Effects Of Different Light Constitution On The Spectral Characteristics And Quality In Flue-cured Tobacco

This paper studied the effects of different light constitution on the spectralcharacteristics and quality in flue-cured tobacco. The experiment was carried out ingolden leaf zone of Nanyang tobacco corporation. Flue-cured tobacco Yunyan87wasused in this experiment in the year of2012and2013. The experiment set up fivedifferent light constitution treatments with covering white filter membrane, greenfilter membrane, red filter membrane, blue filter membrane and yellow filtermembrane when30days after transplanting tobacco seedlings to research the effectsof different light constitution on the growth of flue-cured tobacco and build thehyperspectral prediction model of leaf pigment and nicotine content. The main resultswere showed as follows.1Leaf and canopy spectral characteristics of flue-cured tobacco in the differentlight constitutionLeaf and canopy spectral characteristics of flue-cured tobacco under the differentlight constitution had typical plant spectral curves.Hyperspectral curves of tobaccounder the different light quality were similar but the spectral reflectancedifferent.However, Leaf spectrum in the visible and near-infrared short-wave rangesignificantly, no significant differences in the near-infrared wavelengthregions.Leaves spectrum in the near-infrared short-wave range (850-1300nm) rangeas follows: white> yellow> red> Blue> green.Difference between canopy spectralreflectance in the350-1100nm were notable.spectral reflectivity in350-650nm visiblelight wavelength show as follows: white> yellow> green> Blue> red. Thereflection rate reaches its maximum in the plateau area of near infrared (750-1000nm),showing as follows: white> green> yellow> blue> red.And between1000-1100nm,spectral reflectance in green filter membrane with the highest, followed by white filtermembrane, yellow filter membrane> blue filter membrane> yellow filter membrane.2Hyperspectral prediction model of flue-cured tobacco leaf pigment contentRelationship between21leaf hyperspectral parameters and pigment content wasanalyzed by using relevance analysis.Twenty spectral parametersassociated with pigment had achieved very significant level, PSSRa and chlorophyll b not reaching asignificant level, and chlorophyll a and chlorophyll b had reached significantlevels.Spectral parameters G_NDVI and TCARI respectively had a better correlationbetween the contents of chlorophyll and carotenoids, then established predictionmodels of chlorophyll and carotenoids using spectral parameters.These models wereproved to be reliable for the content of leaf pigment monitoring by the index of rootmean square deviation (RMSE) and relative error (RE%).Power function model wasthe best hyperspectral prediction models of chlorophyll a.Parabolic function modelswere the best hyperspectral prediction model of chlorophyll b, chlorophyll a+b andcarotenoids. Best estimation modelsrespectively were:chla=0.368*（G_NDVI）^0.242，chlb=0.336+0.053*（G_NDVI）+0.095*（G_NDVI）2，chla+b=0.355-0.011*（G_NDVI）+0.015*（G_NDVI）2，car=0.980-3.867*（TCARI)+5.850*（TCARI)2.3Predicting nicotine content of flue-cured tobacco using hyperspectral dataThe study established the hyperspectral prediction model of flue-curedtobacconicotine contentusing principal component regression and stepwise regressionbased on vegetation index to provide technical support for flue-cured tobaccoqualityevaluation.The results showed that the correlation coefficients between leaf spectralparameters and nicotine were all greater，red edge area/blue edge area index SDr/SDb associated with nicotine content reached a maximum of0.97；For three kinds ofmodeling methods, the principal component regression modeling effect is best, andmodel tests of the decision coefficient and the root mean square error is0.924,0.29.Therefore, principal component regression method is optimal to establish themodel of flue-cured tobacco nicotine content under the condition of different lightconstitution. Best estimation model of flue-cured tobacco nicotine content were:-7.63+0.13*SDr/SDb+1.11*OSAVI+0.89*mNR705*0.01*NIR/R+0.01*REIP.4The effects of different light constitution on the quality of flue-cured tobaccoThe effects of different light constitution on agronomic characters of flue-curedtobacco were remarkable.Red and white treatments of agronomic performancewerecomprehensivebetter, while blue and yellow treatmentswerecomprehensive poorperformance. Red treatment increased tobacco leaf area and stem growth, while bluetreatment may act as a disincentive. Effects of different light constitution onpetroleum ether extract content slightly varied among different cultivar. Coveringfilter membrane could effectively increased the content of nitrogen-containing compound such as nicotine and total nitrogen, improved the content of potassium inlower leaves and decreased the content of total sugar and reducing sugar in upperleaves and the content of total sugar in middle and lower leaves.Except for greentreatment,covering filter membrane could reduce the content of neutral aromaconstituents in upper leaves and increase the content of neutral aroma constituentsinlower leaves. Blue and yellow treatments increased the content of neutral aromaconstituents inmiddle leaves, while green and blue treatment decreased.