| The experiments were carried out on the experiment farm of Ustc, Changting county,Shanghang county in Fujian province ,Guiyang county in Hunan province and Hunan agricultural university in Changsha city from year 2002 to year 2004.By using the principle and methods of tobacco chemistry, pathology, biochemistry, tobacco cultivation, tobacco biochemistry, Principle of nourishment in flue-cured tobacco, tobacco aromaion, to study the technology of chemical control of improvement of upper leaf in flue-cured. The main results were as follows:1 Effects of exogenous plant hormone (EPH) on growth and chemical compounds in upper leaf were studied, the results indicated that optimum mixture can improve the growth and development of the upper leaf, leaf width and leaf area increased, palisade tissue, sponge tissue, thickness of leaf, density and weight per leaf area decreased. The nicotine and total nitrogen content significantly got down, while the reducing sugar, total sugar, potassium, polyphenolics content increased. Some treatments have passively effect on physical property and main chemical compounds. By gray incidence analysis the results showed H6 treatment was superior to others on improvement of qualities of upper leaf in flue-cured tobacco.2 Effects of different spraying times with exogenous plant hormone on physical property and chemical in upper leaf were studied, the results showed that with the spraying times increased, the physical property increased, but the chemical compounds had different affected. H5 and H6 can improve stalk height, retain leaf, stalk circumference, yield and income, percent of middle and upper-class leaf under spraying one or two times, also reducing sugar content increased, nicotine and starch decreased. The agronomic character and physical property are best with H9 spraying two or three times. Nicotine was lower, while reducing sugar higher. The polyphenolic and petroleum ether extract decreased with spraying times increased. In a conclusion, H5 and H6 spraying one time and H9 spring two times are superior to others times.3 In budding period spraying EPH can significantly improve the physical property and tissue structure of upper leaf, and nicotine, total nitrogen, reducing sugar and starch have a optimum period, but have negative on potassium, total sugar, polyphenolics and petroleum ether extract. When All-flower period spraying, had negative on physical property. The budding and leaf parallel period was superior to others periods.4.The accumulation dynamical of the main chemical compounds after topping in flue-cured tobacco were studied, The results were as follows:Firstly, Effect of different topping stages on physical property and chemical compounds in upper leaf in flue-cured tobacco were studied, the results indicated that the more early topping, the more height nicotine content, and leaf structure of upper leaf rigidity, changes of total nitrogen insignificant, reducing sugar, total sugar, polyphenolics and petroleum ether extract decreased, have a passively effect on starch and ash content. When topping stages of central flower topping or All-flower topping have excellence effects on physical property and chemical compounds in upper leaf in flue-cured tobacco.Secondly, After topping in flue-cured tobacco, nicotine content quickly increased (upper leaf:Y=-0.0015X2+0.1427X+0.2558,R2=0.9985**;middle leaf:Y=-0.00218X2 +0.13705X +0.43726,R2=0.9977**),there are the highest climax 45days in upper leaf and 30days in middle leaf after topping. Total nitrogen content decreased gradually (upper:Y= -0.0026X2 -0.0327X+5.0258,R2=0.952*ï¼›middle leaf:Y=-0.0027X2-0.0034X+3.9486,R2=0.9801**).nitrogen/nicotine had a increase trend of exponent index(upper:Y=143.52e-0.1257x,R2=0.9835**ï¼›middle:Y=82.94e-0.1592x,R2=0.9806**). Total sugar content (upper:Y=-0.0076X2+0.5691X+4.2583,R2=0.9427**ï¼›middle:Y=0.0053X2+0.1986X +6.6314,R2=0.9594**) and reducing sugar content increased gradually. Starch contents have a contrast between upper leaf and middle leaf: upper leaf increased... |
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