FITOTOXICIDAD DE ACEITES ESENCIALES Y EXTRACTOS ACUOSOS DE PLANTAS MEDITERRÁNEAS PARA EL CONTROL DE ARVENSES

El hombre, desde que puso en práctica la domesticación y cultivo de plantas, a principios del Neolítico, ha ido incorporando mejoras de forma paulatina, a fin de conseguir el máximo rendimiento de la tierra. Introdujo para ello, y de forma progresiva, el abonado, la irrigación y el control de las plagas, enfermedades y arvenses. Las prácticas, basadas fundamentalmente en operaciones manuales, fueron muy rudimentarias hasta bien entrado el siglo XX. Con el gran desarrollo de los productos químicos para uso agrícola, a partir de los años 40, se produce un gran incremento en la productividad agraria, basado en el empleo de abonos y pesticidas de síntesis, y en la introducción de cultivares procedentes de mejora genética. Con el tiempo se manifestaron las consecuencias negativas de la utilización abusiva de estos productos. En concreto, el empleo excesivo de herbicidas sintéticos provoca la aparición de estirpes de arvenses resistentes, y su acumulación en el suelo y aguas subterráneas produce efectos perjudiciales sobre los seres vivos y la salud de las personas. Desde los años 90, la normativa que regula los productos agroquímicos impone más restricciones respondiendo a una sociedad cada vez más concienciada de los peligros de su empleo intensivo. Ello ha impulsado la búsqueda de otros métodos alternativos para el control de arvenses, basados en productos naturales, que sean respetuosos con el medio ambiente. Los fenómenos alelopáticos, basados en la interacción de plantas a través de sus metabolitos secundarios, liberados mediante volatilización, exudación y lixiviación de tejidos vegetales, constituye en este sentido un campo de investigación relativamente moderno. Los aleloquímicos que impiden el desarrollo de plantas en el entorno de la planta fuente han recibido especial atención debido a su potencial como herbicidas naturales selectivos. La presente Tesis doctoral tiene como objetivo principal el ensayo de la actividad fitotóxica de diferentes aceites esenciales y extractos acuosos de plantas mediterráneas sobre la germinación y el crecimiento de arvenses, con el fin de escoger los más activos, para desarrollarlos en un futuro como herbicidas naturales.Verdeguer Sancho, MM. (2011). FITOTOXICIDAD DE ACEITES ESENCIALES Y EXTRACTOS ACUOSOS DE PLANTAS MEDITERRÁNEAS PARA EL CONTROL DE ARVENSES [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/13827Palanci

Capped polyethylene glycol esters of fatty acids as novel active principles for weed control

[EN] BACKGROUND Ever since the beginning of agriculture, yields have been threatened by weeds. Chemical weed control is far more effective and economical than other methods. The frequent use of herbicides has led to environmental and human health concerns, resulting in the banning of several herbicides and challenges for the future of important active compounds such as glyphosate. RESULTS The herbicidal activity of sustainable alternatives based on certain esters of fatty acids (FA), the action of which is unrelated to the free acid, on common weeds is assessed and reported. The 13 derivatives of FA showed better physicochemical properties than pelargonic acid-based herbicides. All the reported compounds have phytotoxic activity, the highest efficacy being displayed by the methyl end-capped polyethylene glycol (mPEG) ester of pelargonic acid having 6EO (ethylene oxide). This mPEG ester showed equal or better phytotoxicity than the pelargonic acid benchmark at reduced application rate and spray volume. The active compound is a liquid at ambient temperatures, has no bad smell and is not volatile, in contrast to pelargonic acid. Notably, this active compound can be the final product, can be sprayed without adjuvants and is relatively easy to co-formulate. CONCLUSION A new lead substance is presented that is a sustainable alternative to current contact herbicides. In particular, it has potential application on railways, in precision agriculture and as a harvest aid. Its good performance and technical properties suggest this mPEG ester group may also overcome the volatility-related problems of other organic acids such as auxins.Campos, J.; Verdeguer Sancho, MM.; Baur, P. (2021). Capped polyethylene glycol esters of fatty acids as novel active principles for weed control. Pest Management Science. 77(10):4648-4657. https://doi.org/10.1002/ps.6505S46484657771

Mechanistic Aspects and Effects of Selected Tank-Mix Partners on Herbicidal Activity of a Novel Fatty Acid Ester

