., Torres-Pagan, N., Llorens-Molina, J. A., & Carrubba, A. (2020). Control of Erigeron bonariensis with Thymbra capitata, Mentha piperita, Eucalyptus camaldulensis, and Santolina chamaecyparissus Essential Oils. Molecules, 25(3), 562. doi:10.3390/molecules25030562Scavo, A., Pandino, G., Restuccia, A., & Mauromicale, G. (2020). Leaf extracts of cultivated cardoon as potential bioherbicide. Scientia Horticulturae, 261, 109024. doi:10.1016/j.scienta.2019.109024Ma, S., Fu, L., He, S., Lu, X., Wu, Y., Ma, Z., & Zhang, X. (2018). Potent herbicidal activity of Sapindus mukorossi Gaertn. against Avena fatua L. and Amaranthus retroflexus L. Industrial Crops and Products, 122, 1-6. doi:10.1016/j.indcrop.2018.05.046Pacanoski, Z., & Mehmeti, A. (2019). Allelopathic effect of Siberian iris (Iris sibirica) on the early growth of wild oat (Avena fatua) and Canada thistle (Cirsium arvense). Journal of Central European Agriculture, 20(4), 1179-1187. doi:10.5513/jcea01/20.4.2047Bainard, L. D., Isman, M. B., & Upadhyaya, M. K. (2006). Phytotoxicity of clove oil and its primary constituent eugenol and the role of leaf epicuticular wax in the susceptibility to these essential oils. Weed Science, 54(5), 833-837. doi:10.1614/ws-06-039r.1Ahuja, N., Singh, H. P., Batish, D. R., & Kohli, R. K. (2015). Eugenol-inhibited root growth in Avena fatua involves ROS-mediated oxidative damage. Pesticide Biochemistry and Physiology, 118, 64-70. doi:10.1016/j.pestbp.2014.11.012Vaughn, S. F., & Spencer, G. F. (1993). Volatile Monoterpenes as Potential Parent Structures for New Herbicides. Weed Science, 41(1), 114-119. doi:10.1017/s0043174500057672Verdeguer, M., García-Rellán, D., Boira, H., Pérez, E., Gandolfo, S., & Blázquez, M. A. (2011). Herbicidal Activity of Peumus boldus and Drimys winterii Essential Oils from Chile. Molecules, 16(1), 403-411. doi:10.3390/molecules16010403Saad, M. M. G., Abdelgaleil, S. A. M., & Suganuma, T. (2012). Herbicidal potential of pseudoguaninolide sesquiterpenes on wild oat, Avena fatua L. Biochemical Systematics and Ecology, 44, 333-337. doi:10.1016/j.bse.2012.06.004Araniti, F., Sánchez-Moreiras, A. M., Graña, E., Reigosa, M. J., & Abenavoli, M. R. (2016). Terpenoidtrans-caryophyllene inhibits weed germination and induces plant water status alteration and oxidative damage in adultArabidopsis. Plant Biology, 19(1), 79-89. doi:10.1111/plb.12471Coleman, R., & Penner, D. (2008). Organic Acid Enhancement of Pelargonic Acid. Weed Technology, 22(1), 38-41. doi:10.1614/wt-06-195.1Dayan, F. E., & Duke, S. O. (2014). Natural Compounds as Next-Generation Herbicides. PLANT PHYSIOLOGY, 166(3), 1090-1105. doi:10.1104/pp.114.239061Lebecque, S., Lins, L., Dayan, F. E., Fauconnier, M.-L., & Deleu, M. (2019). Interactions Between Natural Herbicides and Lipid Bilayers Mimicking the Plant Plasma Membrane. Frontiers in Plant Science, 10. doi:10.3389/fpls.2019.00329Gruenwald, J., Freder, J., & Armbruester, N. (2010). Cinnamon and Health. Critical Reviews in Food Science and Nutrition, 50(9), 822-834. doi:10.1080/10408390902773052Viazis, S., Akhtar, M., Feirtag, J., & Diez-Gonzalez, F. (2011). Reduction of Escherichia coli O157:H7 viability on leafy green vegetables by treatment with a bacteriophage mixture and trans-cinnamaldehyde. Food Microbiology, 28(1), 149-157. doi:10.1016/j.fm.2010.09.009Kwon, J. A., Yu, C. B., & Park, H. D. (2003). Bacteriocidal effects and inhibition of cell separation of cinnamic aldehyde on Bacillus cereus. Letters in Applied Microbiology, 37(1), 61-65. doi:10.1046/j.1472-765x.2003.01350.xFriedman, M. (2017). Chemistry, Antimicrobial Mechanisms, and Antibiotic Activities of Cinnamaldehyde against Pathogenic Bacteria in Animal Feeds and Human Foods. Journal of Agricultural and Food Chemistry, 65(48), 10406-10423. doi:10.1021/acs.jafc.7b04344Saad, M. M. G., Gouda, N. A. A., & Abdelgaleil, S. A. M. (2019). Bioherbicidal activity of terpenes and phenylpropenes against Echinochloa crus-galli. Journal of Environmental Science and Health, Part B, 54(12), 954-963. doi:10.1080/03601234.2019.1653121Roselló, J., Sempere, F., Sanz-Berzosa, I., Chiralt, A., & Santamarina, M. P. (2015). Antifungal Activity and Potential Use of Essential Oils AgainstFusarium culmorumandFusarium verticillioides. Journal of Essential Oil Bearing Plants, 18(2), 359-367. doi:10.1080/0972060x.2015.1010601Santamarina, M., Ibáñez, M., Marqués, M., Roselló, J., Giménez, S., & Blázquez, M. (2017). Bioactivity of essential oils in phytopathogenic and post-harvest fungi control. Natural Product Research, 31(22), 2675-2679. doi:10.1080/14786419.2017.1286479Krepker, M., Shemesh, R., Danin Poleg, Y., Kashi, Y., Vaxman, A., & Segal, E. (2017). Active food packaging films with synergistic antimicrobial activity. Food Control, 76, 117-126. doi:10.1016/j.foodcont.2017.01.014Ye, H., Shen, S., Xu, J., Lin, S., Yuan, Y., & Jones, G. S. (2013). Synergistic interactions of cinnamaldehyde in combination with carvacrol against food-borne bacteria. Food Control, 34(2), 619-623. doi:10.1016/j.foodcont.2013.05.032WU, H., WALKER, S., ROLLIN, M. J., TAN, D. K. Y., ROBINSON, G., & WERTH, J. (2007). Germination, persistence, and emergence of flaxleaf fleabane (Conyza bonariensis [L.] Cronquist). Weed Biology and Management, 7(3), 192-199. doi:10.1111/j.1445-6664.2007.00256.xMithila, J., Swanton, C. J., Blackshaw, R. E., Cathcart, R. J., & Hall, J. C. (2008). Physiological Basis for Reduced Glyphosate Efficacy on Weeds Grown Under Low Soil Nitrogen. Weed Science, 56(1), 12-17. doi:10.1614/ws-07-072.1SANDBERG, C. L., MEGGITT, W. F., & PENNER, D. (1980). Absorption, translocation and metabolism of 14C-glyphosate in several weed species*. Weed Research, 20(4), 195-200. doi:10.1111/j.1365-3180.1980.tb00068.xLederer, B., Fujimori, T., Tsujino, Y., Wakabayashi, K., & Böger, P. (2004). Phytotoxic activity of middle-chain fatty acids II: peroxidation and membrane effects. Pesticide Biochemistry and Physiology, 80(3), 151-156. doi:10.1016/j.pestbp.2004.06.010Hasanuzzaman, M., Mohsin, S. M., Bhuyan, M. H. M. B., Bhuiyan, T. F., Anee, T. I., Masud, A. A. C., & Nahar, K. (2020). Phytotoxicity, environmental and health hazards of herbicides: challenges and ways forward. Agrochemicals Detection, Treatment and Remediation, 55-99. doi:10.1016/b978-0-08-103017-2.00003-

