[Evaluation of cucumber' s chilling tolerance at germination and seedling stages]

A total of 13 cucumber materials were used to study the relationships of cucumber's chilling tolerance with the 12 growth indices at germination and seedling stages. There existed significant differences in the relative germination rate, germination index, hypocotyl length, and vigor index at 17 degrees C among the 13 materials (P < 0.05), which also significantly correlated to the chilling tolerance. At seedling stage, the physiology among the materials after treated at 4 degrees C for 2 days had obvious difference. Chilling injury index had significant correlation with the survival rate after recovery, but less correlation with the soluble protein (SP) content, electric conductivity (EC), and superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX) activities. The chilling tolerance of the materials was classified into three levels by clustering analysis, and the cucumber' s chilling tolerance equations at the two stages were established through stepwise regression analysis. Based on confidence interval value, the chilling tolerance of cucumber could be well assessed.