| This experiment was conducted in Nanyang, Henan Gold Leaf Garden in2012,and YunYan87was taked as experimental materials,The pot experiment was conducted toinvestigate the effects of different cadmium （Cd） concentrations(0、3、6、10、30、60mg·kg-1)on the physiological characteristic、chemical composition、spectral characteristics offlue-cured Tobacco.The main research results were as follows:1. The effects of Cd stress on physiological characteristics of flue-cured tobaccoWith the increase of Cd concentration, the pigments contents in the root elongationstage and the vigorous growth stage increased first and then decreased; while that in theharvesting stage decreased slowly; when Cd＞0mg·kg-1in the soil,the pigments contentswere all significantly less than the CK in the three growth periods. Cd stress on thechlorophyll a/b in three growth periods showed different trends. The total chlorophyllcontent of three growth periods was significantly and negatively correlated with the Cdcontents of leaves,which was the ideal physiological index of Cd stress of flue-curedtobacco.The order of the physiological indexes sensitivity was the total chlorophyll（chlorophylla+b）＞MDA＞carotenoids＞soluble sugar＞PRO.2. The effects of Cd stress on Cd accumulation characteristics in flue-cured tobacco andconventional chemical, mineral elements in cured tobacco leavesWith the increase of Cd concentration, the Cd contents in the three tobacco nutritionorgans were clearly higher than CK; From the nutrition organs, when Cd≤10mg·kg-1in theroot elongation stage and the Cd stress treatments in the vigorous growth stage, the order ofthe Cd content was leaf>root> stem; when Cd>10mg·kg-1in the root elongation stage andthe the Cd stress treatments in the harvesting stage, the order of the cd content was root＞leaf>stem. From the leaf parts,the order of the Cd content was lower leaf>middle leaf>upper leaf. From the growth period, the highest Cd contents of leaves appeared in thevigorous growth stage.With the increase of Cd concentration, the percentage content of the total sugar, nicotine,potassium, chlorine of the cured tobacco leaves increased first and then decreased; while thereducing sugars, total nitrogen, potassium chlorine ratio straightly decreased. According thethe effects of Cd stress on mineral nutrient elements, the eight mineral nutrient elementswere divided to two groups. Promoting effect group could be noted for Mn, Fe, resulting in increased concentration. Inhibiting effect group was found for P, B, Zn, Mg, Cu, Ca, thusresulting in reduced concentration. With the increase of Cd concentration, The adverseeffects of Cd stress on chemical composition increased gradually, and broke the balance ofleaf mineral nutrition of the cured tobacco leaves, which was not conducive for theformation of high quality tobacco leaves.3. Spectral characteristics of flue-cured tobacco leaves under Cd stressTaking the sensitive bands（551nm,672nm,760nm） into consideration,the normalizedpollution index （CNDPI） was build. With the increase of Cd concentration, CNDPI showedthe tendency of increase, and with the development of growth period,CNDPI increasedgradually.Through the analysis of tobacco hyperspeetral reflectance and CNDPI, thequalitative objectives of whether Cd pollution be or not be in the flue-cured tobacco wasimplementted. The leaf spectral reflectance in visible light（A1） and the range of red edgeshift（S） increased in every growth period,and what positively correlated with the Cdcontents of leaves;the leaf spectral reflectance in the near infrared light（A2）decreased,which negatively correlated with the Cd contents of leaves. Through theestablishment of the linear regression equation between Cd contents of leaves and thespectral characteristics factor A1, A2, S, satisfactory results were reached in the multiplecorrelation coefficient between the Cd content and A1, A2, S in the equation. |
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