Physiological and Biochemical Responses to Water Stress and Salinity of the Invasive Moth Plant, Araujia sericifera Brot., during Seed Germination and Vegetative Growth

[EN] Araujia sericifera is an invasive plant with an increasing presence in South East Spain, where it produces damage to native trees and shrubs and citric orchards. As the climatic conditions in the study area are becoming harsher due to the climate change, the stress tolerance of this species has been studied during germination and vegetative growth. Growth parameters, photosynthetic pigments, ion accumulation, and antioxidant mechanisms were analysed in plants that were subjected to water deficit and salt stress. Seed germination was reduced by salinity but 50% of the seeds still germinated at 50 mM NaCl. The ungerminated seeds did not lose their germination capacity as shown in `recovery¿ germination assays in distilled water. Germination was less affected by osmotic stress that was induced by polyethylene glycol (PEG), and germination velocity increased in the recovery treatments after exposure to NaCl or PEG. Plant growth was practically unaffected by 150 mM NaCl but inhibited by higher NaCl concentrations or severe drought stress. Nevertheless, all the plants survived throughout the experiment, even under high salinity (600 mM NaCl). A. sericifera relative stress tolerance relies, at least to some extent, on effective antioxidant mechanisms that are based on flavonoid biosynthesis and the activation of antioxidant enzymes such as superoxide dismutase, ascorbate peroxidase, and glutathione reductase.Bellache, M.; Moltó, N.; Allal Benfekih, L.; Torres-Pagán, N.; Mir Moreno, R.; Verdeguer Sancho, MM.; Boscaiu, M.... (2022). Physiological and Biochemical Responses to Water Stress and Salinity of the Invasive Moth Plant, Araujia sericifera Brot., during Seed Germination and Vegetative Growth. Agronomy. 11(2):1-20. https://doi.org/10.3390/agronomy1202036112011

Essential Oils of Three Aromatic Plant Species as Natural Herbicides for Environmentally Friendly Agriculture

[EN] Natural herbicides based on essential oils (EOs) extracted from aromatic plants are gaining relevance in contemporary agriculture. Due to their allelopathic properties, they have an inhibitory effect on the germination and growth of different species, having, in general, the advantage of high specificity. For this reason, the analysis of the effects of these natural compounds on noxious weeds is continuously increasing. In the present study, three commercial EOs extracted from Mentha piperita L., Thymbra capitata (L.) Cav. and Santolina chamaecyparissus L. were tested on two invasive weeds with an increasing presence in southern Europe, Erigeron bonariensis L. and Araujia sericifera Brot. Five concentrations (0.125, 0.25, 0.50, 1 and 2 mu L mL(-1)) were tested in a randomized manner for each essential oil and five replicates with 20 seeds each for E. bonariensis and 10 replicates with 10 seeds each for A. sericifera. Two higher concentrations of 4 and 8 mu L mL(-1) of the three EOs were applied with irrigation on the plants of the two species at the vegetative growth stage. The number of replicas for each treatment and species was 7. The results obtained confirmed the significant inhibitory effects on seed germination and early seedling development, especially in E. bonariensis; of the three EOs, peppermint had the strongest effect, completely preventing germination in both species. Multivariate analysis, performed on several morphological traits scored after one month of treatment in young plants, showed a different pattern: the highest inhibition was recorded in A. sericifera and the greatest reduction in growth in the treatment with the highest dose of Santolina EO. The results obtained revealed the efficacy of these natural compounds and the specificity of their toxicity according to the species and stage of development.Bellache, M.; Torres-Pagan, N.; Verdeguer Sancho, MM.; Benfekih, LA.; Vicente, O.; Sestras, RE.; Sestras, AF.... (2022). Essential Oils of Three Aromatic Plant Species as Natural Herbicides for Environmentally Friendly Agriculture. Sustainability. 14(6):1-22. https://doi.org/10.3390/su1406359612214

Essential Oils of Three Aromatic Plant Species as Natural Herbicides for Environmentally Friendly Agriculture

Natural herbicides based on essential oils (EOs) extracted from aromatic plants are gaining relevance in contemporary agriculture. Due to their allelopathic properties, they have an inhibitory effect on the germination and growth of different species, having, in general, the advantage of high specificity. For this reason, the analysis of the effects of these natural compounds on noxious weeds is continuously increasing. In the present study, three commercial EOs extracted from Mentha piperita L., Thymbra capitata (L.) Cav. and Santolina chamaecyparissus L. were tested on two invasive weeds with an increasing presence in southern Europe, Erigeron bonariensis L. and Araujia sericifera Brot. Five concentrations (0.125, 0.25, 0.50, 1 and 2 µL mL–1) were tested in a randomized manner for each essential oil and five replicates with 20 seeds each for E. bonariensis and 10 replicates with 10 seeds each for A. sericifera. Two higher concentrations of 4 and 8 μL mL–1 of the three EOs were applied with irrigation on the plants of the two species at the vegetative growth stage. The number of replicas for each treatment and species was 7. The results obtained confirmed the significant inhibitory effects on seed germination and early seedling development, especially in E. bonariensis; of the three EOs, peppermint had the strongest effect, completely preventing germination in both species. Multivariate analysis, performed on several morphological traits scored after one month of treatment in young plants, showed a different pattern: the highest inhibition was recorded in A. sericifera and the greatest reduction in growth in the treatment with the highest dose of Santolina EO. The results obtained revealed the efficacy of these natural compounds and the specificity of their toxicity according to the species and stage of development

