Abstract: Based on the 1961-2008 daily maximum and minimum temperature data of 110 observational stations in South China, the spatiotemporal change characteristics of annual and seasonal extreme maximum and minimum temperature were studied by using linear regression analysis and Mann-Kendall test. In the recent 48 years in South China, the annual extreme maximum and minimum temperature had an obvious increasing trend, and had an abrupt change in 2003 and 1978, respectively. Asymmetric changes were observed in the annual extreme maximum and minimum temperature. The linear increasing rate of annual extreme minimum temperature (0.48 ℃·10 a^-1) was obviously higher than that of annual extreme maximum temperature (0.20 ℃·10 a^-1). An obvious difference was also found in the changes of extreme maximum and minimum temperature among four seasons. The extreme maximum temperature was upward obviously in spring, but the extreme minimum temperature was upward obviously in summer and winter. There were also obvious regional differences in the changes of extreme temperature. The increasing trend of extreme temperature was most obvious in the Pearl River Delta area, southeast coastal areas of Guangdong, and part of Hainan, while the decreasing trend of extreme maximum temperature was obvious in southwest areas of Guangxi in winter.

Key words: Identification, Biocontrol strain X₃, 16S rDNA, Cucumber, Seedling damping-off