The improvement of backbone maize inbred line ZH6218 by using radiation mutagenesis technology and relevant phenotypic trait variation analysis

【Objective】The improvement and phenotypic variation of the radiation progeny plants of ZH6218 inbred line of backbone maize were analyzed，the phenotypic diversity of relevant radiation progenies was analyzed. This could provide new theoretical basis for improving backbone maize inbred lines and creating superior new gene resources by using radiation mutagenesis technology.【Method】The backbone maize inbred line ZH6218，which was widely used in the southwestern region，was selected to be material in this paper. Its kernels were treated using 200 Gy dosage of ⁶⁰Co-γ rays. After that，1300 radiation progenies were obtained and relevant diversity of yield，plant architecture，and growth period related traits were analyzed. The genetic diversity of the radiation progenies was assessed by calculating the ShannonWeaver genetic diversity index（H'）.【Result】For these radiation progenies，11 phenotypic traits showed abundant diversity，with variation coefficients varied from 6.93% to 45.79%，and average value of 19.69%，wherein bract length and kernel length showed respectively the largest and smallest variations. The variation coefficient of grain length was the smallest，and except grain length and grain width，the variation coefficients other traits were greater than 10.00%. The H' value of 11 phenotypic traits ranged from 1.19 to 2.10，with an average of 1.97. Wherein，ear height and grain number per row showed the highest H' value，and ear row number showed the lowest H' value. Correlation analysis showed that， among the 11 phenotypic traits，most of the traits had extremely significant correlation（P<0.01，the same below）. There was extremely significant correlation between hundred-grain weight and plant height，blade angle，ear length，ear diameter，grain length and grain width. These radiation progenies were classified into 4 subgroups，with 3 progenies in group Ⅰ，they could be further screened as high yield germplasms；2 progenies in group Ⅱ，which had high ear height，low hundred-grain weight，poor overall traits；511 progenies in group Ⅲ，hundred-grain weight was high，the comprehensive performance was at medium level，and they had the potential of high yield；and 365 progenies in group Ⅳ，the plant height and ear height were the shortest，which could be used as the genetic resources of dwarf material for subsequent improvement. Finally，based on the comprehensive evaluation results of principal component analysis，10 excellent radiation progenies were identified.【Conclusion】The use of radiation mutagenesis technology can quickly improve the backbone inbred lines and create new gene resources. The radiation progenies have abundant variation in other traits and high genetic diversity except grain length and grain width. The selected 10 radiation progenies with excellent phenotypic traits can be used as new materials derived from ZH6218 for maize breeding research.