Effects Of Nitrogen Application And Planting Density On Carbon Assimilation And Nitrogen Distribution Of Flue-cured Tobacco

In this experiment,in Xiangyun County of Dali,Yunnan Province,flue-cured tobacco variety YUANYAN 87 was used as experimental materials.Randomized block experiment which planting density as factor one,nitrogen as factor two,set different planting densities and N application levels were carried out.¹³C labeling method was used to study characteristics of flue-cured tobacco leaf carbon assimilation and distribution of photosynthate transportation law.By ¹⁵N tracer technique,flue-cured tobacco was studied on utilization of nitrogen in its body after the absorption of nitrogen distribution.In order to provide theoretical basis and technical reference for rational fertilization and high quality production.The main results were as follows:1.¹³C assimilation on different parts and different areas of leafThe middle leaf of flue-cured tobacco has the strongest assimilation ability in round top stage,followed by the upper leaves and lower leaves.Compared to different areas on the same leaf,the central area of the high carbon assimilation ability,followed by the lower area,the tip area is the lowest.Combining to the experiment of actual production,generally,the Middle leaves of one single flue-cured tobacco plant have better quality and the middle area of one single leaf has the better quality,this data shows that the high quality tobacco leaves are related to its carbon assimilation ability and photosynthate adequate supplies.2.The effects of planting density on ¹³C assimilative capacityThe influence of assimilation product distribution Planting density of carbon assimilation ability has a significant effect.when the density reaches D3?20190 plants/hm²?,leaf of ¹³C assimilative capacity significantly reduced,the distribution of assimilation product to different parts of tobacco plant decreased.The results manifest the planting density is beneficial to the increase of capability of carbon assimilation of leaves.The upper leaves and the middle leaves and the lower leaves,which carbon assimilation products in addition to the stalk and root,mainly allocated to the corresponding feeding leaves.This suggests that the substancial foundation of tobacco yield and quality,mainly associated with the assimilation of leaf growth period.Under this experimental condition,the flue-cured tobacco planting density in D2 levels?about 18180 plants/hm²?is more appropriate.3.Applied amount of nitrogen fertilizer on ¹33 C assimilative capacity of the leaves and the influence of assimilation product distributionNitrogen application rate of carbon assimilation capacity of the different parts of the leaf has significantly effect.Experiment shows that appropriate nitrogen application rate can enhance the carbon assimilation ability of leaves.Nitrogen application rate of 75 kg/hm²¹20 kg/hm²,the following three parts,which carbon assimilation product distribute to the nearest leaves and roots and stalks in corresponding;Improve applying nitrogen fertilizer content,will help to promote the transportation and distribution of the upper leaf photosynthate to roots and stalks.Therefore,in order to further promote blade carbon assimilation ability,coordination of assimilation product transportation and distribution,the production practice should adopt appropriate fertilizer levels,under the condition of this experiment,flue-cured tobacco adopt N2 nitrogen level?97.5 kg/hm²?is more appropriate.4.The absorption of ¹⁵N by tobacco plant and the regulating effect of the densityThe comparison of total nitrogen content of different areas on same leaf shows the result that central area>lower area>tip area,Each part nitrogen absorption proportion Ndff?%?shows the result that lower leaf>middle leaf>stem>upper leaf>root.The percentage of ¹⁵N in different part of tobacco plants account for the total absorption of the ¹⁵N was determined.In the round top stage,the nitrogen absorption percentage Ndff?%?of each part shows the result:lower leaves>middle leaves>stalks>upper leaves>roots;after the the harvest of primings,shows the result:middle leaves>upper leaves>stalks>roots;after the harvest of middle leaves,shows the result:upper leaves>stalks>roots.thus it can be seen,the nitrogen from fertilizer which are absorbed by tobacco plants are mainly distributed to leaves,which are used for their growth.Different planting density affect the ¹⁵N uptake of tobacco plant.From the total nitrogen content of different parts of tobacco plant,each part Ndff?%?along with the increase of planting density and present the significantly increasing trend,in D2 level?18180plants/hm²?planting density,the nitrogen absorption and accumulation of tobacco plant has the significantly advantages,especially in the later stage of growth,each part of tobacco in the D2 level,Ndff?%?is significantly higher than D1 level?16530 plants/hm²?and D3level?20190 plants/hm²?,after the harvesting of primings,the nitrogen absorption from fertilizer of plants is still mainly used for the growth of leaves,especially the growth of middle leaves.Different planting density effect the utilization efficiency of nitrogen fertilizer of the tobacco plants.In the round top stage,nitrogen utilization efficiency is the highest in D2density level,followed by D3?20190 plants/hm²?and D1?16530 plants/hm²?.In mature early period?after the harvest of priming leaves?and the mature interim period?after the harvest of middle leaves?,along with the increase of planting density,the utilization of nitrogen of tobacco plant has a tendency to increase.Above all,in order to enhance the tobacco plants carbon assimilation ability,coordination of assimilation product distribution,under this experimental condition,enhance the nitrogen absorbing ability of tobacco plant,plant density in D2 levels?18180 plants/hm²?,nitrogen levels with N2?97.5 kg/hm²?as appropriate.