Abstract: Based on daily mean and minimum temperature of 73 meteorological stations in Northeast China during 1961-2005,authors analyzed the annual and seasonal responses of consecutive cold day index (CCDI) to temperature change,and discussed its probable effects on agricultural production in this paper.The results showed that the annual and seasonal mean temperature had a increasing trend in recent 45 years with the largest rise in winter and the smallest rise in summer,in contrast to a small decrease in seasonal mean temperature and slight increase in interannual variability for summer,autumn and winter from 2001 to 2005.Annual CCDI and seasonal CCDI decreased and their interannual variations increased as a whole,characterized by obvious differences among four seasons during 1961-2005,the annual and seasonal CCDIs from 2001 to 2005 were bigger than that from 1991 to 2000.Temperature sensitivity coefficients of the two CCDI indices were positive,which indicated that they decreased with accordingly mean temperature rise.Sensitivities of the annual and seasonal CCDI and correlations between CCDI and mean temperature decreased from early 1960s to middle 1990s,and then increased.Although the annual mean temperature went up and CCDIs tended to decrease during recent 45 years,the occurrence of low temperature damage to crop tended to frequent due to the smallest CCDI change rates,smallest temperature sensitivity coefficient,largest interannual variation in summer and planting of later maturity variety crops blindly,precaution should be taken in application of later maturity variety crops in Northeast China.

Key words: Northeast China, Chilling damage, Consecutive cold day index(CCDI), Temperature sensitivity coefficient