Abstract
Background: Alfalfa overwintering ability is a key limiting factor for its stable yield and large-scale popularization in cold regions. Root and crown traits are critical to alfalfa’s cold resistance and productivity. Methods: 25 alfalfa cultivars with different fall dormancy grades planted in the Tumote region of Inner Mongolia were selected as materials; plant height, aboveground biomass, root and crown characteristics in the establishment year and overwintering rate in the next year were measured to explore the relationship between root traits and overwintering rate of alfalfa in the establishment year and select suitable alfalfa varieties for the Tumote region. Result: Significant differences were observed among alfalfa varieties in aboveground growth, root and crown traits and subsequent overwintering rates. Correlation analysis revealed that crown burial depth and crown diameter were closely associated with overwintering survival. In contrast, taproot diameter and lateral root characteristics primarily influenced aboveground biomass production rather than directly determining winter survival. Based on the subordinate function comprehensive evaluation, WL298, Algonquin and Bara416 attained the highest scores, indicating robust root development and strong overwintering potential. This study clarifies the differentiated cold-resistance functions of crown and root traits; crown traits can serve as useful indicators for evaluating cold resistance. It proposes targeted variety promotion for the Tumote area of Inner Mongolia and provides germplasm resources for breeding cold-resistant, high-yield alfalfa varieties in similar cold northern regions.