Abstract: Late spring coldness is an important factor limiting the stable and high yield of wheat in Huang-huai winter wheat region. New wheat varieties with tolerance to late spring coldness is an important strategy to reduce the damage of late spring coldness. It is of great significance to establish a simple, easy to popularize and comprehensive evaluation methods and indices system of wheat tolerance to late spring coldness for ensuring food security. In this paper, the methods and indices for identification of winter wheat tolerance to late spring coldness were summarized, compared and evaluated, and the identification principles and procedures were also put forward. (1) The identification methods of winter wheat tolerance to late spring coldness mainly consisted of direct identification method, indirect identification method and comprehensive identification method. Direct identification methods consisted of field natural identification method, artificial climate chamber method and growth recovery method. The field natural identification method had the characteristics of most widely used in the introduction and cultivation, but it had long cycle and heavy workload. Artificial climate chamber method had the characteristics of short cycle and strong repeatability, but it had high requirements for equipment and technology. The growth recovery method was widely used in the identification of freezing injury before winter, but it was less used in the identification of tolerance to late spring coldness. The indirect identification method was helpful to study the temperature threshold of late spring coldness, but the relationship between the indices and cold resistance had not been clear, so its application was limited. The comprehensive identification method had the characteristics of comprehensive and accurate appraisal results, but it had high requirements for technology, cost and workload. Therefore, in the identification process, it was necessary to combine the actual situation, reasonable collocation and comprehensive use of a variety of methods. (2) The identification indices mainly consisted of morphological and agronomic, physiological and biochemical, meteorological and ecological indices. Morphological and agronomic indices were generally used in field natural identification, and the quantity, quality, color and morphological changes were often used as reference items. Physiological and biochemical indices were generally used for indirect identification, including reactive oxygen species, osmotic adjustment substances, endogenous hormone content, antioxidant enzyme activity, photosynthetic and respiratory characteristics, etc. Meteorological and ecological indices were often used in various identification methods. Air temperature, ground temperature, canopy temperature, half lethal temperature and minimum temperature of restoration growth were often used as identification indices, while factors such as light, CO2, humidity and fertility could affect the accuracy of results. (3) Appraisal principles and procedures. This paper put forward the identification principles, such as the regionality of identification results, the pertinence of indices selection, the comprehensiveness and practicability of identification methods and indices, etc. The identification procedures were mainly composed of disaster prone period, variety sensitive period, sensitive organs, identification methods and indices, low temperature degree, field or pot experiment, evaluation and classification of cold resistance by mathematical analysis method and writing report. Finally, the prospects of cold resistance physiology research, identification research and application of emerging technologies and identification product development were made.

Key words: Winter wheat, Late spring coldness, Identification, Index, Method