Relationships Between The Maturity And Quality And Physiological Index Of Light Sun-Cured Tobacco

Field experiments were conducted in Ningxiang,Hunan province,during 2005-2006 to investigate leaves squares,pigment,leaf structure,endogenous hormone in leaves of different maturity,and chemical components,physical characteristics, smoking taste quality,and aroma constituents in cured leaves.The results were as follows:1.During whole growing period the leaf squares presented a slow-fast-slow increasing trend,a dissymmetrical "S" curve line.The time leaves grew up of the two spices was upper-leaves(45d)＞cutter-leaves(40d)＞lug-leaves(35d).2.The contents of Chlorophylls and Carotene decreased with maturity decreasing in the same position of the two different Light sun-cured tobacco spices from upper-leaves to lug-leaves.The thickness of Surface,Palisade tissues,Sponge tissues increased with the position increasing,but in the same position the contents decreased with maturity decreasing.It demonstrated that with maturity increasing the tissue structure became sparse and yield decreased obviously.3.With maturity increasing the contents of the IAA and ZR decreased,ABA increased, GA increased firstly and then decreased in the two spices.In the maturing process of spices Cunsanpi,the IAA,GA and ZR were highly significant positive-correlation (r1=0.538^*,r2=0.619^*);the ZR and ABA were highly significant negative-correlation (r=-0.698^**).But with regard to spices 87-11-3,the IAA and ZR were highly significant positive-correlation(r=0.826^**),GA and ABA were highly significant negative-correlation(r=0.613^*).All of these proved that the hormone worked in systematic methods.4.With maturity increasing,the contents of nicotine,starch,total sugar,reducing sugar increased firstly and then decreased.In same maturity,the contents of nicotine and total nitrogen in leaves were upper-leaves＞cutter-leaves＞lug-leaves.The contents of total sugar and reducing sugar in utter-leaves were the best.5.The weight per area,leaf thickness,tensile,and tensile strong in same positions increased and then decreased with maturity increasing,but the filling power increased all the time.The stem content had no obviously change.6.With maturity increasing the total amount of aroma constituents increased firstly and then decreased.The contents of aroma constituents of M₂ treatment of spices Cunanpi was the highest.But to spices 87-11-3 the M₄ treatment was the best.The results of smoking showed that taste quality of M₄ treatment of the two spices in upper and utter leaves was the best.7.The smoking taste quality of M₂ treatment of spices Cunsanpi in upper-leaves was the best,in utter-leaves treatment was the best.The M₃ treatment of spices 87-11-3 was the best in upper-leaves and utter-leaves.8.About the spices Cunsanpi,the economic benefits of M₃ treatment of upper-leaves and lug-leaves was the best;the M₂ treatment of the cutter-leaves was the best.About spices 87-11-3,the economic benefits of M₃ treatment of upper-leaves and lug-leaves was the best;the M4 treatment of the cutter-leaves was the best.In total,physical characteristics,chemical components,taste quality,and economic benefits of M₂ treatment in lug-leaves was the best,but the M₃ treatment was the best in upper and cutter leaves.The mature characteristics in lug-leaves were as follows:the leaf color was mainly green with a little yellow,about 4/5 of main veins and 1/4 of side veins tuned white,the hair fell of slightly.Leaf apex trooped and leaf edge tuned over obviously.The mature characteristics in cutter and upper leaves were as follow:the leaf color was light yellow.Main vein and 1/3 of side vein tuned white,the color of leaf apex and leaf edge was yellow.Leaf apex trooped and leaf edge tuned over obviously like lug-leaves.