Effect of Different Parameters (Treatment Administration Mode, Concentration and Phenological Weed Stage) on Thymbra capitata L. Essential Oil Herbicidal Activity

[EN] The essential oil (EO) of Thymbra capitata has been demonstrated to possess herbicidal activity and could be used as an alternative to synthetic herbicides with reduced persistence in soil and new mode of action. Nevertheless, it is necessary to determine the adequate doses for its use, the proper way for its application and the best phenological stage of weeds and crops in which the EO should be applied to obtain maximum efficacy against weeds without compromising crop production. In this work, T. capitata EO was tested at three different concentrations against weeds grown from a citrus orchard soil seedbank untreated with herbicides and against three important weed species grown in substrate to determine the efficacy of the concentrations on different weed species. All experiments were carried out under greenhouse conditions. To find out the best way for applying the EO, it was applied by irrigation and by spraying on the targeted weeds, and to verify the influence of timing, it was tested on Lolium rigidum at two different phenological stages and on wheat at a later phenological stage than weeds. The highest concentration tested (12 µL·mL¿1) showed the best performance to control weeds. The more effective mode of application was by spraying on dicotyledons and by irrigation on monocotyledons at the earliest phenological stage. T. capitata EO was phytotoxic for wheat. More trials in different crops are needed to determine the best conditions for its use.This research was funded by the Spanish Society of Weed Science.Torres-Pagán, N.; Jouini, A.; Melero-Carnero, N.; Peiró Barber, RM.; Sánchez-Moreiras, A.; Carrubba, A.; Verdeguer Sancho, MM. (2023). Effect of Different Parameters (Treatment Administration Mode, Concentration and Phenological Weed Stage) on Thymbra capitata L. Essential Oil Herbicidal Activity. Agronomy. 13(12):1-16. https://doi.org/10.3390/agronomy13122938116131

