Effects Of Transplanting Period On Carbon And Nitrogen Metabolism Of Yunyan 87 And Sweetness Of Flue-cured Tobacco Leave

In order to explore the effects of transplanting period on carbon and nitrogen metabolism,sweetness and other sensory quality of flue-cured tobacco leaves,this study used Yunyan 87 as the experimental material,using a randomized block design,and conducted a field experiment in Weining County,Bijie City,Guizhou Province from 2022 to 2023.The effects of transplanting period on the field growth and economic characteristics of flue-cured tobacco,carbon and nitrogen metabolites,their key enzyme activities,and gene expression during field period,sweet and moist sensation of flue-cured tobacco leaves,and other sensory qualities were studied at four levels: April 10 th,April 20 th,April 30 th,and May 10 th.The effects of carbon and nitrogen metabolites on sweet and moist sensation of flue-cured tobacco leaves were analyzed.The main conclusions are as follows:1.Effects of Transplantation Period on Field Growth and Economic Characters of Flue-cured TobaccoGrowth process: The transplanting period has a significant impact on the growth process of flue-cured tobacco in the field.The time required for the earlier transplanting treatment to reach the cluster stage is shorter(about 30 days),while the time required for the later transplanting treatment to reach the cluster stage is relatively longer(35-38 days).The time required for the cluster stage to bud emergence decreases with the delay of the transplanting period;From the perspective of the field growth period,with the postponement of the transplanting period,the time required for the field growth period of flue-cured tobacco gradually shortened.Agronomic traits: The main agronomic traits of tobacco plants from the seedling stage to the bud stage were generally better under the treatment of late transplanting.Economic traits: Properly delaying the transplanting period is beneficial to the optimization of economic traits of flue-cured tobacco in Weining tobacco region.The highest yield and output value of tobacco leaves were obtained by transplanting on April 30 th,but the effect of transplanting period on the rate of top and medium tobacco was not significant.2.Effects of Transplantation Period on Carbon and Nitrogen Metabolism of Flue-cured Tobacco in Field StageCarbon metabolism: From the perspective of the accumulation of main products of carbon metabolism during the field stage,early transplanting treatment is beneficial to the accumulation of total sugar and reducing sugar in the lower leaves of the tobacco plant before budding,and is beneficial to the accumulation of total sugar in the upper leaves after flourishing;The treatment of late transplanting was beneficial to the accumulation of starch in the middle and lower leaves before the tobacco plant flourished,and the accumulation reached its maximum at the mature stage;From the perspective of key enzyme activities and enzyme gene expression in carbon metabolism during the field stage,α-The overall activity of Amylase was higher in the treatment of early transplanting;The activities of SS,INV,and SPS were generally higher in the treatment of late transplanting.The overall expression of Ntα-Amylase、NtSS gene was higher in the treatment of early transplanting.Nitrogen metabolism: From the perspective of the accumulation of nitrogen metabolites during the field stage,the treatment of late transplanting is beneficial to the accumulation of nicotine and total nitrogen during the flourishing period of the middle leaves,but not conducive to the accumulation of total nitrogen and protein during the flourishing period.With the advancement of the growth process,the nicotine content of each transplant period treatment showed a slow increase trend,while the total nitrogen and protein content showed a downward trend.From the perspective of the activities of key enzymes in nitrogen metabolism and the expression of enzyme genes during the field stage,the activities of NR,Ni R,and GS were higher in the early transplanting treatments at various growth stages,but the activities of GOGAT were only higher before the flourishing period;The expression levels of NtNR and NtGS were generally higher in earlier transplanting treatments.3.Effects of transplanting period on chemical components of flue-cured tobacco leavesCarbonaceous compounds: Early transplanting is beneficial to the accumulation of starch,total sugar,and reducing sugar;With the postponement of the transplanting period,the total organic acid content showed a trend of increasing first and then decreasing,with the highest content of the transplanting treatment on April 30 th.Nitrogen compounds and inorganic ions: There was no significant difference in the main nitrogen compounds,potassium,and chlorine content among the treatments at each transplanting stage,with the total nitrogen,nicotine,and protein content generally higher,while the potassium and chlorine content lower.4.Effects of transplanting period on sweetness and other sensory qualities of cured tobacco leavesSweet and moist sense: the transplanting period had no significant effect on sweet and moist sense of lower leaves,but earlier transplanting was beneficial to show sweet and moist sense of middle and upper leaves.After flue-cured,the middle and upper leaves were transplanted on April 20 th and April 10 th,with the best scores of 6.3 and 5.8,respectively.Other sensory qualities: From the perspective of the lower leaves,the transplanting period had no significant impact on other sensory qualities of the lower leaves;From the perspective of the middle leaves,the middle leaves of the earlier transplanting treatment had better fineness and clustering,and the evaluation results showed moderate concentration,moderate strength,slightly fine smoke,and good clustering;From the perspective of upper leaves,the upper leaves treated with earlier transplanting had better aroma quality,aroma amount,and hair permeability.The evaluation results showed that the aroma quality was slightly better,the aroma amount was still sufficient,and the smoke was slightly transparent.The aroma quality,concentration,strength,fineness,and clustering of different transplant treatments were generally better in the middle leaves,while the aroma content and hair permeability were generally better in the upper leaves.5.Effects of Carbon and Nitrogen Metabolites on Sweetness of Post-cured Tobacco LeavesAfter flue-cured tobacco leaves,carbon and nitrogen metabolites and sugar base coordination had a significant impact on the formation of sweetness.Sweetness was significantly positively correlated with the content of reducing sugar,total nitrogen,nicotine,protein,etc.,while it was significantly negatively correlated with total organic acid content,sugar base ratio,and nitrogen base ratio.According to the multiple stepwise regression analysis results of carbon and nitrogen metabolites and sweetness sensation in flue-cured tobacco leaves,reducing sugar,nicotine,and protein are the main substances that affect the formation of sweetness sensation,with the degree of influence being nicotine>protein>reducing sugar.From the correlation between other sensory qualities and sweetness of cured tobacco leaves and the results of multiple stepwise regression analysis,it can be seen that the aroma characteristics,smoke characteristics,and taste characteristics of sensory qualities are significantly positively correlated with sweetness,while the transparency of aroma characteristics,and the fineness of smoke characteristics are closely related to sweetness;From the results of multiple stepwise regression analysis of carbon and nitrogen metabolites,fineness,and permeability of flue-cured tobacco leaves,it can be seen that the content of total nitrogen and reducing sugar is the main factor affecting the fineness of tobacco leaves,while the content of nicotine and reducing sugar is the main factor affecting the permeability of tobacco leaves.