Effects Of Nitrogen Application Rate On Distribution Of Carbon Assimilates And Nitrogen Uptake And Utilization Of Flue-cured Tobacco

Nitrogen absorption and utilization capacity,carbon assimilation capacity and pr oductdistribution are important factors in determining the yield and quality of flue-cur ed tobacco.In this paper,the effects of different nitrogen application rates on the carbo n assimilation capacity,the distribution of product transport and the uptake and utiliza tion of nitrogen were studied by using the stable isotope 13 C and 15 N marker technol ogy.The aim of this study was to provide a theoretical basis for rational fertilization o f flue-cured tobacco in accordance with.The main results are as follows: 1.13 C assimilation ability of various parts of flue-cured tobacco and the relationship with nitrogen application rateThe carbonization ability of the middle leaves of the flue-cured tobacco was stronger,followed by the weak ability of the upper leaves and the lower leaves.The effect of nitrogen application on the carbon assimilation ability of different parts of tobacco leaves had different effects.The upper and lower leaves showed the increase of nitrogen application rate and the increase of carbon assimilation ability,and the carbon assimilation ability of the middle leaves was the strongest.2.the relationship between 13 C assimilation ability and the amount of nitrogen a pplied in different sections of flue-cured tobacco leavesAll the leaves had the strongest ability to assimilate 13 C in the central segment,a nd the base segment assimilation capacity of the remaining leaves was higher than tha t of the tip of the leaves except the N3 treated middle leaves compared to the tip and b ase sections.In general,the 13 C assimilation ability of the same leaf region was in the order of leaf center> leaf base> leaf tip.Compared with N and N treatments,the upta ke of N3 and 13 C increased from N1 to N2 and 13 C,but decreased from N2 to N3 an d 13 C.The lower leaves have the highest ability of N3 13 C assimilation,followed by N2 and N1.3.Distribution of Carbon Assimilates in Flue-cured Tobacco and Its Relationship with Nitrogen ApplicationThe amount of nitrogen applied had significant effect on the carbon assimilation ability of leaves in different parts.The suitable nitrogen content could increase the carbon assimilation ability of the leaves.In the range of 75.0 kg / hm2 ~ 120.5 kg / hm2,the upper,middle and lower The carbon assimilation products of the leaves were distributed in the corresponding parts of the leaves and roots and stems.The increased nitrogen application had the tendency to promote the distribution of the upper leaves to the roots and the shoots.This means that the material basis of tobacco leaf production and quality is mainly derived from the assimilation of its own during the growth of tobacco leaves.Therefore,in the production practice to adopt appropriate control measures to enhance the ability of the assimilation of leaves.Under the experimental conditions,the optimum nitrogen application rate of flue-cured tobacco was about 97.5kg / hm2.4.Relationship between Nitrogen Absorption and Nitrogen Application in Flue-cured TobaccoUnder the three fertilization levels of N1,N2 and N3,the dry matter content and N uptake of flue-cured tobacco were all the roots> stem> roots,and the relationship between dry matter content and nitrogen uptake was For the middle leaves> lower leaves> upper leaves.The dry matter and nitrogen content of the leaves were the highest in the same leaf.The dry matter uptake and nitrogen content of the tobacco plant were the most significant,but the difference with N2 was not significant.5.Nitrogen Invasion of Flue-cured Tobacco and Its Relationship with Nitrogen FertilizerAt the dome stage,the Ndff(%)of each part increased with the increase of nitrog en application rate,and the difference of Ndff(%)was found under the same nitrogen application rate.N1,N2,N3 Under the nitrogen level,the leaching ability of 15 N in t he fertilizer was lower than that of the middle leaf> middle leaf> stem> upper leaf> ro ot system.The second crop of the second plant is mainly distributed in the leaves,foll owed by the stem and root.And the distribution rate of fertilizer was higher than that of N1 and N3,and the distribution of fertilizer nitrogen in the same part of different ni trogen application levels could be seen.,And the 15 N uptake of stem and root increas ed with the increase of nitrogen application rate,that is,N3> N2> N1,different parts of the fertilizer nitrogen absorption is not the same,the leaf more than a certain amou nt of nitrogen fertilizer The absorption rate will become low,the stem and root with th e increase of nitrogen application of 15 N absorption will continue to increase.The rel ationship between Ndff(%)and nitrogen application level was N2> N3> N1,but the Ndff(%)in the leaves was not significantly different The The contents of Ndff(%)w ere stem> root> upper leaves.Compared with the Ndff(%)value of three tobacco pla nts,it can be seen that the nitrogen source absorbed by the tobacco plant is mainly from the soil,not fertilizer nitrogen.15 N of the levy capacity,can be seen is a downward trend,indicating that the more backward,the proportion of tobacco absorption of ferti lizer nitrogen is smaller,the proportion of nitrogen absorption is increasing.6.the distribution of 15 N flue-cured tobacco and the relationship with the amount of nitrogenThe nitrogen fertilizers absorbed by flue-cured tobacco at various periods were leaf> stem> root,and 15 N absorbed by flue-cured tobacco was mainly concentrated in leaves.Compared with NN and N3,the distribution of nitrogen in different parts of N2 was significantly higher than that of N1 and N3,and the distribution of nitrogen in the leaves was mainly N2>N3>N1,the distribution ratio was the opposite,N3 nitrogen level in the leaves of fertilizer nitrogen distribution rate of the highest,N2 nitrogen level is the lowest.7.Utilization rate of nitrogen in flue-cured tobacco and its relationship with nit rogen application rateThe efficiency of nitrogen fertilizer utilization at different nitrogen application rates was measured respectively.The changes of nitrogen use efficiency and the utilization efficiency of nitrogen fertilizer were studied under different nitrogen application conditions.The results showed that with the maturation of tobacco plants and the harvest of tobacco leaves,the utilization rate of nitrogen fertilizer was gradually decreased.And the difference of stem and root was not significant.After the harvest of central tobacco leaves,the utilization rate of nitrogen fertilizer decreased gradually with the increase of nitrogen application level.In general,under the condition of nitrogen application,Nitrogen use rate is the highest.The results showed that the suitable nitrogen content could enhance the carbon as similation ability of the leaves,which was beneficial to the growth and dry matter acc umulation of the tobacco plants,and promoted the uptake and utilization of nitrogen f ertilizer in the tobacco plants and reduced the nitrogen loss rate to a certain extent.In t he tested nitrogen supply range(97.5kg / hm2),the carbon assimilation capacity,yield,nitrogen use efficiency and loss rate of flue-cured tobacco reached the optimum level.