Analysis Of Population Structure Characteristics And Photosynthetic Physiological Characterstics Of Tobacco Based On Effect Of Nitrogen

This study was based on the ecological environment in Luoyang tobacco growing area of Henan Province,from the regulation of the growth and quality of flue-cured tobacco in Luoyang.The experiments were conducted with three flue-cured tobacco cultivars(QIN96,YU12 and YUN87)and the flue-cured tobacco groups in different nitrogen levels was constructed.The indexes of leaf area index,active accumulated temperature,photosynthetic active radiation,single leaf weight,leaf weight,photosynthetic pigments,chloroplast fluorescence parameters,and gas exchange parameters of leaves were measured.The dynamic change characteristics of leaf area index,vertical distribution characteristics of flue-cured tobacco leaves and Photosynthetic Physiological Characteristics of flue cured tobacco population were studied.The results showed that:1.The dynamic change characteristics of leaf area index of flue-cured tobacco population were analyzed,the results showed that: There was a unimodal curve between leaf area index and the accumulated temperature after transplanting for the flue-cured tobacco,with skewness less than 0.The leaf area index increased with increasing nitrogen levels,and the peak value of leaf area index was in the order of QIN96>YUN97>YU12 at same nitrogen level.Based on Curve Expert 1.40 software and limit method,the normalized accumulated temperature model was established.The Ration model y =(a+bx)/(1+cx+dx2)had a good simulation on results and would be used significantly in biological applications,the parameters of the simulated equation are a=0.0201,b=0.2785,c=3.3122,d=3.3019,the precision(R2)was 0.9807**;The accuracy and precision of the normalized model were tested with the data of 2015,the simulation accuracy(k)was all above 0.958,the precision(R2)was all above 0.95 and the RMSE was below 6.04%.The parameter a represents the leaf area index of flue-cured tobacco when transplanted,and its influence on the model is minimal,there are certain differences in parameters b,c and d between different varieties and nitrogen application rates.The relative leaf area index of different treatments showed a "N" change.The secondary parameters such as the average leaf area index,the maximum leaf area index,the average crop growth rate and the average net assimilation rate of the flue-cured tobacco population were obtained through deep excavation and other indexes,all of which showed an increasing trend with the increase of nitrogen supply,which could be used to synthetically judge the growth and development process of the pretest flue-cured tobacco.2.The vertical distribution characteristics of tobacco leaves in flue-cured tobacco population were analyzed,the results showed that: The leaf area index(LAI)of group transfer to the upper layer with the advance of the growth stage,and the LAI was first increased and then decreased with canopy height,the regulating effects of nitrogen levels on LAI varied with canopy height and different genotype.The angle between stem and leaf increased with the increase of canopy height and nitrogen application rate,but the increase of canopy height and genotype was different;The vertical angle of stem and leaf decreased with the increase of canopy height at N1 and N2 level,but decreased with the increase of canopy height at the N3 level;The change tendency of leaf curvature and stem leaf angle was the same.When canopy height increased,the transmittance of flue-cured tobacco group showed two times curve change,and leaf nitrogen content,leaf weight and single leaf weight all showed a general increasing trend;When nitrogen supply increased,the transmittance of flue-cured tobacco population decreased,and leaf nitrogen content,leaf weight and single leaf weight increased.The light transmittance of the flue-cured tobacco population decreased exponentially with the increase of the cumulative leaf area index,and the leaf single leaf weight increased with the increase of leaf nitrogen content,and there was a linear regression relationship with the nitrogen content of leaves.The blade bending degree changed with the two polynomial curve of the single leaf weight,and the characteristics of each leaf influenced each other,and had a common effect on the vertical distribution of flue-cured tobacco.3.The photosynthetic physiological characteristics of flue cured tobacco leaves were analyzed,the results showed that: The chlorophyll content of flue-cured tobacco leaves decreased with time,and decreased from top to bottom in vertical distribution.The increase of nitrogen content would increase chlorophyll and carotenoid content and decrease the rate of chlorophyll degradation,the chlorophyll content of different varieties is QIN96 > YU12 > YUN87,which may be related to the height of tobacco plants.With the increase of canopy height,the change trend of leaf weight and chlorophyll content is consistent.The increase of chlorophyll content was beneficial to the increase of photosynthesis and the increase of the accumulation of photosynthetic products,which increased leaf area,leaf weight and single leaf weight of flue-cured tobacco,and then affected the population structure of flue-cured tobacco.The Pn and Gs of leaves of flue-cured tobacco decreased with time,while Ci and Tr showed an increasing trend.With the increase of nitrogen application,Pn showed a tendency to increase,Gs had no obvious change,Ci showed a decreasing trend,and Tr showed a slight increase in the trend.The Pn of QIN96 was the highest,while Ci and Tr was the lowest,the difference between the varieties was not significant enough.The Fv/Fm,?PSII,q P of tobacco leaves in the mature period decreased with the time,and the NPQ increased.When the amount of nitrogen increased,Fv/Fm and ?PSII showed the first increase and then decreased,and the NPQ performance was reduced first and then increased,and the q P changed a little.Fv/Fm,?PSII and q P showed QIN96 > YU12 > YUN87,while NPQ showed YUN87 > YU12 > QIN96.