Resource And Quality Evaluation Of Genus Nicotiana Tabacum L. And The Remnant Of Organochlorine Pestricides In Agricultural Soils

To explore the good germplasm of burley tobacco (Nicotiana tabacum L.) and establish an effective evaluation method of the chemical and biologiacal, we analyzed with the agronomy traits, chemical composition, genetic relationships, and organochlorine pesticides residues in soil of tobacco ares in China and Wuhan, Hubei province, China. It will provide theoretical support and application infrastructure to broaden the genetic base and select quality germplasm of burley tobacco.Part One Analysis of the agronomic/quality traits of the germplasm resources of burley tobaccoIn order to access the similarity among burley tobacco germplasm,149burley tobacco cultivars from China and abroad were systematicall clustered by cluster software NTSYS2.10e based on data of19traits. Results showed that all burley tobacco cultivars can be clustered into6large cultivar groups and2samll cultivar subgroups at dissimilitude coefficient of0.0375. Group1to group6included25,22,23,18,24and37cultivars, respectively. Total coefficient of all burley tobacco cultivars ranged from0.01to0.53, indicating that there existed some diversity among various germplasm.Part Two Phytochemical evaluaion of the germplasm of burley tobaccoThis chapter we use two kinds of burley tobacco leaves:diallel cross and dynamic material, UV spectrophotometry was used for the secretions initial screening in36diallel burley leaf samples, screening a higher secretion of species or foliar crosses were:B37x KY8959, KY14x KY8959, BX2003x KY14, Jianxuan3x B37, B37, B37×B21.In addition, gas chromatography-mass spectrometry technique was used to analysis the aroma components of the leaves of diallel and dynamic group.31kinds of tobacco aroma components were detected in the tobacco leaves, which neophytadiene was the highest content.Through comprenshensive analysis of36diallel burley varieties resources, screening f or potential usage value of burley varieties or hybrid varieties:B37xBX2003、B21×KY14、 KY8959xBX2003、KY8959×B21、B37xKY8959、Jianxuan3×B37、Jianxuan3号×KY14B21xBX2003、B37xB21。Analyses on the dynamic changes of aroma constituents in growth process of burley tobacco by GC/MS. six samples were measured56days after transplanting,63days,70days,77days,84days aroma substance content and make dynamic maps, determine the different varieties of burley best harvest.Part Three Molecular biological evaluation of the germplasm of burley tobaccoTo assess the genetic diversity of germplasm resources of burley tobacco (Nicotiana tabacum L.), we investigated genetic relationships among119burley tobacco accessions by using inter simple sequences repeat (ISSR) markers. A total of14ISSR primers generated131bands, of which,127bands were polymorphic with an average of9.1bands per primer pair. Based on the ISSR band data, similarity indices between the accessions ranged from0.40to0.99. An unweighted pair group method using arithmetic averages algorithm (UPGMA) dendrogram was constructed and demonstrated that all119accessions could be assorted into3main groups. This result has certain differences with the clustering result, which was based on agronomic/quality traits. Accompanied with the genetic background and agronomic/quality traits of germplasm resources of burley tobacco, these results will help in the formulation of appropriate strategies for assisting burley tobacco breeding programme by maker assisted selection.Part Four Residues of organochlorin pestricides in agricultural soilsSoil samples collected from soils at six main tobacco growing regions in China were studied, and the levels and distributions of OCPs were analyzed. The results were as following.1. The method for the determination of21organochlorine pesticides (OCPs) by gas chromatography with μ-electron capture detection was constructed, soil samples were extracted by Soxhlet method by a mixed solvent, and purified by a florisil chromatographic column.2. Organochlorine pesticides residues in planting soils were widespread. DDTs and chlorobenzene had the highest detection rate of90%. The main residues of organochlorine pesticides in the soil were HCHs and DDTs, and the average content of EDDTs and∑HCHs was6.69μg/kg,5.91μg/kg respectively, which were lower than the limitation of national standard (HJ332-2006). Risk assessment indicated that the soil could guarantee the normal agricultural production and human health.3. According to the measured concentrations and detection frequencies in agricultural soils of Wuhan, dichlorodiphenyltrichloroethanes(DDTs), hexachlorocyclohexanes(HCHs), hepta chlor (HEPT), hexachlorobenzene(HCB) and aldrin were the predominant compounds in soil. DDTs accounted for77.10%of total OCPs, followed by HCHs(7.83%), aldrin(4.21%), HEPTs(2.82%) and HCB (1.53%). The total DDT concentration sranged from nd to1198.0ng.g-1and the main contaminated areas were distributed in Hannan and Xinzhou districts of Wuhan. The total HCH concentration sranged from nd to100.58ng.g-1in soil and relatively higher levels were observed in soil samples from Huangpi and Hannan districts. Source analysis showed that OCPs residues except heptachlor originated mainly from historical application, besides slight recent introduction at some sites. Based on the China National Soil Quality Standard, DDT pollution in most samples of Wuhan agricultural soils could be considered as no and low contamination, while the level of HCHs was classified as no pollution. Our study indicated that there existed potential exposure risk of OCPs in Wuhan agricultural soils although the use of OCPs has been banned.