Assessment of allelopathic potential of the salicylic acid on target plants: Euphorbia heterophylla and Bidens pilosa

Salicylic acid has one of its characteristics the allelopathic potential. The present paper, is a research quantitative in nature aimed to assess the allelopathic potential of salicylic acid to identify the best concentration range for other pure substances. The bioassays were performed in a BOD incubator, seeking to assess the seedling growth by measuring the radicle and hypocotyl length. Each bioassay occurred for 12 days. The concentrations of salicylic acid used in the bioassays were: 1000, 750, 500, 250, 125, and 62.5 ppm and control. The obtained data were submitted to the tests: Kolmogorov-Smirnov normality, the two-way ANOVA with repetition, and Tukey. Based on the results obtained, it was possible to observe that several concentrations demonstrated significant differences, i.e., there is an allelopathic activity in both species (Euphorbia heterophylla and Bidens pilosa). The highlights were for the concentrations of 750 and 1000 ppm for E. heterophylla and 500, 750 and 1000 ppm for B. pilosa. However, there was no significant difference between these concentration groups. The radicle’s length was the part most negatively affected. These results can be used to identify better concentrations for other pure substances, which are usually obtained in small quantities, being useful in the formulation of a product with characteristics of bio-herbicides.

Allelopathic Activity of Water-Soluble Secretions of Crocus Sativus L. (Iridaceae) Flowers when Introduced in the Northern Black Sea Region

The purpose of the article is to study the allelopathic activity of generative organs of Crocus sativus L. (saffron crocus) as a new promising crop for the agrophytocenoses of Ukraine, which has valuable properties and it is used in various industries: the official pharmacopoeia for the treatment of nervous disorders, cancer and the food industry as a valuable spice and organic dye. For safe cultivation of the crop and prevention of soil fatigue, it is necessary to study the effect of water-soluble flower secretions that remain in the fields after removing the stigmas of pistils. Materials and methods. The materials for the research were plants of Crocus sativus, grown on the plots of the Mykolaiv National Agrarian University during 2019-2020. The research was conducted in 2020 on the basis of university laboratories. The collection of flowers and the study of allelopathic activity of water-soluble secretions were carried out in accordance with generally accepted methods. Results and discussion. As a result of our research, it was found that water-soluble secretions of Crocus sativus flowers and their parts at different concentrations stimulated the energy of seed germination and the growth of single-day seedlings L. sativum. There was a lower germination energy in the "perianth+pistil" variant at a filtrate concentration of 0.02%. With an increase in the filtrate concentration, there was a decrease in root growth for all variants except the "perianth+pistil" variant: the lowest decrease was at a concentration of 0.09 and the highest one was at 0.02 compared to the control (7.58 and 4.77%). The coefficient of variation in the root length of one-day seedlings of the test plant had a very high coefficient of variation (>40%) for all variants, except for the "perianth+pistil" variant, which was characterized by a high indicator. For perianth secretions, when the concentration increased, allelopathic activity increased from insignificant inhibitory activity (-0.98) up to stimulating activity (35.70). Other variants were characterized by an inhibitory effect. Conclusion. The growth of allelopathic activity of water-soluble secretions of flower elements at different concentrations can be depicted in the following order: for the perianth it was 0.01<0.02<0.09; for the flower it was 0.01<0.02>0.09; for the perianth and stamen it was 0.01<0.02>0.09, for the perianth with a pistil it was 0.01<0.02>0.09. The highest indicators of allelopathic activity of water-soluble secretions of flowers detected at a concentration of 0.02%

Antioxidant, allelopathic activities of leaf extracts and essential oil compositions of Acronychia pedunculata (L.) Miq.

This research aims to exploit total polyphenol, flavonoid contents, antioxidant and allelopathic activities of leaf extracts, and essential oil compositions from leaves of Acronychia pedunculata (L.) Miq. The results indicated that the leaf extract from ethanol 100% (E100) possessed a lower total polyphenol and flavonoid content than the extract from ethanol 70% (E70). In contrast, the antioxidant activity from E100 extract with IC50=612.9±12.9 μg/ml was stronger than that of E70 extract with IC50=1225.5±6.9 μg/ml. Regarding allelopathic activity, while the extracts from E100 and E70 inhibited root growth of radish, both extracts promoted root growth of lettuce. Especially, E100 extract with 3 mg/ml inhibited root growth of radish up to 48.1%. Moreover, using water solvents, the extracts reduced root growth of both the radish and lettuce. By GC-MS analyses, 33 compounds were identified from A. pedunculata essential oil. The major constituents were caryophyllene (47.09%), humulene (17.28%), α-copaene (4.98%), isoledene (3.59%), and (-)-α-panasinsen (3.51%), other compounds were accounted for lower 3%.

Fimbristylis littoralis (lesser fimbristylis).

F. littoralis is a tufted leafy annual or short-lived herb (sedge) included in the Global Compendium of Weeds where it is listed as an agricultural and environmental weed (Randall, 2012). It has escaped from cultivation and become established along waterways and wetlands (Flora of China Editorial Committee, 2014). The species is of particular concern in rice plantations around the world (Holm et al., 1977). It shows allelopathic activity and once established it can change features of ecosystem functions including hydrological cycles, biophysical dynamics, nutrient cycles, and community composition (Holm et al., 1977; Holou et al., 2013).