Objective To systematically evaluate the genetic diversity of medium indica rice germplasm resources, and enhance the scientificity and efficiency of parental selection and utilization in medium indica rice breeding.

Method A total of 35 medium indica rice germplasm resources were analyzed, and 14 key phenotypic traits were systematically evaluated using statistical methods of coefficient of variation, genetic diversity index, principal component analysis, two-dimensional ordination analysis, and stepwise regression analysis.

Result The coefficients of variation for the 14 traits ranged from 9.31% to 78.39%, with genetic diversity indices ranging from 4.82 to 5.12. The resources ‘Beitiandao’ ‘Zaohuaqiu’ ‘Wukexiang’ and ‘Shiyueqing’ clustered closely in two-dimensional sorting diagram, suggesting their potential as breeding parents or intermediate materials. ‘Wukexiang’ ranked the first in overall trait performance. Stepwise regression analysis identified the six key traits, including plant height, flag leaf length, falling grains per panicle, shriveled grains per panicle, 1000-grain weight, and grain width, as the critical indicators for comprehensively evaluating medium indica rice germplasm. Hierarchical cluster analysis based on the square sum of deviations method grouped the 35 accessions into three distinct clusters with obvious differences in trait performance among clusters.

Conclusion The studied medium indica rice germplasm exhibits a high level of phenotypic genetic diversity. These findings provide a theoretical basis and valuable materials for the identification of elite resources and rational parental combinations of new medium indica rice, and offer an important support for the development of new medium indica rice cultivars.