Effects Of Wounding Signal Molecule Regulator On Nicotine Content And Growth Of Flue-cured Tobacco Upper Leaf

Upper leaf is an important component of China's tobacco leaf production and account for 40%of yield per plant.It's quality direct impact on the tobacco market competitiveness and the income of the farmers.The problems in quality and availability of upper leaf are high nicotine content,organizational structure tightness, chemical composition inherent lack of coordination and so on.This experimentation is on the basis of abroad research on plant wounding signal. The increased nicotine accumulation after topping is induced by wounding signal molecule.Effects of two wounding signal molecule regulations were investigated to suppress the synthesis of nicotine in tobacco plants and their effects on upper leaf growth and other chemical constituents where also been tested.Experiment carded out in February 2006 to March 2008 for two consecutive years in University of Science and Technology of China Experiment Station and Bengbu City of Anhui Province.Experiment related to tobacco chemistry,tobacco physiology and biochemistry.Wounding signal molecule regulators on chemical composition such as nicotine,petroleum ether extract,nitrogen,total sugar,reducing sugar,and the new leaf growth were tested,in order to explore the use wounding signal molecule regulators control the nicotine content of upper leaf,raising the possibility of its availability.Key findings are as follows:1.Two wounding signal molecule regulators can reduce nicotine content of the upper after topping.In three species tobacco,nicotine content of IRa treatment lower than the control by 32.9 percent,the largest decrease 49.2%;IRb can also inhibit the increase of nicotine,but the effect did not significant as IRa.In the low N level circumstances,the signal molecule regulators on leaf nitrogen content is not significantly affected,but in the high N circumstances,they can reduce the nitrogen content in the leaves;test results show that,IRa and IRb on tobacco in petroleum ether extract,total sugar,reducing sugar,potassium and chlorine content almost no impact.The results confirmed the use of wounding signal molecule regulators can weaken tobacco defensive reaction after topping,reduction of nicotine synthesize and reduce the nicotine content of upper leaf.2.Mechanical damage to tobacco seedlings have a strong effect on the growth of new leaves,after 5 day,the growth rate of 8^th leaf decreased nearly 30 percent compared with CK,leaf epidermal cells smaller than CK by 17.9%,leaf area reduction 35.2%. Photosynthetic has not changed,but a rapid increase in cell wall POD activity,and maintain 4 days.Cell wall POD activity returns to normal levels in the 5^th day.The result showed that the growth of the new tobacco leaf is inhibited by mechanical damage because the increased cell wall POD activity.3.Wounding signal molecule regulators can reduce the accumulation of signal material after mechanical damage,weakening its effect on new leaf.The seedlings test results showed that,IRa,IRb can increased the growth rate of new leaf by 66.56% and 54.78%;the leaf area also increased,5 days apply the wounding signal molecule regulators,leaf area larger than CK by 38.91%and 33.38%.Field test results show that:leaf area of IRa treatment larger than CK by10.09%,which of IRb is 5.71%.This result has proved that the inhibition of growth is mainly due to induced signal substances—jasmonic acid(JA).