Abstract: Based on the 1961-2004 mean daily air temperature data from 27 weatherstations in East China, the change characteristics and trends of the beginning
and ending dates, duration, and accumulative temperature of daily temperature > 0 ℃ in this area were studied. In the study area, the > 0 ℃ accumulative tempe
rature and its duration were increased by 5.18-9.53 ℃·d·a^-1 and 0.22-0.60 d·a^-1, respectively. The beginning date of > 0 ℃ was advanced 0.22-0.46 d·a¹, and the ending date was postponed 0.01-0.14 d·a^-1 (except for Fujian Province). With a 1 ℃ increment in mean annual temperature, the > 0 ℃ accumulative temperature increased by 285-402 ℃·d, and its duration increased by 7-18 d. The accumulative temperature of the daily temperature > 0 ℃ in all seasons showed an increasing trend, except that in Shandong Province which had a decreasing one in summer. In 2070, the accumulative temperature of daily temperature > ℃ would be 6831.4-8585.6 ℃·d, with an increment of 283.5-1803.8 ℃·d. Except Shandong, the provinces in East China would have a mean daily temperature > 0 ℃ in the whole year. In order to adapt these changes, increasing multiple cropping indices, strengthening monitoring forecast of diseases, insect pests and weeds, and enhancing the application of advanced technologies were recommended.

Key words: Allelochemical, Phenolic acids, Weed-suppressive effect, Orthogonally gyral regression design