Effects of Low Temperature Stress on the Physiological and Biochemical Characteristics of Cold Tolerance in Micro-endosperm Super Sweet and Super High Oil Maize

Abstract

In the germination and seedling stages of the maize, five micro-endosperm super sweet and super high oil maize(abbreviation as ME) hybrid combinations, two control materials Gaoyou 115 and Zhengtian 68 were used to study the changes of physiological and biochemical characteristics, such as germination rate, germination energy, relative conductivity, contents of MDA, proline, soluble sugar, soluble protein, chlorophyll, and SOD, POD activities under low temperature stress. At the same time, the identification of cold tolerance of the materials were conducted. Based on the multiple physiological and biochemical parameters, we employed the fuzzy membership function to evaluate the cold tolerance of the experiment materials comprehensively. The results showed that the relative conductivity had a little increase, but the proline content and SOD activity increased largely in ME1, ME2, ME3, and Gaoyou 115, as compared with ME5, ME4 and Zhengtian 68 in the germination stage. It was advised that relative conductivity, proline content and SOD activity could be used to predict cold tolerance of the materials more effectively in germination stage. In the seedling stage, compared with ME5 and Zhengtian 68, the MDA content increased a little and activities of SOD, POD and proline content increased largely in ME2, ME1, and Gaoyou 115. Therefore, we thought that MDA content, proline content, SOD and POD activities can be used to predict the cold tolerance of the experiment materials in seedling stage. Meanwhile, membership function value showed that the cold tolerance of the five ME materials was stronger than that of Zhengtian 68. Among the five ME materials, ME2 showed a strong ability to tolerate low temperature stress in germination and seedling stages, ME1 and ME3 showed moderate tolerance, and ME4 and ME5 showed weak tolerance.