Effects Of Carbon-nitrogen Metabolism And Sensory Evaluation Of Sweet Aroma In Flue-cured Tobacco For Different Texture Soils In South Anhui

This experiment was carried out in in South Anhui . Flued-cured tobacco yunyan 87 was used during 2008. Different Typical tobacco soils in South Anhui and different N fertilization rate were selected to investigate the dynamic changes in carbon-nitrogen metabolism and sensory evaluation of sweet aroma in flue-cured tobacco.Dynamic Changes in Key Enzyme Activities of Carbon-Nitrogen Metabolism and degraded substances Content in Flue-cured Tobacco for different texture soils4 Typical tobacco soils in South Anhui were selected to investigate the dynamic changes in key enzyme activities of carbon-nitrogen metabolism and total sugar content during growth and development of flue-cured tobacco. The results showed that carbon-nitrogen metabolism from tobaccos grown on Alluvial sandy soil and coarse sandy soil had similar dynamic changing patterns. During the early and middle stages of tobacco growth, both carbon metabolism and nitrogen metabolism were at the high levels. The nitrate reductase activities decreased significantly after 45d after transplant for bottom leaves, after 60d after transplant for middle leaves and top leaves. The invertase activities also decreased after peak values, but the degree of decrease was much less than that of nitrate reductase. Activities. The sugar contents were at the highest levels for the two sandy soils. For the rice clay soil, the carbon-nitrogen metabolism at early and middle plant growth stages were at less level than that for Alluvial and coarse sandy soils, and the peak time was much delayed. At late growth stage, the metabolism level was relatively and unreasonably high, and the sugar content was low. For powder sandy soil, the peak time of carbon-nitrogen metabolism appeared early, and the metabolism remained at low level during the whole plant growth season; the sugar content was also low.Differences in Contents of Neutral Aroma Components and Sensory Evaluation of Sweet Aroma in Soils with Different Textures in South Anhui3 Typical tobacco soils with different textures in South Anhui were selected to investigate the differences in the contents of aroma components and regular compounds in flue-cured tobacco leaves and the differences in the sensory evaluation on aroma quality. The results showed that tobacco leaves from alluvial sandy soil had high levels of carotenoid catabolites and sugar catabolites in all stalk positions, and high levels of solanone in middle leaves and high levels of phenylalanine catabolites in low leaves. Both sugar and nicotine contents were high and the ratio of sugar to nicotine was suitable. The sensory quality was good with rich sweet aroma. For clayey paddy soil, the contents of carotenoid catabolites were low in bottom and middle leaves, solanone was also low in middle leaves, while phenylalanine and carotenoid catabolites were high in up leaves. The content of sugar was low, while the contents of nicotine and total nitrogen were high in up leaves, which led to lower sugar nicotine ratio. The sweet aroma was not significant and the smoke was strong for up leaves. For silty sand soil, the neutral aroma components were generally at low level for middle and up leaves. The sugar content was high, while the nicotine content was low, and the ratio of sugar to nicotine was high. Sensory evaluation showed the samples had week sweet aroma and lack of aroma.Different contents of neutral aroma components compounds of different leavesSolsnone compounds were much higher in the middle and top leaves, tobacco leaves from alluvial sandy soil had high levels of carotenoid catabolites in bottom and middle stalk positions, so did the chromoplast pigment degraded products, such as 3-hydroxyl-β-dimascone,β-damoscone,geranyl acetone. Phenylalanine degraded substances of tobacco leaves from alluvial sandy soil obviously increased with the leaves increasing, Phenylalanine degraded substances of tobacco leaves from Coarse sandy soil were totally much lower. Tobacco leaves from alluvial sandy soil had the highest levels of carotenes degraded substances in the top and middle stalk positions, and 21～22 leaves reached the highest contents. The contents of cembrane degraded substances all increased with the increasing of leaves, the contents of cembrane degraded substances were much lower in the 1～2 leaves, 3～5 leaves,6～8 leaves; the contents of cembrane degraded substances which had the highest contents were the sandy soil