| Prickly ash belongs to genus Zanthoxylum of the family Rutaceae and its relative species are widely cultivated in China.Because of extensive cultivation areas,various cultivars,nonstandard naming notations,and morphology similarity among relative cultivars,the quality and price of prickly ash pericarps differ obviously in the marketplaces.However,it is difficult to accurately evaluate the quality of the pericarps due to nonstandard quality grading standard.Previous researches on pericarp quality evaluation are not systematic and comprehensive,usually only based on a certain aspect.The traits of prickly ash pericarps are easily affected by tree cultivars,geographical,climatic,and soil conditions,and management measures.It is necessary to determine the cultivars in main production areas and determine the difference of each trait to better utilize germplasm resources of prickly ash.Moreover,the influence of cultivars and cultivated environments(geographical,climate,and soil conditions)on the pericarp quality need to be explored.Firstly,prickly ash cultivars from 72 plantations were identified based on ITS2 sequences.Main quality indicators,color,thousand-grain weight,numb taste intensity,volatile oil content,volatile and volatile oil composition,alkylamide and fatty acid profiling,and potentially toxic elements of pericarps were tested and evaluated.The key difference indicators among different species were determined based on chemometrics and influences of environmental factors on the key traits were screened out combined the correlation analysis and redundant analysis.Overall,this study provides information on how to classify the prickly ash species and determine the key environmental factors on main quality indicators.The results indicated that:(1)The 72 germplasm resources of prickly ash were divided into four groups based on ITS2 sequences: ZA(n=17)represented Zanthoxylum armatum,which were mostly distributed in the southwest region with high mean temperature,high mean relative humidity,and high mean precipitation;ZB1(n=29)were derived from Z.bungeanum from Hancheng,which were distributed in high-altitude and low-pressure areas;ZB2(n=13)were derived from Z.bungeanum from Fengxian;Others(n=13)referred to the rest of the samples that have red pericarps,but do not derive from Z.bungeanum,which were mainly distributed in the northeast of the main production area with lower altitude,mean temperature,mean precipitation,and mean relative humidity,and higher atmospheric pressure.(2)Physical and chemical properties and heavy metal contents in soils among different germplasm resources were different.The contents of p H,total potassium,aluminum and arsenic in soils were significantly different among different groups.The pollution levels of arsenic,lead,and nickel were low in the soils.The pollution levels of cadmium in soils were divided into three categories: low pollution(26.4%);medium pollution(66.7%);high pollution(6.9%).Most of the soils(94.4%)were lightly polluted based on the integrated pollution index.The geographical location and atmospheric pressure had no significant effect on soil conditions,while the average annual temperature,average annual relative humidity and average annual rainfall affected soil p H and the contents of Al,As and Pb.The intrinsic effects of soil basic physicochemical and potentially harmful elements were obvious.Aluminum,manganese,lead,nickel posed a non-carcinogenic risk,while arsenic and cadmium caused carcinogenic risk.Except cadmium,most heavy metals were difficult to get into pericarps from the soil.Mean temperature,mean relative humidity,total phosphorus,total potassium,organic matter,and available phosphorus were the key environmental factors that affected the accumulation of heavy metals in prickly ash pericarps.(3)The differences in color traits(luminance,red-greenness,yellow-blueness,chroma,hue),thousand-grain weight,and volatile oil content of prickly ash pericarps were significant among different groups,while the difference of numb taste intensity was not significant.Mean relative humidity significantly affected the volatile oil content and numb taste intensity of ZA pericarps;the mean temperature and longitude significantly affected hue,red-greenness,thousand-grain weight and numb taste intensity of ZB1 pericarps;soil available potassium,atmospheric pressure and latitude significantly affected the quality traits of ZB2 pericarps.It can identify ZA pericarps successfully.Two measures were proposed: Firstly,ZA pericarps can be successfully identified based on the red-greenness and hue,then ZB1 pericarps can be identified based on the volatile oil content,and finally ZB2 and Others pericarps can be distinguished based on the thousand-grain weight.8quality traits were substituted into three equations,and the unknown samples were compared to the means of the canonical variables obtained from the discriminant analysis with a certain misjudgment for some pericarps.(4)Electronic nose combined with GC-MS technology can effectively identify different germplasm resources of prickly ash.It can distinguish different pericarps but cannot accurately distinguish prickly ash groups in the use of electronic nose.36 common volatile components were identified in prickly ash pericarps using headspace solid phase microextraction combined with GC-MS technology,mainly belonging to monoterpenes and sesquiterpenes.Sabinane,á-myrcene,d-limonene and linalool were the dominating components.Linalool,linalyl acetate,and à-terpinyl acetate were the differentiated volatile components to distinguish ZA pericarps.However,it was difficult to distinguish groups of red pericarps due to similar volatile profiling in these pericarps.Mean relative humidity was a key environmental factor that affected the volatile profiling of ZA pericarps.The longitude was the key environmental factor that affected the volatile profiling of ZB1 pericarps.Soil cadmium was a key environmental factor that affected the volatile profiling of ZB2 pericarps.A total of 47 components were identified in the volatile oils of prickly ash pericarps.D-limonene,á-myrcene,and linalool were the dominating oil components.The components,á-ocimene,linalool,d-limonene,terpinolene and à-terpinyl acetate,were the key indicators in distinguishing ZA pericarps.Soil lead,total nitrogen,total phosphorus,and arsenic were the key environmental factors that affected the oil profiling of ZA pericarps.Longitude and soil manganese were key environmental factors that affected oil profiling of ZB1 pericarp oils.Soil available potassium,atmospheric pressure,soil organic matter,and soil lead were the key environmental factors that affected the oil profiling of ZB2 pericarps.(5)A total of nine alkylamide components and ten main fatty acids in prickly ash pericarps were identified.ZP-amide C and ZP-amide D were the most common alkylamide components of the prickly ash pericarps and palmitic acid,palmitoleic acid,oleic acid,linoleic acid,linolenic acid were the most common fatty acid components in these prickly ash samples.ZP-amide D is a key indicators in distinguishing the groups of prickly ash,especially in the identification of Others pericarps.Longitude and soil aluminum content were the key environmental factors that affected alkylamide profiling in prickly ash pericarps.The fatty acid content in pericarps was significantly affected by the type of prickly ash species and environmental factors(altitude,organic matter,and lead content for ZA,mean annual precipitation and available potassium content in soil for ZB1,total potassium and available potassium content in soil for ZB2). |
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