Abstract: Based on meteorological data and maize yield data of 36 meteorological stations, and maize growth and development period data of different varieties of 10 agro meteorological stations in Inner Mongolia from 1981 to 2010, the heat requirement of the 5 varieties of maize in normal years was analyzed, and the average dates of the growth and development period of different varieties and the limitation of active accumulated temperature was determined. By using the expressions of relative active accumulated temperature distance (TXJ), the TXJ of the different developmental period of the 30 years on stations was calculated, and the TXJ index of the slight and serious degree chilling damage was determined, based on the relationship between the negative distance and yield reduction rate.The analysis results of 24 typical years and 36 stations in 30 years showed that the highest agreement between chilling damage years and yield reduction was in spinning milky stage (69%), followed by milky maturity stage (67.1%). Late maturing varieties were higher than early maturing varieties and serious chilling damage years (76.6%) were higher than slight chilling damage years (57.2%). In typical years, the average accuracy of the judgment was 95.8%, which could increase to 100% after the spinning stage. Spinning milky was the most sensitive period to the chilling damage. The index could reflect the cumulative effects of low temperature and compensation benefit of high temperature in different growth stages during the whole growth season, and could be applied in chilling damage monitoring service in Inner Mongolia.

Key words: Difference of relative active accumulated temperature, Chilling damage, Index, Maize