| In order to find out the material change law and mature characteristics of Yunyan105 and Yunyan 116 during the ripening process,and provide theoretical and technical basis for their production supporting technology and promotion,the changes of appearance characteristics,key physiological and biochemical indexes and other mature characteristics of the middle leaves of the two varieties were studied in the banliang mountain area of Weining by using continuous sampling analysis method and comparative research method.The results showed that 10-38 days after topping of the two varieties:1.Changes in appearance characteristics of tobacco leavesThe change trend of tobacco appearance characteristics of the two varieties is roughly the same.The leaf color is from green to light green to yellow green to green yellow;The main and lateral veins are green light green white;The leaf tip and the leaf margin near the leaf tip change from light green to slightly yellow to yellow and bend inward;The color of tobacco leaves began to turn yellow(about 86.2%)before the main vein and about 14 days after the main vein,and gradually changed to yellow(about86.2%)after 14 days;The change of appearance characteristics(leaf color,main vein,side vein,etc.)of Yunyan 105 was 4 days later than that of Yunyan 116,about 70%turned yellow at 38 days,the yellowing speed was about 2.50% / D,and the yellowing speed of Yunyan 105 was slightly slower.2.Changes of main physiological and biochemical indexes(1)The SPAD value,chlorophyll content and carotenoid content of the two varieties decreased gradually with the increase of maturity.The overall decreasing range and rate of the SPAD value of Yunyan 116 were 11.34% and 0.17/d higher than that of Yunyan 105;The overall decline range and rate of chlorophyll content were 7.37%and 0.003(mg/gfw)/d higher than that of Yunyan 105;The overall decrease range and rate of carotenoid content were 5.32% and 0.0004(mg/gfw)/d higher than that of Yunyan 105.(2)The nitrate reductase(NR)activity and superoxide dismutase(SOD)activity of the two varieties decreased gradually with the increase of maturity.In the whole stage,the decreasing range and rate of Yunyan 116 nr and SOD activities were 12.2% and0.0002 higher than that of Yunyan 105(μ/ Mol/0.1g)/d and 6.26%,0.09(u/mgprot)/d;The activity of amylase(Amy)and polyphenol oxidase(PPO)of the two varieties increased first and then decreased with the increase of maturity.In the whole stage,the change range and rate of amylase in Yunyan 116 were 17.48% higher than that in Yunyan 105,and 0.0004(u/mgprot)/d.The change amplitude and rate of PPO activity in Yunyan 116 were 1.99% and 1.49(u/mgprot)/d higher than that in Yunyan 105;The content of malondialdehyde(MDA)in the two varieties showed a gradual upward trend with the increase of maturity.The growth rate and rising rate of Yunyan 116 were 12.28%and 0.31% higher than that of Yunyan 105 in the whole process μ/ mol/g/d。(3)The contents of the main indicators of carbon metabolism(total sugar,reducing sugar and starch)of the two varieties increased first and then decreased with the increase of maturity.Total sugar: Yunyan 116 rose to the highest of 10.43% 30 days after topping,and then decreased gradually;Yunyan 105 rose to the highest of 11.24%on the 34 th day after topping,and then decreased gradually.Its range and rate of change were 2.19% and 0.008% higher than Yunyan 116;The change trend of reducing sugar in the two varieties was similar to that of total sugar;Starch: Yunyan 116 rose to 24.47%at the 26 th day after topping,and then decreased gradually;Yunyan 105 rose to a maximum of 25.05% 30 days after topping,and then decreased gradually.Its range and rate of change were 2.58% and 0.01% higher than Yunyan 116.The contents of the main indicators of nitrogen metabolism(total nitrogen and protein)of the two varieties showed a gradual downward trend with the increase of maturity,while the content of nicotine showed a gradual upward trend with the increase of maturity.The decrease range and rate of total nitrogen and protein in Yunyan 116 were 7.63% and 0.0004%/d,7.63% and 0.0023%/d higher than that in Yunyan 105,respectively;In terms of nicotine,the change amplitude and change rate of Yunyan 116 were 4.68% and 0.0032% lower than that of Yunyan 105;The c/n of the two varieties showed a gradually increasing trend with the increase of maturity.The growth rate and rising rate of Yunyan 116 were 20.73% and 0.04/d higher than that of Yunyan 105.3.Correlation analysis(1)Pearson correlation analysis showed that 16 of the 17 physiological and biochemical indexes in the process of tobacco ripening had correlation,while the two sugar ratio had no correlation with all other indexes.