Abstract: 【Objective】This experiment was carried out to understand the viability and physiological variation rule of different genotypes maize seeds under critical stress storage conditions, evaluate its of storability objectivity, provide a theoretical basis for clearing the physiological and biochemical mechanisms of maize seed storability. 【Method】 Major maize hybrids(ZD958, ND108, XY335, ZD619, JK968) were used as experimental materials. Seed initial moisture content, vigor and physiological indicators was measured. The moisture content of experimental materials wet back to 14% and stored at temperature of 35℃, for one year, then the germination energy, germination rate, germination index, vigor index, electrical conductivity, MDA concentration, soluble protein and soluble sugar content and dehydrogenase activity of materials were measured every month. The germination experiment was conducted by using sand culture method, DDS-ⅡA conductivity meter was used to measure the seed electrical conductivity, the TBA was used to measure the MDA content, coomassie brilliant blue G-250 method was used to analyze the soluble sugar content, and dehydrogenase activity was determined by TTC method. The vigor and physiological indicators change of different genotypes maize seeds were compared under the critical stress storage conditions.【Result】Seed genotype was the determinative factor under the same storage condition. The initial moisture content of experimental materials was at a low level, between 7.39% and 8.71%. The germination potential and germination rate of different genotypes maize seed were over 90%, showing a stronger germination ability. After storage for one year, the germination potential and germination rate of JK968 was 50%-60%, germination index was 25%, and vigor index was 0.3. The germination potential and germination rate of ND108, XY335, ZD619 was 15%-25%, germination index was 8%-25%, and vigor index was 0-0.08. The germination potential, germination rate, germination index and vigor index of ZD958 decreased to 0 after storage for one year. Different degrees in decline of germination potential, seed soluble protein content and soluble sugar content changes showed a close relationship with seed vigor. Germination rate, germination index, vigor index were almost the same, however, there was a number of differences in amplitude of variation. Different germination speeds lead to different germination indexes of each genotype of maize seed, seed vigor index declined was always ahead of seed germination ability, which reflected the degree of real seed aging and deterioration. With the storage time extension, the membrane permeability variation of different genotypes of maize seeds, electrical conductivity and MDA content were increased and the change trend was negatively related with seed vigor(R²=0.752). A membrane permeability difference existed among different genotypes of maize seeds. The vigor of different genotypes of maize seed had no significant correlation with the MDA(R²=-0.171-0.094), it significantly positively correlated with soluble protein, soluble sugar and dehydrogenase (R²=0.284- 0.517), but the mechanism of physiological changes of different genotypes of maize seed was complex, the gap was bigger.【Conclusion】 Different genotypes of maize seed were more sensitive to critical stress storage condition, ZD958 was sensitive to critical stress, the vigor and physiological indicator changes of JK968 were stable, showed a higher storability.

Key words: maize, critical stress, vigor, seed physiology, storability