Variety Trait Evolution Approval and Comprehensive Analysis of Common Maize in Inner Mongolia Autonomous Region from 2002 to 2021

In order to better understand the evolution of maize varieties and utilization of backbone inbred lines in Inner Mongolia Autonomous Region, nine agronomic traits of 821 common maize varieties from 2002 to 2021 in Inner Mongolia were collected and analyzed. The results showed that the breeding institutions of new maize varieties in Inner Mongolia Autonomous Region mainly came from four directions, which were scientific research institutes, enterprises, individuals and cooperative breeding, among which the varieties directly bred by enterprises were the most, accounting for 78.81% of all varieties. The backbone inbred lines were from a wide range of sources, including the inbred lines Chang 7-2, K 12 and Ji 853 derived from Huangzao Ⅳ belonging to the Tangsiping head group, K 10 from Ried group and Mo 17 from Lancaster group, etc. The variation coefficients of agronomic traits of maize varieties approved in Inner Mongolia Autonomous Region ranged from 2.49 to 16.74 in the past 20 years, among which the higher variation coefficients were ear position, plant height, yield and 100-grain weight, indicating that these traits changed the most during trait succession. There was strong correlation among the agronomic characters of maize. The average yield and plant height of the Approval varieties were increasing, and the agronomic traits such as 100-grain weight, ear length, ear diameter, ear rows, ear grains, ear position and seed rate of the early maturing varieties were decreasing, except that the ear position height of the early maturing varieties was decreasing first and then increasing. Thirteen maize varieties with excellent comprehensive characters were screened by principal component analysis and DTOPSIS, which could be further improved to participate in the breeding of new maize varieties. The evolution trend of agronomic traits of maize varieties approval by the Inner Mongolia Autonomous Region was in line with the increase of planting density and caused change of the corn plant biomass decline, it was necessary to pay attention to take the interaction among traits into account when improving tolerance to density of maize varieties in the process of breeding so as to cultivate new maize varieties with density tolerance, high yield, high quality and adaptability to mechanization.