Effect Of Sulfur And Selenium Combanition On Uptake Of Sulfur And Selenium, Physiological Characteristics And Quality Of Flue-cured Tobacco

Selenium and sulfur are two important nutrients for flue-cured tobacco.Combined application of Se and S has an important role in improving quality of flue-cured tobacco.Pot experient and field experiment were conducted in Luoyang in henan province to study the effect of S and Se combination on uptake and accumulation of S and Se,the activities of key enzymes related to S and Se metabolism,growth and development of flue-cured tobacco and quality of tobacco leaf(veriaty yuyan 10),aiming at studying the complicated physiological response to S and Se and providing evidence for S and Se fertilization in flue-cured tobacco.The main conclusion was as followed:1.The effect of S and Se combination on uptake and accumulation of S and Se and activities of key enzymes related to S and Se metabolism was analyzed.The result showed that:(1)Se content and accumulation in tobacco increased with Se level and decreased with increase of S level.(2)For S uptake and accumulation,Se application promoted S accumulation.At low S level,S content of tobacco leaf was increased by low level of Se and not considerably affected by high level of Se.At high level,S content was increased remarkably by application of Se.(3)For S and Se key enzymes,at equivalent Se level,APR activity of tobacco leaf at high S level was depressed at early stage,and SAT activity increased and shifted to a later stage.And at equivalent S level,Se application increased SAT activity of tobacco leaf,but had no influence on APR activity.For tobacco leaf usability,S1Se2 treatment was optimum because of higher Se content and lower S content.2.The effect of S and Se combination on physiological index of flue-cured tobacco was analyzed.The result showed that:(1)S and Se treatments increased the SOD and POD activity of tobacco leaf.The SOD activity increased with the rise of Se level.And the influence of Se on POD activity had relationship with S.At low S level,with the rise of Se level,POD activity rised firstly and then decreased in resetting stage,and showed the tend to increase in the late growth stage.At high S level,POD activity rised with the rise of Se level at each growth stage.Thus S and Se treatment with suitable concentration could promote activity of antioxidant enzymes and stress resisitance of flue-cured tobacco.(2)Increasing S level and Se application promoted the chlorine content.At low S level,with the rise of Se level,the chlorine content rised firstly and then decreased.At high S level,the chlorine content rised with the rise of Se level.The result of S and Se combination was that S2Se1 and S2Se2 treatments’ chlorine content were the highest at each growth stage,resulting in the possibility of late maturity of tobacco leaf.S1Se2 treatment was optimum in chlorine content,because it increased the chlorine content of tobacco leaf,promoted photosynthetic capacity of tobacco and avoiding high content of chlorine in the mature stage.(3)In mature stage,compared with S1Se0 treatment,there was more thylakoid lamellae in chloroplast in S2Se0 treatment,and exsited no grainy lipoprotein class material of high electronic density in vacuole.Thus high S level could enhance photosynthesis of tobacco leaf,keep the function of the chloroplast,but adversely affected the maturity of tobacco.S1Se2 and S2Se2 treatment increased the osmiophilic substances,thus Se application could promote the formation of osmiophilic substances.(4)Increasing S level improved N,K and Mn content,and decreased Fe and B content.Se application significantly improved N,B,K and Cl content,and decreased Fe and Mn content.S and Se interaction had significant influence on K,Cl,Mn and B,but had no influence on Cu,Zn,P and Fe content.Hence,S1Se2 treatment behaved best in physiological signs and quality of flue-cured tobacco.3.The effect of S and Se combination on quality of tobacco leaves was analyzed.The result showed that:(1)Se application increased leaf length,leaf width and single leaf weight of tobacco leaf at different leaf positions,and increased slightly filling value of tobacco leaf,especially in middle and upper leaf,and increased tensile strength in upper leaf,which was beneficial to the improvement of usaibility of tobacco leaf.(2)S and Se treatment obviously increased total nitrogen and nicotine content in bottom and middle leaf,and decreased slightly total nitrogen and nicotine content in upper leaf.And S and Se treatment obviously increased total sugar,reducing sugar and potassium content.T2 treatment’s potassium-chlorine ratio was the highest at different leaf positions,and sugar-nicotine ratio and nitrogen-nicotine ratio approached optimum value.(3)S and Se treatment could increased the neutral aroma component amount.T1 treatment’s carotenoid content was the highest,and T2 treatment’s maillard reaction products,phenylalanine content,cembranoids content,neophytadiene content was the highest.As for the aroma constituents,the content of β-dam-ascone,megastigmatrienone(1,3),furfural,2-acetylpyrrole,5-methyl-2furaldehyd,neophytadiene,solanone and hyacinthin of T2 treatment was the highest,and t-he content of megastigmatrienone(4),dihydroactinidiolide,geranyl acetone,furfu-ry,alcohol benzaldehyde,benzyl alcohol of T1 treatment was the highest.In total,Se application could improve the physical characteristic parameters,homony the chemical components,increase the aroma component content and improve the quality of flue-cured tobacco.The effect of T2 treatment was the best.