treatments for in the middle leaves, top tobacco leaves from alluvial sandy soil had prominently higher levels of cembrane degraded substances than course sandy soil and rice clay soil . with the increasing of leaves,sugar degraded substances from alluvial sandy soil didn't obviously increase. sugar degraded substances in the bottom leaves were much higher than middle and top leaves from rice clay soil were much higher.Differences of regular chemical compounds of different flue-cured tobacco leavesSugar content was much higher in the middle and top leaves in the different leaves, also sugar in the Alluvial sandy soil and coarse sandy soil were much higher than in the rice clay soil .The differences of the sugar content and dynamic changing patterns were significant. The content of starch increased in the beginning, however it decreased when it reached the mature period. The content of starch had the highest content in 1～2 leaves, 3～5 leaves,6～8 leaves,9～11 leaves,12～14 leaves,15～17 leaves in the alluvial sandy soil. The content of starch in the coarse sandy soil was prominently higher than in the rice clay soil. The content of total N in the 15～17 leaves,18～20 leaves in the rice clay soil were prominently much higher than other two sandy soil, which the difference reached of the ratio of 1% . The content of nicotine increased with the leaves increasing, the content of nicotine reached the highest which were the top leaves. The difference of the content of the nicotine among the 1～2 leaves, 3～5 leaves,9～11leaves and the 12～14 leaves was significant, which reach the most prominent ratio of 1%, it showed that the content of the nicotine in the Alluvial sandy soil reached the highest. The differences of the nicotine content in the 18～20 leaves and the 21～22 leaves weren't significant for the three different texture soils.Changes of Carbon-Nitrogen Metabolism of Flue-Cured Tobacco with Sweet Aroma in South Anhui Under Different Fertilization RatesTypical tobacco soils in South Anhui were selected to investigate the changes of the activities of some enzymes and product contents of carbon-nitrogen metabolism during the growth of flue-cured tobacco. The results showed that the nitrate reductase activity increased first with the increase of N fertilization rate, but decreased significantly after 40 d of transplant for bottom leaves and 55 d for middle leaves and top leaves. The peak value of nitrate reductase activity was N8(N 8 kg/667m2)>N7(N 7 kg/667m2)>N6(N 6 kg/667m2)>N5(N 5 kg/667m2). The invertase activity also decreased significantly after reaching the peak value. The accumulative content of total nitrogen, the content and accumulative content of nicotine in tobacco leaves increased gradually, showed positive responses to the increase of N fertilization rate. The content of total sugar decreased with the increase of N fertilization rate, the accumulation of total sugar in top leaves was lower than those in middle and bottom leaves. N8 treatment showed the lowest content of total sugar.Differences in contents of regular chemical compounds of flue—tobacco leaves under different N fertilization rateFor the C3F,The sugar contents at the highest level were the N6 treatment, which were much more prominent than other three N treatments; the contents of nicotine and total nitrogen all increased with the increasing of nitrogen-applied amount; the contents of cl were all lower than1%; N7 treatment has the highest cl contents.For the B2F,The sugar contents at the highest level were the N6 treatment, which weren't much more prominent than other three N treatments; the contents of nicotine and total nitrogen all increased with the increasing of nitrogen-applied amount; the contents of cl were much prominent ,while only N6 treatment were lower than1%; N8 treatment has the highest cl contents .Effects of major economic character of flue—tobacco leaves under different N fertilization rateYield(N5 besides)was increased with the increasing of nitrogen-applied amount; while the differences weren't much more prominent ; average price(N5 besides)was prominently decreased with the increasing of nitrogen-applied amount; output value(N5 besides) was decreased with the increasing of nitrogen-applied amount, but the difference wasn't more prominent; the ratio of high-grade leaves(N5 besides)was prominently increased with the increasing of nitrogen-applied amount; the ratio of mid-grade leaves ( N5 besides ) wasn't prominent with the increasing of nitrogen-applied amount. The N6 treatment was the best for the major economic characters.