Effects Of Soil C/N With Increasing Compost Wheat Straw On The Carbon And Nitrogen Metabolism And The Quality Of Flue-cured Tobacco Leaves

The pot experiment was carried out during 2009～2010 in the farm of Henan agricultural university. The study was to research the effects on the carbon and nitrogen metabolism and the quality of flue-cured tobacco leaves with adjust soil C/N by application wheat stalk to soil. The test analyzed the effects from the key enzymes,chemical composition of tobacco leaves,aroma,enzyme activities and nutrient of soil etc. The main results as follows:1.The effects of different soil C/N on the soil of flue-cured tobacco.The activities of soil urease and sucrase significantly improved with the increasing the soil C/N,which is beneficial to the early growth of tobacco plant.During the whole growth soil urease activity increased first and then decreased to stabilize,urease activity reached the peak after transplanting 45 days in the whole growth. Soil sucrase decreased and reached valley after transplanting 60 days,then remained stable,a slight increase at maturity stage.Improving the soil C/N,organic matter,available nitrogen,available phosphorus and available potassium increased with varying degree. The increase of the processing T3(C/N=24) was most obvious.2.The effects of improving soil C/N on the growth and the quality of flue-cured tobacco.The increase was obvious on the leaf nitrate reductase activity, invertase activity, amylase activity increased with soil C/N increasing.Between the soil C/N 24 and 28,the largest and most conductive to the growth of flue-cured tobacco and the timely conversion of carbon and nitrogen metabolism.most these enzyme activities peaked at 60 days after transplanting.only the upper leaves amylase activity peaked at 75 days,the lower leaves nitrate reductase activity peaked at 45 days after transplanting.But after T3(C/N=24),the rate of increase tobacco activity slowed.The processing of improving the soil C/N,the leaf content of total sugar, reducing sugar,reducing sugar/total sugar ratio and reducing sugar/nicotine ratio increased.Total nitrogen,nicotine and total nitrogen/nicotine decreased.T3(C/N=24) was coordinate on the chemical composition of tobacco leaf than other processing. Improving the soil C/N the total amount of tobacco neutral aroma was increased,T4(C/N=28) dealing with the highest content of aromatic substances.In the major categories of arma,the grey correlation degree was maximum on the brown reaction productsneutral aroma and the soil C/N,it was minimum on phenylalamine degradation products and the soil C/N.Overall,the soil C/N between 24～28 the quality of tobacco leaf was best.The dynamics changes of mineral elements in the middle leaf were that increasing the soil C/N increased the content of P,K and Fe,the content of Ca and Mn increased little,the influence of ealy tobacco growth was larger than later.Comprehensive analysis of results showed that it was conductive to improve the balance of carbon and nitrogen metabolism and enhance the quality of tobacco by adding compost wheat straw to improve soil C/N. Especially the soil C/N was between 24～28,the enzyme activity increasing rage and the effectiveness of plant soil were largest,it provided the best environment for plant growth,it had favorable chemical composition and best aromatic matter.The pot experiment put forward preliminarily the best soil C/N ,but it was still need for many years in order to further verify,and then to repair tobacco soil,increase yield and quality of tobacco,promote the sustainable development.