[EN] Only a limited number of contact herbicides exist in agricultural production. While systemic herbicides are more efficient also at suboptimum spray coverage with long-lasting weed control, contact herbicides provide several advantages. There is no translocation to fruits or roots of plantation and other crop, low risk for resistance development, and minor risk for spray-drift damage. Besides, synthetic products that often have toxicological or residues issues, natural fatty acids, particularly pelargonic acid (PA), have contact activity and are safer for home and garden use. We recently described a methyl capped polyethylene glycol ester of pelargonic acid (PA-MPEG) that acts independent of acid formation. Both, PA-MPEG and PA are applied at high rates per hectare to achieve excellent weed control. Here, we report about potential additives to increase PA-MPEG efficacy. The herbicidal active, 1-decanol, and the non-phytotoxic alkylated seed oil-based adjuvant, HastenTM, improved performance and outperformed a commercial PA herbicide. Both, PA-MPEG and PA appear to mainly act by the disintegration of bio-membranes besides having effects on transpiration. The main suggested effect is desiccation due to cutting the water continuum at the site of evaporation in the intercellular spaces. The synergistic action of the adjuvant HastenTM and its practical uses are also discussedThis work was supported by ClariantCampos, J.; Bodelon, L.; Verdeguer Sancho, MM.; Baur, P. (2022). Mechanistic Aspects and Effects of Selected Tank-Mix Partners on Herbicidal Activity of a Novel Fatty Acid Ester. Plants. 11(3):1-16. https://doi.org/10.3390/plants11030279S11611

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

Contact herbicidal activity optimization of methyl capped polyethylene glycol ester of pelargonic acid

[EN] The loss of important contact herbicides like paraquat opens opportunities for more potentially sustainable solutions demanded by consumers and organizations. Frequently, for adequate weed control, the alternatives to classical synthetic products need well-defined and executed labels and even more detailed use descriptions. One novel candidate with rare contact activity is a pelargonic acid ester of methyl polyethylene glycol (PA-MPEG) with advantages over free pelargonic acid (PA), such as reduced volatility and ease of formulation. Here, we report on the role of the application parameters such as spray volume, rate, sprayer set-up, and climate conditions for weed control with PA-MPEG. At a dose rate of 12.8 kg ae ha¿1 in a spray volume of 500 L ha¿1, control of Digitaria sanguinalis (L.) Scop. and Solanum nigrum L. was excellent. These values for product rate and spray volume are lower than applications with commercial PA herbicides, at equal or better efficacy. Coverage was too low at spray volumes of 100 to 200 L ha¿1, for adequate contact activity of both PA-MPEG and PA. Weed control was significantly increased when PA-MPEG application was made at lower boom height with reduced distance to weed canopy, or under warm and dry climate conditions. The results indicate the potential of PA-MPEG under optimal use conditions as a new contact herbicide in integrated weed management.Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature.Campos, J.; Mansour, P.; Verdeguer Sancho, MM.; Baur, P. (2023). Contact herbicidal activity optimization of methyl capped polyethylene glycol ester of pelargonic acid. Journal of Plant Diseases and Protection. 130(1):93-103. https://doi.org/10.1007/s41348-022-00661-093103130

