Fagopyrum esculentum Moench (buckwheat) is a dicot species from the Polygonaceae family used as a cover crop in agricultural systems featured with a remarkable allelopathic potential for weed control, helping herbicid...Fagopyrum esculentum Moench (buckwheat) is a dicot species from the Polygonaceae family used as a cover crop in agricultural systems featured with a remarkable allelopathic potential for weed control, helping herbicide-resistance management and promoting substantial reductions in herbicide applications. The aim of this research was to examine the allelopathic potential of aqueous extracts from seeds and aerial part of buckwheat on seed germination and initial development of Bidens pilosa and Euphorbia heterophylla. Bioassay experiments were conducted under a completely randomized experimental design with four replications, containing 50 seeds each. Both weed seed species were harvested in a soybean field, and seed viability was previously assessed. Seeds were exposed to four concentrations (0, 25, 50, and 100%) from extracts of seeds (ES) and aerial part (EAP) of buckwheat. Germination speed index (GSI) in B. pilosa and E. heterophylla was daily evaluated throughout 14 and 16 days, respectively, whereas percentage of germination, abnormal seedlings, as well as non-germinated seeds, root (RL) and aerial part length (APL), and total dry matter (TDM) were rated at final germination test. EAP reduced the GSI, especially under the 100% concentration. Germination percentage was lower and abnormal seedlings increased for both weed species when seeds were exposed to EAP concentrations greater than 25%. However, ES did not impinge upon E. heterophylla germination. EAP and ES reduced the APL, RL, and TDM for concentrations greater than 50%, except for ES which did not affect E. heterophylla development. Both extracts from buckwheat have a high capacity to inhibit germination and compromise seedling development, culminating in such a potential alternative for B. pilosa and E. heterophylla management in agricultural systems.展开更多
A total of 479 bacterial strains were isolated from brine （Bohai, Qinhuangdao City, Hebei Province, China）. Bioassay results indicated that 4 strains named Hal, Hal7, Ha38, and Ha384 had herbicidal activity. And str...A total of 479 bacterial strains were isolated from brine （Bohai, Qinhuangdao City, Hebei Province, China）. Bioassay results indicated that 4 strains named Hal, Hal7, Ha38, and Ha384 had herbicidal activity. And strain Hal had the highest effective herbicidal activity. As a result, this study aims to JdentJfy strain Hal, characterize its physiological and biological activities, evaluate the herbicidal activity of its metabolites, and develop a ＇pesta＇ formulation and assess its effectiveness on Digitaria sanguinalis. Hal was identified as Serratia marcescens based on 16S rDNA sequencing. This strain has a flagellum, a diameter of 0.5 to 0.8 IJm, and a length of 0.9 to 2.0 IJm. The indole test shows positive results, and the catalase enzyme exhibits strong positive reactions. Results further showed that the inhibitory concentration （IC50） of the crude extracts to D. sanguinalis radicula and coleoptile were 3.332 and 2.828 mg mL-1, respectively. Both the suppression of D. sanguinalis and the cell viability of the Hal formulation in ＇pesta＇ were higher when stored at 4℃ than at （25＋2）℃. These results indi- cated that S. marcescens Hal can potentially be used as a biocontrol agent against D. sanguinalis.展开更多
CB-4, a bacterial strain with highly effective herbicidal activity, was isolated from infected corn leaves. Through morphology, physiological and biochemical tests, and 16 S ribosomal DNA gene sequencing methods, CB-4...CB-4, a bacterial strain with highly effective herbicidal activity, was isolated from infected corn leaves. Through morphology, physiological and biochemical tests, and 16 S ribosomal DNA gene sequencing methods, CB-4 was identified as Pseudomonas aeruginosa. We conducted activity-evaluation experiments in the laboratory to assess the herbicidal potential of metabolites produced by strain CB-4. Crude extracts of strain CB-4 have high inhibition activity on Digitaria sanguinalis. In general, the root and shoot growth parameters of D. sanguinalis were significantly reduced by metabolites of strain CB-4. The IC50 of the culture filtrate extracts for the radicula and coleoptile of D. sanguinalis were 0.299 and 0.210 mg mL-1, respectively. Component 2 of the herbicidal activity of the crude toxin from strain CB-4 was successfully purified for the first time by using high-speed counter current chromatography with a two-phase solvent system composed of petroleum ether-ethyl acetate-methanol-water（4：5：4：5, v/v） and high-performance liquid chromatography. We concluded that the metabolites of strain CB-4 have the potential to be developed as a microbe-based herbicide.展开更多
