Studies On The Carbon And Nitrogen Metabolism And Its Relationship To Leaf Quality In Flue-cured Tobacco In Yanbian

During the year2011to2012, this study was conducted in Dunhua City,Longjing City and Wangqing County of Yanbian Korean Autonomous Prefecture, JilinProvince. In the study, the changing regularity of photosynthetic characteristics andkey enzyme activities of carbon and nitrogen metabolism, the accumulation andtransformation rules of carbon compounds and nitrogenous compounds wereresearched preliminarily. At the same time, it identified the inversion point of nitrogenmetabolism to carbon metabolism in three experimental points. And the research alsoestablished mathematical models on the carbon and nitrogen metabolism and itsrelationship to quality in flue-cured tobacco with the method of stepwise regressionanalysis. The results were as follows:1. The changing regularity of photosynthetic characteristics in the growing process offlue-cured tobacco in YanbianIn Yanbian region, with the growth of flue-cured tobacco, the net photosyntheticrate, stomatal conductance and transpiration rate of different parts showed as singlepeak curves, and the middle and lower leaves had a maximum value at50days aftertransplanted, but the upper leaf had a maximum value at80days after transplanted.The intercellular CO2concentration of different parts showed a first descending andthen rising trend, the middle and lower leaves had a minimum value at50days aftertransplanted, the upper leaf had a minimum value at80days after transplanted.2. The changing regularity of key enzyme activities of carbon and nitrogenmetabolism in the growing process of flue-cured tobacco in YanbianIn the process of flue-cured tobacco growth, the activity of nitrate reductase inthe upper and lower leaves were shown to have a downward trend, while the middleleaves showed as single peak curves, and the peak appeared at50days aftertransplanted. The invertase activity showed as single peak curves at different eco-sitesand parts, the peak of invertase activity in the lower leaves appeared at50days aftertransplanted in Dunhua and Wangqing, but in Longjing it appeared at65days aftertransplanted, and the peak of invertase activity of middle leaves appeared at65daysafter transplanted, but in upper leaves it appeared at80days after transplanted in3 experimental points.3. The accumulation and transformation of the products which were related to carbonand nitrogen metabolism of flue-cured tobacco in YanbianIn the process of growth in Yanbian area, the content of starch in the upper andlower leaves of flue-cured tobacco overall performanced “rise-drop” for change trend,and respectively in95days and65days after transplanted there was a peak, but in themiddle leaves it overall performanced "rise-drop-up" for change trend, respectively in65days and80days after transplanted there was a peak and a trough. Each part of thetotal sugar content performanced for "rise-drop" the change trend, and respectively at65days,80days and95days after transplanted there was a peak. Each part offlue-cured tobacco leaves, the total nitrogen content decreased all along with thegrowth of tobacco, but the nicotine content had an opposite change. There weredifferences among the total amino acid content in different parts of flue-cured tobaccoleaves, the change of total amino acid content in lower leaves performanced “V”shape, and had a trough in65days after transplanted, but the changes of total aminoacid content in middle and upper leaves declined all along with the growth offlue-cured tobacco.4. The conversion point of nitrogen and carbon metabolism of flue-cured tobaccoinYanbianIn Yanbian area, the conversion time of nitrogen metabolism to carbon metabolicin lower leaves occurred about at50-60days after transplanted, the nitrogenmetabolism was dominant before50days after transplanted and the carbon metabolicwas dominant after60days after transplanted. The conversion time of nitrogenmetabolism to carbon metabolic in middle leaves occurred about at60-65days aftertransplanted, the nitrogen metabolism was dominant before60days after transplantedand the carbon metabolic was dominant after65days after transplanted. Theconversion time of nitrogen metabolism to carbon metabolic in upper leaves occurredabout at70days after transplanted, the nitrogen metabolism was dominant before65days after transplanted and the carbon metabolic was dominant after80days aftertransplanted.5. The relationship between the tobacco leaf quality and carbon and nitrogenmetabolism of flue-cured tobacco in YanbianIn Yanbian area, there were significant or very significant correlations betweencarbon and nitrogen metabolism and starch, total sugar, total nitrogen, total amino acid content and nicotine, the ratio of total sugar and nicotine among different parts oftobacco leaves. And we found that the correlation coefficient between nicotine contentand carbon and nitrogen metabolism in lower and upper leaves was the largest, but inthe middle leaves the correlation coefficient between the ratio of total sugar andnicotine and carbon and nitrogen metabolism was largest.In Yanbian area, there were differences among different parts of tobacco leavesin the relationship between tobacco carbon and nitrogen metabolism and smokingquality. In the lower leaves, except offensive and smoke concentration, there weresignificant or very significant correlations between carbon and nitrogen metabolismand other smoking quality index. In the middle leaves, except ash and irritation, therewere significant or very significant correlations between carbon and nitrogenmetabolism and other smoking quality index. In the upper leaves, the smoking qualityindex except smoke concentration had significant or very significant correlations withcarbon and nitrogen metabolism. And we found that the correlation coefficientbetween total score of smoking quality, aroma quality and carbon and nitrogenmetabolism in lower and middle leaves was the largest, but in the upper leaves thecorrelation coefficient between total score of smoking quality, amount of aroma andoffensive and carbon and nitrogen metabolism was largest.