Phytotoxic potential of Citrus essential oils on weed species

Environmental constraints of crop production systems have stimulated interest in alternative weed management strategies. In fact, the continued use of synthetic herbicides may threaten sustainable agricultural production and result in serious ecological and environmental problems, such as the increased incidence of resistance in weeds to important herbicides and increased environmental pollution and health hazards. Public awareness and demand for environmentally safer herbicides with less persistence and less contaminating potential make searches for new weed control strategies. Citrus Essential oils are generally used in the cosmetic, medicinal, and food industries, and are thought to be safe compounds for humans, animals, and the environment. EOs can be extracted by hydro distillation and cold pressing. The two methods are based on different procedures. Hydro distillation is carried out with a Clevenger-apparatus that conducts the distillation process by boiling, condensing and decantation to separate the EOs. The cold pressing consist of crushing and pressing the peels thus leading to the formation of a watery emulsion. Then, the emulsion is centrifuged to separate out the EOs. Since no external substance are needed, this process ensures that the resulting EOs retains all their properties. The allelopathic and phytotoxic effects of EOs obtained from other species and their potential use for weed management has been well documented. The objectives of this study were to evaluate in vitro the phytotoxic effects of Citrus EOs (Citrus sinensis, Citrus limon and Citrus reticulata) extracted by hydro distillation and cold pressing on main weed species (Amaranthus retroflexus, Portulaca oleracea., Echinochloa crus-galli, Avena sativa). For all EOs six concentrations were tested (0.5, 1, 2, 4, 8, 12) μl/ml and 5 repetitions with 20 seeds each (for dicotyledons) or 10 repetitions with 10 seeds each (for monocotyledons) were performed. They were applied for one hundred seeds for concentration. Twenty seeds were placed into 9 cm diameter Petri dishes for Amarantus and Portulaca. In each Petri dish, 5 ml of distilled water were added. This volume kept the filter papers uniformly soaked-wet without flooding. For Avena and Echinocloa ten seeds were placed into petri dishes and 6 ml of distilled water was added. The essential oil was placed in a sheet of filter papers in contact with the seeds. The controls were prepared with the same quantities of distilled water. Petri dishes were incubated in the room germination (EQUITEC) at 20/30 °C (±1 °C), alternating temperature (6/18 h dark and light (cool white Radium NL 36W/840; 3100 lm)). Dishes were sealed to reduce evaporation, and no more additional water was supplied during the tests. To evaluate the possible phytotoxic effects of the essential oils and their main compounds on seed germination and seedling growth data were registered by taking photos after 3,5, 7, 10 and 14 days after incubation and will be processed using Digimizer. Then data will be analysed and discussed

Seasonal variation of Thymus piperella L. essential oil composition. Relationship among ¿-terpinene, p-cymene and carvacrol

[EN] A wild population of Thymus piperella L. was monitored for two years in order to correlate phenological stages and meteorological data with yield and, essential oil (EO) composition. The plant material was extracted by hydrodistillation and the EO was submitted to GC-MS and GC-FID analysis. To achieve reliable quantification, relative response factors were applied. The results showed a progressive increase in the proportion of carvacrol according to the sunlight duration and temperature increase, until reaching a maximum at the beginning of flowering stage (52.9 % and 41.0 % in 2018 and 2019, respectively). A simultaneous decrease was found in the amount of p-cymene (8.2 % and 12.8 % respectively) in the same stage, whereas gamma-terpinene showed a similar evolution to that observed for carvacrol but with lower values (3.3 % - 14.6 %). From statistical analysis, significant changes in the relative proportions of carvacrol and its metabolic precursors: gamma-terpinene and p-cymene were found. They have been explained based on the proposed metabolic pathways in the literature. On the other hand, when relating the changes in the EO profiles with rainfall data, a strong influence of the water supply on the evolution of the chemical composition was observed.Llorens Molina, JA.; Vacas, S.; Escrivá, N.; Verdeguer Sancho, MM. (2022). Seasonal variation of Thymus piperella L. essential oil composition. Relationship among ¿-terpinene, p-cymene and carvacrol. Journal of Essential Oil Research. 34(6):502-513. https://doi.org/10.1080/10412905.2022.210319150251334

Seasonal variations of essential oils from five accessions of Mentha longifolia (L.) L. with selected chemical profiles

