| Cigar is a unique cigarette product.In recent years,the domestic consumption has grown rapidly and there is a huge potential market.However,because of the late start of cigar research in China,cigar products and high-quality tobacco raw materials mainly rely on imports.At present,the main problems of cigar development in China include:lack of high-quality germplasm resources,immature field production technology,relatively backward late-stage modulation technology and equipment.Therefore,based on the climate characteristics and production status of Enshi tobacco-producing area in Hubei Province,this paper studied and compared the adaptability of different cigar varieties by using field plot experiment and field character investigation,as well as stress resistance reaction,conventional chemical composition and untargeted metabolomics.And the effects of different rates of nitrogen fertilizer,different rates of organic fertilizer and its ratio,number of top dressing and shading on the growth and quality physiology of cigar.The results provide suggestions for fertilization and cultivation of cigar in experimental tobacco area.The main results obtained are as follows:1 Comparison of adaptability of different cigar varietiesThe adaptability of cigar varieties CX-007,CX-010 and CX-012 in Enshi tobacco-growing area of Hubei province was compared.It was found that there were no significant differences in chemical composition among the three varieties,among which nitrogen(N)concentration,N to Alkali ratio and K to Cl ratio were moderate.In terms of agronomic traits,CX-012 had higher SPAD,and its leaf length was 11%and 9%longer than CX-007 and CX-010,and its leaf width was 10%and 4%wider than CX-007 and CX-010,respectively.In terms of stress resistance index,the soluble sugar concentration of CX-012 is 87%and 78%higher than CX-007 and CX-10,and the soluble protein concentration is 52%and 31%higher than CX-007 and CX-10,indicating that CX-012 has better resistance to stress.Therefore,the adaptability of CX-012 was better than that of CX-010 and CX-007 in Enshi tobacco-growing area.2 Effects of N application rates on growth and metabolism of cigar tobaccoWith the increase of N application rate,dry matter accumulation of tobacco leaf increased,and leaf dry weight of 112.5,150.0 and 187.5 kg/hm~2 treatments increased by 12%,21%and 52%compared with 75.0 kg/hm~2 treatments,respectively.In the mature stage and curing stage,the nutritional quality of tobacco leaves treated with different N rates was similar.The results showed that N application rate of 187.5 kg/hm~2could increase the N concentration and dry matter weight of tobacco leaves,and K concentration,N to Alkali ratio,total sugar and amino acid concentrations were appropriate.Therefore,187.5 kg/hm~2 could be considered as an appropriate N application rate in Enshi tobacco-growing area.Further untargeted metabolomics technique was used to detect 1899 kinds of differential metabolites,which were mainly concentrated in Biosynthesis of other secondary metabolites and Amino acid metabolism.At the same time,six key metabolites including Phenylalanine,Phosphoserine,Glutamate,Oxoproline,Succinylhomoserine and Homoserine were identified,and the main metabolic pathways around the TCA cycle were established.3 Effects of organic fertilizer on growth and quality physiology of cigar tobaccoSet 750,1500,2250,3000 kg/hm~2 of organic fertilizer application rates treatment,analyze the effect on cigar tobacco.The results showed that the Cl content of 1500 kg/hm~2 treatment was significantly lower than that of other treatments during drying period,which was 11%,29%and45%lower than that of other treatments.Therefore,the application of 1500 kg/hm~2 of organic fertilizer can improve the regulation of tobacco chemical composition,and the appropriate rate of organic fertilizer should be selected according to specific environmental factors in actual production.By controlling the total application rate of organic fertilizer,two kinds of organic fertilizer and their ratio were studied:100%cake fertilizer,75%cake fertilizer+25%fishbone fertilizer,50%cake fertilizer+50%fishbone fertilizer,25%cake fertilizer+75%fishbone fertilizer,100%fishbone fertilizer.The results showed that the plant height,stem circumference and leaf dry matter of 100%cake fertilizer were 21%,11%and 35%higher than those of 100%fish bone fertilizer.However,the selection and proportion of organic fertilizer did not have a significant effect on cigar nutrition in different periods,which may be because the fertilizer supply capacity of organic fertilizer was not changed.In conclusion,100%cake fertilizer can accelerate the development of cigar and is more suitable for field production.4 Effects of different topdressing times on growth of cigar tobaccoIn this experiment,three treatments of fertilizer fertilization were set up:twice topdressing,once topdressing and no topdressing.The results showed that the twice topdressing treatment could improve some agronomic traits of cigar,and the MDA accumulation in the twice topdressing treatment was the lowest among the three treatments,and the MDA accumulation in the twice topdressing treatment was 10%and 15%lower than that in the once topdressing and no topdressing,respectively.At the same time,the twice topdressing can regulate the chemical composition of cigar,increase the sugar level and reduce the Cl content,and improve the chemical composition,which is beneficial to improve the quality of cigar tobacco.Therefore,it is considered that the twice topdressing is the most suitable topdressing.5 Effects of shading on photosynthesis and metabolism of cigar tobaccoWith the decrease of light transmittance,5 treatments were set:100%,90%,80%,70%and60%light transmittance.The results showed that the soluble sugar concentration and soluble protein concentration of 70%and 60%shading treatments increased by 149%and 118%,respectively,and 174%and 196%,respectively,compared with 100%light transmittance at mature stage.It was found that the accumulation of primary metabolites in 70%and 60%treatments was significantly higher than that in other treatments,which was beneficial to cigar plant growth and quality formation.Untargeted metabonomics were detected in 702 metabolites,mainly contain Flavonoids,Monolignols and Sesquiterpenoids,rich in Amino acid metabolism,Biosynthesis of other secondary metabolites and Lipid metabolism,and further screening of Chlorogenic Acid,D-Glucosaminide,D-Urobilin,Farnesylcysteine,Hydroxyatrazine,Sucrose.In a word,it was found that CX-012 has better suitability than other two varieties in the test area.The optimum N application rate for cigar tobacco was 187.5 kg N/hm~2,and 1500 kg/hm~2 of cake fertilizer was applied.The nutrient management technology of twice topdressing fertilizers had better yield and quality of cigar tobacco. |
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