| In this study, the physiological and biochemical characteristics, and some traits of 44 maize inbred lines at germination stage were identified, and the chilling tolerance was also evaluated by the membership function method under indoor low temperature condition. Based on the membership function analysis, we identified three inbred lines with high tolerance including Va35-2, Va102 and ND246, one with medium tolerance, sixteen sensitive, and twenty-two high sensitive at germination stage. We found that germination rate, plumule length, radical length and root number gradually decreased with decrease in temperature (25℃, 15℃, 10℃, 6℃). And there were different degree of decrease among maize inbred lines. From 25℃ to 6℃, the germination indexes of the sensitive lines were nearly 0 under 15℃, while high tolerant lines like K22, B68 and H105W had lower germination indexes. Based on the results of chilling-tolerant evaluation at germination stage, we identified high chilling-tolerant maize inbred lines including Va35-2, Va102, ND246 and chilling sensitive lines like K22, B68, H105W, which were used to perform the analysis of chilling tolerance at seedling stage. After 0, 2, 4, 6 days under 6℃ low temperature stress at seedling stage, there was marked difference in growth indexes and physiological and biochemical indexes between the two kinds maize inbred lines. Compared with three sensitive lines, chilling-tolerant lines had a smaller variation. In general, the growth indexes (plant height, root length, shoot fresh weight, shoot dry weight, root fresh weight and root dry weight) and physiological and biochemical indexes (the relative water content, proline content, soluble sugar content and the enzyme activities of SOD, POD, and CAT decreased as the duration of low temperature stress increased, Compared with chilling sensitive maize inbred lines, chilling-tolerant lines had smaller decrease. In addition, the leaves relative conductivity and MDA content increased, and chilling-tolerant lines were higher than the sensitive lines. Correlation analysis showed that seedling growth and physiological-biochemical indexes were significantly correlated at seedlings stage. |