Occurrence of frost temperature in Huanghuai wheat production zone after winter wheat elongation

Data on minimum day air temperature after wheat elongation was collected over a period of 20 years from 37 agro-meteorological observation stations in Huanghuai wheat production zone and the environs. Using the data, cumulative occurrence probability of temperatures lower than 0℃(G_＜0℃)and -1.4℃(G_＜-1.4℃) were statistically analyzed. Results indicate variations in G_＜0℃and G_＜-1.4℃ with time are well described by exponential functions. Variations in area of b value, function characteristic parameter,and approximate termination dates of air temperatures lower than 0℃ and -1.4℃ were also analyzed. Based on the occurrence probability of low temperatures and spatio-temporal variations in wheat elongation time, potential areas of frequent frost occurrence were delineated. Finally, application of b value in frost prevention strategies was discussed.