(2)Principal component analysis showed that there were 14 important indexes affecting tobacco maturity,of which 11 were more important,including chlorophyll,protein,total nitrogen,carotenoid,nitrate reductase,total sugar,pod,SOD,MDA,two sugar ratio,nitrogen alkali ratio,followed by reducing sugar,amylase and sugar alkali ratio.These indicators can reflect the maturity of tobacco leaves to a certain extent.4.Relationship between maturity and quality of flue-cured tobacco leaves(1)In terms of grade quality,with the improvement of maturity,the average price,top grade tobacco rate and orange tobacco rate of the two varieties increased first and then decreased,while the rate of variegated tobacco was on the contrary,and cm3 was the best.(2)In terms of chemical composition,the total nitrogen,protein,starch,nitrogen alkali ratio and sugar alkali ratio of the two varieties showed a gradual downward trend,reducing sugar,total sugar,potassium and petroleum ether extracts showed a first upward and then downward trend,nicotine showed an upward trend,and cm3 had the best chemical composition and coordination,which met the requirements of highquality tobacco.(3)In terms of suction quality,there was little difference between the four treatments of the two varieties,and cm3 was the best.The total cm3 score of Yunyan116 was 0.2-0.3 higher than that of other treatments,and the total cm3 score of Yunyan105 was 0.1-0.3 higher than that of other treatments.Through the comprehensive analysis of the quality of flue-cured tobacco leaves treated with different maturity of the two varieties(grade quality of flue-cured tobacco leaves,chemical composition of flue-cured tobacco leaves and smoking quality of fluecured tobacco leaves)and combined with the appearance maturity characteristics in the process of tobacco leaf maturity,the middle leaf collection standards of Yunyan 105 and Yunyan 116 in banliangshan tobacco area of Weining can be summarized.5.Collection standard of middle leaves of Yunyan 105 and Yunyan 116 in banliangshan tobacco area of WeiningHarvest standard of Yunyan 116: tobacco leaves have more yellowing(more yellow and less green),the comprehensive yellowing degree is about 70%,the SPAD value is about 19,the main vein turns white by about 2 / 3,the branch vein turns white by 2 / 3,the thicker leaves have a small amount of mature spots,the leaf tip is slightly withered and hooked down,and the leaf margin is bent inward.Collection standard of Yunyan 105: refer to Yunyan 116,but it is worth noting that Yunyan 105 turns yellow slowly and matures late.On the whole,the changes of appearance characteristics and main physiological and biochemical indexes of Yunyan 116 and Yunyan 105 after topping are basically the same,but the change rate and range are different.Compared with Yunyan 116,the SPAD value of Yunyan 105 decreased slowly and the degradation of plastid pigment was slow;The intensity of enzyme activity and the peak time of rise or fall,the peak time of decline of nitrogen metabolism and carbon metabolism will be later,and the rising rate and amplitude of C / N will be slower.Therefore,in general,the yellowing speed and maturity speed of Yunyan 105 are later than that of Yunyan 116.From the point of view of improving the quality of tobacco leaves,the harvesting standard of the two varieties of tobacco leaves is that the leaves fall yellow more(yellow more and green less),the comprehensive yellowing degree is about 70%,the SPAD value is about19-20,the main vein turns white about 2/3,the branch vein turns white 2/3,the thicker leaves have a small number of mature spots,the leaf tips are slightly withered and hooked down,and the leaf edges are inward curved. |
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