文摘Fagopyrum esculentum Moench (buckwheat) is a dicot species from the Polygonaceae family used as a cover crop in agricultural systems featured with a remarkable allelopathic potential for weed control, helping herbicide-resistance management and promoting substantial reductions in herbicide applications. The aim of this research was to examine the allelopathic potential of aqueous extracts from seeds and aerial part of buckwheat on seed germination and initial development of Bidens pilosa and Euphorbia heterophylla. Bioassay experiments were conducted under a completely randomized experimental design with four replications, containing 50 seeds each. Both weed seed species were harvested in a soybean field, and seed viability was previously assessed. Seeds were exposed to four concentrations (0, 25, 50, and 100%) from extracts of seeds (ES) and aerial part (EAP) of buckwheat. Germination speed index (GSI) in B. pilosa and E. heterophylla was daily evaluated throughout 14 and 16 days, respectively, whereas percentage of germination, abnormal seedlings, as well as non-germinated seeds, root (RL) and aerial part length (APL), and total dry matter (TDM) were rated at final germination test. EAP reduced the GSI, especially under the 100% concentration. Germination percentage was lower and abnormal seedlings increased for both weed species when seeds were exposed to EAP concentrations greater than 25%. However, ES did not impinge upon E. heterophylla germination. EAP and ES reduced the APL, RL, and TDM for concentrations greater than 50%, except for ES which did not affect E. heterophylla development. Both extracts from buckwheat have a high capacity to inhibit germination and compromise seedling development, culminating in such a potential alternative for B. pilosa and E. heterophylla management in agricultural systems.
基金supported by the grants from the National High Technology Research and Development Program of China (2011AA10A206)the China Agriculture Research System (CARS-02)the Science and Technology Support Program of Hebei, China (12220301D)
文摘A total of 479 bacterial strains were isolated from brine （Bohai, Qinhuangdao City, Hebei Province, China）. Bioassay results indicated that 4 strains named Hal, Hal7, Ha38, and Ha384 had herbicidal activity. And strain Hal had the highest effective herbicidal activity. As a result, this study aims to JdentJfy strain Hal, characterize its physiological and biological activities, evaluate the herbicidal activity of its metabolites, and develop a ＇pesta＇ formulation and assess its effectiveness on Digitaria sanguinalis. Hal was identified as Serratia marcescens based on 16S rDNA sequencing. This strain has a flagellum, a diameter of 0.5 to 0.8 IJm, and a length of 0.9 to 2.0 IJm. The indole test shows positive results, and the catalase enzyme exhibits strong positive reactions. Results further showed that the inhibitory concentration （IC50） of the crude extracts to D. sanguinalis radicula and coleoptile were 3.332 and 2.828 mg mL-1, respectively. Both the suppression of D. sanguinalis and the cell viability of the Hal formulation in ＇pesta＇ were higher when stored at 4℃ than at （25＋2）℃. These results indi- cated that S. marcescens Hal can potentially be used as a biocontrol agent against D. sanguinalis.
基金supported by grants from the National High Technology Research and Development Program of China (2011AA10A206)the Science and Technology Support Program of Hebei, China (20121124001)
文摘CB-4, a bacterial strain with highly effective herbicidal activity, was isolated from infected corn leaves. Through morphology, physiological and biochemical tests, and 16 S ribosomal DNA gene sequencing methods, CB-4 was identified as Pseudomonas aeruginosa. We conducted activity-evaluation experiments in the laboratory to assess the herbicidal potential of metabolites produced by strain CB-4. Crude extracts of strain CB-4 have high inhibition activity on Digitaria sanguinalis. In general, the root and shoot growth parameters of D. sanguinalis were significantly reduced by metabolites of strain CB-4. The IC50 of the culture filtrate extracts for the radicula and coleoptile of D. sanguinalis were 0.299 and 0.210 mg mL-1, respectively. Component 2 of the herbicidal activity of the crude toxin from strain CB-4 was successfully purified for the first time by using high-speed counter current chromatography with a two-phase solvent system composed of petroleum ether-ethyl acetate-methanol-water（4：5：4：5, v/v） and high-performance liquid chromatography. We concluded that the metabolites of strain CB-4 have the potential to be developed as a microbe-based herbicide.
