-
[show abstract]
[hide abstract]
ABSTRACT: The net greenhouse gas balance (NGHGB), estimated by combining direct and indirect greenhouse gas (GHG) emissions, can reveal whether an agricultural system is a sink or source of GHGs. Currently, two types of methods, referred to here as crop-based and soil-based approaches, are widely used to estimate the NGHGB of agricultural systems on annual and seasonal crop timescales. However, the two approaches may produce contradictory results, and few studies have tested which approach is more reliable. In this study, we examined the two approaches using experimental data from an intercropping trial with straw removal and a tillage trial with straw return. The results of the two approaches provided different views of the two trials. In the intercropping trial, NGHGB estimated by the crop-based approach indicated that monocultured maize (M) was a source of GHGs (-1315kgCO2(-eq)ha(-1)), whereas maize-soybean intercropping (MS) was a sink (107kgCO2(-eq)ha(-1)). When estimated by the soil-based approach, both cropping systems were sources (-3410 for M and -2638kgCO2(-eq)ha(-1) for MS). In the tillage trial, mouldboard ploughing (MP) and rotary tillage (RT) mitigated GHG emissions by 22,451 and 21,500kgCO2(-eq)ha(-1), respectively, as estimated by the crop-based approach. However, by the soil-based approach, both tillage methods were sources of GHGs: -3533 for MP and -2241kgCO2(-eq)ha(-1) for RT. The crop-based approach calculates a GHG sink on the basis of the returned crop biomass (and other organic matter input) and estimates considerably more GHG mitigation potential than that calculated from the variations in soil organic carbon storage by the soil-based approach. These results indicate that the crop-based approach estimates higher GHG mitigation benefits compared to the soil-based approach and may overestimate the potential of GHG mitigation in agricultural systems.
Science of The Total Environment 04/2013; 456-457C:299-306. · 3.29 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: A bioassay-guided fractionation of the ethyl acetate extract from the twigs of the hybrid poplar 'Neva', Populus nigra L. × Populus deltoides Marsh, led to the isolation of three flavonoids, which were identified by means of spectrometric and physicochemical analysis as 5-hydroxy-7-methoxy-flavone (1), 5,7-dihydoxy-flavone (2) and 5,7-dihydroxy-flavonol (3). These compounds were further screened for their antimicrobial activity against plant pathogens, including three bacteria (Pseudomonas lachrymans, Ralstonia solanacearum and Xanthomonas vesicatoria) and one fungus (Magnaporthe oryzae). Compounds 2 and 3 showed significant antibacterial activity, with minimum inhibitory concentrations (MICs) ranging from 15 to 25 µg mL(-1), and median inhibitory concentrations (IC(50) values) from 4 to 18 µg mL(-1). The results obtained provide promising baseline information for the potential use of the extract and flavonoids from this plant as antimicrobial agents to help control plant diseases.
Natural product research 01/2011; 26(4):307-13. · 1.01 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The root bark essential oil of Periploca sepium Bunge (Asclepiadaceae/ Apocynaceae) obtained by hydrodistillation was investigated by GC and GC-MS. 2-Hydroxy-4-methoxybenzaldehyde was found to be the main component (78.8% of the total) among 17 identified compounds. 2-Hydroxy-4-methoxybenzaldehyde was separated and purified by preparative thin layer chromatography, and was further identified by means of physicochemical and spectrometric analysis. Both the essential oil and 2-hydroxy-4-methoxybenzaldehyde exhibited antimicrobial activities on all test bacteria and fungi, with MBC/MFC values ranging from 125 microg/mL to 300 microg/mL, MIC values from 80 microg/mL to 300 microg/mL, and IC(50) values from 63.29 microg/mL to 167.30 microg/mL. They also showed moderate antioxidant activity in the DPPH free radical scavenging, beta-carotene bleaching and ferrozine-ferrous ions assays. The results indicated that the major portion of these antimicrobial and antioxidant activities was due to the presence of 2-hydroxy-4-methoxy-benzaldehyde in the oil, which could potentially be developed as an antimicrobial and antioxidant agent in the future.
Molecules 08/2010; 15(8):5807-17. · 2.39 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Diosgenin accumulation in cell suspension cultures of Dioscorea zingiberensis C. H. Wright was enhanced by treatment with saccharide elicitors from its endophytic fungus Fusarium oxysporum isolate Dzf17. The crude oligosaccharide was prepared by partial acid hydrolysis of the isolated Dzf17 fungal cell wall fragments. Optimal elicitation of diosgenin production by the isolated Dzf17 oligosaccharide in cell suspension culture was achieved when the oligosaccharide was added to the medium at a concentration of 30 mg/L after 16-day's continuous cell suspension culture, and the cells were cultured for another 8 days before harvesting. By using these optimal conditions, the diosgenin yield of the cultured cells reached its maximum of 5.25 mg/L, which was over a three-fold increase.
Natural product communications 11/2009; 4(11):1459-62. · 1.24 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Stem blister canker is a serious stem disease in the Populus genus in China. The pathogen was confirmed as Botryosphaeria dothidea (Moug. ex Fr.) Ces. et de Not. based on its morphological, pathological and molecular features. Seven selected plant species
Artemisia annua, Gleditsia sinensis, Lonicera japonica, Macleaya cordata, Phyllodendron chinense, Polygonum cuspidatum and Scutellaria baicalensis, belonging to different families from China, were extracted with the solvent 95% (v/v) ethanol to yield ethanol extracts
which were used to evaluate their antifungal activity against poplar stem canker pathogen by a mycelial radial growth inhibition
test. Of them, the extracts of M. cordata, P. cuspidatum and S. baicalensis showed stronger antifungal activity, the median inhibitory concentration (IC50) was 0.3125, 1.0219 and 0.9675mgml−1 separately. The control effect of extracts of M. cordata, P. cuspidatum and S. baicalensis on poplar stem canker disease was between 62% and 85%. The inhibitory effect of the extracts indicated the importance of
some plant species as possible natural source of fungicidal material.
World Journal of Microbiology and Biotechnology 01/2008; 24(8):1579-1584. · 1.53 Impact Factor
