Seed germination is the initial stage of crop morphology, which is determined by its own properties and environmental factors. Low temperature is one of the most important factors affecting seed germination. It is crucial to explore the relationship between seed properties and germination under low temperature environmental conditions for maize production in Northeast China. In the present study, 36 maize hybrids released in Northeast China were selected and the germination culture experiment was conducted under 6℃ (low temperature stress) and 15℃ (the control). The seedling vigor, seed germination rate, seed morphology and storage substances content were determined. The germination potential and germination rate of 36 maize hybrids were evaluated by the principal component analysis (PCA), the comprehensive evaluation value of cold tolerance (CL-value), and the membership function value (R-value). The relationship between the seed morphology (kernel length, kernel width, kernel thickness, kernel length/kernel width ratio, 100-kernel volume, and 100-kernel weight) and the seed storage substances (starch, protein, and fat) of 36 maize varieties were investigated. The results showed that the seedling vigor and germination rate of 36 maize hybrids were inhibited to some content, and the variation of relative seedling vigor cold injury rate and relative germination cold injury rate was the largest under low temperature stress. There was a significant correlation among the seven individual indicators that characterized cold tolerance. Principal component analysis could transform seven individual indicators into two independent comprehensive indicators. Among them, relative seedling vigor and relative germination rate had the largest positive contribution rate, which could be used as the key indicators for cold resistance evaluation at germination stage in maize. We classified 36 hybrids into four types of strong cold tolerance (19.4%), cold tolerance (30.6%), medium cold tolerance (33.3%), and cold sensitive (16.7%) by cluster analysis. Among them, Jidan 56, Kenji 267, Suiyu 23, Jidan 953, Kenji 268, Jidan 96, and Jidan 95 were strong cold-tolerant hybrids. The correlation analysis revealed that there was no significant correlation between seed morphology and cold tolerance. Starch content was significantly correlated with relative seedling vigor, relative germination rate, relative seedling vigor chilling injury rate, relative germination chilling injury rate, and relative germination time (r = 0.396**, r = 0.404 **, r = -0.401 **, r = -0.391 **, and r = 0.362 **). There was a significant negative correlation between protein content and relative seedling vigor (r = -0.379**). Regression analysis indicated that the types with high starch content had higher relative seedling vigor, relative germination rate, relative germination time, and lower relative seedling vigor, relative germination rate, and chilling injury rate. The regression model demonstrated that the seed starch content was 72.0%-74.0%, the relative seedling vigor was ≥70.0%, the relative germination rate was ≥80.5%, and the chilling injury rate of relative seedling vigor and relative germination rate was ≤50.0% under 6℃ stress. Under low temperature stress, the higher seed starch content was helpful to improve seed germination and reduce chilling injury. The varieties with starch content of 72.0%-74.0% were recommended to meet the requirements of seed germination in Northeast China.
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