Effects of Low Temperature Treatment on the Physiological Characteristics of Cassava Tissue Culture Seedling Leaves

Cassava accessions SC8 and MS5 were taken as test materials. After with five different time(0, 7, 10, 12,15 d) of treatments at 5 ℃ low temperature stress, the relative conductivity, soluble protein content, soluble sugar content, proline content, MDA content, enzyme activity of SOD and POD were measured. The experimental result reveals that as the extension of stress time, cassava seedling leaves' relative conductivity rate, soluble sugar content and MDA content presented a constantly rising trend, while soluble protein content, proline content,enzyme activity of SOD and POD firstly increased and then decreased finally. Under cold stress, cassava relative conductivity rate was very significantly positively correlated to MDA and soluble sugar content, while very significantly negatively correlated to enzyme activity of SOD and soluble protein content. Soluble protein content was significantly negatively correlated to MDA content and very significantly positively correlated to proline content and enzyme activity of SOD and POD, and SOD activity was very significantly negatively correlated to soluble sugar content and very significantly positively correlated to POD activity. Principal component analysis indicates that SOD activity, soluble protein content, soluble sugar content and the relative conductivity account for the largest amount of information in the first principal components, closely related to cassava cold tolerance, which could be used as physio1 ogical in dices to identify cold resistance of cassava accessions or varieties. MS5 had much stronger cold-resistance than SC8 by using the Comprehensive analysis of biological data. The result provideda reference method for large-scale screening of cold resistant cassava germplasm by using tissue culture tube seedling directly.