| Straw returned is one of the effective ways of agricultural sustainable development in our country.In the Yangtze river region of rice and rape cropping pattern,the faults caused by rice straw counters-field directly under bad rape emergence not neat,seedling growth,problems often occur.Many research in straw counters-field directly produce negative effects,straw decay caused by allelopathy plays an important influence,and phenolic acids compounds produced by lignin degradation of monomer(hereinafter referred to as phenolic acid)is widely regarded as the decomposing and the main plant material allelochemicals,but the amount of rice straw returned in the current production can lead to phenolic acid damage caused by the achieve effective concentrations in soil,rice straw returned after the emergence of the cole not neat,the phenomenon such as inhibition of seedling growth whether as the result of the role of phenolic acids,still needs further research to clarify.In addition,the mechanism of the allelopathy and mechanism study on it is technical bottleneck.To accurately measure the real dynamic soil sinochem feeling material is considered to be break through the bottleneck,realize the scientific evaluation of the correct path of allelopathic effect.This study first USES the parker bioassay method for rape and weed as receptor biological test,from the biological test results:straw processing of rapeseed and weed have allelopathy,high and low performance for promoting inhibition.Mixed soil cultivation of 7 d-14 d of the rice straw allelopathic inhibition of the rape seed germ biomass is the most obvious,and biomass loss mainly comes from the lower,above ground biomass of radicle biomass had a tendency to increase.In all times did not have significant influence on rape seed germination rate.During the whole test,total straw processing only the rape seedling biomass showed significant negative effects,straw treatment on the allelopathic effect of total biomass index at 21 d,the highest reached-17.7%,inhibitory effect than weed.This fully affirmed the rice straw treatment on rapeseed seedlings have allelopathy.From experiments by the straw soil mixed after decomposing and cultivate the soil water extract of phenolic acids in case:p-hydroxy benzoic acid decomposing and time in different,different amount of straw processing samples were detected in most times,the total content is the highest in all samples.The experiment of soil water extract phenolic acid composition and content of the statistical results showed that soil water extract phenolic acids content in the 3.3 49.0 mu g/g,with the previous results in the same order of magnitude.Rice straw processing caused by soil water soluble state the biggest increase of the total phenolic acids also appeared on the cultivation of 7 d-14 d,and rape germ above ground biomass of allelopathic inhibition rate was significantly negative correlation,affirmed the phenolic acids for rice straw the significance of allelopathy.Soil water soluble and water soluble C states existed significant positive correlation between total phenolic acids,is definitely the straw treated soil water soluble state of phenolic acids increase is the result of the rice straw decay.This study as the breakthrough of allelopathy research technology bottleneck,innovation in the study of soil allelochemicals into micro dialysis technology,in different experimental conditions,targeted micro dialysis technology was used to simulate the soil medium are material to the real-time of hydroxy benzoic acid in situ collection and test results show that in different perfusion fluid and different medium environment,dialysate within 45 min?90 min to balance it.Between 10??35? temperature levels of sense of targeted substances extraction recovery rate have significant difference(P<0.01).Extraction is characterized by the influence of medium for recovery,acid medium pH environment is conducive to enhance extraction rate,and alkaline and neutral environment was not significant effect on recovery.Look from different perfusion fluid,under different perfusion fluid on the recovery rate of hydroxy benzoic acid size respectively:pure water<0.01 M NaNO3<0.01 M HC1<0.1 M HC1.Acid perfusion liquid,such as 0.1 M HCL and 0.01 M HCL significantly improved the extraction rate(0.01<p<0.05).This study finally with two kinds of typical rice-tanker system soil as the medium,the rightness hydroxy benzoic acid concentration in the soil two stimulation of time after the dynamic path of continuous sampling,with HPLC/ms detection,experiment shows that the adsorption of phenol acids allelochemicals in the soil in reconciliation adsorption are highly dependent on soil pH levels,clay content,organic matter content and metal oxide content;pH value is between 2.5 5.0,and the soil on the adsorption effect of low molecular weight organic acids are supposed to reach its peak.In soil saturated absorption,can be a probe "capture" to free phenol acid drops rapidly and the phenolic acids caused the soil microbial degradation are linked.Therefore,this paper affirms the use of micro dialysis technology in soil was used to extract dynamic change and study the targeted matter time trajectory of potential.And in the dialysis was developed on the basis of the conclusion extraction-HPLC analysis method in the study on dynamics of soil phenolic acids. |
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