Studies On Evaluation Of Frost Resistance Of Winter Wheat Varieties And The Correlative Physiological Characteristics

Frost injury of winter wheat that occurs during elongation growth stage has become one of the main factors that restricts wheat production in Huanghuai and Jianghuai regions, the main producing areas of winter wheat in China. Thus, Comparison of frost resistant of different wheat varieties and its physiological characteristics are of significance for high yield. During 2007-2009, the experiments were carried out on the farm of Henan agricultural university using artificial climate chamber. In this study,4 winter wheat varieties differing in vernalization trail, Bainongaikang58, Yumai49-198, Yunong 949 and Yanzhan4110 were used to compare their frost resistant and its physiological mechanism. The main results are as follows:1. Differentiation stage of young ears is an important factor that affects frost resistance of winter wheat. In pot experiments, frost injury was observed in terms of different differentiation stage of spikelet using the microscopes. The results showed that there was a decreasing trend for frost resistance of young ears (FRYE) with young panicle development and a sharp drop was observed at earlier stage of anther connective formation phase (ACFP), which suggested that the sensitive phase to low temperature for young ears started with ACFP. The concave was the most sensitive stage to low temperature of "Bainong aikang58" and "Yumai49-198", while pistil and stamen was the most sensitive stage to cold of "Yunong949" and "Yanzhan4110". With the peroid of low-temperature extended, the degree of frost damage was increased. The response to low temperature treatment for different wheat varieties is different. At -3℃low temperature treatment, the four wheat varieties had not found a dead single stem. At -7℃treatment for 8h and 12h, "Yanzhan4110" appeared the highest freeze to death rates, followed by "Yunong 949", "Yumai49-198", and "Bainongaikang58". Under the same low temperature sensitive stage, the degree of frost resistant for different wheat was measured. The results showed that the frost resistance of "Yumai49-198" was weaker than "Bainongaikang58", and "Yanzhan4110" was weaker than"Yunong 949". Therefore, evaluation of FRYE and selection whet cultivars with frost resistance need to perform in the same development stage, especially in the frost-sensitive stage.2. Effects of freezing treatment on wheat leaf physiological characteristics were measured. Results indicated that the soluble sugar, soluble protein and ascorbic acid content of leaf under low temperature treatment were higher than control. The lowest increasing range of these three parameters was observed in concave for two semi-winter varieties and that of weak-spring wheat was observed in pistil and stamen stage. The results showed that these three physiological parameters were closed related to young panicle development and plant frost resistant.The free proline contents of "Bainong58" and "Yunong949" increased significantly in the low-temperature treatment for 4h and 8h, while the proline content of "Yumai49-198" and "Yanzhan4110" increased significantly than control only in the low temperature treatment for 12h. Under low temperature stress in short peroid, proline content in wheat varieties can be used as reference for frost resistant. Proline accumulation increased markedly under continued long-term low temperature stress, which means that proline can be regarded as the result of low temperature injury.The MDA results showed that the highest MDA content in leaves was observed in the high degree of frost damage to spikelet, which means that the protection was weaker when MDA content in wheat leaves was accumulated greatly. MDA can be used as the identification of wheat frost resistant.In summary, Frost resistance and panicle development process was close related. Therefore, identification and screening frost-resistant varieties should be chosen in the same developmental stages, particularly in low-temperature-sensitive phases. Soluble sugar, soluble protein and ascorbic acid content were closed related to panicle development period and the frost resistance of plants and can be used as physiological parameters for screening wheat cultivars for frost resistant. Meanwhile, in a short period of low temperature stress, proline content in wheat varieties can be used as reference for freezing, but continued long-term low temperature stress proline content can be seen as a result of low temperature injury. MDA can be used as the identification of wheat frost power indicator.