The Degradation Rules Of Plastic Pigment And Its Differences Response To Nierogn And Light Intensity In Different Flu-cured Tobacco Varieties

The accumulation, transformation and degradation of plastid pigment inprocesses of tobacco growing, maturing, curing, aging and combusting, will directlyaffect the aroma style,quality and quantity of flue-cured tobacco. Our experimentstudied the characteristics and differences of plastid pigment metabolism in theprocess of maturing and aging in different varieties of flue-cured tobacco leaf, andfurther research on the influence of tobacco plastid pigment degradation by varieties,culture, ecology, maturity, curing conditions, in order to find the best conditionalcombinations, make chlorophyll degraded completely, carotenoids content moreharmonious in tobacco leaves,. The results showed that:1. The degradation of chlorophyll and soluble protein is a sign of leaf senescence,chlorophyll a has a large amount of degradation during leaf aging, low residualamount after curing, chlorophyll b also dropped significantly. The differences ofchlorophyll total degradation content among Varieties are:YuYan10is higher thanZhongYan100, NC89is the lowest, and YuYan10, ZhongYan100have the higherdegradation content in the early stage of leaf senescence, and NC89degradationcontent increased gradually in late aging. The activity of SOD, POD and CAT changetrend is consistent, SOD and POD activity reached the peak in leaf age60d, CATactivity in the leaf age50d. YuYan10with low enzyme activity has largedegradationcontent of chlorophyll and soluble protein, aging fast, has largeaccumulation of malondialdehyde, high LOX activity, means its high degree ofmembrane lipid peroxidation, membrane damage is serious. And ZhongYan100haslarge chlorophyll degradation during senescence, small amount of soluble proteindegradation probably related to its strong scavenging ability on active oxygen,therefore ZhongYan100has strong ability to protect protein, which leads to slow degradation of protein. The content of Chlorophyll a and total chlorophyll and itsdegradation during aging were extremely significant or significant positive correlatedwith the total content of aroma, the total degradation of neophytadiene and maincomponents of carotenoids degradation. And the faster the aging speed of the variety,the higher conversion efficiency of its degradation products. The total degradation ofcarotenoids were extremely significant or significant positive correlated with the totalamounts of aroma degradation and the main aroma components content.2. The chlorophyll content of YuYan10and ZhongYan100peaked in leaf age30days, Y8190in the leaf age40days, the highest peak contents: YuYan10> Y892>ZhongYan100. The degradation content of chlorophyll during maturing have thesame order with the content of peaked; Amount of degradation during curing: Y8190> ZhongYan100> YuYan10; The differences of total chlorophyll degradation contentamong varieties show YuYan10is higher than Y8190, and ZhongYan100is thelowest. Degradation content during growing is higher than during curing, thedifference between the two, YuYan10maximum:51.84%, followed by Y8190:26.90%, ZhongYan100were minimum, is only1.65%. From the point of totalcarotenoids degradation rate, Y8190degradation rate is the highest (90.52%), secondis YuYan10(83.40%), ZhongYan100is the lowest (82.14%), curing after96h,tobacco leaf carotenoid content of YuYan10, Y8190and ZhongYan100than beforecuring was respectively reduced69.69%,87.50%and68.03%, while tobacco leafcarotenoids can further degraded and transformed during aging process, but it isdifficult to offset lower degradation rate during curing, it seems, improve carotenoidsdegradation rate of YuYan10,can make the tobacco aroma more enrich and full.3. By determining the change rule of related indicators of tobacco plastidpigment and senescence in3varieties of flue-cured tobacco under3different nitrogennutrition levels, leaf was studied the relationship between tobacco leaves senescenceand plastid pigment degradation and the content of its degradation products indifferent varieties of tobacco under different conditions of nitrogen nutrition. Theresults showed that the varieties or treatments with higher content of plastid pigment degradation products and main composition, will have the larger amount of plastidpigment and soluble protein degradation, the higher LOX activity and MDAaccumulation, the lower superoxide dismutase (SOD), peroxidase (POD), catalase(CAT) and glutamine synthetase (GS) activity. Increase the application amount ofnitrogen, the accumulation of chlorophyll in tobacco leaf will significant increase, thehighest carotenoid content in the treatment under middle or high level of nitrogenapplication, chlorophyll degradation increased, carotenoids degradation increasedafter first decreased, tobacco leaf aging will slow. Different varieties response tonitrogen differently, during senescence YuYan10has large amount of soluble proteindegradation, high LOX activity, high accumulation quantity of MDA, low activity ofSOD, POD, CAT, tobacco leaf aging fast, aging degree is high, the correspondingcontent of tobacco plastid pigment and its degradation products is high, maintain arapid speed of aging even under high applied nitrogen treatment. The results showedthat tobacco leaf response to nitrogen nutrition differently, show a difference of theaging properties, then affected the degradation and transformation of plastid pigment.The content of plastid pigment degradation and its degradation products is correlatedwith tobacco leaf aging properties. According to different varieties, choose theappropriate nitrogen application rate and increase the degree of tobacco leaf aging,iscrucial to plastid pigment degradation and the formation of aroma matter.4. Illumination significantly affect the content of plastid pigment degradationproducts in flue-cured tobacco leaves, the content of chlorophyll especiallychlorophyll a under shading treatment is higher than that under natural light treatment,it may be that the tobacco leaf under poor light need more chlorophyll to gather lightand complete the photosynthesis, which provide materials and energy to the normalgrowth, The total contents of volatile aroma components and neophytadiene reducedin YuYan10, YunYan87leaves under shading, shading treatment has disadvantage tothe degradation of chlorophyll in the mature period, increased the the content ofcarotenoids in fresh tobacco leaf, the content of carotenoids degradation products,especially the content of beta-Damascone, megastigmatrienone in cured tobacco leaves under natural light treatment is significantly higher than under the shadingtreatment, the content of carotenoids degradation products in YuYan10, YunYan97cured tobacco leaves respectively increased28.5%and33.8%. This is probably dueto shading treatment is beneficial to the accumulation of carotenoids, but harmful tothe degradation of carotenoids.The formation of neutral aroma substances in varieties has nothing to do with thehighest accumulation of plastid pigment, but it is related with the degradation ofplastid pigment, varieties (or strains) with larger quantity of plastid pigmentdegradation, have higher content of neutral aroma substances. In the process of leafgrowing, promote the accumulation of plastid pigment, and fully degradation oftobacco plastid pigment in the process of maturing and curing, improve the quantityof pigment degradation, will be conducive to promote the formation of tobacco aromasubstance, increase the aroma quality of tobacco leaf.