Relationship Between the First and Last Frost Dates and the Jointing Stage of Winter Wheat in Shangqiu,Henan Province

Zhang Yanling; Shi Guifen; He Fuwei; Zhang Hui; Zhang Yunxia

doi:10.16765/j.cnki.1673-7148.2024.03.007

Abstract：Based on the daily minimum surface temperature in Shangqiu City of Henan Province from 1961 to 2020 and the observation of winter wheat in the growth periods in 1978-2020,in this re-search statistical analysis and the M-K inspection methods are used to analyze the change characteristics of the first frost and last frost dates in Shangqiu as well as their relationship with air temperature and the growth period of winter wheat.The results indicate that the average first frost date shows a significantly delaying trend at the rate of 2.4 d/decade,and the average final frost date has a significantly advancing trend of 2.1 d/decade.The first frost date and the last frost date experiences mutations in 2013 and in 1996,respectively.The average first frost date is later in the southeast of Shangqiu but earlier in the northwest and central part,while the average final frost date is earlier in the southeast of Shangqiu but later in the northwest and central part.The average first frost date is positively correlated to the mean temperature from September to November,delayed by 7.4 d with the increase of 1 ℃ of the mean tem-perature in this period.However,the average last frost date is negatively correlated to the mean tempera-ture from February to April,4.1 d earlier for every 1 ℃ rise in the mean temperature.In addition,there is a significant positive correlation between the last frost date and the jointing date of winter wheat.The last frost date appears after the jointing date of winter wheat in 72.1％of the years,and in 0-15 days af-ter the wheat jointing in 55.8％of the years.