Abstract: To obtain the convenient indices for identifying the chilling tolerance of tomato rootstocks and to screen out tomato rootstocks with strong chilling tolerance, we examined the effects of different temperatures (28, 20, 15 ℃) on the seed germination and the changes of seedling’s chilling injury of 40 tomato rootstocks under low temperature stress (10 ℃/3 ℃), and analyzed the correlation between seedling chilling injury index and seed germination indices. There was no significant difference in germination rate, germination index and vigor index among the different rootstock’s seeds at 28 ℃, but the germination related indices at 15 and 20 ℃significantly differed with those at 28 ℃. There were significant differences in the chilling index among the seedlings of different rootstocks under the low temperature of 10 ℃/3 ℃ (day/night). The chilling index of the seedlings was significantly correlated with the germination indexes under the low temperature, with the correlation coefficient at 20 ℃ being higher than that at 15 ℃. The regression model of seedling’s chilling injury index was established by multiple stepwise regression analysis. The relative germination rate and relative germination index at 20 ℃ were selected, and the determination coefficient of the model was 0.984 (P<0.001). According to the results ofclustering analysis, the rootstocks could be divided into cold-tolerant, cold-sensitive, and intermediate types. There were six cold-tolerant materials and five cold-sensitive materials. The clusteranalysis by using the two factors selected by the chilling index regression model found that the classification of 39 out of 40 materials was the same as that from the cluster analysis ofseedling’s chilling injury index, except that one material was classified into the cold-sensitive type rather than into the intermediate type. In all, our results showed that the relative germination rate and relative germination index of the seeds at 20 ℃ could be used as convenient indices for identi fying tomato chilling tolerance at seedling stage.

Key words: straw-C distribution, straw return, straw-C conversion, assimilating straw-C microbes, soil organic carbon