| In order to find out the appearance maturity characteristics and quantitative standards of high maturity tobacco leaves,the ripening process of middle leaves(9th and 10 th leaf positions)and upper leaves(15th and 16 th leaf positions)of Yunyan 87(Comprehensive yellowing degree of tobacco leaves gradually changed from 10% to 100%,and middle leaves from 1D to 15d)were studied by continuous investigation and comparative study,The main physiological and biochemical changes and the relationship between harvest and quality of tobacco leaves with different maturity were studied.The results show that: 1.Appearance ripening characteristics and main physiological and biochemical changes of tobacco leaves during ripeningThe changes of middle and upper leaves were basically the same.The leaf color was yellow green green yellow yellow yellow to medium white;the main and lateral veins changed from green to light green white;the leaf tip gradually turned yellow and gradually withered,and the leaf margin near the leaf tip gradually curled and withered;the ear changed from green to light green green yellow to full yellow;the middle leaves began to appear sporadic mature spots on the 5th day,and then increased gradually,and the disease spots and blisters appeared on the 14 th and 15 th days,and the upper leaves began to appear at the 8th day There were sporadic mature spots,and then gradually increased.To the 16 th day,the lesions began to appear and gradually increased.SPAD values of middle and upper leaves decreased gradually,The SPAD value of the middle leaf decreased from 29.1 on the first day to 13.5 on the 15 th day,and the SPAD value of the upper leaf decreased from 30.2 on the first day to 13.5 on the 20 th day.The water content of middle and upper leaves decreased first and then increased.The amylase activity in the middle and upper leaves increased first and then decreased,while the nitrate reductase activity and protease activity decreased gradually.The contents of starch,total sugar,reducing sugar and nicotine in the middle and upper leaves increased first and then decreased,while the contents of protein and total nitrogen decreased gradually.2.Relationship between harvest and quality of tobacco leaves with different maturity(1)Differences in appearance quality of flue cured tobacco leaves with different maturityWith the improvement of maturity,the color of middle and upper leaves gradually deepened,the middle leaves of maturity gradually turned mature,the upper leaves gradually changed from still ripe to mature,the identity gradually changed from a little thick to medium,the oil content gradually increased and then decreased,the color of middle and upper leaves gradually increased and then decreased,and the structure gradually changed from slightly dense to loose.The middle leaves had 70% comprehensive yellowing degree and the upper leaves had 90% comprehensive yellowing degree,which met the requirements of high maturity flue cured tobacco leaves.With the increase of maturity,the average price of middle and upper leaves,the rate of superior tobacco,the rate of orange yellow tobacco and high maturity all increased first and then decreased,while the rate of variegated tobacco increased gradually.The average price,superior tobacco rate and orange yellow tobacco rate of 60% comprehensive yellowing degree of middle leaves were the highest,and the high maturity rate of 70% comprehensive yellowing degree was 74.51%.The average price,superior tobacco rate,orange yellow tobacco rate and high maturity rate of 90% comprehensive yellowing degree of upper leaves were the highest,among which the high maturity rate was 70.81%.(2)Differences of chemical components in flue cured tobacco leaves with different maturityWith the increase of maturity,the contents of total sugar,reducing sugar,nicotine,potassium,petroleum ether extract and the ratio of two sugars in middle and upper leaves increased first and then decreased,the contents of starch,protein and total nitrogen decreased gradually,the ratio of sugar to alkali increased gradually,the ratio of nitrogen to alkali in middle leaves decreased gradually,and the ratio of nitrogen to alkali in upper leaves decreased first and then increased The trend of increase.The results showed that the chemical components of 70% and 90% of middle leaves and upper leaves which could meet the requirements of chemical components of high maturity flue cured tobacco leaves.(3)Difference of smoking quality of flue cured tobacco leaves with different maturityWith the improvement of maturity,the aroma quality,aroma quantity,eating taste,miscellaneous gas,irritancy,strength and total score of smoking evaluation of middle and upper leaves showed a trend of first increase and then decrease.70% of the middle leaves and 90% of the upper leaves were better.3.Appearance maturity characteristics and quantitative standard of high maturity tobacco leavesThe quality of flue-cured tobacco leaves(appearance quality,chemical composition,smoking evaluation quality)is the key to judge the maturity of tobacco leaves.By comparing the quality differences of flue-cured tobacco leaves with different maturity and comparing with the quality requirements of Hunan Zhongyan tobacco for high maturity tobacco leaves,the comprehensive yellowing degree of middle leaves 70% and the comprehensive yellowing degree of upper leaves 90% can best meet the requirements,combined with the appearance maturity process of tobacco leaves According to the characteristics and physiological and biochemical changes,the appearance maturity characteristics and quantitative standards of high maturity tobacco leaves were deduced.Considering the operability of actual field production,the parameters such as water content,starch and total sugar were removed and SPAD value was retained:The appearance maturity characteristics of middle leaves of Yunyan 87 were more yellow(more yellow and less green),slightly withered and hooked leaf tips,slightly withered and inner curved leaf edges,yellow green ears and more mature spots;the quantitative standard was that the comprehensive yellowing degree of leaves was about 70%,the main vein turned White 3 / 4,the lateral vein turned white 2 / 3,and SPAD value was about 17%.The upper leaves of Yunyan 87 were characterized by more yellowing,only a small amount of green at the base of the remaining leaves,a little withered and drooped leaf tip,a little withered and obvious inner curvature of the leaf edge,yellow ear,a small number of disease spots and more mature spots;the quantitative standard was that the comprehensive yellowing degree of leaves was about 90%,the main vein and main vein turned white 4 / 5,the lateral vein turned white 3 / 4,and the SPAD value was about 14%. |
