Study On Selection Of New Flue-cured Tobacco Varieties And Optimum Nitrogen Application Rate In Wumeng Tobacco Growing Area

The differences of biological characteristics and yield and quality of twelve flue-cured tobacco varieties were analyzed by field experiment,and the suitable nitrogen application rate of three good varieties was studied,in order to provide theoretical basis for the production of flue-cured tobacco in Wumeng tobacco growing areas.The results showed that: 1、The screening test of new flue-cured tobacco varieties in Wumeng tobacco growing areasThe comprehensive agronomic traits of Yunyan 97,Yunyan 105,Jiucaiping 2 and Bina 1 in dome stage were better compared to other varieties;the comprehensive agronomic traits of Yunyan 98 and Yunyan 99 were similar to those of the control variety Yunyan 87;the plants of Yunyan 203 was relatively lower,the other agronomic traits of them were the same as those of the control variety;the comprehensive agronomic traits,field uniformity and growth of K326 were relatively worse.The comprehensive disease resistance of Yunyan 100 and Yunyan 105 was strong,while those of Yunyan 97,K326 and Bina 1 was poor.From the view of economic traits,the comprehensive economic characters of Yunyan 99,Yunyan 105 and Yunyan 203 were ideal,especially Yunyan 105,and the K326 showed the worst.From the view of chemical composition and coordination capacity,Yunyan 99,Yunyan 105 and Yunyan 203 performed relatively better,and Yunyan 105 was the best.The appearance quality of Yunyan 98,Yunyan 99,Yunyan 100,Yunyan 105 and Yunyan 203 were better than the control variety;the appearance quality of Yunyan 97 was the same as that of the control variety and the others variety were worse especially Yunyan 110.The sensory quality of Yunyan 97,Yunyan 99,Yunyan 105,Yunyan 203 and Jiucaiping 2 was better than that of the control variety Yunyan 87,and the sensory quality of K326 was similar to the control variety.The sensory evaluation scores of Yunyan 98,Yunyan 100,Yunyan 110,Yunyan 205 and Bina 1 were lower than the control variety,while Yunyan 98 was the worst.The results showed that Yunyan 99,Yunyan 105 and Yunyan 203 were the best in all the tested varieties: field growth was excellent,the comprehensive disease resistance was strong,the chemical composition was coordinated,and the appearance qualities were good,and had higher sensory quality evaluation scores,suitable for planting in Wuneng tobacco growing area.2、Study on appropriate nitrogen application rate of new flue-cured tobacco varieties in Wumeng tobacco growing areaWith the increase of nitrogen application rate,the plant height,leaf length and width,leaf number and stem increased and reached the maximum value at the highest nitrogen level,as the variation of the three cultivars was the same.Yunyan 105 had the best performance.The mainly dry matter accumulation period of tobacco plant and organs was 45-60 d,in which the accumulation amount accounted for about half of the whole of integral growth period.With the increase of nitrogen application rate,the total amount of dry matter accumulation and the accumulation of dry weight of roots,stems and leaves increased,and the maximum dry matter accumulation of 3 varieties in high nitrogen levels.The dry matter distribution of plants was expressed as: leaf > stem > root in each organ.With the delay of growth period,the proportion of dry weight of leaf of total dry matter decreased,while the proportion of dry weight of stem and root increased.The varieties among different cultivars was the same and showed as Yunyan 105 > Yunyang 203 > Yunyan 99.As the increase of agronomic traits and the dry matter accumulation,the yield,the average price and the proportion of upper tobacco leaves showed a trend of increasing first and then decreasing,and had a large value at medium nitrogen level that Yunyan 99,Yunyan 105 and Yunyan 203 reached 37023.45 yuan/hm2,55764.82 yuan/hm2 and 48511.51 yuan/hm2.The output value and average price of Yunyan 105 was the highest,as Yunyan 203 were the second but the average price was equal to that of Yunyan 99.With the increase of nitrogen application rate,the potassium-chlorine ratios of the three cultivars increased first and then decreased,the sugar-nicotine ratios decreased first and then increased,near 1 at medium nitrogen level which showed that they had coordinate chemical composition at that leval.The chemical constituents of yunyan 105 were relatively more coordinated.The contents of carotenoids,phenylalanine degradation,cyproterone,neophytadiene and total aroma in the middle leaves of all cultivars increased first and then decreased with the increase of nitrogen application rate,but the content of the product of blowning reaction increased,and the total amount of fragrant substances of Yunyan 105 was the highest among the three cultivars.The results of sensory quality evaluation showed that the indexes of Yunyan 99,Yunyan 105 and Yunyan 203 were better at medium nitrogen level than those at low nitrogen and high nitrogen,especially in quality of aroma,volume of aroma,gray and flammability.Therefore,under the ecological conditions of Wumeng tobacco growing area,Yunyan 99,Yunyan 105 and Yunyan 203 reached the requirement of high quality flue-cured tobacco at the medium nitrogen level 82.5kg/hm2,at which tobaccos had high economic benefit and aroma content,coordinated chemical composition,good sensory quality evaluation and economic traits,especially Yunyan 105.