Effects Of Planting Density And Nitrogen Application Rate On Population Physiological Characteristics Of Flue-cured Tobacco

Flue-cured tobacco is one of the important economic crops in China,which formation of yield and quality is not only depends on individual growth situation,and close relationship with population development status.Establish a reasonable population structure can guarantee the full growth of individual tobacco plants and the good development of tobacco groups,modify the light distribution in canopy of tobacco,improve the photosynthesis of tobacco canopy.These are the basis of taking High-quality and proper yield tobacco leaves,while the planting density and nitrogen application are important factors in regulating individual growth and population development.In order to research the individual growth characteristics,population development trend,canopy light transmittance,canopy photosynthetic rate and the relationship with tobacco production and quality,this experiment using “K326” as the material,set 3 planting density(D1:16529 strain D2:18182 strain /hm2;/hm2;D3:20202 /hm2 strain)and 3 levels of nitrogen(N1:75.0 kg N/hm2;N2:97.5 kg N/hm2;N3:120.5 kg N/hm2)level to create different population structure mode in Kaiyang County of Guizhou Province.Establishing an appropriate index system of individual development and population structure on this basis,in order to provide theoretical and the technical to enhance quality and yield of flue-cured tobacco.The main research results: 1.The effect of planting density and nitrogen application rate on the agricultural characteristics of flue-cured tobaccoThe effect of nitrogen application on flue-cured tobacco agronomic characteristics plays a main role.The tobacco plant height,stem girth and leaf length of each part are added in different degrees with the increase of nitrogen application levels.And the planting density played a secondary role,the impact of planting density on flue-cured tobacco agronomic characteristics mainly presented that stem girth increase and leaf width decreases with the increase of planting density.Rational closely planting and increasing nitrogen application rate can improve the agronomic characteristics of flue-cured tobacco.2.The effect of planting density and nitrogen application rate on physiological characteristics of flue-cured tobacco populationThe physiological characteristics of tobacco are affected by planting densities and nitrogen application,which planting density plays a major role.Increasing the planting density level can increase the leaf area index(LAI),reduce the canopy light transmittance(LT)and the distance between leaf tips(DLT).Leaf area duration(LAD)and canopy photosynthetic rate(RCP)were significantly increased while the canopy leaf source capacity(CLSC)increased first and then decreased.Integrated three periods,Comparing factors at different levels.In the course of tobacco canopy development,leaf area index(LAI)was highest,but distance between leaf tips of adjacent lines(DLT)and light transmittance(LT)were lowest at round top stage.Afterwards,LAI decreased,DLT and LT increased because leaves were harvested.Accordingly,canopy photosynthetic rate(RCP)was highest at round top stage.The expression of LAI in all growth stages was D3> D2> D1,N3> N2> N1.LAI increased with the increase of planting density and nitrogen application rate,but the difference between D3 and D2,N3 and N2 treatment did not reach significant level.Additionally,leaf area duration(LAD)of D2,N2 treatment was largest during two periods,from round top stage to lower leaves harvest and from lower leaves harvest to middle leaves harvest.During the three growth stages,DLT and LT showed D3,N3 levels were significantly lower than N1 and N2 levels.The performance trend of RCP is D2> D3> D1,N3> N2> N1.There was no significant difference between the levels of D2 and D3,and the difference of nitrogen application rate was significant.Canopy leaf source capacity(CLSC)of D2,N3 treatment was the highest in different developmental stages.3.The relationship between physiological characteristics of flue-cured tobacco populationLAI was positively correlated with RCP,and negatively correlated with DLT and LT: within a certain range,RCP increased significantly as LAI increased,while DLT and LT decreased.DLT was significantly positively correlated with LT,which was significantly negatively correlated with RCP: within a certain range,as DLT increased,LT increased and RCP decreased.LAI increased leads to a decrease in DLT and LT,indicating that excessive LAI can lead to field canal shedding,which may decrease the photosynthetic capacity of the population due to deterioration of canopy micro environment.Therefore,through measures can make LAI and group size suitable coordinated development,so as to conducive to group production.Comprehensive physiological traits and mutual relations between the various groups,the results showed that D2N2 and D2N3 were the most excellent in the physiologic characters.4.The effect of planting densities and nitrogen application rate on flue-cured tobacco yield and quality traitsPlanting densities and nitrogen application rate has a significant effect on tobacco yield and quality.Enhance the level of planting density,lead to the weight per leaf decline,and the yield,output value,first-class tobacco proportion increased first and then decreased;Increasing nitrogen application rate can increase weight per leaf,and the yield,output value increased first and then decreased,the first-class tobacco proportion decreased.Increasing planting density,can rise the cntent of total sugar,reducing sugar and sugar alkali ratio,while decreased the nicotine and total nitrogen content;Increasing N application rate can lower sugar content and sugar alkali,while increased nicotine and total nitrogen content.From the chemical composition in terms of coordination,taking the group of a moderate density(D2)of 18182 plants/hm2 and medium nitrogen application rate(N2)of 97.5 kg N/hm2 fared best.