| Using Mexican Hat Wavelet,wheat climate yields and climatic factors in the middle arid region and in the south mountain region of Ningxia were analyzed.The wave periods of wheat climate yields and climatic factors were separated and picked up.Correlation of wheat climate yields with climatic factors was also analyzed.The results showed that,from 1954 to 2002,yield of wheat was increased with fluctuation in the middle arid region.There was a positive correlation between the climate yield and precipitation in May.Wheat climate yield had wave periods of about 4-year,about 8-year and about 16-year.The wave period of about 8-year was the most notable.Precipitation in May had 4 wave periods of about 4-year,about 8-year,about 16-year and about 32-year.Wave periods of about 8-year, about 16-year and about 32-year were more notable.The wheat climate yield had the same phase with precipitation in May in the 8-year period clearly.From 1957 to 2002,yield of wheat was increased with fluctuation in the south mountain region.There was a positive correlation between the climate yield and precipitation and a negative correlation between the climate yield and mean temperature in May.Wheat climate yield had wave periods of about 4-year and about 8-year.And the wave period of about 4-year was the most notable.Precipitation in May had 4 wave periods of about 4-year,about 8-year,about 16-year and about 32-year.The wave periods of about 8-year,about 16-year and about 32-year were more notable.Mean temperature in May had 2 wave periods of about 8-year and about 16-year.The wave period of about 16-year was the best notable.The wheat climate yield had the same phase with precipitation in May in 8-year period and 16-year period clearly,and had the adverse phase with mean temperature in May in 8-year period.The influence of climate change on wheat yield in the middle arid region and in the mountain region of Ningxia was obvious.Studying measures of answering climate change and scientifically adjusting planting structure of crops is one of the scientific problems to be urgently solved now and in the future. |