IMPACT OF INSECTICIDES ON POLLINATOR POPULATIONS: ROLE OF PHYTOSANITARY PERFORMANCE INDICATORS IN TOMATO CROPS

Agrochemicals are considered to be among the major environmental threats to pollinators, including honey bees. At the time of foraging, bees are at risk of exposure to phytosanitary treatment as a result of widespread treatment and their location, often near orchards. In Algeria, the majority of farmers systematically over-treat their orchards in order to have good quality fruits for as long as possible towards the use of an effective product. We evaluated the comparative effects of lambda-cyhalothrin and spinosad insecticide treatments on bees in tomato plots. Fluctuations of bee populations abundance were established during a 16 days period of exposure using yellow-colored plates with water placed every two days inside the experimental units. Bee populations showed very high sensitivity (0 individuals registered) to both insecticides at the homologated dose and even half dose during 10 days following application of the treatments. Depending on the estimated temporal toxicity of the respective products, differences in recovery of bee activity are presented. Consideration of indicators of the intensity of use of plant protection products is discussed

Effects of Four-Week Exposure to Salt Treatments on Germination and Growth of Two Amaranthus Species

Soil salinity represents one of the most restrictive environmental factors for agriculture worldwide. In the present study, the salt tolerance of two weeds of the genus Amaranthus, A. albus and A. hybridus, the latter cultivated as green vegetable in Africa, were analysed. Both species showed a remarkable salt tolerance phenotype during germination and vegetative growth. To evaluate the percentage and rate of germination, seeds were germinated in Petri dishes in a germination chamber under increasing concentrations up to 300 mM NaCl. Higher concentrations of salt ranging from 150 to 600 mM NaCl were applied for one month to plants grown in individual pots in the greenhouse. All seeds of A. albus germinated in the control and almost half of the seeds under 200 mM NaCl, but only 4% of the seeds under 250 mM NaCl. In A. hybridus, germination was considerably lower in all treatments and was completely prevented at 250 mM NaCl. The plant growth of both species was severely affected by high salt concentrations of 450 and 600 mM NaCl, but not under lower concentrations. At this stage of the biological cycle, A. hybridus showed a higher salt tolerance, as indicated by the smaller reduction in its growth parameters. The dry weight of leaves and roots of plants receiving 600 mM NaCl decreased in comparison to control: less than 60% in A. hybridus but more than 70% in A. albus. The salt tolerance of the two species contributes to their invasive potential, but on the other hand represents a useful trait when considering them as potential crops for the future

Effects of four-week exposure to salt treatments on germination and growth of two Amaranthus species.

[EN] Soil salinity represents one of the most restrictive environmental factors for agriculture worldwide. In the present study, the salt tolerance of two weeds of the genus Amaranthus, A. albus and A. hybridus, the latter cultivated as green vegetable in Africa, were analysed. Both species showed a remarkable salt tolerance phenotype during germination and vegetative growth. To evaluate the percentage and rate of germination, seeds were germinated in Petri dishes in a germination chamber under increasing concentrations up to 300 mM NaCl. Higher concentrations of salt ranging from 150 to 600 mM NaCl were applied for one month to plants grown in individual pots in the greenhouse. All seeds of A. albus germinated in the control and almost half of the seeds under 200 mM NaCl, but only 4% of the seeds under 250 mM NaCl. In A. hybridus, germination was considerably lower in all treatments and was completely prevented at 250 mM NaCl. The plant growth of both species was severely affected by high salt concentrations of 450 and 600 mM NaCl, but not under lower concentrations. At this stage of the biological cycle, A. hybridus showed a higher salt tolerance, as indicated by the smaller reduction in its growth parameters. The dry weight of leaves and roots of plants receiving 600 mM NaCl decreased in comparison to control: less than 60% in A. hybridus but more than 70% in A. albus. The salt tolerance of the two species contributes to their invasive potential, but on the other hand represents a useful trait when considering them as potential crops for the future.Bellache, M.; Benfekih, LA.; Torres-Pagán, N.; Mir Moreno, R.; Verdeguer Sancho, MM.; Vicente, O.; Boscaiu, M. (2022). Effects of four-week exposure to salt treatments on germination and growth of two Amaranthus species. Soil Systems. 6(3):1-16. https://doi.org/10.3390/soilsystems60300571166

Comparative Analysis of Tolerance to Salt Stress and Water Deficit in Two Invasive Weeds of the Genus Erigeron (Asteraceae)

Erigeron bonariensis and E. sumatrensis are two noxious weeds present in many parts of the world. Their tolerance to salinity and water deficit was analysed at the seed germination stage and during vegetative development. Seed germination was tested in solutions with different concentrations of NaCl and polyethylene glycol (PEG). Growth parameters, photosynthetic pigments, ion accumulation, and antioxidant mechanisms were analysed in plants that were subjected to increasing NaCl solutions, or severe water deficit by completely restricting irrigation. Seed germination was mostly affected by NaCl, but less by PEG in both species. E. bonariensis had a faster germination in all treatments and maintained a higher percentage of germination under the highest concentration of salt applied. Growth responses were similar in the two species, both being more affected by higher salt concentrations than by water deficit. The main differences in the responses of the two species to stress regard K+ and proline concentration. K+ in roots decreased under salt stress in E. sumatrensis, but remained constant in leaves, whereas in E. bonariensis increased in roots and leaves in salt-stressed plants. Proline concentration increased in all E. bonariensis plants under salt stress, but only in those under the highest salt concentration in E. sumatrensis. The results obtained indicate that the two species are relatively tolerant to water deficit and medium salinity but are susceptible to high NaCl concentrations