It is important to evaluate nitrogen use effi-ciency and nitrogen tolerance of trees in order to improve their productivity.In this study,both were evaluated for 338 Populus deltoides genotypes from six provenances.The plants were cultured under normal nitrogen (750 μM NH4NO3) and low nitrogen (5 μM NH4NO3) conditions for 3 months.Growth,chlorophyll content and glutamine synthetase activity of each genotype were measured.Under low nitrogen,heights,ground diameter,leaf area,leaf and root biomass,and chlorophyll contents were significantly lower than those under normal nitrogen level.Correlation analysis showed that nutrient distribution changed under dif-ferent nitrogen treatments.There was a negative correlation between leaf traits and root biomass under normal nitro-gen level,however,the correlation became positive in low nitrogen treatment.Moreover,with the decrease of nitrogen level,the negative correlation between leaf morphology and chlorophyll levels became weakened.The growth of the genotypes under the two treatments was evaluated by combining principal component analysis with a fuzzy math-ematical membership function;the results showed that leaf traits accounted for a large proportion of the variation in the evaluation model.According to the results of comprehensive evaluation of plants under the two treatments,the 338 P.deltoides genotypes could be divided into nine categories,with wide genotypic diversity in nitrogen use efficiency and low nitrogen tolerance.As a result,26 N-efficient genotypes and 24 N-inefficient genotypes were selected.By compara-tive analysis of their morphological and physiological traits under the two treatments,leaf traits could be significant indicators for nitrogen use efficiency and nitrogen tolerance,which is of considerable significance for breeding poplar varieties with high nitrogen use efficiencies.

Cun Chen;Yanguang Chu;Qinjun Huang;Changjun Ding;Weixi Zhang;Bo Li;Jing Zhang;Xiaohua Su

State Key Laboratory of Tree Genetics and Breeding,Research Institute of Forestry,Chinese Academy of Forestry,Beijing 100091,People's Republic of China;Key Laboratory of Tree Breeding and Cultivation,State Forestry and Grassland Administration,Beijing 100091,People's Republic of China;Co-Innovation Center for Sustainable Forestry in Southern China,Nanjing Forestry University,Nanjing 210037,People's Republic of China

林业研究（英文版）

[1]Cun Chen;Yanguang Chu;Qinjun Huang;Changjun Ding;Weixi Zhang;Bo Li;Jing Zhang;Xiaohua Su-.Morphological and physiological plasticity response to low nitrogen stress in black cottonwood (Populus deltoides Marsh.))[J].林业研究（英文版）,2022(01):51-62

cottonwood,provenances

Morphological,physiological,plasticity,response,nitrogen,stress,black,Populus,deltoides,Marsh,It,important,use,tolerance,trees,order,improve,their,productivity,In,this,study,both,were,evaluated,genotypes,from,six,plants,cultured,under,normal,NH4NO3,conditions,months,Growth,chlorophyll,glutamine,synthetase,activity,each,measured,Under,heights,ground,diameter,leaf,area,root,biomass,contents,significantly,lower,than,those,Correlation,analysis,showed,that,nutrient,distribution,changed,dif,ferent,treatments,There,was,negative,correlation,between,traits,however,became,positive,Moreover,decrease,morphology,levels,weakened,growth,two,by,combining,principal,component,fuzzy,math,ematical,membership,function,results,accounted,large,proportion,variation,evaluation,model,According,comprehensive,could,divided,into,nine,categories,wide,genotypic,diversity,efficiency,inefficient,selected,By,compara,morphological,indicators,which,considerable,significance,breeding,poplar,varieties,high,efficiencies

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