[EN] Essential oil (EO) yield and composition of five accessions ofMentha longifolia(L.) L. (leaves) were determined throughout their vegetative cycle by GC-MS and GC-FID analysis. These accessions were selected based on TLC profiles of dichloromethane extracts from wild individuals. The profile rich in alpha-terpinyl acetate and 8-acetoxy carvotanacetone has not been previously reported. The maximum value of EO yield was obtained in advanced flowering stage. The major composition changes were noted at the beginning of the vegetative cycle, whereas more stability was found during the flowering stage. Thus, significant changes in the major compounds were found in some accessions: piperitone and piperitenone oxides, alpha-terpineol acetate and 8-acetoxy carvotanacetone, which showed a considerable increase (6.0% to 20.1%) during the vegetative growth, the same way that pulegone and piperitenone oxide in other accessions. As biological activities depend on EO composition, the knowledge of its seasonal changes should be emphasized.Llorens Molina, JA.; Vacas, S.; Castell-Zeising, V.; Verdeguer Sancho, MM. (2020). Seasonal variations of essential oils from five accessions of Mentha longifolia (L.) L. with selected chemical profiles. Journal of Essential Oil Research. 32(5):1-10. https://doi.org/10.1080/10412905.2020.1773328S110325Chapter 1Introduction. (2015). Handbook of Essential Oils, 18-21. doi:10.1201/b19393-5De Sousa Barros, A., de Morais, S. M., Ferreira, P. A. T., Vieira, Í. G. P., Craveiro, A. A., dos Santos Fontenelle, R. O., … de Sousa, H. A. (2015). Chemical composition and functional properties of essential oils from Mentha species. Industrial Crops and Products, 76, 557-564. doi:10.1016/j.indcrop.2015.07.004Gupta, A. K., Mishra, R., Singh, A. K., Srivastava, A., & Lal, R. K. (2017). Genetic variability and correlations of essential oil yield with agro-economic traits in Mentha species and identification of promising cultivars. Industrial Crops and Products, 95, 726-732. doi:10.1016/j.indcrop.2016.11.041Moshrefi Araghi, A., Nemati, H., Azizi, M., Moshtaghi, N., Shoor, M., & Hadian, J. (2019). Assessment of phytochemical and agro-morphological variability among different wild accessions of Mentha longifolia L. cultivated in field condition. Industrial Crops and Products, 140, 111698. doi:10.1016/j.indcrop.2019.111698Mathela, C. S., Padalia, R. C., Chanotiya, C. S., & Tiwari, A. (2005). Carvone richMentha longifolia(Linn.): Chemical Variation and Commercial Potential. Journal of Essential Oil Bearing Plants, 8(2), 130-133. doi:10.1080/0972060x.2005.10643432Schippmann, U., Leaman, D., & Cunningham, A. B. (s. f.). A Comparison of Cultivation and Wild Collection of Medicinal and Aromatic Plants Under Sustainability Aspects. Wageningen UR Frontis Series, 75-95. doi:10.1007/1-4020-5449-1_6Németh, E. (2005). CHANGES IN ESSENTIAL OIL QUANTITY AND QUALITY INFLUENCED BY ONTOGENETIC FACTORS. Acta Horticulturae, (675), 159-165. doi:10.17660/actahortic.2005.675.23Pothier, J., Galand, N., El Ouali, M., & Viel, C. (2001). Comparison of planar chromatographic methods (TLC, OPLC, AMD) applied to essential oils of wild thyme and seven chemotypes of thyme. Il Farmaco, 56(5-7), 505-511. doi:10.1016/s0014-827x(01)01085-0Franz, C. M. (2010). Essential oil research: past, present and future. Flavour and Fragrance Journal, 25(3), 112-113. doi:10.1002/ffj.1983Oil Composition of Other Mentha Species and Hybrids. (2006). Mint, 341-362. doi:10.1201/9780849307980-15Younis, Y. M. H., & Beshir, S. M. (2004). Carvone-Rich Essential Oils fromMentha longifolia(L.) Huds. ssp.schimperiBriq. andMentha spicataL. Grown in Sudan. Journal of Essential Oil Research, 16(6), 539-541. doi:10.1080/10412905.2004.9698792Koliopoulos, G., Pitarokili, D., Kioulos, E., Michaelakis, A., & Tzakou, O. (2010). Chemical composition and larvicidal evaluation of Mentha, Salvia, and Melissa essential oils against the West Nile virus mosquito Culex pipiens. Parasitology Research, 107(2), 327-335. doi:10.1007/s00436-010-1865-3Nazem, V., Sabzalian, M. R., Saeidi, G., & Rahimmalek, M. (2019). Essential oil yield and composition and secondary metabolites in self- and open-pollinated populations of mint (Mentha spp.). Industrial Crops and Products, 130, 332-340. doi:10.1016/j.indcrop.2018.12.018Maffei, M. (1988). A chemotype ofMentha longifolia (L.) hudson particularly rich in piperitenone oxide. Flavour and Fragrance Journal, 3(1), 23-26. doi:10.1002/ffj.2730030105Segev, D., Nitzan, N., Chaimovitsh, D., Eshel, A., & Dudai, N. (2012). Chemical and Morphological Diversity in Wild Populations of Mentha longifolia in Israel. Chemistry & Biodiversity, 9(3), 577-588. doi:10.1002/cbdv.201100108Hajlaoui, H., Snoussi, M., Ben Jannet, H., Mighri, Z., & Bakhrouf, A. (2008). Comparison of chemical composition and antimicrobial activities ofMentha longifolia L. ssp.longifolia essential oil from two Tunisian localities (Gabes and Sidi Bouzid). Annals of Microbiology, 58(3), 513-520. doi:10.1007/bf03175551Abdel-Hameed, E.