春小麦耐低氮种质资源的筛选与综合评价OA

[Objective]Excessive dependence on nitrogen(N)fertilizer to achieve high crop yields in modern agricultural production has increased production costs and caused serious environmental problems,such as soil acidification and water eutrophication.Screening low-nitrogen-tolerant wheat cultivars is a key approach to improving nitrogen use efficiency and significantly reducing nitrogen fertilizer input.This study aimed to elucidate the low-nitrogen tolerance characteristics of spring wheat,provide germplasm resources,and establish a theoretical basis for gene mining and breeding of low-nitrogen-tolerant wheat varieties.[Method]A total of 285 spring wheat accessions were used as experimental materials.Seedling-stage germination bag experiments were conducted under low nitrogen(0.05 mmol·L-1)and normal nitrogen(5 mmol·L-1)treatments.Nine traits,including seedling length,root length,shoot dry weight,and root dry weight,were measured,and the low-nitrogen tolerance coefficient for each trait was calculated.A comprehensive evaluation of seedling-stage low-nitrogen tolerance was performed using principal component analysis and the membership function method.Selected materials were further subjected to precise field screening and identification.Representative low-nitrogen-tolerant and nitrogen-sensitive materials were used to analyze changes in nitrogen uptake,assimilation,and transport-related enzyme activities under low-nitrogen stress,as well as grain quality traits.[Result]Based on comprehensive evaluation using principal component analysis and the membership function method,the 285 spring wheat accessions were classified into five groups.Group Ⅰ consisted of extremely nitrogen-sensitive materials(5 accessions)with D values ranging from 0.14 to 0.20,including WN-269,WN-247,WN-244,WN-149,and WN-249.Group Ⅱ included nitrogen-sensitive materials(84 accessions)with D values of 0.20 to 0.34.Group Ⅲ comprised moderately nitrogen-efficient materials(162 accessions)with D values of 0.34 to 0.51.Group Ⅳ consisted of low-nitrogen-tolerant materials(29 accessions)with D values of 0.51 to 0.61.Group Ⅴ included extremely low-nitrogen-tolerant materials(5 accessions)with D values of 0.61 to 0.70,namely WN-49,WN-186,WN-237,WN-294,and WN-235.Five extremely nitrogen-sensitive and five extremely low-nitrogen-tolerant accessions were selected for field identification,resulting in the final identification of one nitrogen-sensitive accession(WN-269)and one low-nitrogen-tolerant accession(WN-235).Analysis of nitrate reductase,glutamate synthase,and glutamine synthetase activities showed that enzyme activities in leaves significantly decreased under low-nitrogen stress,while enzyme activities in the low-nitrogen-tolerant material were significantly higher than those in the nitrogen-sensitive material.[Conclusion]One low-nitrogen-tolerant wheat accession and one nitrogen-sensitive accession were successfully identified.A comprehensive evaluation system for low-nitrogen tolerance at both seedling and adult stages in wheat was established,and root surface area,root volume,and root dry weight were identified as core indicators for evaluating low-nitrogen tolerance.