Herbicidal potential of the natural compounds carvacrol, thymol, eugenol, p-cymene, citral and pelargonic acid in field conditions: indications for better performance

In recent years, interest in natural products with herbicidal activity as new tools for integrated weed management has increased. The European Union is demanding a reduction in the number of herbicides used, forbidding use of the most toxic ones, despite the problem of weed resistance increasing. Pelargonic acid (PA) is the only natural herbicide available in Spain. In this work, two field assays were performed with the natural compounds carvacrol (CAR), citral (CIT), eugenol (EUG), thymol (THY), p-cymene (P-CYM), (PA), and the combination of PA with CIT—all except P-CYM formulated by Seipasa—to test their herbicidal efficacy in real conditions. They were compared with commercial PA, glyphosate (GLY) and oxyfluorfen (OXY). In both experiments, GLY achieved the best weed control. Considering the natural herbicides, PA formulated by Seipasa and PA plus CIT were the most effective. From both experiments, some conclusions can be extracted for better herbicidal performance of natural products: (1) use products on sensitive weed species, (2) treat weeds at earlier phenological stages, (3) find the active doses in field conditions, (4) cover weeds well when treating, (5) ensure adequate formulation of products, and (6) develop a strategy for correct application.AGROSUS | Ref. 101084084Agencia Estatal de Investigación | Ref. RTI2018-094716-B-I0

Potential of different common (Fagopyrum esculentum Moench) and Tartary (Fagopyrum tataricum (L.) Gaertn.) buckwheat accessions to sustainably manage surrounding weeds

Twenty-nine accessions of two buckwheat species (Fagopyrum esculentum Moench (common buckwheat) and Fagopyrum tataricum (L.) Gaertn. (Tartary buckwheat) were evaluated for their allelopathic potential against two resistant weeds, the monocot Lolium rigidum Gaud. and the dicot Portulaca oleracea L. The bulking use of synthetic herbicides and their consequent contamination of the environment and resulting increment of herbicide-resistant weeds, imminently requires a solution to achieve sustainable weed management without chemical inputs. The results obtained in this study suggest that buckwheat accessions can sustainably manage weeds through plant interference as competition or allelopathy. This research showed that accessions differ in their potential for sustainably managing both weeds with F. esculentum accessions being more effective against L. rigidum and F. tataricum accessions against both, monocot and dicot weeds. The chemical profile of buckwheat accessions was evaluated to know the content of polyphenols in common and Tartary buckwheat accessions and to know more about their ability to manage weeds sustainably. Differences in the chemical profile between the two buckwheat species were clear. While common buckwheat accessions showed more orientin, vitexin and hyperoside, Tartary buckwheat accessions had higher amounts of rutin, quercetin and kaempferol. We propose that the screening and selection of accessions with strong polyphenol content and vigorous growth can be a step towards organic farming due to its relation to the weed management.Universidade de Vigo/CISU

Specialized metabolites accumulation pattern in buckwheat Is strongly influenced by accession choice and co-existing weeds

Screening suitable allelopathic crops and crop genotypes that are competitive with weeds can be a sustainable weed control strategy to reduce the massive use of herbicides. In this study, three accessions of common buckwheat Fagopyrum esculentum Moench. (Gema, Kora, and Eva) and one of Tartary buckwheat Fagopyrum tataricum Gaertn. (PI481671) were screened against the germination and growth of the herbicide-resistant weeds Lolium rigidum Gaud. and Portulaca oleracea L. The chemical profile of the four buckwheat accessions was characterised in their shoots, roots, and root exudates in order to know more about their ability to sustainably manage weeds and the relation of this ability with the polyphenol accumulation and exudation from buckwheat plants. Our results show that different buckwheat genotypes may have different capacities to produce and exude several types of specialized metabolites, which lead to a wide range of allelopathic and defence functions in the agroecosystem to sustainably manage the growing weeds in their vicinity. The ability of the different buckwheat accessions to suppress weeds was accession-dependent without differences between species, as the common (Eva, Gema, and Kora) and Tartary (PI481671) accessions did not show any species-dependent pattern in their ability to control the germination and growth of the target weeds. Finally, Gema appeared to be the most promising accession to be evaluated in organic farming due to its capacity to sustainably control target weeds while stimulating the root growth of buckwheat plants