-S. S., Salman, M. S., Fadl, M. A., Elkhateeb, A., & Hassan, M. M. (2018). Chemical Composition and Biological Activity ofMentha longifoliaL. Essential Oil Growing in Taif, KSA Extracted by Hydrodistillation, Solvent Free Microwave and Microwave Hydrodistillation. Journal of Essential Oil Bearing Plants, 21(1), 1-14. doi:10.1080/0972060x.2018.1454343Zouari-Bouassida, K., Trigui, M., Makni, S., Jlaiel, L., & Tounsi, S. (2018). Seasonal Variation in Essential Oils Composition and the Biological and Pharmaceutical Protective Effects of Mentha longifolia Leaves Grown in Tunisia. BioMed Research International, 2018, 1-12. doi:10.1155/2018/7856517Soilhi, Z., Rhimi, A., Heuskin, S., Fauconnier, M. L., & Mekki, M. (2019). Essential oil chemical diversity of Tunisian Mentha spp. collection. Industrial Crops and Products, 131, 330-340. doi:10.1016/j.indcrop.2019.01.041Asghari, B., Zengin, G., Bahadori, M. B., Abbas-Mohammadi, M., & Dinparast, L. (2018). Amylase, glucosidase, tyrosinase, and cholinesterases inhibitory, antioxidant effects, and GC-MS analysis of wild mint (Mentha longifolia var. calliantha) essential oil: A natural remedy. European Journal of Integrative Medicine, 22, 44-49. doi:10.1016/j.eujim.2018.08.004Ibrahim, S. R. M., Abdallah, H. M., Mohamed, G. A., Farag, M. A., Alshali, K. Z., Alsherif, E. A., & Ross, S. A. (2016). Volatile oil profile of some lamiaceous plants growing in Saudi Arabia and their biological activities. Zeitschrift für Naturforschung C, 72(1-2), 35-41. doi:10.1515/znc-2015-0234Hussain, A. I., Anwar, F., Nigam, P. S., Ashraf, M., & Gilani, A. H. (2010). Seasonal variation in content, chemical composition and antimicrobial and cytotoxic activities of essential oils from four Mentha species. Journal of the Science of Food and Agriculture, 90(11), 1827-1836. doi:10.1002/jsfa.4021Baser, K. H. C., Kürkçüoglu, M., Tarimcilar, G., & Kaynak, G. (1999). Essential Oils ofMenthaSpecies from Northern Turkey. Journal of Essential Oil Research, 11(5), 579-588. doi:10.1080/10412905.1999.9701218Kokkini, S., & Papageorgiou, V. (1988). Constituents of Essential Oils fromMentha longifoliaGrowing Wild in Greece. Planta Medica, 54(01), 59-60. doi:10.1055/s-2006-962338De Frutos, M., Sanz, J., & Martínez-Castro, I. (1988). Simultaneous distillation-extraction (SDE) method in the qualitative and quantitative GC analysis of cheese volatile components. Chromatographia, 25(10), 861-864. doi:10.1007/bf02311418Croteau, R. (1991). Metabolism of Monoterpenes in Mint (Mentha) Species. Planta Medica, 57(S 1), S10-S14. doi:10.1055/s-2006-96022

Phytotoxic potential of Lantana camara, Eucalyptus camaldulensis, Eriocephalus africanus, Cistus ladanifer and Artemisia gallica aqueous extracts to control weeds

[EN] Weed management is necessary in natural and agricultural ecosystems. The most used control method in developed countries has been the application of chemical herbicides, which has caused many problems in human health and the environment as well as the development of resistant weeds due to the repeated use of herbicides with the same mode of action. Natural products could be an alternative to synthetic herbicides for weed management. The society is demanding new solutions and research of bioherbicides has increased in the last years. Aqueous extracts from some plant species contain allelopathic compounds that can inhibit the germination and the development and growth of other plants or organisms. In this work the phytotoxic potential of aqueous extracts from Mediterranean plants are studied in order to find new solutions for integrated weed management.Verdeguer Sancho, MM.; Blazquez, M.; Boira Tortajada, H. (2018). Phytotoxic potential of Lantana camara, Eucalyptus camaldulensis, Eriocephalus africanus, Cistus ladanifer and Artemisia gallica aqueous extracts to control weeds. Journal of Allelochemical Interactions. 4(2):17-26. http://hdl.handle.net/10251/121086S17264